Bending Bridges Project

BENDING BRIDGES Double Layered Lightweight Load Bearing Structures Strip Strategies Studio FEB/NOV 2018

BENDING BRIDGES Double Layered Lightweight Load Bearing Structures

BENDING BRIDGES

Double Layered Lightweight Load Bearing Structures CEDIM School of Architecture FEB-DEC 2018 Academic Director: David Durán Professor: Djordje Stanojevic Advisor Foundation: Jorge Alberto Jiménez Structure Consultant: Kenryo Takahashi Students: Linda G. Carmona, Grecia C. Cortes, Ivan A. Durán, Mónica V. García, José L. García, A. Karen Garza, Isaac E. Garza, Patricia Gutiérrez, Denise Llano, Frania Y. Logan, Sergio Martinez, Carlos A. Muñoz, Alberto Ortega, J. Adrián Reyna, Ma. Fernanda Ruíz, Jesús E. Villalobos With the support of: Gabriela García, I. Fabrizio Hernandez, Christian Ortiz, Regina Zermeño Sponsors: STM Robotics Ezequiel Cadena Bernal Madera Aceros FERCOM Rar S.A. de C.V Herramientas, Birlos y Tornillos Pinturas Osel Coragui Rental S.A. de C.V Montajes y Estructuras Delta Andamios Monterrey Edited By: Linda Carmona Reyes

Centro de Estudios Superiores de Diseño de Monterrey

INDEX 1. Research

09 10

1.1 Types of Bridges

1.1.1 Main Components of a Bridge

1.1.2 Types of Bridges

1.1.3 Moveable Bridges

1.1.4 Shell Bridges

1.1.5 Musmeci Bridge

1.1.6 Bamboo as a Construction Material

1.1.7 Bamboo Joinings

1.1.8 Bamboo Bending 22

1.2 Bridge Foundation

1.2.1 Two Types of Foundation

1.2.2 Ground Foundations 1.2.3 Abutments

1.2.4 Ground Anchoring

1.2.5 Water Foundations

1.2.6 Structural Details 29

1.3 Boat Construction

1.3.1 Plank on Frame

1.3.2 Carvel Planking

1.3.3 Lapstrake and Clinker Planking

1.3.4 Double Planking

1.3.5 Sheet Plywood Planking

1.3.6 Strip Planking

1.3.7 Construction Steps

1.3.8 Final Layers

1.3.9 Strip Specifications

1.3.10 Strips Fitting

1.3.11 Wood Environment 45

1.4 Double Layered Shells 1.4.1 Duck-work

1.4.2 The Annen Project 1.4.3 Bend9

1.4.4 The ICD Robot-Made: Large Scale Robotic Timber Fabrication

1.4.5 Vidy Theater

1.4.6 ICD | ITKE Research Pavilion 2015-2016

1.4.7 ICD Robot-Made Double-layered Elastic Bending 2015-2016

1.4.8 Free Form Catalan Thin-tile Vault

1.4.9 ICD | ITKE Research Pavilion 2013-2014

1.4.10 A Bridge Too Far 58

1.5 Wood Steaming 1.5.1 Summary

1.5.2 Three Key Elements for Wood Steaming

1.5.3 Examples in Architecture

1.5.4 Uses and Benefits of Steamed Wood

1.5.5 Examples of Different Bends

1.5.6 Diffrerent Types of Bending 1.5.7 Steambox

1.5.8 Parts of a Steaming Box

1.5.9 Wood Bending Stock

1.5.10 Steam Producers and Connections

1.5.11 Steambox Size

1.5.12 Pressure Holes and Steam Hose

1.5.13 Steambox Rods Materials

1.5.14 Wood Bending Without a Steambox

1.5.15 Heating Methods

1.5.16 Conservation of Heat (Insulation)

1.5.17 Temperatures and Steaming Time

1.5.18 Measuring Humidity Inside The Box

1.5.19 Measuring Water Levels in The Steamer

1.5.20 Shaping The Wood

1.5.21 Drying and Setting The Wood 1.5.22 Conclusions

2. The Project

75 76

2.1 Context 2.1.1 Bridges

2.1.2 Wood Bending

2.1.3 Double Layer

2.2 State of Art 78

2.2.1 Summary of Chapter 1.Research 80

2.3 Aim 82

2.4 Methods

2.4.1 Steaming Box System

2.4.2 Steaming Box Relative Humidity

2.4.3 Steaming Box Maintenance

2.4.4 Material Tests 2.4.5 CNC 98

2.5 Design Development

2.5.1 Scaled Models

2.5.2 Design Concept

2.5.3 Structure Design

2.5.4 Design Criteria 2.5.5 Nesting

2.5.6 Strip Length and Curvature

2.5.7 Scaffolds for Bridge Construction

2.5.8 Foundation Design

2.5.9 The Code

2.5.10 Team and Financial Organization

2.6 Construction 112

2.6.1 Concrete Foundation Pouring

2.6.2 Foundation Construction

2.6.3 Strip Assembly 2.6.4 Varnishing 2.6.5 Errors

2.6.6 Drone Documentation 123

2.7 Realized Project 128

2.8 Sponsors 130

2.9 References

2.9.1 Image References

2.9.2 Text References

Edited By: Linda Graciela Carmona Reyes

CHAPTER 01

RESEARCH

BENDING BRIDGES

1.1 Types of Bridges Introduction

The first bridges were believed to be made by nature and were as simple as a log that had fallen across a stream.

On ancient times humans needed to pass over obstacles such as valleys, rough terrain, rivers, etc. For these purposes they took natural resources like wooden logs and stone and started building. Without knowing it they were leaving a mark on history.

Bridges are structures built to overcome physical obstacles without closing the way underneath such as a body of water, valley or a road for the purpose of providing passage over the obstacle. Over time the use of different materials like wood, concrete, steel, bricks and others were popularized and used all over the world.

Bridge History has continuously been filled with incredible achievements and new technologies that have made the bridges become one of the most important tools for bringing cities together and connecting humanity. During the Roman Empire 10

bridge building techniques were revolutionized with the invention of the arch. The ancient civilizations built bridges and aqueducts which carried water and goods from all parts of Europe to Italy.

Before the colonization of america, the Incas developed the first cable bridges suspended by a simple cable structure in the Andes Mountains in Center and South America. Entering the 18th century, Iron enabled the creation of new bridge designs such as truss systems but unfortunately iron did not have enough tensile strength to support heavy structures. This problem was solved with the invention of steel.

Types of Bridges

IMAGE 01. Keshwa Chaca bridge, Huinchiri, Peru (1518).

IMAGE 02 Alcantara Bridge in Caceres, Spain, was built on 5th or 6th century by Roman Empire.

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BENDING BRIDGES

IMAGE 03. Girders / Beams.

1.1.1 Main Components of a Bridge

Super Structure of Bridges All components of bridges which are placed on the supporting system are defined as super structure. This part mainly supports traffic and comprises of girders, slabs, deck, etc.

Girders/Beams Is basically designed for bending and used in bridge engineering.

It can bear live load along the span. Defined as a load bearing member which sustains the deck.

Bearing Is a structural part used to relocate loads from girders to piers during the allowance of the specific movements. The movements can be angular or linear.

Sub-Structure Is the part which is very supportive to super structure of bridge.

It forms piers, abutments and foundations. Typically pile foundations are used in bridges.

Piers From bearing to the end of the span of the pier part of the substructure that supports the superstructure and also relocates load from super structure to piles.

Prestressed concrete is the main component of piers. It is generally of circular or rectangular in shape.

Foundations Due to the nature and magnitude of loads typically piles are widely used for bridges. To build up piles concrete is mostly used and they also can be driven in situ.

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IMAGE 04. Concrete water foudnation

Types of Bridges

IMAGE 05. Building Process of a Water Bridge Foundation

IMAGE 06. Bearing section of the bridge.

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BENDING BRIDGES

1.1.2 Types of Bridges

Stationary Bridges There are many types and classifications of bridges, depending on their structure, their use, and their kinetics.

The most used types of bridges structures, are the beam bridge, the arch bridge, and the suspension bridge.

Beam Bridges Is the simplest and oldest bridge type and appeared as an imitation of nature. Prehistoric humans saw a tree that had fallen across a stream and used the same technique nut in places where it was convenient for them.

Made by a horizontal beam that is supported by vertical piers and uses strong yet flexible materials.

The weight of the beam pushes straight down on the piers.

Under load, the beam’s top surface is pushed down or compressed while the bottom edge is stretched or placed under tension.

Arch Bridge The arch bridge, used since the pre-roman era, have great natural strength. Uses an arch to transfer the weight to its sides that are called abutments. Instead of pushing straight down, the load of an arch bridge is carried outward along the curve of the arch to the abutments at each end. The weight is transferred to the supports at either end. Originally built of stone or brick but these days are built of reinforced concrete or steel.

IMAGE 07. Bridge Crossing Indian River in Vero Beach, Florida, USA.

IMAGE 08. Hunan Province, China.

These three structures have been known and built since ancient times and are the origins from which engineers and builders derived various combinations such as cantilever, truss, tied arch, cable-stayed, bending bridges.

Cantilever Bridge Normally use pairs of cantilevers back to back with a short beam bridge in between the cantilever. It’s supported by two horizontal structures that support a third one carrying the weight, the anchorages in this bridge are located in one side of the structure but not the other.

Truss Bridge The main element is a truss which is a structure of connected elements that form triangular units. The rigid structure of a truss transfers the load from a single point to a much wider area. Truss bridge can have deck on top, in the middle, or at the bottom of the truss.

Cable-Stayed Bridge Similar to suspended bridge, in that it has towers and a deck that is held by cables, but its cables hold the deck by connecting it directly to the towers instead via suspender cables.

Uses deck cables that are connected directly to one or more vertical columns and uses a harp or fan design. It is used in places where spans need to be longer than cantilever bridges can achieve.

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IMAGE 09. Brooklyn Bridge, New York, USA.

IMAGE 10. Forth Bridge, East of Scotland.

Types of Bridges

Tied Arch Bridge Can be considered as a bridge between arch bridge and a suspension bridge. Has an arch rib on each side of the deck, and one tie beam on each arches, that support the deck, which tries to flatten the arch and to push its tips outward into the abutments.

Differs from the arch bridge because it transfers the weight to the top chord that is connected to the bottom chords in the bridge foundation. This types of bridges does not depend on horizontal compression forces for its integrity which allows them to be built off-site and then transported into place.

IMAGE 11. Ikitzuki Bridge, Hirado Island, Japan.

IMAGE 12. Chaotianmen Bridge. Chongqing, China.

IMAGE 13. Lowry Avenue Bridge, Minneapolis, USA.

IMAGE 14. Arched Bridge, Kaunas (Lithuania).

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BENDING BRIDGES

IMAGE 15. London Tower, United Kingdom.

IMAGE 16. Rolling Bridge. London, United Kingdom.

IMAGE 17. Three-Segment Folding Bridge Kieler Hörn. Kiel, Germany..

IMAGE 18. Pont Jacques Chaban-Delmas. Bordeaux, France.

1.1.3 Moveable Bridges

Bascule Bridge Can have one or both spans which have counterweights that balance them and make lifting easier. Rolling Bascule Bridge has no counterweights but it is lifted by the rolling of a large gear segment along a horizontal rack.

Folding Bridge Has more sections that are connected to each other by hinges and collapse together horizontally.

Curling Bridge Has many segments and when it is lifted it curls into a cylinder.

There is, for now, only one such bridge: “The Rolling Bridge” at Grand Union Canal office & retail development project at Paddington Basin, London. It has hydraulics in the posts of a handrail which lift and curl the bridge.

Vertical-lift Bridge Has a span that rises vertically while remaining parallel with the deck and allows river traffic to pass below. It uses 16

counterweights or hydraulics which are placed in towers on both end of the span to lift the span.

Submersible Bridge Does what it says on the tin – it is submerged into water to clear way for boats. It allows high boats to pass but it limits their draft.

Tilt Bridge Is a bridge that rotates around hinges at its ends and is lifted at the angle.

Swing Bridge Has a deck that rotates horizontally around a fixed point (at center or at one of the ends if they are smaller) and is placed parallel with the river when it is open.

Transporter Bridge (other names are “ferry bridge” or “aerial transfer bridge”) have a construction that carries a segment of roadway across a river. There are no more than twelve bridges of this type in operation today.

Types of Bridges

IMAGE 19. Isthmia Submersible Bridge. Corinth, Greece.

IMAGE 20. Gateshead Millennium Bridge. Gateshead-New Castle, United Kingdom.

1.1.4 Shell Bridges

This type of bridges are made by a shell structure which is characterized by its geometry.

A shell is a thin, curved plate structure shaped to transmit applied forces by compressive, tensile, and shear stresses that act in the plane of the surface. This kind of bridges are usually made of concrete or steel structure. The shell structure is made not for peatonal crossing, but for reinforcing the path that cross along the bridge.

The best example is The Basento Viaduct, a bridge built in 1969 in Potenza (Italy). It is made of only one membrane of reinforced concrete (about 30 cm (1 ft) thick) molded to form four contiguous arches. The concrete sheet is shaped into a “finger-like� structure, which supports the whole bridge, and it is also used as a pedestrian walkway. The bridge was built without using prefabricated elements, but only shuttering of concrete. Is a continuous surface minimized in its area while maximizing its structural function. Sergio Musmeci managed to create a magnificent concrete surface whose aesthetics directly derived from its efficiency studied using analog models and form-finding techniques.

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BENDING BRIDGES

IMAGE 21. The basento Viaduct bridge by Sergio Musmeci, Italy. 1972.

IMAGE 22. The basento Viaduct bridge by Sergio Musmeci, Italy. 1972.

IMAGE 23. The basento Viaduct bridge by Sergio Musmeci, Italy. 1972.

IMAGE 24. The basento Viaduct bridge by Sergio Musmeci, Italy. 1972.

1.1.5 Musmeci Bridge

The “Viadotto dell’Industria” or Musmeci Bridge, connects Potenza city centre exit on the Sicignano-Potenza motorway with the main access roads in the southern part of the italian city.

It was designed by the Italian engineer Sergio Musmeci in 1967; built between 1971 and 1976 and with a cost of about 920.000.000 Italian liras it was built without using prefabricated elemets by only using shuttering of concrete. The structure is considered very unique due to it’s construction consisting of a thick 30cm membrane of concrete that was molded to form four contiguous arches in a finger-like manner that works as the support of the entire bridge and also a pedestrian passage.

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Types of Bridges

IMAGE 25. Guadua Bridge, bamboo bridge in Colombia, by Arnulf Brinceño.

IMAGE 28. Guadua Bridge, bamboo bridge in Colombia.

IMAGE 27. Guadua Bridge, bamboo bridge in Colombia, by Arnulf Brinceño.

IMAGE 28. Guadua Bridge, bamboo bridge in Colombia.

1.1.6 Bamboo as a construction material

Started with bamboo catamarans more than 60,000 years ago, 1250 bamboo species around the world, most commonly found on civilizations around the tropical area of the Ecuador as it is Ecuador, Peru, Camboia, Indonesia, Colombia, among a few others.

This bridges are contructed by joining bamboo trunks making different types structures like truss, arch or tide-arch.

One of the best examples of this kind of bridges is one made by Leonardo Da Vinci who created a system of intertwining the trunks of bamboo.

Bamboo can be bent when it’s a freshly cut one by using heating techniques, but, once a bamboo pole is dry you will not be able to bend it anymore unless heating with a butane torch under tension and with a lower curvature than the one you can do with freshly cut bamboo.

The most common method to bend bamboo poles is by heating the poles with a torch while applying tension to maintain the new shape. It is really important to use techniques to prevent the bamboo from breaking, these are drilling small holes in the nodes of the pole so the heat that’s building inside it can escape

from them and not cause more tension, moving the torch from the thickest end to the narrower end, and filling the pole with sand so it won’t break that easily.

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BENDING BRIDGES

IMAGE 29. Connection Technique.

IMAGE 30. Connection Technique.

IMAGE 31. Connection Technique.

IMAGE 32. Right way to join.

1.1.7 Bamboo Joinings

Bamboo is a truly sustainable unrivalled timber, with the compressive strength of concrete and the tensile strength of steel. It’s lightweight, hollow, round, curving, and tapering. It’s also flexible, making it ideal for earthquakes, as it will bend and flex long before it breaks. There are more than a thousand species of Bamboo in the world.

The treatment is the key to construct, without it, bamboo cannot be considered a permanent building material.

There are some parameters that follows the use of bamboo in constructions. Some are the next ones. Do not use green, fresh cut bamboo, bamboo has to be completely dry before using it in construction (preferable air dried).

Only use mature bamboo of 4-6 years. Do not use conventional wood nails in bamboo joinery, they will cause the bamboo to split. Instead use nylon, steel or vegetal cord of the appropriate diameter.

When using bamboo as a column make sure that the lower part connecting with the surface ends with a node. If not the bamboo 20

will splinter when struck (for example to position the column).

The most common cuts to use when making bamboo joints are one ear, two ear, beveled, flute mouth, fish mouth.

Making basic cuts in bamboo doesn’t require expensive or heavy power tools, just a few traditional hand tools will work fine.

Making good and aesthetically pleasing bamboo joints is rather complicated because bamboo is hollow, tapered, has nodes at varying distances, and is not perfectly circular. It is important to keep all these constraints in mind when designing a bamboo joint.

Types of Bridges

IMAGE 33. Bamboo Bending Technique.

IMAGE 34. Bamboo Bending Technique.

1.1.8 Bamboo Bending

This type of bridge is known for being constructed by joining and bending simple bamboo trunks making arch, tide-arch, supensions, and truss structures.

One of the best examples of this types of bridges is one made by Leonardo Da Vinci who created a system of intertwining the trunks of bamboo.

Bamboo can be bent when it’s freshly cut by using heating techniques, but, once a bamboo pole is dry you will not be able to bend it anymore unless it’s heated with a butane torch under tension and with a lower curvature than the one you can do with freshly cut bamboo.

The most common method to bend bamboo poles is by heating the poles with a torch while applying tension to maintain the new shape. It is really important to use techniques to prevent the bamboo from breaking, these are drilling small holes in the nodes of the pole so the heat that’s building inside it can escape from them and not cause more tension, moving the torch from the thickest end to the narrower end, and filling the pole with sand so it won’t break that easily.

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BENDING BRIDGES

1.2 Bridge Foundation The base and support for load-bearing structures

The foundation of a bridge is particularly critical because it is what will support the entire weight loads that said structure will carry. Many aspects are to be taken into consideration when planning a bridge foundation such as location, type of foundation that will be used and size of the project given the fact that it will provide stability, making the building process possible and the bridge durable during its whole service life.

The construction of a good foundation for the bridges is fundamental at the time that the structure offers a good behavior during its life, providing security to its users . There are two types of foundations: superficial and deep.

To start the foundation, it is necessary to carry out the clearing and cleaning of the land, carrying out a rethinking of the elements that will form the foundation. Once these tasks are completed, an excavation will be carried out, in which different criteria will be taken into account, such as the characteristics of the terrain, the stability of the excavations, or the rainwater that can alter the resistant capacity of the soil.

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In some cases it may also be necessary to improve the terrain.

Injections called jet-grouting are one of the most common methods of improvement. Â Afterwards, a cleaning concreting should be carried out, about 10 centimeters thick, since this way the following operations can be carried out on a level and clean area. Once the foundation is completed it is necessary to fill the part of the excavation not occupied by the structural elements and, for reasons of durability, it is advisable to cover the top face of the foundation with at least 0.5 meters of the material used to the stuffing

Bridge Foundation

1.2.1 Two Types of Foundation

We have to distinguish between two types of foundations: the superficial and the deep. The first, superficial, are made using footings and foundation slabs, while the latter can be by piles or screens.

IMAGE 35. Excavation for foundation.

IMAGE 36. Shallow and deep foundations difference.

Surface Foundations When the cleaning concreting has been carried out, the rebar will start to be available, which can be done in situ, or already prepared, using spacers so that the reinforcements are not in contact with the formwork. The next step consists of placing the lateral formworks in such a way that they do not move, so that concreting can be carried out without problems. Before concreting it is necessary to check that the formwork is clean and that the armatures arranged are those indicated by the project.

Deep Foundations The deep foundations are carried out by means of piles. These can be of two types: driven or drilled / excavated in situ. The driven piles can be placed by hammering with a hammer or by vibration. These can be prefabricated and of different materials (concrete, wood or steel). Piles drilled or excavated in situ can be of three types: concreted piles with recoverable metal sleeves, piles excavated without casing and drilled piles. There must be objective data for the acceptance of the piloting, for example: sonic tests, parts of jacking or measurement of lengths embedded in rock.

In the case of deep foundations, screens could also be used.

For the execution of these is necessary the realization of some guiding walls, which have to be placed at the ends where the screen will be placed, then the rebar will be placed and it will be concreted.

The screens can have different thicknesses, ranging between 0.45 and 1.20 meters. Both in the piles and in the screens it is necessary to carry out a headless in order to eliminate the bad quality concrete from the upper part and to discover the reinforcements that should be anchored in the pile cap.

IMAGE 37. Deep Foundations Example.

The micropiles could also be another solution in the case of deep foundations, with holes in the ground, which will be placed a metal element and then be injected in order that these metal elements are in contact with the ground .

IMAGE 38. Perforation and piles completed.

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BENDING BRIDGES

1.2.2 Ground Foundations

Strip Foundation As we can see here strip footing or spread footing is a type of shallow foundation.

Strip footing (wall footing) is a relatively small strip of concrete placed into a trench and reinforced with steel. This type footing is commonly used for the foundations of load bearing walls or supports a slab.

When it is necessary to stiffen the strip to resist differential settlements then tee or inverted tee strip footings can be adopted The overall size of strip footings is determined by considering the effects of vertical and rotational loads.

The combination of these two must neither exceed the safe bearing capacity of the stratum or produce uplift.

The thickness of the footings is generally about 0.8 to 1.0 m but must be capable of withstanding moments and shears produced by piers or abutments.

