Constructing Environments: A01 -‐ Final Logbook ENVS10003 Juhyun Son 354978
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CONSTRUCTION The meaning of building construction is the process of preparing; planning, design and financing. In the first week, we have studied about materials for the construction, basic structural forces, site analysis, load path diagrams and bluestone that often used in construction in Melbourne. Moreover, we construct a tower by using MDF (Medium Density Fibreboard) to understand the nature and behaviour of modular mass construction and how loads can be transferred through the compression structures.
Figure 1 Construction site
Figure 2 knowledge map of construction
Materials-‐Melbourne’s bluestone Bluestone is the material of cultural or commercial or building stone varieties. It is often used in Melbourne’s construction. Building stone of bluestone is basalt that can easily found in volcanoes around Melbourne area. Basalt is used in construction because it is easy to find near Melbourne, however, sandstone is normally used in Sydney and clay for bricks and limestone is used in Perth. Basalt is commonly dark colouring, therefore, it makes city dark.
Figure 3 bluestones (basalt) with bubbles
Figure 4 knowledge map of Melbourne's bluestone (basalt)
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Basic structural forces The change in the shape or movement of a body can be determined as a Force. Both magnitude and direction need to be considered as a vector function by an arrow whose length is proportional to the magnitude and whose orientation in space represents the direction. In the construction, the force can be divided into tension forces and compression forces.
Figure 5 Force diagram
Figure 6 force diagram with description.
Tension forces Tension force is pulling force. For example, when a structural member is pulled over by an external load, it is moving apart and undergoes tension. It will cause the extension on a member depending on the stiffness of the material, cross sectional area, and the magnitude of the load. Tension can be determined as opposite of compression. Tension force on a structural member is most often used as it can span large distances.
Figure 7 tension force described by green colour
Figure 8 the changes of member shape after applied tension force
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Compression forces Compression forces on a structural member are pressed from each end of a member. It is the opposite effect of a tension force as mentioned above. It will cause the compaction of a member and the material will be shortened by compression force. Compression members are commonly used in columns.
Figure 11 Examples of the load path diagram on a structure
Figure 10 the shape changes after applied compression force
Figure 9 A compression force is pushing outward along the curve
Load path diagram For this part of studies, live load is the only one has to be considered. Live load is an applied load and it has to be considered how it transfers to the ground. When an applied load is placed on the beam, it only transfers to the column and reaction forces from the ground to stable the structure will support it.
Figure 12 Load path diagram of simple structure and description
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Site analysis One of the most important thing in construction is site planning. It includes the boundaries of architecture, landscape architecture, engineering, real-‐estate development, urban planning and economics. There are several points that significantly important for site analysis; location, neighborhood context, site and zoning, legal elements, natural physical features, utilities, human and cultural. Also, the climate is really important issues in construction, therefore, it is considered well by engineer’s site analysis.
Figure 13 Examples of site analysi
Figure 14 Examples of site analysis 2
Studio session-‐Mass Construction Tower (Pavilion) Build a Mass Construction Tower as high as possible using the least amount of MDF. There are two methods of constructing the MDF blocks; Stack Bond and Stretcher Bond. One of these methods has to be decided to construct a tower as high as possible. Our group has chosen the stretcher bond method because the force from upper block can be transferred to two different blocks that placed below. It will make the tower more stable. Furthermore, it will prevent the collapse of the tower even if we remove the blocks in the middle of the construction.
Figure 16 how the load transfer to the ground for each structure method
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Figure 15 Stretcher Bond method
One side of the tower should be open with the gate to obtain the object the size of 17blocks for the height 11 blocks for the width; however, our group has decided to construct a tower with one side open from the bottom to the top as shown in figure 17. Actually, the first designed tower was with the gate at the bottom. But the purpose of this workshop is to build a tower as high as possible with the least amount of blocks. Therefore, to obtain the object and build a tower as high as possible, the design has been changed as shown in following figures. Furthermore, the rubber band which makes the top of the gate stable makes the tower unstable when it gets higher.