The critical shearing stress may be assumed to occur on a plane at a distance equal to the effective depth of the base from the face of the column.

Piling A pile is a long, narrow post that is hoisted into the air by a crane in order to de bยกdriven into the ground with the use of a large hammer called a piledriver. Once this pile reaches the required depth, it`s capped off and tied.

Although it is common the use of prefabricated piles made out of concrete it is possible for piles to be made out of a variety of materials such as: steel and even wood.

IMAGE 39. Strip Footing.

IMAGE 40. Soloreperum eratur solendam reius volupta cusame.

IMAGE 41. Strip footing diagram.

IMAGE 42. Cast in a pile.

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Bridge Foundation

IMAGE 43. Abutments Components.

1.2.3 Abutments

Abutments are used at the ends of bridges with the goal of preventing the excessive lateral movements the bridge may have and to carry the vertical and horizontal loads from the superstructure to the foundation. They are subjected to both horizontal and vertical loads from the structure. The number and spacing of the girders determine the number and location of the concentrated reactions that are resisted by it. There can be used different types of abutments, the following are the existing types of abutments: Full Retaining This abutment is built in the bottom of the embankment and it must retain all of it. Usually rigid-frame structures use a full-retaining abutment poured in a uniform way with the superstructure. This is the most expensive out of the other types of abutments.

Semi-Retaining This abutment provides more horizontal clearance and sight distance than a full-retaining abutment. Semi-retaining abutments are generally designed with a fixed base, allowing wing walls to be rigidly attached to the abutment body.

IMAGE 44. Primary Functions of an Abutment.

Spill-Through or Open A spill-through or open abutment is mostly used where an additional span of the bridge may be constructed in the future.

This abutment type is situated on columns that extend upward from the natural ground. Erosion and early settlement are problems that are frequently encountered when using this abutment.

Pile-encase This are usually used when the cost turns out to be more economical than sill abutments due to site conditions. This abutments may require additional erosion control measures that increase construction cost. The wall height of pileencased abutments is limited to a maximum of 10 feet since increased wall height will increase soil pressure, resulting in uneconomical pile design due to size or spacing requirements.

Most abutments are supported on piles, drilled shafts and spread footings are the general types of abutment supports used to prevent the settlement of the abutment.

Sill The sill abutment helps to eliminate the difficulties of obtaining adequate compaction adjacent to the relatively high walls of closed abutments. Since the approach embankment may settle by forcing up or bulging up the slope in front of the abutment body. To prevent this bulging from happening a berm is often constructed at the front of the body whose weight helps prevent the bulging. It is also the least expensive abutment if compared to the others.

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BENDING BRIDGES

IMAGE 45. Types of Anchors.

IMAGE 46. Soil Nails.

IMAGE 47. Types of Anchors for in-situ cast.

IMAGE 48. Post stressed tendons.

1.2.4 Ground Anchoring

Ground anchoring a Bridge is the most important task because without this the bridge would most likely collapse. There are two main types of ground anchoring.

Post stressed tendons This consists of using high-strength steel strands; also known as tendons; to reinforce concrete or other materials which after correct curing the tendons are tensioned by jacks on the sides and grouts are filled.

Soil nails This are soil mass retaining devices that are in charge of transmitting the applied tensile load along its axis into either the soil behind the structure or into the underlying soil layers. Soil nails are normally prestressed but they can also de unstressed or lightly tensioned and are usually grouted.

Depending on the goal of the project and its design both type of anchors can be used for temporary or permanent work although post stressed anchors are made to resist high forces imposed by 26

retained soils and even water pressures.

Anchors must be supervised by a specialist and must make sure that they are assembled the right way and protected.

Bridge Foundation

IMAGE 49. Underwater Foundations.

IMAGE 50. Battered Piles Foundations.

IMAGE 51. Sheet Piles Example.

IMAGE 52. Cofferdam Example.

1.2.5 Water Foundations When planning an underwater foundation there have to be precautions to ensure the security and stability of the bridge; one clear example of this is protecting the piles against corrosion so that the durability of the foundation and the bridge is extended. In this text, some examples of underwater foundation construction will be explained.

Battered Piles A relatively simple method for underwater piling is Battered piles; it’s typically used for smaller bridges in shallow water. In this method several beams are used instead of just one; made according to the water depth these piles look like a twisted fork. Dropped into the water from a barge and driven into soft mud, the “tines” spread the weight in several directions for the greatest amount of support.

Sheet Piles Sheet piling Size and Grade must be checked. It is Often Driven Using a Temporary Guide Structure, all sheet piles must be plumb and a Vibratory Hammer is often used to complete the task.

Each sheet piling section is driven about 3 feet at a time and all are driven progressively around the cofferdam until the required depth is reached.

Vent Holes are required to do the process. Vent holes must be cut at high water elevation for they will allow water to enter de cofferdam and prevent any failures. Adequate bracing is required for the completion of the cofferdam.

Cofferdam The cofferdam is a water-tight enclosure usually in a circular or rectangular shape that makes the construction of a bridge foundation in the dry possible. Typically used in or near water, the cofferdam consists of several thin, sheet-like piles are fitted together to create a watertight chamber which is later driven to the soil where the water is pumped out. Once free of water; the towers are built by workers in the dry cofferdam. Despite being a risky method for the workers, it is an effective one. In the case of the impossibility to drive the sheet piling to sufficient depth a seal will be used along with a different process to cut off the water flow.

Construction Steps with Seal: Drive Sheet Piles, Cut Vent Holes, Install Bracing, Excavate, Drive Foundation Piles, Placing Concrete Seal Construction Steps with Seal Cont’d: De-water, Construct Footing and Column in The Dry, Flood Cofferdam, Remove Cofferdam, Place Riprap

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BENDING BRIDGES

IMAGE 53. The Kruununmylly Bridge in Finland.

IMAGE 54. Joints in Kruununmylly bridge.

IMAGE 55. Diagram of Connections.

IMAGE 56. Typical connection in a truss.

1.2.6 Structural Details

Wood-Concrete Compound Bridge When it comes to building a bridge that’s lightweight and strong the use of wood and concrete is a very viable option because it can improve the load bearing and distribution capacity, and therefore leads to ecological and sustainable constructions.

Compound constructions use each material according to their capabilities. In this case concrete works great under compression loads whereas wood works efficiently under tension forces just like steel does. With this being said if you add a concrete slab to a wooden bridge you are improving its ability to transfer concentrated loads and its stiffness.

This technology has been used in the past mainly on some Nordic countries and some other parts of Europe; A couple of examples of this are:The Kruununmylly Bridge in Finland, The Vihantasalmi Bridge in Finland, Sanne Bridge in France.

Connectors and Joints The correct conception of the connections in a bridge is essential both to ensure sufficient load-bearing capacity and to ensure adequate durability.

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Nails, bolts, dowels and screws are connectors typically used in most joints for timber structures. In the design, in addition to the ultimate resistance, stiffness of the connections is an important issue. A low stiffness of the connections, for example, could result in excessive deformation of the bridge and, in the case of compressed elements, even in a possible reduction of the bearing capacity due to second-order effects. In the case of road bridges the strength of the connection to cyclic loading (possible fatigue failure of the steel parts) need also to be checked.

When it comes to transmission of high forces between elements, the connections that are commonly used are: -Connections with bonded-in rods, typically used for the transmission of axial forces -Connections with inclined screws, typically used for the transmission of shear forces -Connections with slotted-in plates and dowels, typically used for the transmission of both shear and axial forces.

The connections with slotted-in plates and dowels are particularly used in structures subjected to very large forces, for example in truss nodes.These connections also have satisfactory fatigue resistance.

Boat Construction

1.3 Boat Construction Materials and techniques used for boat construction

Centuries ago boats were used by ancient civilizations to travel and transport godos from one place to another. The techniques they used back in the day are still used in modern day but thanks to technology we were able to perfect this technique and we were able to enhance the life of the boats itself. Depending on the techinque you’ll be implementing in the build, the type of wood you are going to use you might get an idea of how well the boat is going to turn out and how durable it’ll be.

With time your boat may start to decay due to the external forces it’s exposed to, but if you apply a specific number of coatings of different varnishes and protective coats your boat will become resistant to said forces. Although the protective coatings won’t last forever it’ll extend the life of your boat for quite some time.

In the following research we explain the techniques used for the construction of a boat, the types of wood that can be used and how to make it more resistant qith the help of protective layers.

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IMAGE 57. Illustration of the plank on frame method.

1.3.1 Plank on Frame Over the years there has been developed many different methods for boatbuilding.

The most traditional method for building a boat is the plank on frame. This method consists in the creation of a frame and a waterproof shell. This frame provides structural strength of the boat, while the outer surface keeps the water so this way the boat can float.

The fundamental structure of a plank-on-frame vessel is defined by a keel, which is the horizontal backbone of the hull; a more vertical stem, which forms the bow; and a vertical sternpost which forms the back of the boat. On deep keel vessels, especially on sailboats, there is also often what is called deadwood fastened beneath the keel. This forms part of the lateral plane well below the waterline and makes up a good part of what sailors normally call the “keel,� particularly its aft section. The forward section is normally inhabited by a solid casting of metal ballast, preferably lead, that is fastened to the bottom of the boat.

The deck of the boat, meanwhile, is supported by a series of transverse deck beams, the ends of which are fastened to lateral shelves installed along the inside of the hull at the top of the frames. Traditionally, the deck consists of planking fastened to the deck beams with all seams, again, carefully caulked.

Plank on frame boats also often have deck leaks. The problem here is that wood in the deck is constantly swelling and shrinking as it gets wet and dries out. If the deck has open seams, all this expanding and contracting is apt to create gaps somewhere. Even with painted canvas covering the seams, or with a solid plywood deck sealed in epoxy, there are again many fasteners securing hardware, each offering a potential route for water intrusion. Other structures sprouting from the deck-deckhouses, hatches, raised gunwales, etc.--also present seams and cracks where they join the deck that water can eventually seep through.

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IMAGE 58. Illustration of a traditional plank on frame boat.

Boat Construction

IMAGE 59. Illustration of the carvel method.

IMAGE 60. International Boatbuilding Training College Lowestoft.

1.3.2 Carvel Planking

Carvel built or carvel planking is a method of boat building where hull planks are fastened edge to edge, gaining support from the frame and forming a smooth surface.

This method was developed through transition from the age-old Mediterranean mortise and tenon joint method to the skeletonfirst hull building technique, which gradually emerged in the medieval period.

The first carvel-built ships were the carracks and caravels of the fourteenth and fifteenth centuries. Both were developed in Iberia and were sailed by the kingdoms of Portugal and Spain in the early trans-oceanic voyages of the Age of Discovery. At the same time as their appearance, the centuries-long battles to expel the Muslims from Iberia were gradually swinging to the Christian side, represented by the Kingdom of Aragon and the Kingdom of Castile, which were not united into Spain until the time of Christopher Columbus. Their invention is generally credited to the Portuguese, who first explored the Atlantic islands and south along the coast of Africa, searching for a trade route to the Far East in order to avoid the costly middlemen of the Eastern Mediterranean civilizations who sat upon the routes of the spice trade. Spices, in the era, were expensive luxuries and were used medicinally.

Traditional carvel methods leave a small gap between each plank that in the past was filled with any suitable soft, flexible, fibrous material, sometimes combined with a thick binding substance. This caulking would gradually wear out and the hull would leak. Likewise, when the boat was beached for a length of time, the planks would dry and shrink, so when first refloated, the hull would leak badly unless recalled a very time consuming and physically demanding job.

The modern variation is to use much narrower planks that are edge glued instead of caulked. With modern power sanders a much smoother hull is produced, as all the small ridges between the planks can be removed. This method started to become more common.

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IMAGE 61. Photo of a boat made with the lapstrake planking method.

1.3.3 Lapstrake and Clinker Planking

The technique of clinker developed in the Nordic (Germanic) shipbuilding tradition as distinct from the Mediterranean mortise and tenon planking technique which was introduced to the provinces of the north in the wake of Roman expansion.

Overlapping seams already appear in the 4th century BC Hjortspring boat. The oldest evidence for a clinker-built vessel, dendrochronologically dated to 190 AD, are boat fragments which were found in recent excavations at the site of the famous Nydam Boat. The Nydam Boat itself, built ca. 320 AD, is the oldest preserved clinker-built boat. Clinker-built ships were a trademark of Nordic navigation throughout the Middle Ages, particularly of the long ships of the Viking raiders, and the trading cogs of the Hanseatic League.

In building a simple pulling boat, the keel, hog, stem, apron, deadwoods, sternpost and perhaps transom are assembled and securely set up. In normal practice, this will be the same way up as they will be in use. From the hog, the garboard, bottom, bilge, topside and sheer strakes are planked up, held together along their lands by copper rivets. At the stem and, in a double-ended 32

boat, the sternpost, geralds are formed. That is, in each case, the land of the lower strake is tapered to a feather edge at the end of the strake where it meets the stem or stern-post. This allows the end of the strake to be screwed to the apron with the outside of the planking mutually flush at that point and flush with the stem. This means that the boat’s passage through the water will not tend to lift the ends of the planking away from the stem. W

Boat Construction

IMAGE 62. Ilustration of the side view of a lapstrake boat.

This means that the boat’s passage through the water will not tend to lift the ends of the planking away from the stem. . Before the next plank is laid up, the face of the land on the lower strake is beveled to suit the angle at which the next strake will lie in relation with it. This varies all along the land. Gripes are used to hold the new strake in position on the preceding one before the fastening is done.

Timbering or framing out. Once the shell of planking is assembled, transverse battens of oak, ash or elm, called timbers are steam-bent to fit the internal, concave side. Elm species are not durable where the boat is used frequently in fresh water.

As the timbers are bent in, they are copper riveted to the shell, through the lands of the planking.

Sometimes the timbers in larger craft were also joggled before being steamed in.

With the timbers all fitted, longitudinal members are bent in.

The thwart risings are fastened through the timbers with its upper edge on the level of the undersides of the thwarts. Bilge keels are added to the outside of the land on which the boat would lie on a hard surface to stiffen it and protect it from wear. A stringer is usually fitted round the inside of each bilge to strengthen it. In a small boat, this is usually arranged to serve also as a means of retaining the bottom boards. These are removable assemblies, shaped to lie over the bottom timbers and be walked upon. They spread the stresses from the crew’s weight across the bottom structure.

Finishing That more or less finishes the boatbuilder’s work but the painter has yet to varnish or paint it. At stages along the way, he will have been called in to prime the timber, particularly immediately before the timbering is done. The boatbuilder will clean up the inside of the planking and the painter will prime it and probably more, partly because it is easier that way and partly so as to put some preservative on the planking behind the

IMAGE 63. Type of join of the lapstrake (clinker) method.

timbers. Similarly, it is best to have the varnishing done after the fittings are fitted but before they are shipped. Thus, the keel band will be shaped and drilled and the screw holes drilled in the wood of keel and stem then the band will be put aside while the varnishing is done.

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IMAGE 64. Detail well-oiled or varnished in double planking boat.

IMAGE 65. How the strips join among them.

IMAGE 66. Intersected angles in the method of double planking strips.

IMAGE 67. Double Planking Example.

1.3.4 Double Planking

Process. The double or multi diagonal method, consisting of two or more layers of planking laid at angles to one another. The inner planking might be laid from keel to gunwale, for example, and the outer planking from bow to stern. Unbleached calico, well-oiled or varnished, was often inserted between the skins; the result was a strong light hull.

Advantages. Planks can be steamed to fit complex shapes.

Easy to build. Produces a strong, light hull. Very good quality finishes are obtainable that last for many years with minimal maintenance.Disadvantages. Can be difficult to repair. Damage or deterioration of the internal layers of planking is very difficult to detect. Time consuming to build.

Construction. Planks between 150mm to 230mm in width and up to approximately 9.5mm thickness (depending on the length of the vessel) are laid at 45 degrees to the centerline.

The subsequent layer is laid at 90 degrees to the previous layer.

Sometimes a fore and aft layer is added to the outside. Each layer of planking is glued and fastened to the previous layer. The hull planking is supported by light, closely-spaced, fore and aft stringers and widely-spaced laminated frames, all of which are 34

fastened into a heavy laminated backbone.

The completed hull should be fiberglass using an epoxy system to seal the exterior. The internal structure should be saturated with an epoxy-based timber preservative to completely seal the timber from any water penetration. The completed hull will be very rigid and should be finished with a two-pot polyurethane or epoxy paint.

Boat Construction

IMAGE 68. Sheet plywood planking finished boat.

IMAGE 69. Sheet plywood detail in sections.

IMAGE 70. Stich and glue method.

IMAGE 71. Finished stitch and glue method.

1.3.5 Sheet Plywood Planking

This method uses sheets of plywood panels usually fixed to longitudinal long wood such the chines, in whales (sheer clamps) or intermediate stringers which are all bent around a series of frames. By attaching the ply sheets to the long wood rather than directly to the frames this avoids hard spots or an unfair hull. Plywood may be laminated into a round hull or used in single sheets. These hulls generally have one or more chines and the method is called Ply on Frame construction.

Stich and glue technique A subdivision of the sheet plywood boat building method is known as the stitch-and-glue method.

The technique consists of stitching together plywood panels with some sort of wire or other suitable device, such as cable ties or duct tape and staples. All these methods of stitching or suturing the plywood panels of the hull are simple methods of clamping the hull parts together before they are permanently welded or fused by epoxy and fiberglass tape joints. Once the epoxy sets solid in most cases the stitches or other clamping structures are removed leaving only the fused plywood panels behind. Copper wire is popular because the wires can be twisted tighter or looser to precisely adjust fit, and because it is easy to sand after gluing, and it is suitable in a marine environment if left in place, but mild steel electric fencing wire can be used just as easily and then can be removed completely from the hull

structure. To join, the cut panels are drilled with small holes along the joining edges and stitched. Once together, the joint is glued, usually with thickened epoxy and fiberglass on the inside of the hull.

On the outside of the hull, the wire is snipped and the joints filled and sanded over. The outside of the joint, or entire hull, may be fiber glassed and glued as well, providing additional strength.

The combination of fiberglass tape and epoxy glue results in a composite material providing an extremely strong joint, something close to 8-10 times the strength of fastenings and timber framing that might have been used in more conventional plywood construction.

An alternative is to use dabs of thickened epoxy in between the “stitching� to join the panels, and after it has cured, completely remove the wire stitches instead of just snipping them off on the outside. With the wires removed, a fillet of thickened epoxy is applied over the entire length of the joint.

True stitch and glue designs generally have few bulkheads, relying instead on the geometry of the panels to provide shape, and forming a monocoque or semi-monocoque structure.

But larger stitch and glue boats may have many athwart ship (sideways) or longitudinal (lengthwise) bulkheads in effect egg crating the interior with these members also fused into the final structure with the same type of glass tape and epoxy joints as the major hull seams.

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IMAGE 72. Strip planking in boat construction.

1.3.6 Strip planking

This technique fastens multiple wood strips from edge to edge and then the shell is cover under layers of fabric and glue, this is called the Strip Planking method. Whit the strip-built construction, the outer shell gives both the structure and the water resistance.

The single shell structure gives the strength of the ribs and also the backbone into this waterproof skin of the boat integrated in one strong and lightweight piece.

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Strip building is simple because it consists in just bend a bunch of narrow, flexible strips around a set of forms, and cover them with a waterproof reinforcement so this technique is best for the making of small boats because it is simple to do and it requires minimal tools, so you don’t need extensive training, and also mistakes are very tolerant with this method.

These are the most popular among boatbuilders, commonly used for canoes and kayaks, but also suitable for larger boats.

Boat Construction

IMAGE 73. Skeleton strips.

Process This technique fastens multiple wood strips from edge to edge and then the shell is cover under layers of fabric and glue, this is called the Strip Planking method. Whit the strip-built construction, the outer shell gives both the structure and the water resistance.

The single shell structure gives the strength of the ribs and also the backbone into this waterproof skin of the boat integrated in one strong and lightweight piece.

Strip building is simple because it consists in just bend a bunch of narrow, flexible strips around a set of forms, and cover them with a waterproof reinforcement so this technique is best for the making of small boats because it is simple to do and it requires minimal tools, so you don’t need extensive training, and also mistakes are very tolerant with this method.

These are the most popular among boatbuilders, commonly used for canoes and kayaks, but also suitable for larger boats.

IMAGE 74. Boat skeleton strips.

Types of Strips Because the strips are bent around the shape of the hull the wood has to be thin enough to bend. For this reason, it is rarely thicker than 3/8 and more often 1/4 inch or even 3/16 inch thick. Extreme thin strips made to produce ultra, ultra-light boats have gone down to 1/8 inch.

The width of the strips is also quite small often no more than about 3 times the thickness. If the hull shape is simple with gentle curves then slightly wider strips can be used. For complex shapes and keels, narrower boards can more easily be bent around the narrow curves. Narrower boards are also easier to fair than wider boards because there are not such large flat areas.

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IMAGE 75. Bead and cove.

IMAGE 76. Rectangular/Square.

IMAGE 77. Ship lap.

IMAGE 78. Tongue and groove.

1.3.7 Construction Steps

Two methods are commonly used to fit flat strips around a curved form and not end up with gaps. Some builders rout a bead and cove in the edges of the strips. The bead of one board fits neatly in the cove of the next with no gap in between.

Alternatively, the builder shapes the angle of each strip as it is added to the hull.

Most longer boats have joins called scarfs. The 2 boards to be joined get long bevels and these are glued together. Although strips are not subject to much stress and don’t need long scarfs for reason of strength, they need to bend evenly and long scarfs do this. It is not unusual to have 7 or 8 times the thickness as the length of the scarf bevel.

Construction steps A. The chipboard molds (sectional shapes) are carefully erected onto a simple wood strong back.

B. In this case, the internal stem has been laminated but may be made up from solid wood - note the hog which is laminated in situ on the molds.

C. Planking starts - in this case from the gunwale until bending 38

the wood strips becomes too difficult - in some cases, depending on the hull shape, you can plank right from the gunwale up to the hog.

D. In this case, planking was stopped at the bilge and then started again from the hog to meet the previous planking - this means that some of the strips have to be tapered at their ends. If the builder prefers - to make sure that the planking can be done without the need to stop and change direction - the first plank can be positioned at the bilge and allowed to lay along the “great circle” route - planking then continues above and below this first plank.

E. In some designs, other internal items are fitted before the hull is planked - in this example, a bilge stringer has been laminated in situ on one of our 25’6” Snow Bunting designs.

F. Once planking is complete and cleaned up the hull is sheathed in glass cloth or wood veneer.

G. External wood keels/skegs can be laminated on the hull whilst it is still upside down, cleaned up off the boat and then refitted before the hull is turned over - the example above is one of our Edwardian 26’s.

Boat Construction

IMAGE 79. See step (A) in construction steps.

IMAGE 80. See step (B) in construction steps.

IMAGE 81. See step (C) in construction steps.

IMAGE 82. See step (D) in construction steps.

IMAGE 83. See step (E) in construction steps.

IMAGE 84. See step (F) in construction steps.

IMAGE 85.See step (G) in construction steps.

IMAGE 86. Final Result of strip planking in boat construction.

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IMAGE 87. Layers in strip planking.

IMAGE 88. Strip built details.

IMAGE 89. Finished glassing hull in boat.

IMAGE 90. Varnishing in wood strips.

1.3.8 Final Layers Glassing the hull After fairing and cleaning the dust off the hull, it gets a coat of fiberglass cloth. Various thicknesses are available. The plans will specify what weight of cloth is necessary. Some cloth is very thin and adds almost no weight to the boat. If no instructions are available 6-ounce glass will do the job. Once wetted out with epoxy the cloth will be virtually invisible. Take care not to get bubbles and to thoroughly wet out the cloth. It will take 2 or 3 coats of epoxy to get the weave fully saturated and the coating smooth. At this point you can sand to your heart’s content to get a perfectly smooth surface before you varnish. Once the outside is sanded, the boat is removed from the frame / strong back and turned over. The inside now needs to be smoothed, faired and glassed, then sanded again.

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Varnishing Varnish (or paint) is necessary to protect the epoxy which degrades in sunlight. Use Spar Varnish with UV protection. It comes as traditional or Polyurethane based. The Traditional varnish is often a more golden color while the polyurethane can be crystal clear, although sometimes it is tinted.

Polyurethane based spar varnish can be applied over traditional varnishes but traditional varnish cannot be used over polyurethane. It will eventually peel off.

The last step is putting on whatever hardware you have decided to include. This could be an eye at the front for a painter, or rowlocks, or stem bands to protect the bow and stern.

Boat Construction

IMAGE 91. Illustration of the carvel join.

IMAGE 92. Illustration of the lapstrake join.

IMAGE 93. Illustration of the strip plank join.

IMAGE 94. Illustration of the plywood join.

1.3.9 Strip Specifications

Many people decide to manufacture the strips themselves.

For a large project, the process can get tedious. The following suggestions will make the job go more smoothly.

Make enough material. When figuring how much stock to buy, make allowance for material lost when machining. If you are making 1/4thick strips, up to 50% of the original material is turned into saw dust when you mill it, depending on the thickness of your table saw blade. Thicker strips result in less waste.

Machining edge treatments creates additional waste. For example, if you want tongue and groove on a strip that is 1 1/2 wide, you will have to start with a strip that is 1 3/4 wide because the tongue requires 1/4 of extra stock.

Calculate the number of strips carefully and add 10% or so more.

We all make mistakes and it is important to have additional stock available. Natural-finished projects require more wood to allow for color-matching the strips. The fussier you are, the more material you’ll need.

Cut wood strips from the edge of slab sawn wood. A flat grain board is cheaper than vertical grain boards and when you saw a strip from the edge, it yields vertical grain strips. Vertical grain is dimensionally stable and easier to finish than flat grain.

When figuring the length of the strip material, it also helps to make the planks a foot or so longer than they need to be. When

you are trying to force a plank into position, it is nice to have the extra length for leverage. Allow for the extra length in your calculations.

1.3.10 Strips Fitting

Two methods are commonly used to fit flat strips around a curved form and not end up with gaps. Some builders rout a bead and cove in the edges of the strips. The bead of one board fits neatly in the cove of the next with no gap in between.

Alternatively, the builder shapes the angle of each strip as it is added to the hull.

Now for a bit of heresy. It is possible to assemble a hull with no significant shaping of the strips as they are fitted onto the forms. Gaps are filled with thickened epoxy, faired, and the hull covered with fiberglass and epoxy, then usually painted. Since the main purpose of the strips is to create a core, there is no loss of strength. However, since strip-built boats are usually put together to look beautiful, in fact it is often the main reason to choose wood strip construction, few people go this route.

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Hardwoods

Softwoods

IMAGE 95. Oak wood.

IMAGE 96. Maple wood.

IMAGE 103. Pine wood.

IMAGE 104. Ash wood,

IMAGE 97. Mahogany wood.

IMAGE 98. Cherry wood.

IMAGE 105. Hickory wood.

IMAGE 106. Beech wood.

IMAGE 99. Walnut wood.

IMAGE 100. Rosewood wood.

IMAGE 107. Birch wood.

IMAGE 108. Cedar wood,

IMAGE 101. Butternut wood.

IMAGE 102. Ashwood

IMAGE 109. Redwood.

IMAGE 110. Firwood.

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Boat Construction

IMAGE 111. Boats left in the interperience.

IMAGE 112. Fungi infection in wood strips.

IMAGE 113. Wood strips without varnishing.

IMAGE 114. Prevention of the fungus with the insecticide.

1.3.11 Wood Environment

The first and most difficult problem for the boats and the wood specially is the water.

The reaction of the wood (raw) when is in contact with the water the cells start to suck the water into the strip and then lose their properties like strength. Also, when the strips aren’t right covered they are exposed to fungus and plagues that in a future are going to rot every strip and then the whole boat. If you don’t cut the right way the wood you probably are going to mess up the boat because immediately the wood loses their natural inner structure. fungi can infest and consume it, causing what is known as dry rot. Marine borers like the Teredo worm, or boring insects like carpenter ants and termites, can also chew their way through a boat pretty quickly. Wood also rots when it gets too wet, is easily ignited, and is soft, with poor abrasion resistance. Structurally, in one important sense, it is deficient in that it is much less dense than other materials and thus takes up a lot of space. A wood hull must normally be much thicker than an equivalent glass hull, and its interior structural parts must also be larger.

Indeed, wood cannot be used at all to make certain small parts that carry great loads (such as bolts, tie-rods, and rigging wire) simply because it is too soft and too fat to fit.

How to maintain a good-looking boat

To prevent the wood from damage here is a list of advices for keep your boat in good conditions.

Prevent water to getting into the wood.

Protect wood from UV- radiation.

Make a wooden surface and boat food looking (colored, natural, bright, shiny, matt) Poison the wood in such a way, that rot would not grow.

Make a boat visible.

Decrease the temperature changes caused by direct sunlight.

Poison the surface of the hull to prevent algae and barnacle growth.

Make the wood surface mechanically stronger.

Make the wood surface dirt repellent.

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Double Layered Shells

1.4 Double Layered Shells Double layered shells using wood as main material & their importance

A double layered system is a lightweight construction system for rapid and automatic manufacture of double curved shells, built from two interconnected layers of structural plates using the minimum amount of materials, the way plates are placed and joined transfer an equilibrium of forces within the structure that provide resistance and stability.

One of the advantages of double curvature is that it helps avoiding undesirable deformation modes of the pavilion.

An example in nature is found in bird skulls tissues, they are extraordinary impact-resistant structures and extremely light, this performance and physical property can be applied in structure or architecture design.

Because of the voids between solid material areas reducing the overall weight of the structure without affecting its strength.

The resultant configuration of the system relies on different cell components that are integrated into a major system and it is not focalized just on the outer layer, the bone tissues of song bird skulls are formed by very thin external layers that enclose a internal tissue.

Although a very elegant way to build large structures with minimal use of material, the high production costs and fabrication complexity of double-curved components often renders their application in engineering prohibitive.

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IMAGEN 115. Andy Harris bone-inspired canopy.

IMAGE 116. Andy Harris bone-inspired canopy.

46

Double Layered Shells

IMAGE 117. Detail of the support assembly.

1.4.1 Duck-Work

Duck-Work was a pavilion designed for the Urban Timber exhibition in the Boston Society of Architects (BSA) Space Gallery located in Boston, MA.The design was made by Sean Gaffney and Christina Nguyen;NADAAA/ Nader Tehrani(Architecture Mentor) and Lera/Benjamin M(Engineering Mentor). Cornelius It functions as a structural mockup for a building system that could be deployed at a larger scale and take on a number of other programs, configurations and finishes.

Combines two tools from traditional wood building techniques in order to create a new construction method: “ducks,� or spline weights,used to aid in the drafting of curved timber elements in shipbuilding, such as the ribs of a hull;and the otherone used when pouring vertical concrete elements in buildings, such as walls and wirth both of these tools the design team created a curved wooden structural module able to hold its shape through the integration of form-ties and/or ducks directly within.

The wood may have been steamed, laminated or cut into a desired curve, but they decided to invent a new type of wood construction method that integrates the tools used to bend wood directly into the assembly itself. It breaks down complex curvature into a series of smaller bends that can be assembled on site. Like plywood which is comprised of multiple layers of wood and glue, this is made out of a series of plywood sheets formed by tension rods able to support large loads.

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BENDING BRIDGES

1.4.1 Duck-Work

IMAGE 118. Multiple layers of wood and glue.

IMAGE 119. Detail of surface support gasket.

IMAGE 120. Detail of the support assembly.

IMAGE 121. Support and surface.

IMAGE 122. Assembly of modules.

IMAGE 123. Tension rods.

IMAGE 124. Duck-Work.

IMAGE 125. Duck-Work test.

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Double Layered Shells

IMAGE 126. 1DOF integral joints-Detail.

IMAGE 127. Trapezoidal shaped hexahedron segment.

IMAGE 128. 4X7 segment-assembly order diagram.

IMAGE 129. Annen Project-Open Days 2016 of the EPFL.

1.4.2 The Annen Project

It made it by Dr. Christopher Robeller (Scientific Development), Max Annen, Anh Chi Nguyen, Pierre-Olivier Coanon.

Consists in a series of 23 vaults with spans ranging from 22.5 m to 53.7 m (due to the constraints of the project and the terrain) and constant high and width of 9 and 6 m respectively. Each arch is a double-curved shell structure with a design inspired by Eladio Dieste’s Gaussian masonry vaults. The shell is made out of two interconnected layers of timber plates assembled with through-tenon joints, instead of a thick layer, taking advantage of the ability of the joints to connect thin plates, which provides a high resistance.

The first step that they did was generated the 3D geometry based on a Freeform Surface.

Then they designed the vaults present overlapping s-shaped cross-sections. The plates are interconnected using 1DOF integral joints between all the plates (vertical and horizontal) to benefit at its most of the locator and connector properties and adopted trapezoidal shaped hexahedron segments was chosen to optimize the assembly of the structure, the mechanical strength of the joints and the transfer of forces within the

structure.

Built with 15 mm-thick spruce plywood panels, the arch was decomposed 4x7 segments for make assembling the structure easier.

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IMAGE 130. Steps of the design process.

IMAGE 131. Diagram of final form exploration.

IMAGE 132. Detail of both layers connections.

IMAGE 133. Front view in real scale.

1.4.3 Bend9

Developed by Riccardo La Magna the Bend9 pavilion further explores the potential of engineering systems that use bending as a shape-forming strategy.

This pavilion was built thinking on intelligent material usage in order to manufacture complex free-form surface, as well they managed to explore the properties of bending and using its own properties as limits to built a load-bearing shell structure arbitrary in shape and geometry. Opposite as the normal form use of elements, they embrace the defoarmation characteristics of planar sheets to achieve the wanted shape. The final shape was directed by the plywood own mechanical properties, the output geometry was an equilibrium of parameters between the mechanical limit of the material and its deformation capabilities. The thin sheets of plywood had to be reinforced through additional means.

A second layer was added to the pavilion to provide further load resistance. Both layers were connected using 5cm x 5cm square wood profiles. The offset of the surfaces changes along the span of the pavilion.

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The pavilion spans 5.2 m and presents a peculiar geometry which seamlessly transitions from an area of positive curvature (sphere-like) to one of negative curvature (saddle-like). The whole structure weighs only 160 kg, a characteristic which also highlights the efficiency of the system and its potential for lightweight construction.

The own nature of the project required a tight integration of design, simulation and assessment of the fabrication and assembly constraints. In conclusion pavilion exemplifies the capacity of bending surface structures to be employed as a shape-generating process.

Double Layered Shells

IMAGE 134. Diagrid plan.

IMAGE 135. Components of the structure.

IMAGE 136. Picture of the double layered diagrid.

IMAGE 137. Picture of the finish diagrid.

1.4.4 The ICD, Robot-Made: Large-Scale Robotic Timber Fabrication

Using advanced timber fabrication techniques and taking full advantage of the extended fabrication range of the multiaxis set up, large sections of plywood were custom milled and assembled on-site into a unique one-to-one scale architectural prototype. The prefabricated elements serve as a diagrid substructure for off-the-shelf faรงade planks. Once assembled, they form a stable, doubly-curved building system.

The prototype showcases distinctive wood fabrication possibilities that integrate computational design, material characteristics, and digital fabrication in a direct design to production paradigm. Taking a double-curved design surface as an input, the tool generates a buildable structure within the material and machine constraints. Robotic milling process and export of robot control files are fully integrated in the computational design process allowing it to form a digital loop between design and fabrication leading not only to innovation in timber construction, but also for a re-interpretation of wood architecture.

By using advanced timber fabrication techniques and taking full advantage of the extended fabrication range of the multiaxis set up, large sections of plywood were custom milled and assembled on-site into a unique one-to-one scale architectural prototype. The prefabricated elements serve as a diagrid substructure for off-the-shelf faรงade planks. Once assembled, they form a stable, doubly-curved building system.

The prototype showcases distinctive wood fabrication possibilities that integrate computational design, material characteristics, and digital fabrication in a direct design to production paradigm. Taking a double-curved design surface as an input, the tool generates a buildable structure within the material and machine constraints. A simulation of the robotic milling process and export of robot control files are fully integrated in the computational design process. It allowed to form a digital loop between design and fabrication leading not only to innovation in timber construction, but also for a reinterpretation of wood architecture.

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IMAGE 138. Connected Plates Explanation.

IMAGE 139. Segment Connections.

IMAGE 140. Picture of the finished assemble.

IMAGE 141. Interior view of the construction.

1.4.5 Vidy theater

The vidy theater is an open space for everybody and dedicated to contemporary creation. This theater was developed by the institute du bois (BOIS) and architects of the atelier Cube and is located in a building designed and built by architect Max Bill on the edge of Lake Geneva, Switzerland.

The construction of the vidy theater, has a support structure exclusively made of wood panels with a double layer. The panels are joined by wood-wood connections. It is a two-layer construction with a distance of two parallel layers of 300 mm. The intermediate cavity contains perforated insulation materials (cellulose fibers from waste paper). The construction of the folded wall is 9 m high with an area of 538 m2. The height of the roof is 10.45 m. The 11 m deep stage shows an opening of 14 m.

This method of union makes a greater strength and rigidity between its components, and minimizing metal connectors for such structure.For the manufacture of these unions is the 5-axis CNC technology, which is found in wood construction companies.

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The objective is to continue implementing this method acquired by the wood construction laboratory, EPFL-IBOIS. These wood-wood connections will be soon applied for the first time to larger scales such as buildings. The peculiarity of this is that the connectors are part of the panels, therefore for its construction requires a customized prefabrication. The panels and connectors are cut in a single operation

Double Layered Shells

IMAGE 142. Detail of the robot sewing the segments.

IMAGE 143. Finished pavilion.

IMAGE 144. Detail of the sewing segments connections.

IMAGE 145. Rendered pavilion.

1.4.6 ICD/ITKE Research Pavilion 2015 - 2016 The Institute for Computational Design (ICD) and the Institute of Building Structures and Structural Design (ITKE) of the University of Stuttgart have completed a new research pavilion demonstrating robotic textile fabrication techniques for segmented timber shells, employing industrial sewing of wood elements on an architectural scale.

The project was designed and realized by students and researchers based on the biomimetic investigation of natural segmented plate structures and several species in order to understand the intricate internal structures of sea urchins and sand dollars. The project commenced with the analysis and developed by a fabrication technique, enabling the production of elastically bent, double-layered segments.

The pavillion consists of 151 segments of thin layers of plywood prefabricated by a robotic sewing. Each segment is made out of three individual laminated beech plywood strips and are raging between 0,5 and 1,5 in diameter, this segments have specific shapes to fit by adding a textile connection in between making it lighter and with no need of metal in it.

Were performed on several species in order to understand the intricate internal structures of sea urchins and sand dollars, and was concluded that the performance of these segmented lightweight structures relies not only on the arrangement of its individual calcite plates, but also on the geometric morphology of a double layered system and the differentiation within the material.

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1.4.7 The ICD, Robot-Made: Double-Layered Elastic Bending for Large Scale Folded Plate Structures

The University of British Columbia, and research associates David Correa and Oliver Krieg of the Institute for Computational Design (ICD) explored elastic bending of large scale timber sheets for double-layered timber structures through a combined approach of material oriented design and robotic fabrication techniques.

While many industries have made leaps and bounds in adopting highly flexible and fully automated fabrication workflows using robotics, the construction and design industry are only just starting to open the door to these technologies. Recent developments in robotics combined with more accessible design-to-fabrication tools can now offer architects, designers and fabricators unprecedented access to a new design paradigm.

Using elastically bent plywood sheets form double layer panels that are interconnected using finger joints with hygroscopicity actuated fasteners informing the final geometry during assembly. Employing the concept of design to fabrication as a feedback loop, the bending radius for each sheet and panel is defined by a computational design tool that exports the fabrication data directly to the robot. The coupling of elastic bending and hygroscopic expansion allows for the complete assembly of the self standing structure without the need for any metal fasteners or molds. With the eight-axis industrial robot configuration, the participants were guided through the unique technical and conceptual foundations that underpin robotic milling in wood through development and construction of a full-scale assembly.

Taking a double-curved design surface as an input, the tool generates a buildable structure within the material and machine constraints. A simulation of the robotic milling process and export of robot control files are fully integrated in the computational design process. It allowed to form a digital loop between design and fabrication leading not only to innovation in timber construction, but also for a re-interpretation of wood architecture.

IMAGE 146. Detail of assembly.

IMAGE 147. Assembly process.

IMAGE 148. Finished pavilion.

IMAGE 149. Detail of the finished pavilion.

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1.4.8 Free-form Catalan Thin-tile Vault

IMAGE 150. Reference vault-orientation bricks.

IMAGE 151. Cardboard formwork.

Block research froup-Philippe Block,Lara Davis, Matthais Rippmann, eith Tom Pawlofks Eth Zurich-2010. David López López and Marta Domènech Rodríguez-2015.

The designers of this system used a computational tool, they developed calles Thrust Network Analysis (TNA- based in Compression-only structures, Unreinforced masonry vaults, Funicular analysis, Thrust network analysis, Reciprocal diagrams, Form-finding, Limit analysis) which allowed for the optimization of complex three dimensions equilibrium shells.

This project experimented through a series of gravity-formed tests, using fabric formwork to establish thin shell compressiononly form.

Typical domes of thin-tile vaulting are composed of more layers at the base of the dome and fewer as the rows approach the cusp of the dome.

The designers’ analysis concluded that there would be between one and three layers of tiles necessary, they decided to assemble the system with two layers throughout and the third layer nested between the create the appropriate arc form each structural form, the result was two different thicknesses in the pavilion: 11.5 cm at the higher and bigger vault and 6.5 at the rest of the building because the addition of self-weight would be positive as it helps to stabilize the structure against possible punctual or asymmetrical loading. For the installation used a cardboard formwork assembles above a filler of shipping pallets. Also they based in Catalan vault that are made by several layers of thin bricks of very little weight, the first layer caught with quick plaster, and the others (the bending) usually with cement mortar and placing the bricks with another orientation, finally forming a fairly strong assembly.

IMAGE 152. Laying of bricks in different directions on the structure.

IMAGE 153. Workshop at IFAC 2013. Two views of the result.

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IMAGE 154. Pavilion’s Final design after construction

IMAGE 155. Robotic winding process.

IMAGE 156. Carbon fiber Module.

IMAGE 157. Process Diagram

1.4.9 ICD/ITKE Research Pavilion 2013-14

The project was developed by academics from University of Stuttgart’s Institute for Computational Design (ICD) and Institute of Building Structures and Structural Design (ITKE), who have previously collaborated for a pavilion based on a lobster’s exoskeleton and a structure modelled on a sea urchin’s skeleton, it was located in Keplerstraße 11, University of Stuttgart, 70174 Stuttgart, Germany-2013/2014.

The focus of the project is a parallel design strategy for the biomimetic investigation of natural fiber composite shells and the development of novel robotic fabrication methods for fiber reinforced polymer structures. The team of researchers and students used high-resolution 3D models of various beetle shells – known as elytra – to conduct an analysis of the intricate internal structures.

The Elytra morphology is based on a double layered structure which is connected by column-like doubly curved support elements – the trabeculae. These structures were then translated into a design, using glass for the structure and carbon-fibre reinforced polymers to give the pavilion an optimum strength-to-weight ratio.

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Two robots wound the fibres around the custom-made steel frames, and could be adapted to suit the propositions of all 36 necessary geometries. And finally to assemble each module, only connect with the control points that are found in the outline of the modules.

Double Layered Shells

IMAGE 158. Design process.

IMAGE 159. The metallic panels.

IMAGE 160. The bridge exhibited at the research exhibition Complex Modelling KADK.