Figure 17 A tower with whole side open
Figure 18 original design of our tower
The material that we used in this workshop is MDF (Medium-‐density fibreboard). The material is very strong and much more dense that particle board, therefore, it is often used as a building material similar in application to plywood. To test the stability of the tower, the blocks in the middle of the tower had been removed. The construction method was stretcher bond; therefore, the tower was really stable even if many blocks were removed in the middle. (Shown in the following figures)
Figure 19 The stability of the tower when the blocks are removed in the middle
Figure 20 Load path diagram shows the stability of the tower by transffering the load through the hole
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LOGBOOK By comparing the project with other group, the tower that we constructed was the highest and used the least amount of blocks. Nevertheless, all other groups had the gate at the bottom or in the middle of the tower. It causes other groups to take more time to get higher towers. Our group has chosen not to have a gate at the front, but the purpose of the constructing mass tower was to build a tower as high as possible by using the least amount of blocks.
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STRUCTURAL ELEMENT Structural Element is classified into strut, tie, beam and slab/plates. Each element has own distinct characteristics. Firstly, a strut is a slender element design to carry load parallel to its long axis. The load produces compression such as columns. A tie is a slender element design to carry load parallel to its long axis. The load produces tension such as a cable storey bridge. Figure 22 compression and tension in strut and tie
Figure 23 beam and slab diagrams in construction drawing Figure 21 Examples of tie and strut
A beam is generally a horizontal element designed to carry vertical load using its bending resistance. The load applies normally from the top middle of the beam and both end of the beam supports it. The slab/plate is a wide horizontal element designed to carry vertical load in bending usually supported by beams. The following diagrams and photos are presenting the beams and slabs.
Figure 24 Beam and slab/plate force diagram
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Foundations and Footings Foundations are found at the bottom of buildings where the building meets the ground. The foundations are the substructures of the building and their function is to safely transfer all loads acting on the building structure to the ground. Where parts of the substructure are located below the ground, the foundations must also resist the force of the soil pressing against the foundation or retaining walls. Settlement: over time, buildings compress the earth beneath them and the buildings tend to sink a little into the earth. Footings and foundations should be designed to ensure that this settlement occurs evenly and that the bearing capacity of the soil is not exceeded. Cracking in a building often occurs with differential settlement.
Figure 25 Foundations and Footings (ching)
Figure 27 Foundations and Footings in construction site
Figure 26 Foundations and footings reaction forces (ching)
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There are several types of footings: Shallow Footings: are used where soil conditions are stable and where the required soil bearing capacity is adequate close to the surface of the ground. Load is transferred vertically from the foundation to the ground. Deep foundations: are used where soil conditions are unstable or where the soil bearing capacity is inadequate. Load is transferred from the foundations, through the unsuitable soil and down to levels where bed rock, stiff clay, dense sand/gravel is located. Pad Footings: also called isolated footings, these types of footings help to spread a point load over a wider area of ground. Strip footings: used when loads from a wall or a series of column are spread in a linear manner. Raft foundation: sometimes also called a raft slab, this type of foundation provides increased stability by joining
the individual strips together as a single mat.
Figure 29 Examples of footing (www.sustland.umn.edu)
Figure 28 Different types of footings (ching)
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Deep foundations Deep foundations can generally be divided into two types: End bearing piles: extend the foundations down to rock or soil that will provide support for the building loads. Friction piles: rely on the resistance of the surrounding earth to support the structure. Various methods and materials can be used for constructing these piles, including: -‐ Driving along timber, steel or concrete members into the ground -‐ Drilling into the ground and then filling the hole with concrete (cages of steel reinforcing are of the placed into the holes before the holes are filled with concrete).
Figure 31 Showing the installations of deep foundations (astm.nufu.eu)
Figure 30 installations of deep foundations (ching)
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LOGBOOK Retaining and foundation walls Are used when sites are excavated to create basements or where changes in site levels need to be stabilized. The pressure load of the earth behind the wall needs to be considered to prevent the wall from overturning.