IMAGE 161. Final result.

1.4.10 A Bridge Too Far

Paul Nicholas , Centre for IT and Architecture, Royal Danish Academy of Fine Art, School ofArchitecture, Copenhagen, Denmark.

The structure consists in a double layer of thin metal panels.

These are used in contemporary architecture as a nonstructural coating system. The geometric characteristics of the sheet increase its structural depth, avoiding the bending force.

The material chosen was Aluminum 5005H14, which has a good balance between formability, initial thickness and initial hardness. The objective was to inform other design scales that it is possible to use this type of material with this manufacturing process.

this iteration expands materials into aluminum and plastics as well as forming from both sides – double point incremental forming (DPIF).

The project was installed and exhibited on the campus of the Danish Royal Academy (September – December 2016) as part of the Complex Modelling exhibition.

Dec. 2015 - Aug. 2016 installation Team: Paul Nicholas, Esben Clausen Nørgaard, Mateusz Zwierzycki, Christopher Hitchinson, RMIT Melbourne, Riccardo La Magna, ICD Stuttgart.

A Bridge Too Far is the second product of incremental forming research at CITA. After the first project, Stressed Skins, used single point incremental forming (SPIF) with 0.5mm mild steel, 57

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1.5 Wood Steaming Wood bending processes

Is an ecological and economic wood-bending technique that gives strips of wood the ability to bend and form more organic or complex shapes through a process by which it is steamed with vapor on a “steam box” for a certain amount of time and a certain temperature and humidity depending on the type of wood and the desired flexibility.

Steam treatments are often applied in wood and have many different uses. The most common one is beech wood (Fagus Orientalis Lipsky). These treatments are used to improve stability and permeability of said wood as well as to obtain a much more desired color and bring the wood to a softer state.

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Steaming has been studied extensively through the years, given the fact that heat does possess the ability to change the mechanical and chemical properties of wood.

Some of the benefits of using this process is that the wood is not expensive and it’s color and texture will allow more elegant and clean details. It is also important to consider that most types of wood can be bended by changing the variables of the process.

Wood Steaming

IMAGE 162. Wood being steamed.

IMAGE 163. Bending Wood.

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1.5.1 Summary

The use of heat and water to bend wood is centuries old,in the past people used this technique to form: Baskets from willow branches, fishing hooks, barrel staves, planks for boat hulls among other things.

The old and conventional atmospheric steaming technique they used was time consuming, non-uniform, and could result in failures and breakage of the wood.

Vacuum steaming technology offers a more efficient way to bend wood in comparison with the old atmospheric technique.

Why and How is this possible? Due to water vapor bulk flow and constant temperature rise the wood loses its rigidity and therefore becomes flexible and malleable.

The vacuum steam technique dates back to 1929 year in which this method started in the form of a presentation at the annual meeting of the American Society of Mechanical Engineers in Rockford, IL. In the year 1955 a 64-page technical report called “Bending Solid Wood to form” by Edward Peckwas submitted. This document contains every important element of steam bending wood that can be found in all current literature on the subject.

IMAGE 164. Helsinki Zoo Lookout Tower by Avanto Architects, 2001.

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1.5.2 Three Key Elements for Wood Steaming

Humidity: amount of vapor in a unit of dry air. Achieved through vapor and heat.

Sealed Box-Container: Where the wood can remain for a long period of time at high temperatures.

Heat: High temperatures that change the physical properties of water when it reaches it’s boiling point turning into steam that will penetrate the wood and soften it more effectively.

If you want to apply the steam bending technique in a project to must contemplate all of the factors that play an important part in the process of steaming wood. To achieve a successful steaming and bend this factors must comply with the requirements for wood-steaming, if they do not comply at all then the probabilities of having issues and breakage might increase. If you want to apply the steam bending technique in a project to must contemplate all of the factors that play an important part in the process of steaming wood. To achieve a successful steaming and bend this factors must comply with the requirements for wood-steaming, if they do not comply at all then the probabilities of having issues and breakage might increase.

Wood Steaming

IMAGE 165. Steam-bent wood lattice morphology by Jeffrey Niemasz.

IMAGE 166. Steam Bent House by Tom Raffield.

IMAGE 167. Pieta-Linda Auttila’s Sculptural WISA Wooden Design Hotel.

IMAGE 168. Pieta-Linda Auttila’s Sculptural WISA Wooden Design Hotel.

1.5.3 Examples in Architecture

Throughout the years, steamed wood bending techniques have been applied not only in boats or benches but also in architecture of homes, buildings, bridges, pavillions and even watch towers.

Here are just a few examples of the uses that steam-bending has in architecture.

Project located in Kokeasaari Zoo in Helsinki, Finland. Based it’s free form on nature and uses wood steaming method to achieve the curvatures. (IMAGES 2 & 3) Project By Architect Pieta-Linda Auttila, located in Helsinki, Finland. This house uses traditional wood steaming to create the sculptural pieces out of different species of local wood.

Steam-Bent Wood Lattice Morphology. Project by Jeffrey Niemasz, Jon Sargent and Laura Viklund, Harvard University Graduate School of Design, 2009. This project uses the steam bend method along with the double layered method.

Grand Design. Project by Tom Raffield, located in Cornish woodland uses steam-bent timber that covers the entire lodge.

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IMAGE 169. Twisted wood in bench.

IMAGE 170. Wall decoration at an aroma cooking restaurant in Singapore.

IMAGE 171. Sculpture by Richard Deacon on exhibition at Tate Britain.

IMAGE 172. Twisting of steamed wood to create texture (Richard Deacon).

1.5.4 Uses and Benefits of Steamed Wood

Some of its many benefits are that its Eco-friendly, cheap and clean.

The materials that it requires are a steam maker, steam chamber, wood, jigs, clamps, compression strap. All type of wood can be bended so there aren’t that many limitations.

Nowadays it is used in homes to give a nice aesthetic or in furniture, lamps, decoration, sculptures and stairs.

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1.5.5 Examples of Different Bends

There are different ways to bend wood and create different shapes, for example: Free bending, Compression, Twisting, Coil/hoops, Eye bend, Overlap, Mobius strips, Cleave, Kerf bending, Bundle.

Wood Steaming

IMAGE 173. Bent wood in antique barrel.

IMAGE 174. Steamed wood Table by Seth Rollad.

IMAGE 175. Basket made using steamed wooden twigs.

IMAGE 176. Steamed and bent wood chair by David Trubridge.

IMAGE 177. Bent wood Stairs by Oded Halaf in Tel Aviv´s Skyline.

IMAGE 178. Twisted wood bench by Kino Guerin.

IMAGEN 179. Coily type of bending by Tom Raffield.

IMAGE 180. Steam Bent House by Tom Raffield.

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IMAGE 181. Free Bends.

1.5.6 Different Types of Bending

There is only two types of bending: Free bends and end-pressure bends.

Free bends are those that have slight curvatures where difference in length between the outer and inner faces of the bent piece, is less than 3 percent. Some examples of this are Basket rims, boat frames and planking are often steamed and then bent when installed on the boat by being forced into position and fastened to other framing members.

When free bending wood it is not needed to use heat to bend it but it is definitely an advantage if used because this makes it possible for the concave side to assume a certain amount of compressive strain before enough- tensile strain is developed to cause failure in the fibers of the convex side, in other words, it increases the chance of the figure to retain its figure.

However free bends are not highly permanent, even after drying and fixing. Since the deformation obtained during bending is relatively slight, It may be necessary to overbend slightly. To retain the curvature, it is usually necessary to fasten the ends of the strip together, as in a hoop or to fasten the curved piece to other members of the structure.

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IMAGE 182. End Pressure Bends.

The second type of bend is the end-pressure bend. End pressure can be applied in several ways, but the most common is by means of a metal strap with end fittings, such as end blocks or clamps.

Another way of applying the end pressure end is by placing the bending stock between the forms, either with or without a pan for applying end pressure, and the forms are brought against the stock by hydraulic pressure. A mechanical fastening is used to keep the plates in position after closing. The bent pieces are held to shape and dried between the heated plates.

Wood Steaming

IMAGE 183. Example of a Steaming Box.

1.5.7 Steaming Box

The steam box is the most important tool used in the process of wood bending. It’s made up with a steam-maker and a steamchamber big enough to fit the pieces of wood that are needed.

A steam box can be made out of many materials and it would have a great result. It can be made out of wood, metal, PVC pipes and even with plastic bags. It’s safe to say that the material of the steam box doesn’t have any notable effect on the end result.

To produce the steam needed you can use different tools such as using gas tanks, pots, turkey fryers and not necessarily need to use steam power tools. To produce the steam you need to fill the containers with water and you can use a propane fueled torch placed under the container.

IMAGE 184. Parts of a Steaming Box.

1.5.8 Parts of a Steaming Box

In order to work properly, the steaming box needs the next components.

Box: The container that will store the plank of wood which is going to be steamed.

Steam Producer: We refer as steam producer to both the container that holds the water and to the heating device used to boil the water.

Hose: Is the pipe that connects the steam box and the steam producer by which the steam to travels into the box.

Hygrometer: A device used to measure the humidity in the air.

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IMAGE 185. White Oak (hardwood).

IMAGE 186. Pine (softwood).

IMAGE 187. Birchwood (hardwood).

IMAGE 188. Fir (softwood).

IMAGE 189. Walnut (hardwood).

IMAGE 190. Spruce (softwood).

IMAGE 191. Cherry (hardwood).

IMAGE 192. Hemlock (softwood).

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Wood Steaming

IMAGE 193. Power Steamer.

IMAGE 194. Power Steamer.

IMAGE 195. Boiling Pot.

IMAGE 196. Steaming Wood.

1.5.9 Wood Bending Stock

The bending quality of different species of wood varies.

Depending on the curvature desired one must first choose a type of wood that has the capability of achieving said curvature without breaking or deforming. 20-30% of humidity in the wood is reccomended. As a rule of wood bending, the bending quality of hardwoods is better than those of the softwoods.

Although most hardwoods have great bending quality some species are better than others when it comes to their flexibility after treating them with steam. Hardwoods in descending order based on their capability. The use of one of this species of wood can ensure the user that it won’t break or deform as easy as other species of wood do, but if the wood presents some defect such as decay, cross grain, knots, shake, pith, surface checks, and brash wood, then there will be a higher chance of breakage.

Hardwoods used for bending: Hackberry, white oak, red oak, chestnut oak, magnolia, pecan, black walnut, hickory, beech, American elm, willow, birch, maple, cherryash and poplar.

Softwoods used for bending: pine, fir, spruce, hemlock, cedar and redwood.

1.5.10 Steam Producers and Connections

In order to get the steam box running you first need to connect the steam producer to the enclosure where the steam bending will take place. Depending on the dimensions of the wood plank you want to treat with steam you might need one steam producer tool, but if the dimensions are too big then you´ll need extra steam producing tools, this is done in order to allow the process be more efficient and to increase the rate of success while bending the wood.

To connect both of this devices you need a plastic hose that can stand high temperatures and depending on the steam box used it is recommended that you connect the hose to the back of the box or at one side of the box, that way the wooden plank can have an even distribution and can bend without any trouble or breakage.

The length of the hose is another thing to keep in mind, the length must be a short one because this helps to reduce the loss of heat while passing through into the box.

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IMAGE 197. Industrial wood Steaming Box.

IMAGE 198. Medium sized Steaming Box.

IMAGE 199. PVC Steaming box.

IMAGE 200. Wood Steaming Box.

1.5.11 Steaming Box Size

When it comes to deciding how big should your steam box be you need to have in mind the size of the pieces you need for your project. It is recommended that you use a steam box that is tight, but make sure you don’t make it too tight because this could cause some problems such as building up too much pressure inside the box and making the steam not reach certain places due to the small space it would have to flow through the box.

If you make your steam box bigger this means you will need a greater volume of steam to flow into the box in order to reach the needed temperature for the wood to bend.

For example if you build a wood steam box that is 13-1/2” x 131/2” x 73” then the use of one steamer wouldn’t be enough to heat the entire box, in this case you would need to use an additional steamer. The number of required steamers may vary depending on the volume the steam needs to fill.

An average size wooden steam box has an interior dimension of 4”x 4” or 5”x 5” and has a length from 3 to 5 feet and would need the use of only one steamer.

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1.5.12 Pressure Holes and Steam Hose

Every steam box must have pressure holes to release the accumulated pressure inside the box. The inside of the steam box should never be pressurized, this may happen if the pressure holes get clogged in some way or dosen’t have any holes to release pressure through. A pressurized inside can affect the wood bending and is pretty dangerous because it might be likely to pop if the pressure is too high.

You can determine if you need to add more pressure holes by checking the steam box’s door when it reaches the wanted temperature and if you can feel built up pressure when opening the door/removing the cap or if the door tries to open by itself then you might need to add them.

The material of the hose that connects the steam generator and steam box is another thing to keep in mind.

Like the other materials it needs to stand the heat of the steam that will be passing through it into the steam box itself, to get the best results the best option to use for the connecting hose is to use a rubber hose that can withstand heat and pressure just like the ones used in car engines, they can handle heat and pressure better than other materials do.

Wood Steaming

IMAGE 201. Non-metallic Rods.

IMAGE 202. Steam Hose.

IMAGE 203. Wooden Rods.

IMAGE 204. Steaming in a plastic bag example.

1.5.13 Steaming Box Rods Materials

Your steam box needs to have some sort of support at the bottom for your piece to sit on so the steam gets to every part of the piece.

This support can be dowel rods so it creates a rack for your piece, there are other alternatives to this but the use of dowel rods make the process of installation easier for the user.

When it comes to the material of the dowel rods it can be out of any material that can withstand heat and humidity. You could use dowel rods made out of metal but they may stain your work due to the corrosion of the metal caused by the environment it’s in. The corrosion of the metal dowel can be solved by using stainless steel dowel rods, but it is preferred to use wooden dowels because you reduce the chance of burning yourself if you accidentally touch the dowel rod while working, and wood swells when steamed meaning that you don’t have to worry about them slipping off while using the steam box, in fact this method is the most efficient, easier and cheaper to do.

1.5.14 Wood Bending Without a Steaming Box

Depending on the size of your project you might use different steam boxes. for example: If you are working on a boat deck flooring made out of wooden planks you’ll need a bigger steam box than if you are working on a smaller project like a chair.

You can steam bend wood by getting your material inside a plastic bag. You must make sure to leave all the material completely inside the bag.

There are big benefits about doing this, it’s cheap and it uses materials that are easy to find. The clear color of the bag allows you to see the process and allows you to see the results you want to obtain.

You have to make sure you always keep on filling the water tank because if the water inside the tank runs out the remaining water would star to burn making the steam brown therefore ruining the material.

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IMAGE 205. Gas Method.

IMAGE 206. Induction Method.

IMAGE 207. Solar Heating Method.

IMAGE 208. Electric Method.

1.5.15 Heating Methods

In order to produce steam you need to boil water, but there are different ways to achieve this and some are more efficient than others.

The most common heating methods are: Gas heating, Electric heating and Induction heating.

What does these methods consist of?

Gas: This is the traditional method that’s been used for a long time for cooking. It consists of using gas to create combustion.

Electric: The electric heating method uses electric energy and transforms it into heat with the help of resistors, and revolves around the Joule heating principle.

Induction: To understand how this method operates.

Induction uses electromagnetism to heat metals to really high temperatures even to the point of melting them. If this method is applied to heat a metal container filled with water then it will make water boil and therefore producing steam.

Which one is the most efficient?

To determine this a we searched for a test where this methods were put to test. The test consisted of using each method to boil water up to 200°F and during each test time them.

The test showed the next results: Gas heating took 8 minutes to get water to its boiling point, the electric heating took 7 minutes and finally the Induction heating method took 4 minutes to do so.

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Even though this methods will achieve their objective but some take less time than others to accomplish it.

Solar energy: This method consists pretty much on using the power of the sun to create heat. You can use a solar panel to achieve this or you could use a parabolic mirror to reflect the sunlight onto an object.

This method may not be as fast as the ones mentioned above because it takes about 15 minutes for water inside a metal container to reach a temperature of 90°C but it certainly is a viable way to create heat.

1.5.16 Conservation of Heat (Insulation)

The loss of heat will be an obstacle that you might face while bending wood. This problem has a big effect on the outcome of the piece and if it’s not solved you might not get the results you expected to have.

To preserve and conserve the heat inside the steam box you could insulate the box.

Some of the materials to insulate the box can be: Fiberglass, polyurethane foam, cellulose, polystyrene.

The insulation can be placed in between the walls of the steam box in case you have a double layered steam box or on the outside layer, you must make sure that the insulation you are using can stand heat because not all insulation materials have

Wood Steaming

IMAGE 209. Hygrometer.

the same characteristics. The list of insulation materials we provided above are materials that can stand high temperatures and reduce the loss of heat.

1.5.17 Temperatures and Steaming Time

For an average and small size steaming boxes you should aim to get as close as 212°F but in case of big steaming boxes you might be able to reach a temperature of 200°F (93°C).

The general rule when it comes to steaming wood is: You must leave the plank of wood one hour per inch of thickness. A recommended temperature for the steam box to have is from 200°F - 212°F. Oversteaming is not recommended because wrinkles may appear while bending the wood.

1.5.18 Measuring Humidiy Inside The Box

In order to keep track that the process is gonna go as planned you must check that everything is working fine.

One of this things you need to take a look to is the humidity levels inside the box. To do this you can add an extra hole at top of the box and place a Hygrometer inside to measure it.

A hygrometer is an instrument used to measure humidity in the atmosphere. There are different types of hygrometers but the one that’ll work the best in this situation would be a manual hygrometer which is used for industrial and scientific purposes.

IMAGE 210. Rope and weight to measure water levels.

1.5.19 Measuring Water Levels In The Steamer

You must check for the water level every once in a while to make sure you’ve got enough to keep producing steam, but how can you check the water level?

There are a vast number of ways to do this, the most common way to do this is by using a wooden rod and place it inside the container until one end reaches the bottom, once it reaches the bottom of the container you can proceed to retrieve it, the rod by wetting wet should have a different coloration this coloration shows the water level the tank has.

Another cheap and easy way to do it is by using a rope that is larger than the the length of the water tank and tying a small weight to one end and a lighter weight to the other end.The way this method works is very simple the weight that is the heaviest must go inside the tank and the other end of the rope with the lighter weight should be outside the tank. The one inside the tank should be able to float because of the water. Whenever the water level decreases the weight inside the tank will go down therefore lifting the other end which is used as an indicator of how much water is inside the tank. To have a more precise reading of this you should have a scale that demonstrates how much water there is depending on the position of the indicator.

In this case due to the high temperatures inside the tank you’ll need to use weights that can withstand the heat of the boiling water.

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1.5.20 Shaping The Wood

If a piece of wood is removed from the bending apparatus while still hot and bendable, it tends to straighten or spring back. This is a natural reaction of the wood to the release of the compressive stress imposed during the bending operation.

This stress is greatest along the concave face of the piece, where some wood has failed and de- formed; along the convex face it actually ceases, and a slight tensile stress may exist even during bending. As soon as the piece is out of the bending apparatus, the tensile stress intensifies, tending to pull it straight. Some compressive stress remaining in the wood along the concave face also tends to straighten the piece. However, the permanently deformed wood along the concave face prevents the piece from straightening out completely. To counteract this tendency to spring back, the piece must be held in its bent shape until it has cooled and dried or “set.”

IMAGE 211. Example of Bending Wood

1.5.21 Drying and Setting The Wood

Bent wood has a natural reaction of wanting to spring back or straighten back to its original form while still hot, that’s why it’s important to keep the piece bent until it cools down. To hold the wood in place while it dries you could use the help of a bending apparatus to hold the piece in place,but most of the time the most used tools to hold down bent wood are clamps, tie rods and stays which are fastened to both ends.

In some cases bending the wood to its desired curve may not always get you the outcome you wanted, sometimes it could have a less pronounced curve that it was supposed to have. In this cases it’s advised to overbend the wood piece a little bit more that way if it unbends you can still achieve the curvature you aimed for the piece to have.

A piece bent to varying curvatures is more difficult to hold in shape than a piece with a single curvature and the best way to keep this kind of pieces in place is to let them dry while still clamped onto the form. If the bent pieces are suitably restrained by devices that act both in tension and compression, distortions of curvature are not likely to occur.

When wood steaming it’s possible that the treated piece will have some slight changes when it comes to its dimensions and sometimes it might lose a little bit of strength which even after the drying process it won’t be recovered.

Another thing that is possible to occur is the shrinkage in length and thickness of the wood, this causes the bent piece to attempt to take on a shorter radius of curvature.

IMAGE 212. Step before bending the wood.

IMAGE 213. Tools necessary to bend the wood.

IMAGE 214. Use of tools necessary to bend the wood.

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Wood Steaming

1.5.22 Conclusions

The steam bending method has changed over the years with the goal of bending wood in a much faster and better way in comparison to the ancient method, as a result of this, the steaming box emerged and it allows the process to be very effective, although the size and materials of the steaming box may differ depending on the magnitude and focus of the project; the results will be what was desired if used correctly. With this being said it is safe to state that steam bending is a very helpful technique that has been perfected throughout time and can be used in different scale projects; such as architecture and other fields of work due to its versatility.

IMAGE 215. Curving wood for boat construction

IMAGE 216. Curving wood for a barrel.

IMAGE 217. Clamped drying wood.

IMAGE 218. Use of clamps to give extreme curvature.

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CHAPTER 02

THE PROJECT

BENDING BRIDGES

2.1 Context Bridges, Wood Bending and Double Layer

The main goal of the project “Bending Bridges� is to construct a light-weight, load-bearing structure made out of bent timber that uses a double-layer system to add strength and resistance to it. An extensive research about the topic and related subjects was made to have a better understanding of how this works.

The research covers the topics of steam bending, methods of construction using wood, bridge foundations, types of bridges and double-layer systems. Seeking for further and better understanding scale models were made. The test models were constructed using the same method and materials of what the 1:1 scale structure would be made out of.

The sctucture was designed using CAD softwares and later during the manufacturing and testing process CAM softwares were used.

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Context

2.1.1 Bridges

Research was made about the history of bridges to further understand their shapes and the reason they’re built the way they were built and what’s changed over the years. Most of the bent bridges are made out of bamboo and none have been made with bent plywood before. The bride foundations tend to be half underground to balance the forces and since concrete and wood don’t go very well together, metal anchors are commonly used.

2.1.2 Wood Bending

IMAGE 219. Bent Bamboo Bridge.

The use of wooden bent strips by using steaming and other methods has been a way of construction for centuries and has been proven to be very effective. Nowadays there are many materials from which boats and buildings are made but wood is still one of them. This tradition in boat construction has been kept due to its effectiveness and aesthetic. Extensive research was made about wood and its properties, how to steam it and how to bend it. It was found that the most important thing when steaming the wood is a steaming box that is adequate for the project.

2.1.3 Double Layer

IMAGEN 220. Wooden Planks Being Steamed Inside a Steamer.

The inspiration for double layer comes from nature where many double layered structures can be found to optimize processes, retain shapes and provide stability. Through extensive research it was found that the double layer helps retain the curvatures much better and also provide stability and durability to the structure.

IMAGE 221. Steamed and bent wood chair by David Trubridge.

IMAGE 222. Bone Structure Reference for Double Layered Structures.

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BENDING BRIDGES

2.2 State of Art Double layered structures in architecture

To get an idea of what has been discovered already we looked at some references of similar projects that have been done recently. After this research we had a clearer idea of what we wanted to achieve and how we were going to start designing it.

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State of Art

IMAGE 223. Duck-work Pavilion by Sean Gaffney and his team.

IMAGE 224. Bend9 Pavilion by Riccardo La Magna.

IMAGE 225. The Annen Project by Christopher Robeller.

IMAGE 226. Elastic Bending for Large scale Folded Plate Structures (ICD).

2.2.1 Summary of Chapter 1.Research

Duckwork: This project combines two tools from traditional wood building techniques in order to create a new method that uses spline weights to aid the curvature of the timber. This could be deployed at a much larger scale with different configurations and finishes.

Bend9: Project by Riccardo La Magna that uses a shape-forming strategy and bending of the material to create a light-weight pavillion out of thin sheets of plywood. For further resistance it was given a second layer which was connected to the first existing layer using 5cm wooden squares.

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BENDING BRIDGES

2.3 AIM What do we want to achieve?

The aim of the research is to develop a double layered construction system through thin plywood strips based on active bending assembly with high load bearing capabilities.

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Aim

IMAGE 227. One layer bent strip will normally return to its original planar shape.

IMAGE 228. Double Layer Fixed Curvature.

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BENDING BRIDGES

2.4 METHODS Design, fabrication and assembling techniques

The methods used for the development of this project first started with the creation of the surface for the bridge which was later divided into sections that were unrolled and nested using CAD (Computer Aided Design) softwares. After nesting the strips they are input into a CAM (Computer Aided Manufacturing) software where everything is revised and prepared for the cutting process in the CNC machine.

In order for the bending to occur the strips must go through the steaming process for a couple of hours inside of the steam box. Once the strips of the bridge are flexible enough, they must be bent and assembled so that they retain their curvature.

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Methods

Surface Generation

Strip Divisions

Nesting

CNC

Steaming

Assembly

IMAGE 229. Design, fabrication and assembly process.

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BENDING BRIDGES

2.4.1 Steaming Box System

During the investigation of the process for the construction of the double layered bridge, we developed a very important part of the process. The structure will be made by 18mm plywood strips that need to bend in order to be positioned in each specific place. To bend these plywood strips, it’s required that the wood does not lose its properties, that’s why we had to find a system which the plywood strips can be bent in a very natural way. A wooden steaming box was designed for this process, to put each strip inside, so they can absorb the most steam possible, and be easily bent and placed where each strip belongs. The system is divided into two sections, the steamer and the wooden box.

The steamer is made to generate steam with boiling water and transport it to the box. The system consists on a gas tank that provides gas to a burner that will support two aluminium pots, one of 12L and the other of 6L. Each pots has an outdoor hose faucet which works as the water entrance. The water has to be pre-heated in separate pots before entering to the steamer.

Each pot has a level tube, to check how full it is. At the top of each pot, a flexible 3 inch diameter aluminum hose is situated at 90° degrees, with a 45° degrees aluminium elbow that gets assembled and sealed to the wood box trough an aluminum 3 inch horizontal pipe to transport the produced steam. The box has two entrances for the steam that comes from the pots.

The cover and all the external connections of the pot are sealed with a high-temp epoxy glue which is the most adequate one for seals when working with high temperatures. At the top of the pots, trough a hole in the cover, an electric resistance is colocated to optimize the boiling of the water. This resistances have a removable silicone cap to seal completely the pots. If a resistance cracks it has to be replaced with another and place the same silicon cap on it. Each pot has to be filled a 40% of its capacity with water, because the resistances need to be fully covered with water, otherwise they crack, but if its filled all the way to the top, it takes a long time to produce steam and it will not be effective. At the beginning PVC connectors where placed, but they started melting because of the high temperatures so those pieces were replaced with aluminum connectors, this way it can resist heat.

At the beginning, the steamer was on a testing process so we got to know specific parameters about how to make the system efficient for our purposes, such as water levels, timings of when to fill the pot, timing of how much does the water takes to start evaporating. The system was greatly optimized, resulting in a more effective and less time consuming process.

The wood box has a volume of 2.44 x 1.22 x 0.42 m, is made by 6 pieces of 18mm pine plywood that make the structure of the box. All these pieces of the box structure have 9mm rabbet joints at the edges for the pieces of the box to be assembled and attached with wood 1.5 inch large screws for a better sealing of the box. On the bottom of the left side of the box 2 short 3 inch 84

aluminum pipes are placed horizontally through holes made on the wood. In these pipes, it’s possible to assemble the aluminum hoses that come from the steamers for the steam to come into the box. On the top and right-side parts of the box, an 80x80 and a 20x40cm tempered glass resistant to high temperatures is placed and sealed to the plywood piece with number 221 polyurethane sealant adhesive, so it´s possible to see the inside of the box while its being used without opening the box.

On the left plywood piece, in the outside part a 40cm large 9mm plywood box is situated to support a light bulb that will light up the inside of the box, and a hygrometer that will be measuring the temperature and the humidity on the inside of the box with a sensor connected to a wire that is connected to the hygrometer and goes through a 5mm hole also in the left side plywood piece of the box.

In the inside of the box, on the sides parts, four rails are screwed and sealed, 2 on each sides parts, two at a 9cm height and the others two at 21 cm height. Rails are screwed with stainless steel screws from the outside to prevent rusting. Each rail has five notches of 90x9mm, which are made for the 10 horizontal racks. Each rack, of 119x8x1.8cm, fits in the notches and is easily removable. In the inferior back part of the box at the corners there are 2 holes with a diameter of 10mm to drain the condensed water. The box has an inclination of 2% towards the back side to optimize the draining.

Methods

STEAMING BOX

45° ALUMINUM ELBOW

CYLINDER VALVE HANDWHEEL

REGULATOR

FLEXIBLE ALUMINUM PIPE

HANDLE

GAS TANK 4KG

WATER FAUCET

WATER LEVEL INDICATOR COOKING POT

CONNECTING PIPE

CONNECTION TO BURNER

GAS STOPCOCK TO LIGHTER

BURNER

IMAGE 230. Steam System Diagram.

IMAGE 231. Steaming Box Inside close-up.

IMAGE 232. Steaming Box Door Mechanism Close-up.

IMAGE 233. Steaming System Close-up.

IMAGE 234. Steaming Box Perspective View.

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BENDING BRIDGES

IMAGE 235. Hygrometer and light system close-up

IMAGE 236. Close-up image of pots connected to the Steaming Box.

IMAGE 237. Side view of Steaming Box 3D model.

IMAGE 238. Isometric View of Steaming Box 3D model.

IMAGE 239. Closeup of front view of Steaming System 3D model.

IMAGE 240. Close-up of the Steaming Box inside.

IMAGE 241. Front View of Burner and Pots.

IMAGE 242. Isometric View of the Burner and Pots.

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Methods

The burner used for the steaming box was specifically designed with two outputs for the gas and one input. This was so that it would work with one gas tank and heat up two pots. Both burners have a grill to control the flame and adjust it to new needs. The height of the rods was low so that the entrance of air was less and the effectivity was more, this would prevent the flame from being extinguished. A metallic net was inserted so the pots had some height above the burners and more stability.

IMAGE 243. Burner and pots from the steaming system.

The pots we used were modified so that they could function properly, there was a hole on the lid for the aluminum tubes and we welded them together as well as the lid to the pot. This sealed any escape holes for the steam. We added a water level indicator with a transparent hose and 90° metallic elbows attatched to one side of the pots. We also added an upside down faucet to one of the sides of the pots to make the process of adding water a lot easier and faster.

IMAGE 244. Burner front view.

IMAGE 245. Burner side view.

IMAGE 246. Burner top view.

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BENDING BRIDGES

IMAGE 247. Steaming Box Plans Front View.

IMAGE 248. Steaming Box Plans Top View.

88

Methods

IMAGE 249. Steaming Box Plans Right Side View.

IMAGE 250. Steaming Box Plans Left Side View.

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BENDING BRIDGES

10

9

11

12 8

13

14

15 16

7

6

5

4

17 3

18

2 1

19

IMAGE 251. Isometric View Of Steaming Box Diagram With Labels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

IMAGE 252. Exploded Diagram of Steaming Box. 90

Methods

The door is screwed from the bottom with hinges so that it can be completely opened by one person alone, there are 4 door slide locks screwed from top of the door to the box to close the door.

Also has 2 chains screwed at the sides for support and better sealing. Because of the heavy glass, the wood from the top was starting to deform, it was decided to colocate a metal frame all around the door hole, in the inside, so it can create an extra support for this part and also it would be easier to put the door with a non-deformed wood.

All the plywood in the steaming box was treated with an exterior waterproof varnish and dried at least one day before it was placed in the box. All the corners of the inside and the holes of every screw are also sealed with 732 industrial clear silicone to seal the box completely, polyurethane foam was also used on the door to prevent leaking.

In order to make the system work, there needs to be constant checking of different aspects such as the water levels of the pots (which need to always be filled up to 40%), and the temperature and humidity on the inside (which needs to be above 40ยบ C. and above 20% of humidity) and outside. When the temperature in the inside increases, the humidity might drop down because of the relative humidity. Also constantly check on every element of the steaming box system, if something breaks or stops working, it needs to be replaced, or have the damages replaced, for the steaming box to continue working properly.

To use the system, the first step is to fill 40% of the pots with water, and connect the aluminium elbows of the pots to the aluminium entrances of the box, connect the hygrometer to the wire that comes from inside the box, open the gas tank connected to the burners and turn on the burners with a kitchen lighter. Then connect the electric resistances to a plug. The system takes from 30 minutes to one hour to start boiling the water and generate the steam. Already on, unlock and open the box to put the plywood strips in the racks inside and close the door. With the plywood that we used, each strip requires from 2 to 3 hours of steaming session before being flexible enough to curve and assemble.

IMAGE 253. Steaming Box and Steaming System 91

BENDING BRIDGES

IMAGE 254. Graph Relative Humidity Percentage.

2.4.2 Steaming Box Relative Humidity

This graph represents the relative humidity inside the box, produced by the water and high temperatures inside the steaming box, we can see the initial temperature is low with a high humidity. After lighting the burners, the steam starts coming into the steaming box and it reaches temperatures close to 80°C, a temperature that is relatively adequate for the effective steaming of the plywood so that is bent properly.

When the heat was too much, the humidity became lower so we had to regulate it. As shown in the graph, the temperature got close to 70°c after 3.4 hours since the steaming system was activated. The lows and highs on the graph are affected by the amount of water in the pots, this generates dry hot air. The amount of water in the pots had to be constantly monitored.

By reaching a minimum temperature of 60°C the strips came out with good flexibility and after opening the box to remove or add the strips the temperature decreased to 40°C to 50°C losing 1012 degrees and losing a 5-10% of humidity but these stabilized once the door was closed for 20 minutes. After the steaming 92

system was off for two hours, the humidity and temperature returned to normal.

The temperatures and relative humidity inside the box were measured on intervals of 30 minutes for approximately 4 hours per day.

Methods

2.4.3 Steamig Box Maintenance

In order for the steaming box to work properly it needs constant maintenance due to the durability of the materials and the process in general.

IMAGE 255. Steamers’ aluminum tubes with silicone.

The aluminum tubes that connect directly to the box kept breaking and getting loose so we had to find a solution to avoid the loss of steam. We found that duct tape and worked temporarily so we had replace them constantly. The transparent hoses that indicate the water levels also had to be replaced a few times since they kept on deteriorating not allowing the water levels to be checked. Industrial sealer was applied to the hoses so the water wouldn’t leak and also on the faucets to allow the water to be introduced into the steamer pots without leakage.

Due to the high levels of humidity generated on the inside of the box 3 layers of varnishing were applied to the interior. In the edges of the box industrial silicone was applied to prevent steam from leaking out.

IMAGE 256. Broken resistances.

Since the door was the part that was used the most it kept on getting loose and loosing effectiveness. As a solution to that we added different locking methods from horizontal locks to chains that we secured everytime we opened and closed the box. To make it easier to take out the strips we added hinges in the inferior part of the box so that no one had to hold it while manipulating the strips inside. These were replaced with time to optimize the process.

Every 5 days the gas tank had to be refilled with 13 kgs. This was to ensure the proper functioning of the steaming system and heat up the water faster since other methods weren’t as effective. The water that was introduced in the pots had to be boiling already to ensure a more effective process.

IMAGE 257. Steamer faucet with epoxy.

IMAGE 258. Transparent hoses with silicone.

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BENDING BRIDGES

IMAGE 259. Wood Bending With double Curvature Test #1

IMAGE 260. Wood Bending With double Curvature Test #2

IMAGE 261. Wood Bending With double Curvature Test #3

IMAGE 262. Wood Bending With double Curvature Test #4

2.4.4 Material Tests

In the materials tests we seek to familiarize ourselves and realize the scope and impediments that we have when working with the material. We started by making a test with dry wood to establish a reference in terms of flexibility, strength, and ease with which we could bend a strip of wood whose dimensions were 1200 mm x 150 mm. To get it to bend without losing the starting point or end it was anchored with a piece of wood, it was screwed and after that we bent it until it reached it’s maximum curvature without breaking. For the following tests strips of the same size were taken and placed under water for six hours in a row. After that time we could observe that the humidity had an effect in the wood’s flexibility and without putting too much force it was possible to bend it more easily and much more compared to the test that was done in dry.

We discovered that it is important to take into account the time factor, firstly because leaving the strips in water for a long time can stop working because they begin to lose their properties and swell or become more breakable and secondly because once out 94

of the water the wooden strips begin to dry and we count on 15 to 20 minutes before they feel partially dry. In these tests we discovered that the size and location of the supports directly affect the desired curvature, because if they are very large and positioned in the wrong place, they will prevent any of the two strips from matching properly.

Before this, several tests were carried out, reaching the conclusion that a 70 mm long cube with a 3/4 inch polin was the indicated one and allows us to achieve the desired results.

The next test that we did was with the objective of analyzing the way in which we were going to make the union of one strip with another, and thus be able to increase the length of a strip. For this we use a union of 300 mm x 80 mm which is placed just in the middle, thus giving stability to the two strips. In this test we verify that the size of this element is also a factor to be taken into account, because if it is too large it will prevent the curve from becoming concrete and, if it is too small, it will not provide the ideal support. In order to join the elements in the previous

Methods

IMAGE 263. Wood Bending With double Curvature Test #5

IMAGE 264. Test with Fragment of the Bridge

IMAGE 265. Test of Fragment of the Bridge

IMAGE 266. Test on a 1:1 Scale

IMAGE 267. Double Curvature Tests Unrolled Drawing #1 Top View

IMAGE 268. Double Curvature Tests Drawing #1 Side View

IMAGE 269. Double Curvature Tests Unrolled Drawing #2 Top View

IMAGE 270. Double Curvature Tests Drawing #2 Side View 95

BENDING BRIDGES

IMAGE 271. CNC STM1325 Machine

tests, black beads were used. In each cube two were used per side, in the central part, where the union of 8 was located per side. Before this we could contemplate that the size of the pijas also had to be a factor to take into consideration, because if they are very large they get in the way with each other, since the location of them is planned so that they remain in the same position. Starting from the center of the support, two cubes were added and from there the center of each cube was taken into account to position them every 400 mm until the aforementioned distance could not be achieved. It should be noted that the strips were cut in the short direction of a plate of 2440 mm x 1200 mm thick plywood. Once these tests were completed, it was decided to cut the strips in the long direction of the plywood plate, that is, the length of a single serious strip of 2200 mm by 200 mm wide. The same procedure was carried out before mentioned, however the measures of the central support were modified by 300 mm x 110 mm so that it had the same grip area as those of the previous tests.

Before this test we could conclude that although cutting the strips in the longest sense of the plate provided a greater distance once armed, this reduces rigidity to the prototype, because being the longer side has greater flexibility and less stability.

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2.4.5 CNC The CNC is a machine that uses to generate the cuts after going through the design process, once this process happens it generates files in the RhinoCAM plugin which we run within Rhinoceros.

Once these files are generated, we transfer them to the CNC to proceed with the cutting. For cutting we use two types of different drill bits to perform different jobs; one of 1/4 “to make the marks of the beads and also generate the holes of the screws and the other bit that we use is a 1/2� flat bit to make the cut of the strips.

In the first tests that we generated, we cut with the good face of the wood upwards, but after this we realized that the strips or sections that we made would be much better if they were done with the other side up, this is so the sides that don’t look so good end up facing inwards in the double layers. For this we had to realize that one of the layers had to rotate to be able to cut these from the inside out

Methods

IMAGE 272. Cnc Drilling bit.

IMAGE 273. Flat End Mill 1/2”, Ball End Mill 3/8”, Drilling Bit 1/4”.

IMAGE 274. Board maximum size of Cnc.

IMAGE 275. Operating the controllers of the machine.

IMAGE 276. Securing the boards with screws.

IMAGE 277. Close up of the Vacuum.

IMAGE 278. Close-up of the milling bit working through the strips.

IMAGE 279. Strips as they come out of the cnc.

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BENDING BRIDGES

2.5 Design Development Design, scaled models and prototypes

During the development of the design many tests were done to determine the dimensions and the curvature of the final proposal. After the model tests the final design of the bridge came to be thanks to CAD (Computer Aided Design) being used in the process to create better and more accurate results.

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Design Development

IMAGE 280. Strip OverlappWing of Test Model

2.5.1 Scaled Models

To understand further the way wood bending works, models were made out of plywood. The models were generated using CAD softwares and the strips of the model were later laser cut.

In order for the pieces to bend they went through the process of wood steaming and to assemble the strips it was decided to use nuts and bolts.

After the test with the models it was concluded that although the models had a good resistance, a second layer would improve its load-bearing capabilities.

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BENDING BRIDGES

IMAGE 281. Mountain Bridge isometric view of diagram.

IMAGE 282. Mountain Bridge top view of diagram.

IMAGE 283. Mountain Bridge front view model.

IMAGE 284. Mountain Bridge side view of model

IMAGE 285. Stingray Bridge Front View of Diagram

IMAGE 286. Stingray Bridge Isometric View of Diagram

IMAGE 287. Stingray Bridge Model side View

IMAGE 288. Stingray Bridge Model Isometric View

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Design Development

TOP VIEW

IMAGE 289. Untitled Bridge Front View Diagram

IMAGE 290. Untitled Bridge Top View of Diagram

IMAGE 291. Untitled Bridge Side View of Model

IMAGE 292. Untitled Bridge Isometric View of Model

IMAGE 293. Wave Bridge Front View Diagram

IMAGE 294. Wave Bridge Isometric View Diagram

IMAGE 295. Wave Bridge Side View of Model

IMAGE 296. Wave Bridge Isometric View of Model 101

BENDING BRIDGES

IMAGE 297. Evolution of Geometry

2.5.2 Design Concept

The main goal of the project is to make a double layered bridge out of bent wood meant for pedestrian use only. The bridge needs to bear the weight of a person and must be resistant to external forces.

The reason behind using a double layered system is that this type of structure is stronger and more resistant in comparison to a single layered system, this is due to the internal stresses the double layer structure possess.

2.5.3 Structure Design

The first step in this project was to generate an arch that could distribute along its surface the weight applied onto it and that would serve as a base for the bridge. A Grasshopper Plugin called Kangaroo Physics was used for this task. In this plugin the user can create structures by using form finding which is based on the particle-spring system.

The geometry of the bridge was designed thinking of a one flow path for people to cross it and to ensure the safety of those crossing the bridge we made a handrail that is 90 cm in height and is produced by the bridge’s own curvature.

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Structure Analysis The surface created in Rhinoceros went through an analysis in Karamba in which we tested the displacement the structure would have, considering its anchor points and its curvature, it was found out that the most displacement or deformation happened on the central part of the bridge where the biggest curvature was; this curvature is exponentially diminished until the bridge reaches the anchor points. After this the utility was analyzed, with this we could see the tension points where the structure will tend to open; the structure counts with minimum zones and will mantain the compression at a high level, this allows a greater stability. When making the division of the surface and the overlapping and double layer, the grade of curvature and longitude of each strip were individually analyzed.

2.5.4 Design Criteria

The ends of the bridge are slightly bigger compared to the rest of it; The reason behind this is to give the bridge more stability and to make it more inviting for people to cross it.

The bridge was designed thinking of a one flow path meant for pedestrian use only that’s why the bridge is not too wide. The continuous surface of the bridge is taking advantage of the double curvature to integrate higher lateral edges to serve as handrails and to keep the pedestrians safe while crossing.

Design Development

IMAGE 298. Strip Length Analysis Top View.

IMAGE 299. Strip Length Analysis Perspective View.

+ IMAGE 300. Curvature Analysis Top View.

IMAGE 301. Curvature Analysis Perspective View.

+ IMAGE 302. Displacement Analysis Top View.

-

IMAGE 303. Displacement Analysis Perspective View.

Compression

IMAGE 304. Utilization Analysis Top View.

-

Tension

IMAGE 305. Utilization Analysis Perspective View.

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BENDING BRIDGES

2.5 m

12 m 15 m

IMAGE 306. Side View of Bridge Design.

3m

15 m

IMAGE 307. Top View of the Bridge Design.

104

Design Development

90 cm

IMAGE 308. Front View of The Final Design

1. Connecting system double layer.

[+]1

[+]2

2.Connecting system rows.

IMAGE 309. Double Layer System 105

BENDING BRIDGES

IMAGE 310. Structure render.

IMAGE 311. Render of the Design Proposal.

106

Design Development

2.5.5 Nesting

After unrolling the strips of the bridge the next thing to do is prepare them for cutting, and in order to do so it is required to nest the strips into the wooden boards. Nesting is a process in which the pieces get arranged in the most efficient way possible into the work area assigned for the pieces, in this case it was decided to used an area of 1.22m x 2.44m which represents the standard size of plywood boards available on the mexican market. The nesting of the pieces can be done either by the use of a plugin or it can be done by the user himself.

2.5.6 Strip Length and Curvature

The Strip Length diagrams were developed parting from the code generated in Grasshopper, in which a component that measuread each of the lengths was added to the preciously separated rows, after that the maximum and minimum of the existent length within all the strips that form part of the bridge that has a range of 1,220 mm and 2,050 mm and this is connected to a gradient component that colors the strips according to the already measured lengths. The color becomes more intense as the length becomes greater and it’s accentuated respectively.

The curvature diagrams work quite similar to the strip length diagram when the color is stronger it hints that there is a much higher curvature.

IMAGE 312. Nesting (83 boards, 332 strips, 166 plates) 107

BENDING BRIDGES

IMAGE 313. Scaffolding Plan Render.

IMAGE 314. Closeup of Scaffolding Plans’ Side View Render.

IMAGE 315. Scaffolding Support Pieces.

IMAGE 316. Side View of Scaffolding Plans Drawing.

2.5.7 Scaffolds for Bridge Construction

In order to construct the Double Layer Bridge support is required. It was decided that in order to support the bridge’s curvature 5 scaffolds were needed.

Every scaffold was carefully secured in place depending on the curvature of the bridge. On each of the scaffolds a platform was placed at the top row, each of this platforms has a support wooden piece which follows the curvature of the bridge.

The wooden pieces differ in height due to their position and every wooden support piece is held in place using wooden poles and screws. The wooden poles once assembled act as a frame that prevents the support piece from moving and reinforces it.

To avoid the platfrom from giving in to the weight and direction of the bridge every one of them is secured in place using annealed wire which attaches the sides of the platform to the scaffold top row corners.

This support pieces are meant to bear the weight of the structure while it’s being constructed and they will be removed once the 108

construction phase is finished.

The reason behind using scaffolds is based in efficiency. We required a structure that could not only hold the wooden bridge supports, but it also required to be easy to transport and to be held in place.

It was concluded that using scaffolds also helped us reduce material costs. If it was decided to go the traditional construction route it would’ve involved using various vertical wooden poles to support the bridge which would result in the investment of more money and a less efficient way of supporting the bridge.

The scaffolds were also of great importance, not only by holding the bridge supports, but also by using the scaffolds as platforms during the construction it allowed us to maneuver and assemble the highest bridge sections.

The scaffolds used for this project were provided by our sponsor Andamios Monterrey.

Design Development

IMAGE 317. 3D Model of the Foundation Design.

IMAGE 318. Isometric View of the Foundation 3D Model.

A

A’

B

A’

B’

IMAGE 319. Foundation Drawing TopSection View and Isometric View.

B

2.5.8 Foundation Design

After a long investigation about the structure of a bridge we find as a factor of great importance the part of the foundation that it has. Since it is its main base and how it transmits the dead and living charges towards the ground (soil).

IMAGE 320. Foundation Top View Drawing.

Section A

The entire foundation was generated by a parametric modeling program called grasshopper and with it the 3D model was generted and the calculations of the materials that would be needed were made.

A very important element in the construction of structures is the foundation, these have the task of transmitting the forces and loads generated in the whole structure. After researching the different types of foundations that exist (Shallow and Deep) and consultung with some experts, the necessary type of foundation for this project was defined, due to factors like the terrain which is filled with rocks and is quite dense and the type of structure we wanted to build which was light. After determining that the shallow foundation was the best option for the project, we proceeded to make an exploration to find a way to anchor the structure to it. We generated some supports that are anchored to the foundation and can adapt to the double curvature the structure holds; L shaped metal angles were added to help with the strengths of tension generated by the loads of the structure.

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2.5.9 The Code

To create the double layered bridge and its components we used Grasshopper which is a parametric modelling program that runs within Rhinoceros.

The Grasshopper code was split into 3 sections for easier management; the three sections are the following: Design: In this part of the code we generated the bridge’s strips using as a reference the curvature we did previously with the help of Kangaroo and the base geometry that was lofted in Rhinoceros.

System: This part of the code contains all of the parameters of the bridge’s strips, the second layer and its other components for both of the layers such as:

IMAGE 321. Pieces Unrolling Code.

Screw points: The holes in a piece where the screws will be located.

Connecting cubes: The cubes are in charge of joining both of the layers and are the ones that give the bridge its thickness.

Plates: They keep both of the strips in a section together.

To avoid weak spots on the bridge we decided to shift the part where both of the strips in a section meet; this will be later joined with screws to one of the plates we designed. The parameters we used can be changed and adapted into other scales if desired.

Fabrication: The fabrication part of the code concerns all the parts of the bridge and the way they are going to be produced. In this case the strips will be cut using a CNC machine. To be able to cut on the CNC machine we must first unroll all of the strips of the bridge and the other components.

After this the strips were called nested in an area that represents the wooden board that will be later used for cutting. All of the cubes will have an identical height of 7cm instead of having different sized cubes, this way we can make the process much more efficient while producing them.

IMAGE 322. Pieces Unrolling Code.

IMAGE 323. Pieces Unrolling Code.

IMAGE 324. Unrolling of the strips on Rhinoceros.

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Design Development

MATERIAL EXPENSES Team

Total

Prototypes

$2,080.00

Documentation

$3,293.00

Steaming Box

$11,861.50

Foundation

$22,498.50

Material

$48,491.80

Total Expenses

$88,225.00

Sponsored

$89,750.00

Total Project Cost

$177,975.00 IMAGE 325. Budget Planning and Approximate Total Cost of the Project.

2.5.10 Team and Financial Organization

For the project to work, it had to undergo a serious amount of planning. Aside from the design, the team organization and budget planning was required.

There was a team that was dedicated to the entire management and organization of the projects. The people in that team were in charge of placing the other members in the teams where they would be more efficient. The management and organization team was also in charge of the budget and talking to the sponsors to get the materials we needed.

The Design team was in charge of generating the codes, developing the structure, development of the double layer system and the diagrams. All of the elements had to be exact and tested to be able to come up with an exact result as well.

the foundation construction and the construction of the double layered structure.

The material research team was in charge of finding the right materials so the Cnc team could start cutting the strips.

The steaming box team was in charge of having the steaming box functioning by the time it was needed and for every part of the steaming system to be working properly.

Finally the documentation team was in charge of filming and taking photos so that every part of the process is documented. At last the results of this team are a video, a book and a presentation of the entire project.

The foundation team was in charge of generating the code and designing the foundation of the structure.

The construction team was in charge of the entire process of 111

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2.6 Construction Foundation construction and strip assembly

The construction process is one of the most important and most demanding part of any project and should be planned and executed in a precise manner. Most structures need to have foundations that hold it and this was the first step in the construction of the bridge.

To start the foundations it was needed to determine the location of where the bridge would be and make an outline of the area.

Once the area was established the next step was to start digging and leveling the holes in which the foundations will sit. After the holes were done a mixture of gravel and cement was added as the first layer of the foundation.

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IMAGE 326. Measuring the perimeter.

IMAGE 327. Digging the Hole.

IMAGE 328. Setting the Rods.

IMAGE 329. Levelling the terrain.

2.6.1 Foundation Construction

First, we began to perimeter our terrain where the bridge would be located, which is 20 meters long and 4 meters wide. The ground is cleaned by removing impurities, garbage, vegetation and more. We started with two shovels and peaks 2 rectangles 400 centimeters long by 200 wide and 30 deep. A team of 4 people started with the work; after 4 days of hard work we found a stone right in the middle of the second rectangle, which caused a delay in the process since first we tried to break the stone with peaks and then with machinery but It was very large and it was unknown how deep it was since there were still 20 centimeters left to dig.

The first hole that had no complications was continued, this was executed by a rotating team. The decision was made to walk the Bridge 100 centimeters so that the stone did not affect the base of the Bridge. A team of 6 people continued to hitch until they achieved the desired measurements in each hole with their proper depth. We went back to perimetrate and rectify the design measures to avoid mistakes. After a rod was placed in each hole and with the help of the architect adviser indicated how to take levels that consisted in taking a hose full of water without air bubbles inside it, extend it 1,400 centimeters along the bridge and find the right level that would be 30 centimeters above ground level. When doing the levels there was a difference of 17.8 centimeters more so one level was lower than the other.

The earth was matched to match the same level on both sides.

The first mixture was made for the first layer of cement to leave a stable level, 1 package of cement was mixed with 4 of mixed (sand and stone), then water was added and it was emptied in each hole. The first layer had set and the work continued in the workshop.

Four wooden plates were cut for formwork with a measure of 240 centimeters in length by 120 centimeters in width and 2 in thickness. They armed themselves with hammers and nails, the result were 5 boxes of 190 centimeters long and wide, an armex of 15 centimeters is placed along the boxes (1.90) placing them in the middle of ´´each of the boxes, adding rod to the ends and middle points of the large box (2meters 4meters), tie the foundations with wire and proceed to the casting of mixed and cement to the entire rectangle and level with a rule at the end.

A stone was placed so that the 15x15 centimeters beam cage were not touching the cement plate and that they do not oxidize with time. After 6 beam cage are placed in the direction of the length of the bridge that would be our grid. Afterwards, the 3/8� corrugated rods will be tied perpendicularly to the beam cage so that they leave the first emptying. The second layer of concrete (cement + mixed) with a thickness of 10 centimeters was emptied. Free spaces are filled with earth and leveled with a level rule.

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IMAGE 330. Preparing The Hole for Concrete Pouring.

IMAGE 331. Wetting the ground before compacting the earth.

IMAGE 332. Making the concerete mixture (Sand, gravel and water).

IMAGE 333. Making the concerete mix.

IMAGE 334. Pouring the concrete mix in the hole.

IMAGE 335. Spreading the mix.

IMAGE 336. Hole before concrete pouring.

IMAGE 337. Completed and leveled 4cm concrete base for the foundation.

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Construction

IMAGE 338. 15x15cm Beam Cage.

IMAGE 339. “L” Metal Support Piece with anti-corrosive paint.

IMAGE 340. Variations of Metal Support Pieces.

IMAGE 341. Beam Cage with Support Piece.

IMAGE 342. Beam Cage Placing.

IMAGE 343. Tamping down in preparation for second concrete pouring.

IMAGE 344. Placing of Wire Mesh of (2.25m x 3.95m).

IMAGE 345. Beam Cage Joined with Support Piece.

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IMAGE 346. Flattening the ground with a Hand Trumper.

IMAGE 347. L metal pieces positioned in foundation.

IMAGE 348. Wood stock for foundation pieces (red) and strips (yellow).

IMAGE 349. Clamps used to join the foundation’s wooden pieces.

IMAGE 350. Plasma cut of the metal foundation pieces.

IMAGE 351. Cut and ready foundation metal pieces.

IMAGE 352. Attaching the wooden support pieces to the foundation.

IMAGE 353. Wooden support pieces positioned in the foundation.

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The anchoring pieces that will support the entire structure were tied and then the wire mesh was placed on the firm. The 3rd pouring was made afterwards.

Metal Connectors The “L” metal pieces constitute of 3 parts: 2 square pieces and one small triangular piece which connects both of the square pieces, this pieces were welded together resulting in a 90 degree angle which resembles the shape of an L. Once this is done the next thing to do is to add 2 rebars to the bottom of each piece which will later be attached to the armex.

During the construction of the foundation the “L” pieces must be placed with extreme cautious making sure the pieces are straight with the help of a level tool.

Triangle pieces To be able to support the bridge it was required to make support pieces, it was decided that said pieces were going to be made out of 18mm plywood and cutted in the CNC machine.

Each foundation was going to have 3 supports attached to itself through the “L” metal pieces using nuts and bolts. Every support was formed by gluing 3 triangular pieces giving it a total width of 54mm but different in height with one another.

Angle pieces Connecting pieces was essential in order to connect the triangle supports to the bridge, the connecting pieces were made out of wood at first, but due to the delay in production of the connecting pieces caused by the unavailability of the plasma cutter, the pieces were temporarily fabricated in wood and replaced later with the metal ones.

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2.6.3 Strip Assembly Parts of a bridge section In order to start the assembling process it is required to have a couple of things ready, such as the strips, the plates and the cubes.

The cubes are a fundamental element in the assembling of the bridge sections and must be cut at the precise measurement of 70mm and 52 mm in height. If a cube is either larger or smaller than the previously mentioned measurements then it will affect the curvature of the section.

Once the strips and their respective plates have gone through the steaming process they are ready to be assembled, but keep in mind that some strips might need a bit of an additional time inside the steambox to achieve optimal flexibility.

IMAGE 354. Cutting the wooden poles to the exact measurements.

Assembly of a Bridge section The first step in the assembling process is to join the fist layer strips to one another using the plate as the connecting piece between both strips using nuts and bolts. This process is done to the top and bottom layer of the bridge.

After the strips are finally secured together the next thing to do is to drill in place the cubes using the reference points on the strip. Once the top and bottom sections are attached with the cubes the next thing is to take the assembled section to the bridge in order to start the anchoring process.

Assembly of Bridge sections one to another To assemble the bridge sections to one another we first needed to overlap the edges making sure each opening for the bolts was aligned and once that was achieved, the placing of the bolts, nuts and washers across the section started.

Anchoring process For this part of the construction process the section must be placed according to the direction of the bridge using the position of the plate from the previous section as a reference, the plate must follow the shifting pattern. To secure the section to the rest of the bridge it is required the use of nuts and bolts. The anchoring must begin at the corners of the section and make its way into the center of it.

Once all the bolts are placed in their respective space the next and final step to do is to tighten the nuts and bolts with a wrench and a ratchet with an attached socket of 1/16.

IMAGE 355. Screw the wooden spacers to the strips to attain the shape.

IMAGE 356. Bend the strip until the exact needed shape is attained.

IMAGE 357. Attaching a bridge section.

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Construction

IMAGE 358. Getting the screws to fit in.

IMAGE 359. Making sure the strips are aligned so that both ends meet.

IMAGE 360. Getting the screws in through the two strips.

IMAGE 361. Varnishing the strips.

IMAGE 362. Tightening bolts and nuts.

IMAGE 363. Connecting the temporary wooden L pieces.

IMAGE 364. Closeup of the structure anchored to the foundation

IMAGE 365. Tools used to anchor the structure to the foundation.

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2.6.4 Varnishing

The varnish used for this project came from our sponsor Osel.

After every assembly, the strips had to be left to dry for 24 hours so the process of varnishing could start. First the wood is sanded to remove any imperfections. After this step the first layer of varnish is applied on the outer faces and also on the inside of the structure. This layer will be absorbed by the wood to use as a shield and setter for the second layer. This process also needs 24 hours to dry. The first layer has to be lightly sanded in order for the second layer to be applied. This second layer works to seal the first layer of varnish and to give a shinier and richer color to the wood.

To create the mixture of varnish there are 3 elements needed: the wood varnish, the catalyzer and thinner. To make 1 liter of varnish mixture you mix 50% varnish and 50% catalyzer. To that mixture that is a 100% you mix an aditional 60% thinner.

This applies to the first layer. For the second layer the only variable that changes is the amout of thinner which should be 40% instead of 60%.

While varnishing you have to be careful and take security measures since the mixture is highly toxic. Gloves are required since it’s extremely sticky. You should take your work area into consideration and be careful where you leave your things because once stained it is difficult to get it off skin, clothes and any other objects. A face mask is important since breathing the mixture is dangerous. The brushes have to be constantly washed with thinner which also helps remove stains of varnish.

The varnish is highly flammable and toxic. The weather has to be taken into consideration too because if it´s too humid the strips won’t dry and varnishing will be impossible.

The tools were a problem we had to solve since we had to create our own because there are no tools long enough in any store nearby. We took broomsticks we had available and tied the brushes with duct tape. To varnish on the inside the brushes weren’t of much help so we used sponges tied to the broomsticks with rope and they worked just as well.

IMAGE 366. Measuring the amounts for varnishing mixture.

IMAGE 367. Varnish brand and type.

IMAGE 368. Varnishing the upper surface.

IMAGE 369. Varnishing the lower surface.

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IMAGE 370. Steam leakage.

IMAGE 371. Broken strip due to insufficient moisture.

IMAGE 372. Spacers with unprecise measurements.

IMAGE 373. Foundation wooden pieces opening because of humidity.

2.6.5 Errors

One of our first mistakes was the spacers’ sizes difference. If any of the large cubes measured more than 7cm or less a distortion was generated in the curvatures of the strips and making them more difficult to assemble making the margin of error bigger each time. We had to redo our little progress by the time we noticed and make all the spacers the same exact size.

Another problem we encountered was the breaking of the strips of wood that happened because of many factors like the bad quality of the wood, the layers that the plywood had, the lack of humidity and the use of too much force when assembling while making the curve or assembling since the pressure makes the curvature more fragile.

The steambox had a lot of issues because of the constant use.

First of all it had many openings that we kept taking care of so the steam didn’t leak, we had to maintain the temperature and humidity inside or else the strips would come out not flexible at all. The hinges on the door kept on breaking and needed constant repairing, the wood was rotting on the door due to the humidity even with the varnish we applied before. The pots we used to produce the steam needed a lot of maintenance too,

the tubes that connected them to the pots kept breaking, we realized that the system wasn’t as effective by itself so we added electric resistances and preheated the water before adding it to the steamers to speed up the process.

While the foundation wooden triangles were in place, it rained and due to the humidity and the fact that they weren’t completely varnished, they started to open and they had to be fixed by separating them, sanding them and gluing them back together.

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2.6.6 Drone Documentation

To documentation process of the construction was executed with a drone DJI Mavic Pro. The application DJI Ground Station Pro was used to program the flight without the need of manual control. This application was used to create a path on a map which could be wirelessly synchronized with the drone.

An option that allows a 360º rotation on one axis was used, where it’s possible to adjust parameters such as speed, control points, minimum height, maximum height, diameter of the building and flight diameter, as well as the origin coordinate.

Once the flight route was defined, the control points were assigned through the application for the drone to stop and take a picture. These points were greatly helpful because despite the wind that destabilizes the drone, the picture would not be taken until the drone reached the assigned control point.

IMAGE 374. Drone route mapping.

Speed parameters only affect the flight time. The other variables were the minimum and maximum flight heights. To define them we observed the terrain and the obstacles that the drone had so that it did not collide with any object.

The final parameters for the drone path (2 turns) are: Starting point coordinates - Lat: 25.663702 - Lon: -100.449405

IMAGE 375. Drone programming.

Speed: 4.0 km/H Flight Rad: 22.8 m Building Rad: 7.0 m Min Height: 7.0 m Max Height: 15.5 m Control Points: 90 Its Flight Length: 442 m Photos Set: 90 Estimated Flight Time: 10 min 52 s

IMAGE 376. Aerial view of the construction process

IMAGE 377. Aerial view of the construction process 122

Realized Project

2.7 Realized Project 8/11/2018

The CEDIM project “Bending Bridges” was designed and built by 16 students over the course of one year (Feb-Nov 2018), with the supervision from different experts and the support of sponsors.

Images and post production by Héctor Pineda and Grecia Cortes.

There was a total of 83 strips, 166 plates, 704 spacers, and the connections consist of 4144 screws and 2140 nuts and bolts.

The development of the steaming box was a project itself, a tool which integrates a system to generate steam and high temperatures on the inside of the box, this is one of the most important parts of the project because .

The full scale prototype demonstrates that the double layered system works and that it can support a 12 meter span and people can safely cross it, one of its advantges is that the structure is lightweight, has good resistance for vertical loads and it is built with a fast assembly process. While the development of the construction system required almost a year, the actual construction process of the bridge took 20 days in total.

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2.8 Sponsors Special thanks

STM Robotics Ezequiel Cadena Bernal Madera Aceros FERCOM Rar S.A. de C.V Herramientas, Birlos y Tornillos Pinturas Osel Coragui Rental S.A. de C.V Montajes y Estructuras Delta Andamios Monterrey

128

Acknowledgements

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2.9 References 2.9.1 Image References

IMAGE 01: T. (2017, August 13). Retrieved from https://thecivilian.in/68636/ IMAGE 02: S. (2016, July 26). Alcántara Bridge (#28). Retrieved from http://www.romeacrosseurope.com/?p=4625#sthash.docxu0sC.TDaY5pnT.dpbs IMAGE 03: What Comes After Virtualization? – InFocus Blog | Dell EMC Services. (2017, December 28). Retrieved from https://infocus.dellemc.com/choong_ kengleong/what-comes-after-virtualization/ IMAGE 04: Test: Root Word struct = build. (n.d.). Retrieved from https://quizlet.com/54670265/test IMAGE 05: Srishti Katiyar “ Subscribe 0. (2018, July 05). Control of Corrosion on Underwater Piles. Retrieved from http://ibnox.com/read/7eapo3j/control-ofcorrosion-on-underwater-piles IMAGE 06: Neoprene. (n.d.). Retrieved from http://www.diprotec.com.br/produto/neoprene/ IMAGE 07: Bridge. (n.d.). Retrieved from http://arshiinfrastructure.com/bridge/ IMAGE 08: Mailonline, S. W. (2016, October 25). A bridge too far: Spectacular footage shows China’s gargantuan mountain overpass spanning 5,000 FEET across beautiful valleys. Retrieved from http://www.dailymail.co.uk/news/peoplesdaily/article-3871132/Spectacular-images-China-s-gargantuan-mountain-overpass-spans5-000-feet-beautiful-valleys.html IMAGE 09: Brooklyn Bridge Cardboard. (n.d.). Retrieved from http://www.pinsdaddy.com/brooklyn-bridge-cardboard_ K1gTXT5uwXw|E4aqiv5uKv0FIIEc6noUWpZf*6KbWOk/ IMAGE 10: {{ $root.metadata.title }}. (n.d.). Retrieved from https://www.wowcher.co.uk/deal/edinburgh/4187031/forth-bridge-boat-cruise-cream-tea-2-14 IMAGE 11: JENIS-JENIS JEMBATAN DAN PENGERTIANYA. (n.d.). Retrieved from https://caridokumen.com/download/jenis-jenis-jembatan-dan-pengertianya_5a45dbbfb7d7bc7b7ada9ef6_pdf IMAGE 12: Chaotianmen Bridge - World Record Steel Arch Bridge. (n.d.). Retrieved from https://civildigital.com/things-you-didnt-know-chaotianmen-bridge-worldrecord-steel-arch-bridge/chaotianmen-bridge-world-record-steel-arch-bridge/ IMAGE 13: (n.d.). Retrieved from https://www.mcnarybergeron.com/project_highlights.php?id=35 IMAGE 14: Structures and Forces within the Irrigation Pivot. (2016, April 01). Retrieved from https://insecticideirrigation.wordpress.com/structures-and-angleswithin-the-irrigation-pivot/ IMAGE 15: Destinazioni Centri Londra e Inghilterra per Estate INPSieme 2018. (n.d.). Retrieved from https://www.meridianoinps.net/centri-londra-e-regno-unito/ IMAGE 16: Incrível Obra De Engenharia Permite Que Ponte Se Enrole Transformando-se Numa Bonita Escultura. (2017, June 21). Retrieved from https://www.funco. biz/incrivel-obra-de-engenharia-permite-que-transformando-bonita-escultura/ IMAGE 17: 11 2 puentes móviles curiosos. (2014, October 01). Retrieved from http://www.hidrojing.com/112-puentes-moviles-curiosos/ IMAGE 18: Bordeaux. (n.d.). Retrieved from http://www.qualitydestinations.com/bordeux/ IMAGE 19: Galerie d’images | Canal de Corinthe (Corinthe/Isthmie, 1893). (n.d.). Retrieved from https://structurae.info/ouvrages/canal-de-corinthe/photos IMAGE 20: Newcastle upon Tyne. (n.d.). Retrieved from http://www.wikiwand.com/en/Newcastle_upon_Tyne IMAGE 21: Bridge over the Basento river. (n.d.). Retrieved from https://www.wikidata.org/wiki/Q17651437 IMAGE 22: Baran, A. (2016, March 24). TIME - MOTION & ARCHITECTURE. Retrieved from https://www.pinterest.com.mx/pin/452682200026978205/ IMAGE 23: The Musmeci Bridge. (2017, September 04). Retrieved from http://www.platform-ad.com/the-musmeci-bridge/ IMAGE 24: Mumeditation. (2013, November 17). - vili-ve: Pure Brutalism and breathtaking... Retrieved from http://mumeditation.tumblr.com/post/67229966329/vilive-pure-brutalism-and-breathtaking IMAGE 25: Iqra. (n.d.). Retrieved from https://narendrarasyid.wordpress.com/ IMAGE 26: Zhou, H. (2014, November 06). REF_BRIDGE. Retrieved from https://www.pinterest.com.mx/pin/375628425145294456/ IMAGE 27: . (n.d.). Retrieved from http://blog.daum.net/_blog/BlogTypeView.do?blogid=03Uqt&articleno=15957435&categoryId=0®dt=20161016160236 IMAGE 28-32: Nugroho, H. (2015, April 01). Penggunaan Metode Rietveld Joint pada Sambungan Bambu Rumah Tradisional Indonesia. Retrieved from https:// herunugroho28.wordpress.com/2015/04/01/penggunaan-metode-rietveld-joint-pada-sambungan-bambu-rumah-tradisional-indonesia/ IMAGE 33:Bamboo, W. W. (2010, June 09). Bending Bamboo. Retrieved from https://whisperingwindsbamboo.wordpress.com/2010/03/12/bending-bamboo/ IMAGE 34: G. (2014, March 04). Bending Dry Bamboo Poles. Retrieved from https://www.youtube.com/watch?v=fF20D3wiR6w IMAGE 35: Cimentacion y sus diferentes tipos. (2018, April 28). Retrieved from https://elementosdeconstruccion.com/cimentacion-y-soleras/ IMAGE 36: (n.d.). Retrieved from http://geotip.igt.ethz.ch/index php?&gfield=knowledge&gmenuleft=blocs&gopennodes=4_43_6_68&gblocid=262&PHPSESSID=hdqfp8v86i23i3m1l53jhb80m4 IMAGE 37: Rmnt.ru. (2014, July 11). Retrieved from https://www.rmnt.ru/story/machinery/677800.htm IMAGE 38: F. (1970, January 01). Los Cimientos en la construcción. Retrieved from http://mundodeladrillos.blogspot.mx/2008/12/los-cimientos-en-la-construccin. html IMAGE 39: Strip (continuous) footing. (n.d.). Retrieved from https://www.finesoftware.eu/geotechnical-software/solutions/shallow-foundations/strip-continuousfooting/ IMAGE 40: EMPRESAS DE PILOTES, CIMENTACION Y PERFORACIONES, Guayaquil, SUR - Doplim - 628145. (n.d.). Retrieved from https://guayaquil.doplim.ec/ empresas-de-pilotes-cimentacion-y-perforaciones-id-628145.html IMAGE 41: (n.d.). Retrieved from http://debug.pi.gr/default.aspx?ch=73 IMAGE 42: (n.d.). Retrieved from http://www.teknofor.com/Kategori/2/geoteknik-uygulamalar/36/temel-kaziklari IMAGE 43-44: D. (n.d.). Bridge Substructure. Retrieved from http://www.dinaris.org/bridge-substructure/ IMAGE 45: Anchors Used For An Rock. (n.d.). Retrieved from https://raisedgardenbed.club/read/anchors-used-for-an-rock.html IMAGE 46: Ground anchors, soil nails, rock bolts. (n.d.). Retrieved from http://www.atlasgcc.com/ground-anchors-soil-nails-rock-bolts/ IMAGE 47: Steel Anchors. (n.d.). Retrieved from http://www.castingquality.com/casting-products/marine-fittings-casting/steel-anchors.html IMAGE 48: Surety Association of Houston SAH. (2012, December 27). How Construction Works. Retrieved from https://www.pinterest.com.mx/ pin/273453008596181957/ IMAGE 49: Luftig, J. (2015, October 05). Floating footpath bridges. Retrieved from https://www.pinterest.com/pin/246712885814868263/ IMAGE 50: Soil FEM. (n.d.). Retrieved from https://www.engnovex.com/soil-modeling/ IMAGE 51: Hizmetler. (n.d.). Retrieved from https://navalcon.com/hizmetler/ IMAGE 52: Concrete pour for bridge pylons marks next step for the Mersey Gateway Project. (n.d.). Retrieved from http://www.merseygateway.co.uk/2015/08/concretepour-for-bridge-pylons-marks-next-step-for-the-mersey-gateway-project/ IMAGE 53: Vihantasalmi Bridge (Mäntyharju, 1999). (n.d.). Retrieved from https://structurae.net/structures/vihantasalmi-bridge IMAGE 54: Downtown East Pedestrian Bridge Foundations for U.S Bank Stadium. (n.d.). Retrieved from https://lsblack.com/project-post/downtown-east-pedestrianbridge-u-s-bank-stadium/

130

References

IMAGE 60: Cómo impermeabilizar el casco de una pequeña embarcación de madera. (n.d.). Retrieved from http://www.barcosyatesveleros.com/como-impermeabilizarel-casco-de-una-pequena-embarcacion-de-madera/ IMAGE 61: New build case studies. (2018, January 23). Retrieved from http://www.johnsonandloftus.co.uk/new-build-case-studies/ IMAGE 64: Epoxycraft. (2015, October 23). Wooden boat repair: Double diagonal hull planking, part II. Retrieved from http://www.epoxycraft.com/wooden-boat-repairdouble-diagonal-hull-planks-part-ii/ IMAGE 66: Boatbuilding, N. S. (2014, March 18). IMG_4044 - Port Hadlock WA - Northwest School of Wooden Boatbuilding - Traditional Small Craft - 12-foot doubleended Davis Boat - caulked, plank replaced. Retrieved from https://www.flickr.com/photos/nwswb/13242017703 IMAGE 67:Shetland Amenity Trust. (n.d.). Retrieved from https://www.shetlandamenity.org/shetland-traditional-boat-building-skills-project IMAGE 68: Buat boat. (n.d.). Retrieved from http://boeboatoetan.blogspot.mx/2015/05/flat-bottom-plywood-boat-plans-must-see.html IMAGE 69: 14’5 Iain Oughtred gunter rigged sailing dinghy - Anna Raussmuller. (n.d.). Retrieved from https://www.boatbuildingacademy.com/boats/145-iain-oughtredgunter-rigged-sailing-dinghy IMAGE 70: Build Stitch And Glue Drift Boat Plans DIY PDF downloadable woodworking plans. (2015, May 14). Retrieved from https://savory06lli.wordpress. com/2015/05/14/build-stitch-and-glue-drift-boat-plans-diy-pdf-downloadable-woodworking-plans/ IMAGE 71:Noland, J. (2010, February 10). The Glue in Stitch-and-glue Boatbuilding. Retrieved from https://www.pinterest.com.mx/pin/526921225142011344/ IMAGE 72: Thread: How fast can I build a dinghy? (n.d.). Retrieved from http://www.ybw.com/forums/showthread.php?260891-How-fast-can-I-build-a-dinghy/ page3&s=c9bc59f15b0a5a5ab28338ba9fc63a1a IMAGE 73: Cold Molding Boat Building. (n.d.). Retrieved from http://gethomenow.us/cold-molding-boat-building/ IMAGE 74: Hercules - Home. (n.d.). Retrieved from http://www.hercules.org.uk/ IMAGE 75-79: E. (2016, February 22). Types of Strip Plank Material. Retrieved from https://epoxyworks.com/index.php/types-of-strip-plank-material/ IMAGE 80:(n.d.). Retrieved from https://www.mcnarybergeron.com/project_highlights.php?id=35 IMAGE 81: OJP PUBLICATIONS. (n.d.). Retrieved from https://www.ncjrs.gov/App/Publications/AlphaList.aspx IMAGE 82: Boat Ribs. (n.d.). Retrieved from http://www.topix.com/album/detail/anacortes-wa/CDDPEG5IQ51DDOL4 IMAGE 83: Everything After Z. (n.d.). Retrieved from http://www.dictionary.com/e/s/word-of-the-year-list/ IMAGE 84: I. RÉSZ NAGYHAJÓK ÉPÍTÉSE. (n.d.). Retrieved from http://docplayer.hu/2030810-I-resz-nagyhajok-epitese.html IMAGE 85-87: Rezende, A. (1970, January 01). Diario de Bordo. Retrieved from http://diariodebordoparaty.blogspot.mx/2011/10/ IMAGE 90: Building Strip Plank Boats. (n.d.). Retrieved from https://jordanboats.co.uk/JB/strip_plank.htm IMAGE 91: Šiuolaikinės medienos paviršių apsaugos priemonės. (n.d.). Retrieved from http://lt.lt.allconstructions.com/portal/categories/70/1/0/1/article/8080/ siuolaikines-medienos-pavirsiu-apsaugos-priemones IMAGE 96: Wood texture, seamless repeat pattern. (n.d.). Retrieved from https://www.shutterstock.com/image-illustration/wood-texture-seamless-repeatpattern-54202234 IMAGE 97: M. (n.d.). Maple Wood Uses. Retrieved from https://sleepingbeauty0.blogspot.mx/2014/05/maple-wood-uses.html IMAGE 98:Wanderfit.co. (n.d.). Retrieved from http://wanderfit.co/types-of-wood-for-furniture/types-of-wood-for-furniture-different-types-wood-furniture-types-ofwood-furniture-styles/ IMAGE 99: (n.d.). Retrieved from https://www.reddogandcompany.com/the-mule-ear-chair-collection?lightbox=dataItem-il2i6cjl IMAGE 100:Basement Inspiring. (n.d.). Retrieved from http://vacances-paimpol.com/22939/raised-flooring-for-basement/tasty-raised-flooring-for-basementthermaldry-insulated-floor-decking-a-warm-dry-and-mold-free/ IMAGE 101: Z. (2017, December 04). Zorlag.com. Retrieved from http://zorlag.com/blog/outstanding-ideas-of-modern-kitchen-design-to-revive-your-cookingexperience/ IMAGE 102: Cherry Plywood A-4 Grade 5/32”x12”x12”. (n.d.). Retrieved from http://www.dndplywoodonline.com/cherry IMAGE 103: Teak Lumber - Teak Wood - East Teak Fine Hardwoods. (n.d.). Retrieved from http://www.eastteak.com/exotic-woods/teak-lumber/ IMAGE 104: Fondo De La Pared De Madera Marrón - Stock Foto e Imagen de Stock. (n.d.). Retrieved from https://www.istockphoto.com/mx/fotos/pine-brown-plywoodtexture?excludenudity=true&sort=mostpopular&mediatype=photography&phrase=pine brown plywood texture IMAGE 105: Q. (n.d.). Amtico Wood White Wash Wood 4 1/2. Retrieved from http://www.qualityflooring4less.com/amtico-wood-white-wash-wood-4-x-36-luxuryvinyl-tile-flooring.html IMAGE 106: 2. (n.d.). Retrieved from https://www.turningblanks.net/products/2x2x12-hickory-wood-spindle-turning-blank IMAGE 107: Beech (Fagus grandifolia). (n.d.). Retrieved from https://www.canadianwoodworking.com/get-more/beech-fagus-grandifolia IMAGE 108: Planed All Round European Beech Timber. (n.d.). Retrieved from https://www.britishhardwoods.co.uk/planed-timber-european-beech-wood.html IMAGE 109: Cream Colored Furniture. (n.d.). Retrieved from https://raisedgardenbed.club/read/cream-colored-furniture.html IMAGE 110: Plywood textures seamless. (n.d.). Retrieved from https://www.sketchuptextureclub.com/textures/architecture/wood/plywood IMAGE 111: Gill, P. (2016, October 07). How to Decorate a Room With a Cream Colored Sofa. Retrieved from http://homeguides.sfgate.com/decorate-room-creamcolored-sofa-60874.html IMAGE 112: W. (2016, June 26). Monday Drift For Sanity (37 Pictures). Retrieved from http://www.cruisingoutpost.com/2013/02/monday-drift-sanity-37-pictures/ IMAGE 113: Essentials Weathered Nailhead Plank 33’ x 20.5” Wood Wallpaper Roll. (n.d.). Retrieved from https://www.wayfair.com/decor-pillows/pdp/brewster-homefashions-essentials-weathered-nailhead-plank-33-x-205-wood-wallpaper-roll-bzh7925.html IMAGE 114: Boat Maintenance. (n.d.). Retrieved from https://www.go-sail.je/boat-maintenance.html IMAGE 115: 1.0 Biomimetics. (n.d.). Retrieved from http://www.andres.harris.cl/about/32-2/ IMAGE 116: 1.0 BIOMIMETICS. (n.d.). Retrieved from http://www.andres.harris.cl/about/32-2/IMAGE 117: PRJ - Bread Box Competition. (n.d.). Retrieved from https:// www.pinterest.co.uk/pin/408209153700182243/ IMAGE 118-125: Sean Gaffney/. (n.d.). Retrieved from http://www.gaffney-nguyen.com/index.php/project/duck-work/ IMAGE 126- 130: Annen Project | EPFL. (2017, October 19). Retrieved from https://ibois.epfl.ch/page-139248-en.html IMAGE 131-134: Bend9 – Bending-Active design at Pier 9. (n.d.). Retrieved from https://www.itke.uni-stuttgart.de/archives/portfolio-type/bend9-bending-activedesign-at-pier-9 IMAGE 134-137: Robot-Made: Large-Scale Robotic Timber Fabrication in Architecture. (n.d.). Retrieved from http://icd.uni-stuttgart.de/?p=21333 IMAGE 138-141: Tag: Fabrication. (n.d.). Retrieved from http://digitalstructures.mit.edu/categories/fabrication IMAGE 142-145: ICD/ ITKE Research Pavilion 2015-16 is based on sea-urchin shells. (2017, December 10). Retrieved from https://www.arch2o.com/icd-itke-researchpavilion-2015-16-based-sea-urchin-shells/ IMAGE 146-149: Robot-Made: Double-Layered Elastic Bending. (n.d.). Retrieved from http://icd.uni-stuttgart.de/?p=17102 IMAGE 150-153: Freeform Catalan Thin-tile vault. (n.d.). Retrieved from http://chidostudio.com/2011/09/28/freeform-catalan-thin-tile-vault/ 131

BENDING BRIDGES

IMAGE 154-157: Pabellรณn de fibra de carbono basado en el caparazรณn de un escarabajo. (n.d.). Retrieved from http://www.iiarquitectos.com/2014/09/pabellonde-fibra-de-carbono-basado-en.html IMAGE 158-161: (n.d.). Retrieved from http://theobject.co/research/a-bridge-too-far/ IMAGE 162: Popularwoodworkingcom. (2018). Popularwoodworkingcom. Retrieved 16 February, 2018, from https://www.popularwoodworking.com/wpcontent/uploads/1202_TT_2_Steamer999.jpg IMAGE 163: Home. (n.d.). Retrieved April 19, 2018, from http://www.chuckswoodbarn.com/ IMAGE 164: Googleapiscom. (2018). Googleapiscom. Retrieved 28 February, 2018, from https://storage.googleapis.com/wzukusers/user-16976444/ images/5647d8b4258d8XCSlLFp/Avanto-Architects-UK-and-Sweden.jpg IMAGE 165: Achimmengesnet. (2018). Achimmengesnet. Retrieved 28 February, 2018, from http://www.achimmenges.net/?p=5003 IMAGE 166: Designboomcom. (2018). Designboomcom. Retrieved 28 February, 2018, from https://www.designboom.com/wp-content/uploads/2016/12/tomraffield-steam-bent-wooden-home-cornwall-england-designboom-02.jpg IMAGE 167: Inhabitatcom. (2018). Inhabitatcom. Retrieved 19 April, 2018, from https://inhabitat.com/wp-content/blogs.dir/1/files/2013/03/Pieta-LindaAuttila-Curvy-WISA-Wooden-Design-Hotel-1.jpg IMAGE 168: Inhabitatcom. (2018). Inhabitatcom. Retrieved 28 February, 2018, from https://inhabitat.com/wp-content/blogs.dir/1/files/2013/03/WISA-Hotel. jpeg IMAGE 169: Pinterestcommx. (2018). Pinterest. Retrieved 15 February, 2018, from https://www.pinterest.com.mx/pin/652388695992855906/ IMAGE 170: Aromacookerycom. (2018). Aromacookerycom. Retrieved 15 February, 2018, from http://aromacookery.com/wp-content/uploads/2010/04/ nanxiang-04.jpg IMAGE 171: Googleapiscom. (2018). Googleapiscom. Retrieved 15 February, 2018, from https://storage.googleapis.com/wzukusers/user-16976444/ images/566a299075a342dLrsa2/Richard-Deacon-restless1536LS_d1450.jpg IMAGE 172: Googleapiscom. (2018). Googleapiscom. Retrieved 15 February, 2018, from https://storage.googleapis.com/wzukusers/user-16976444/ images/566a2957ac46eYwFGqZT/Richard-Deacon-with-Matthew-Perry-Still-water-2009.jpg IMAGE 173: Etsystaticcom. (2018). Etsystaticcom. Retrieved 15 February, 2018, from https://img1.etsystatic.com/001/0/5834119/il_fullxfull.391729597_36xe.jpg IMAGE 174: NA, . (2018).Retrieved 15 February, 2018, from https://storage.googleapis.com/wzukusers/user-16976444/images/5647d9b9a7472LqjTsK2/SethRolland-1-USA_1450.jpg IMAGE 175: Woodsmithexperiencecouk. (2018). Woodsmithexperiencecouk. Retrieved 15 February, 2018, from http://woodsmithexperience.co.uk/uploaded/ thumbnails/db_file_img_1123_1000x1000.jpg IMAGE 176: Googleapiscom. (2018). Googleapiscom. Retrieved 19 April, 2018, from https://storage.googleapis.com/wzukusers/user-16976444/ images/5647d9b9a7472LqjTsK2/Seth-Rolland-1-USA_1450.jpg IMAGE 177: Handril. Architecturendesignnet. (2018). Architecturendesignnet. Retrieved 15 February, 2018, from https://cdn.architecturendesign.net/wp-content/ uploads/2016/06/3b.-Photography-by-ITAY-SIKOLSKI-The-reception-desk-was-conceived-as-the-starting-point-for-the-spiraling-wooden-sculpture-completed-with-the-same-wooden-profiles-as-the-railings2.jpg IMAGE 178: Milledcom. (2018). Milled. Retrieved 15 February, 2018, from https://milled.com/touchofmodern/twisting-wood-furniture-vintage-rolex-for-herfuture-maps-practical-electronics-fKF8rDRlseDGITqg IMAGE 179: Designboomcom. (2018). Designboomcom. Retrieved 15 February, 2018, from https://www.designboom.com/wp-content/uploads/2016/12/tomraffield-steam-bent-wooden-home-cornwall-england-designboom-08.jpg IMAGE 180: Designboomcom. (2018). Designboomcom. Retrieved 28 February, 2018, from https://www.designboom.com/wp-content/uploads/2016/12/tomraffield-steam-bent-wooden-home-cornwall-england-designboom-02.jpg IMAGE 181: (n.d.). Retrieved April 19, 2018, from https://woodgears.ca/toys/curvy_board.html IMAGE 182: Woodworking How-To. (n.d.). Retrieved April 19, 2018, from https://www.woodmagazine.com/woodworking-how-to IMAGE 183: Popularwoodworkingcom. (2018). Popularwoodworkingcom. Retrieved 28 February, 2018, from https://www.popularwoodworking.com/wp-content/ uploads/12918_5F00_lead2.jpg IMAGE 184: Steam Bent Music Stand. (2015, February 19). Retrieved April 19, 2018, from https://www.popularwoodworking.com/projects/steam-bent-musicstand IMAGE 185: 3mm SOLID OAK WOOD SHEET - 14.5cm wide. (n.d.). Retrieved February 21, 2018, from https://www.sketchlasercutting.co.uk/products/3mmsolid-oak-wood-sheet-14-5cm-wide IMAGE 186: Pinewood City - United States HD Wallpapers and Photos | http://www.vivowallpaper.com/. (n.d.). Retrieved February 21, 2018, from http://www. vivowallpaper.com/wallpaper/pinewood-08080 IMAGE 187. Yellow Birch. (n.d.). Retrieved February 21, 2018, from http://www.wood-database.com/yellow-birch/ IMAGE 188: Douglas-Fir. (n.d.). Retrieved February 21, 2018, from http://www.wood-database.com/douglas-fir/ IMAGE 189: Here, Y. N. (n.d.). Product Customizations Wood Species Archive. Retrieved February 21, 2018, from http://www.moslowwood.com/productcustomizations/wood-species/ IMAGE 190: Spruce Wood. (n.d.). Retrieved February 21, 2018, from https://flyingarchitecture.com/materials/spruce-wood IMAGE 191: A. (2016, March 15). Cherry Is a Popular Domestic Wood for Cabinets. Retrieved February 21, 2018, from https://www.woodworkingnetwork.com/ wood/wood-month/cherry-considered-best-domestic-cabinet-wood IMAGE 192: Categories. (n.d.). Retrieved February 21, 2018, from https://www.designyourwall.com/products/hemlock-self-adhesive-wood-wall-contact-paper200x2235-pr-2150 IMAGE 193: Popularwoodworkingcom. (2018). Popularwoodworkingcom. Retrieved 16 February, 2018, from https://www.popularwoodworking.com/wp-content/ uploads/1202_TT_2_Steamer999.jpg IMAGE 194: Homerightcom. (2018). Homerightcom. Retrieved 28 February, 2018, from https://www.homeright.com/sites/default/files/images/products/120405_ SteamMachine 1934 1.jpg IMAGE 195: Shopifycom. (2018). Shopifycom. Retrieved 28 February, 2018, from https://cdn.shopify.com/s/files/1/0827/1293/files/blog_MBTF30V-1. jpg?4118231615851903515 IMAGE 196: Squarespacecom. (2018). Squarespacecom. Retrieved 28 February, 2018, from https://static1.squarespace.com/static/56da1835d51cd4e7253eee0e/t/ 572967d122482eafc958cdaa/1462331581266/?format=500w IMAGE 197:Directindustrycom. (2018). Directindustrycom. Retrieved 28 February, 2018, from http://www.directindustry.com/prod/incoplan-srl/ product-115171-1821440.html

132

References

IMAGE 198: Wordpresscom. (2015). Tame15ght. Retrieved 28 February, 2018, from https://tame15ght.wordpress.com/2015/03/14/how-to-make-a-woodsteamer-plans-free-download/ IMAGE 199: Lumberjockscom. (2018). Lumberjockscom. Retrieved 28 February, 2018, from http://lumberjocks.com/assets/pictures/projects/47896.jpg IMAGE 200: Insulated Steam Chamber - Wood Bending. (2018). YouTube. Retrieved 28 February, 2018, from https://www.youtube.com/ watch?v=Qz6A4FFcQA4 IMAGE 201: Plastic and Non Metallic Machining. (n.d.). Retrieved April 19, 2018, from http://www.atlasfibremachining.com/mat_we_mach.html IMAGE 202: Johnston, V. (2015, November 20). What Causes Hoses to Become Swollen? Retrieved April 19, 2018, from https://www.yourmechanic.com/ article/what-causes-hoses-to-become-swollen IMAGE 203: M. (n.d.). Walnut Dowel 1/4” Round. Retrieved April 19, 2018, from https://www.woodcraft.com/products/walnut-dowel-1-4-round IMAGE 204: Steaming wood in plastic. (2018). YouTube. Retrieved 28 February, 2018, from https://www.youtube.com/watch?v=A0mUi0eflcI IMAGE 205: Shaon, A. I. (2017, July 30). Household gas users relieved of second price hike. Retrieved February 21, 2018, from http://www.dhakatribune. com/bangladesh/power-energy/2017/07/30/high-court-second-gas-prices/ IMAGE 206: Products. (2015, October 22). Retrieved February 21, 2018, from https://www.linn-high-therm.de/es/productos/induction-heating.html IMAGE 207: 3 METHODS TO BOIL WATER WITH THE POWER OF SUN. (2018). YouTube. Retrieved 1 March, 2018, from https://www.youtube.com/ watch?v=zGmJClTiAP8 IMAGE 208: Wikimediaorg. (2018). Wikimediaorg. Retrieved 28 February, 2018, from https://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/ Toaster-quartz_element.JPG/450px-Toaster-quartz_element.JPG IMAGE 209: Thermosensedirectcom. (2018). Thermosensedirectcom. Retrieved 28 February, 2018, from http://www.thermosensedirect.com/acatalog/ ht-625_l.jpg IMAGE 210: Quoracdnnet. (2018). Quoracdnnet. Retrieved 28 February, 2018, from https://qph.fs.quoracdn.net/main-qimg-a743bb50b2302081c26872fe a4026c4c-c IMAGE 211: Popularwoodworkingcom. (2014). Popular Woodworking Magazine. Retrieved 28 February, 2018, from https://www.popularwoodworking. com/projects/steam-bent-music-stand IMAGE 212: Netdna-sslcom. (2018). Netdna-sslcom. Retrieved 28 February, 2018, from https://22293-presscdn-pagely.netdna-ssl.com/wp-content/ uploads/12952_5F00_061.jpg IMAGE 213: Na, . (2018). MATERIALS. Retrieved 28 February, 2018, from https://22293-presscdn-pagely.netdna-ssl.com/wp-content/ uploads/12952_5F00_051.jpg IMAGE 214: Insulated Steam Chamber - Wood Bending.(2018). YouTube. Retrieved 28 February, 2018, from https://www.youtube.com/ watch?v=Qz6A4FFcQA4 IMAGE 215: Wordpresscom. (2015). Tame15ght. Retrieved 28 February, 2018, from https://tame15ght.wordpress.com/2015/03/14/how-to-make-a-woodsteamer-plans-free-download/ IMAGE 216: Wordpresscom. (2015). Tame15ght. Retrieved 28 February, 2018, from https://tame15ght.wordpress.com/2015/03/14/how-to-make-a-woodsteamer-plans-free-download/ IMAGE 217: Simplirme. (2018). Simplirme. Retrieved 28 February, 2018, from http://simplir.me/wp-content/uploads/2017/12/how-to-bend-woodbending-wood-without-steam-box.jpg IMAGE 218: Mitedu. (2018). Mitedu. Retrieved 28 February, 2018, from https://ocw.mit.edu/courses/architecture/4-296-furniture-making-spring-2005/ lecture-notes/demo3.jpg

2.9.2 Text Bibliography Types of Bridges Beam Bridge Facts, History and Design. (n.d.). Retrieved from http://www.historyofbridges.com/facts-about-bridges/beam-bridge/ Cantilever bridges - Design Technology. (n.d.). Retrieved from http://www.design-technology.org/cantileverbridges.htm Tied-arch Bridge Facts, History and Examples. (n.d.). Retrieved from http://www.historyofbridges.com/facts-about-bridges/tied-arch-bridge/ Posted: 05/27/2016 2:25 PM | Comments:. (2016, May 27). Provencher Bridge closing for maintenance this weekend. Retrieved from https://www.winnipegfreepress. com/local/provencher-bridge-closing-for-maintenance-this-weekend-381142591.html The top 10 most fabulous bridges in Israel. (n.d.). Retrieved from http://newyorkjewishguide.com/2016/12/15/the-top-10-most-fabulous-bridges-in-israel . (n.d.). World’s first multiple-span cable-stayed bridge to open in Hunan. Retrieved from http://www.chinadaily.com.cn/china/2016-10/25/content_27164952_3. htm#Content Second Vivekananda Bridge (Nivedita Setu) - Checking. (n.d.). Retrieved from https://www.sbp.de/en/project/second-vivekananda-bridge-nivedita-setuchecking/ Movable Bridges Types, Design and History. (n.d.). Retrieved from http://www.historyofbridges.com/facts-about-bridges/movable-bridge/ Cable-stayed Bridge - History, Facts and Types. (n.d.). Retrieved from http://www.historyofbridges.com/facts-about-bridges/cable-stayed-bridges/ Posted: 05/27/2016 2:25 PM | Comments:. (2016, May 27). Provencher Bridge closing for maintenance this weekend. Retrieved from https://www.winnipegfreepress. com/local/provencher-bridge-closing-for-maintenance-this-weekend-381142591.html Tower Bridge | London Attractions | Big Bus Tours. (n.d.). Retrieved from https://www.bigbustours.com/en/london/london-landmarks-tower-bridge/ Three-Segment Folding Bridge Kieler Hörn. (n.d.). Retrieved from https://www.sbp.de/en/project/three-segment-folding-bridge-kieler-hoern/ Pont Jacques Chaban-Delmas. (n.d.). Retrieved from http://www.bordeaux.fr/l31034 Kanakaris-Wirtl, I. (2011, April 06). Isthmia Submersible Bridge, Corinth, Greece. Retrieved from https://www.flickr.com/photos/bridgestream/5595335506/in/ photostream/ Swing Bridge, River Tyne. (2018, April 10). Retrieved from https://en.wikipedia.org/wiki/Swing_Bridge,_River_Tyne#/media/File:High_Level_Bridge_and_ Swing_Bridge_-_Newcastle_Upon_Tyne_-_England_-_14082004.jpg Dale, S. (2015, January 29). Watch: New look gondola at Middlesbrough’s Transporter Bridge takes its first test run. Retrieved from https://www.gazettelive.co.uk/ news/teesside-news/new-look-gondola-middlesbroughs-transporter-8537775 Balasubramanyam, C. (2009, September 09). The Four Major Types of Bridges | Hunker. Retrieved from https://www.hunker.com/12000117/the-four-majortypes-of-bridges Types of Bridges. (n.d.). Retrieved from http://www.historyofbridges.com/facts-about-bridges/types-of-bridges/engg/types-of-bridges/13195/

133

BENDING BRIDGES

Anupoju, S. (2017, March 08). Types of Bridges Based on Span, Materials, Structures, Functions, Utility. Retrieved from https://theconstructor.org/structuralengg/types-of-bridges/13195/ How bridges work. (2017, November 25). Retrieved from http://www.explainthatstuff.com/bridges.html Cantilever bridge. (n.d.). Retrieved from https://www.britannica.com/technology/cantilever-bridge Things You didn’t Know Chaotianmen Bridge - World Record Steel Arch Bridge | CivilDigital |. (2017, October 23). Retrieved from https://civildigital.com/thingsyou-didnt-know-chaotianmen-bridge-world-record-steel-arch-bridge/ Ikitsuki Bridge (Hirado, 1991). (n.d.). Retrieved from https://structurae.net/structures/ikitsuki-bridge Danhe Bridge. (n.d.). Retrieved from http://www.highestbridges.com/wiki/index.php?title=Danhe_Bridge (n.d.). Retrieved from https://www.mcnarybergeron.com/project_highlights.php?id=35 Bamboo Joints and Joinery Techniques. (n.d.). Retrieved from https://www.guaduabamboo.com/working-with-bamboo/joining-bamboo Types of Joints. (n.d.). Retrieved from http://bamboo.wikispaces.asu.edu/7. Types of Joints Bamboo Joints and Joinery Techniques. (n.d.). Retrieved from https://www.pinterest.com.mx/pin/397442735849615856/ The Musmeci Bridge. (2017, September 04). Retrieved from http://www.platform-ad.com/the-musmeci-bridge/ Bamboo bridges | Bamboo Architecture | Chiangmai Life Construction. (n.d.). Retrieved from https://www.bamboo-earth-architecture-construction.com/ portfolio-item/bamboo-bridges/ How to Bend Bamboo. (n.d.). Retrieved from https://www.guaduabamboo.com/working-with-bamboo/bending-bamboo Bridge Foundation Bridge abutment: http://wisconsindot.gov/dtsdManuals/strct/manuals/bridge/ch12.pdf Timber bridges connectors and joints: http://www.forum-holzbau.com/pdf/61_IHF_2014_Crocetti.pdf Anchorage to concrete: http://www.dot.ca.gov/hq/esc/techpubs/manual/bridgemanuals/bridge-design-aids/page/bda_5_81.pdf Lateral spreading: http://www.wsdot.wa.gov/research/reports/fullreports/874-2.pdf A. (n.d.). Anclajes. Retrieved from http://www.arquba.com/monografias-de-arquitectura/anclajes/ Cimentaciones Para Puentes. (n.d.). Retrieved from https://es.scribd.com/doc/23864128/Cimentaciones-Para-Puentes Manual de construcción de puentes de concreto: http://ri.ues.edu.sv/2076/1/Manual_de_construcci%C3%B3n_de_puentes_de_concreto.pdf Boat Construction An illustrated history. (n.d.). Retrieved from http://www.westsysteminternational.com/en/welcome/an-illustrated-history Clinker Boat History & Building(Michael Webb) Archived 2008-12-02 at the Wayback Machine.

Clinker and Carvel – different types of planking”. The Independent. Retrieved 2015-02-10.

Clinker Boat Building (Hobby.net.au Australia) Chisholm, Hugh, ed. (1911). “Clinker”. Encyclopædia Britannica. 6 (11th ed.). Cambridge University Press. p. 527.

Jorgensen et al. 2003 p299, The Spoils of Victory – the north in the shadow of the Roman Empire, Nationalmuseet Zori, Davide (2007). “Nails, RIvers, and Clench Bolts: A Case for Typological Clarity”. Archaeologia Islandica. 6: 32–47.

Greenhill, Basil (1976) Archaeology of the Boat (London: Adam and Charles Black Publishers Ltd) Greenhill, Basil, Morrison, John S. (1995) The Archaeology of Boats & Ships – An Introduction (London: Conway Maritime Press) McKee, Eric (1972) Clenched Lap or Clinker: An Appreciation of a Boatbuilding Technique (Greenwich: National Maritime Museum) Leather, John (1990) Clinker Boatbuilding (Adlard Coles) Harold “Dynamite” Payson. Build the New Instant Boats. International Marine. Camden. 1984. and Instant Boatbuilding with Dynamite Payson. International Marine. Camden. 2007.

“Stitch & Glue” Construction, Devlin Designing Boat Builders Accessed 29 November 2010 Jim Michalak’s Boat Designs. (n.d.). Retrieved from http://www.jimsboats.com/webarchives/2001/15jun01.htm Double Layered Shells Christopher Robeller, A Double-layered Timber Plate Shell Computational Methods for Assembly, Prefabrication and Structural Design. http://lgg.epfl.ch/ publications/2016/DoubleLayeredTimber/paper.pdf ANDRESHARRIS (2018). Biomimetics. http://www.andres.harris.cl/about/32-2/ Bend9-Bending-Active Design At Pier 9 | ITKE. (2016, February 17). Retrieved from https://www.arch2o.com/bend9-bending-active-design-pier-9-itke/ Robot-Made: Large-Scale Robotic Timber Fabrication in Architecture. (n.d.). Retrieved from http://icd.uni-stuttgart.de/?p=20124 (n.d.). Retrieved from http://www.lera.com/duck-work-boston Urban Timber: From seed to city. (n.d.). Retrieved from https://www.architects.org/bsaspace/exhibitions/urban-timber-seed-city Annen Project | EPFL. (2017, October 19). Retrieved from https://ibois.epfl.ch/page-139248-en.html Integral Mechanical Attachment for Timber Folded Plate Structures | EPFL. (2018, March 02). Retrieved from https://ibois.epfl.ch/op/edit/page-102318.html Biomimetic pavilion. (n.d.). Retrieved from https://www.domusweb.it/en/news/2016/05/10/icd_itke_research_pavilion.html Robot-Made: Double-Layered Elastic Bending. (n.d.). Retrieved from http://icd.uni-stuttgart.de/?p=17102 Mele, T. V. (n.d.). Free-form Catalan Thin-tile vault, Zurich, Switzerland. Retrieved from http://www.block.arch.ethz.ch/brg/project/free-form-catalan-thin-tilevault#bibtex_390 ICD-ITKE Research Pavilion 2013-14 / ICD-ITKE University of Stuttgart. (2014, July 08). Retrieved from https://www.archdaily.com/522408/icd-itke-researchpavilion-2015-icd-itke-university-of-stuttgart A Bridge Too Far. (2016, December 12). Retrieved from https://kadk.dk/case/bridge-too-far

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References

Wood Steaming Popularwoodworkingcom. (2014). Popular Woodworking Magazine. Retrieved 16 February, 2018, from https://www.popularwoodworking.com/projects/ steam-bent-music-stand Proquestcom. (2018). Proquestcom. Retrieved 16 February, 2018, from https://search.proquest.com/openview/9aa66ed205400cb1c502fa0e40fee50b/1? pq-origsite=gscholar Thomasnetcom. (2018). Thomasnetcom. Retrieved 16 February, 2018, from https://www.thomasnet.com/articles/process-equipment/how-to-steam Wordpresscom. (2013). Paleotechnics: Learn, Find, Make. Retrieved 16 February, 2018, from https://paleotechnics.wordpress.com/2013/03/27/bendingwood-what-you-need-to-know/ Leevalleycom. (2018). Leevalleycom. Retrieved 16 February, 2018, from https://www.leevalley.com/us/html/05F1501ie.pdf Learnsteambendingcom. (2018). Learnsteambendingcom. Retrieved 16 February, 2018, from http://www.learnsteambending.com/steam-bending Ncsuedu. (2018). Ncsuedu. Retrieved 16 February, 2018, from https://bioresources.cnr.ncsu.edu/BioRes_08/BioRes_08_4_4793_Wright_Bond_Chen_ Editorial_Steam_Bending_Wood_4447.pdf Fsfedus. (2018). Fsfedus. Retrieved 16 February, 2018, from https://www.fpl.fs.fed.us/documnts/usda/ah125.pdf Highlandwoodworkingcom. (2018). Woodworking Tools | Woodworking Supplies. Retrieved 28 February, 2018, from https://www.highlandwoodworking. com/buildingasteambox.aspx Woodworkjunkiecom. (2018). Woodworkjunkiecom. Retrieved 28 February, 2018, from https://woodworkjunkie.com/how-to-bend-wood-at-home-usingsteam-with-a-simple-diy-steam-box Thermaxxjacketscom. (2011). Thermaxx Jackets. Retrieved 28 February, 2018, from https://www.thermaxxjackets.com/5-most-common-thermalinsulation-materials/ Explainthatstuffcom. (2018). Explain that Stuff. Retrieved 28 February, 2018, from http://www.explainthatstuff.com/induction-cooktops.html VIDEO https://www.youtube.com/watch?v=COUBe18_f0s&index=1&t=0s&list=WL Thoughtcocom. (2018). ThoughtCo. Retrieved 28 February, 2018, from https://www.thoughtco.com/what-is-a-hygrometer-3444417 Hygrometernet. (2018). Hygrometer. Retrieved 28 February, 2018, from http://hygrometer.net/types-hygrometers-multiple-uses/ Quoracom. (2018). Quoracom. Retrieved 28 February, 2018, from https://www.quora.com/Art-of-Problem-Solving-How-can-we-find-water-level-in-awater-tank-without-climbing-over-it-to-check-the-water-level Highlandwoodworkingcom. (2018). Woodworking Tools | Woodworking Supplies. Retrieved 28 February, 2018, from https://www.highlandwoodworking. com/buildingasteambox.aspx Woodworkjunkiecom. (2018). Woodworkjunkiecom. Retrieved 28 February, 2018, from https://woodworkjunkie.com/how-to-bend-wood-at-home-usingsteam-with-a-simple-diy-steam-box Thermaxxjacketscom. (2011). Thermaxx Jackets. Retrieved 28 February, 2018, from https://www.thermaxxjackets.com/5-most-common-thermalinsulation-materials/ Explainthatstuffcom. (2018). Explain that Stuff. Retrieved 28 February, 2018, from http://www.explainthatstuff.com/induction-cooktops.html VIDEO https://www.youtube.com/watch?v=COUBe18_f0s&index=1&t=0s&list=WL Thoughtcocom. (2018). ThoughtCo. Retrieved 28 February, 2018, from https://www.thoughtco.com/what-is-a-hygrometer-3444417 Hygrometernet. (2018). Hygrometer. Retrieved 28 February, 2018, from http://hygrometer.net/types-hygrometers-multiple-uses/ Quoracom. (2018). Quoracom. Retrieved 28 February, 2018, from https://www.quora.com/Art-of-Problem-Solving-How-can-we-find-water-level-in-awater-tank-without-climbing-over-it-to-check-the-water-level

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