Figure 32 Retaining walls in LA (www.ultimate-‐ handyman.com)
Figure 33 Retaining and foundation walls (ching)
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Mass Materials These materials are stone, earth, clay and concrete. Stone is a hard material that resists abrasion – scratching and blasting. Earth is compressive strength. Clay is good material for thermal mass. Lastly, Concrete is durable materials. Mass construction can be divided into Modular/Non-‐modular. Modular: clay brick, mud brick (adobe), concrete block, Ashlar stone. Non-‐Modular: concrete, rammed earth, monolithic stone (columns & beams)
Figure 34 Mass construction in site (www.eugenef.com)
Figure 35 knowledge map of mass construction
Masonry materials It refers to building with units of various natural or manufactured products. It is also usually with the use of mortar as a bonding agent. In the details of masonry materials, bond is the pattern or arrangement of the units and course is a horizontal row of masonry units. Joint is the way units are connected to each other. Lastly mortar is mixture of cement or lime, and water used as a bonding agent. The properties of the unit are to a degree applicable to the built element. In other words, the units together act as a monolithic whole.
Figure 36 knowledge map of masonry materials
Figure 37 Examples of masonry concrete joint (www.sustainableconcrete.org)
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Geometry and Equilibrium Equilibrium is a state of balance or rest resulting from the equal action of opposing forces. In other words, as each structural element is loaded, its supporting elements must react with equal but opposite forces. For an object to be in equilibrium, any applied forces must be resisted by equal and opposite forces. These forces are called reaction forces. In a building structure, the reaction forces are developed in the supporting elements.
Figure 39 Example of force equilibrium
Figure 38 Equilibrium diagram (Ching, 'Building construction illustrated', p2.12 (2008)
Free Body Diagrams Objects or systems in equilibrium can be represented in diagrammatic from called free body diagrams. Applied force and reaction forces should be the same amount would cause the equilibrium of the structure. The following diagrams/pictures will show the equilibrium and free body diagrams.
Figure 40 Free body diagram (en.wikiversity.org)
Figure 41 Free body diagram in a beam
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Bricks Bricks are very common material in Australia. A standard size masonry unit made out of clay. It proportions may vary slightly depending on types and countries but it will always be a hand sized unit. Clay bricks are manufactured from clay or shale that is shaped and then hardened by a firing process. As one of the oldest building materials the uses are very broad. Main uses today include walls, arches and paving.
Figure 42 3 main types of brick (e-‐learning)
Figure 43 different bond patterns of bricks (e-‐ learning)
Joints-‐clay bricks Mortar joints are usually 10mm (vertical joints are called perpends and horizontal joints are called bed joints). There are a range of joint finishing profiles that are selected depending on the type of brick, weather exposure and aesthetics.
Figure 44 CLAY BRICKS (E-‐LEARNING)
Properties of Bricks -‐ Hardness: med to high. Can be scratched with a metallic object -‐ Fragility: medium. Can be broken with trowel -‐ Ductility: very low ductility -‐ Flexibility/ plasticity: very low flexibility and plasticity -‐ Porosity/ permeability: med to low. Becomes soaked only if placed in prolonged contact with water -‐ Density: medium. Approximately 2~2.5 times more dense than water -‐ Conductivity: poor conductors of heat and electricity -‐ Durability/ life span: typically very durable -‐ Reusability/ recyclability: high. Can be re-‐used with no change or crushed to be used as recycled aggregate -‐ Sustainability & carbon footprint: tends to be locally produced. The firing process adds to its carbon footprint -‐ Cost: generally cost effective but required labour costs Ju Hyun Son-‐354978 23
Concrete blocks A standard size masonry unit made out of concrete. There is a large range of sizes and proportions available in order to suit different purposes. Concrete blocks are manufactured from cement, sand, gravel and water. The manufacture process involves mixing, moulding and curing.
-‐ Figure 46 brick details drawing
Figure 45 Concrete blocks (e-‐learning)
Concrete blocks have several different styles such as hollow and solid. It can be classified as load-‐bearing or non-‐load bearings are used. Load bearing block is known as a concrete masonry unit.
Properties of concrete blocks -‐ Hardness: med to high. Can be scratched with a metallic object -‐ Fragility: medium. Can be broken with trowel -‐ Ductility: very low ductility -‐ Flexibility/ plasticity: very low flexibility and plasticity -‐ Porosity/ permeability: medium. Some concrete blocks are sealed to reduce the opportunity for water absorption -‐ Density: medium. Approximately 2 to 2.5 times more dense than water -‐ Conductivity: poor conductors of heat and electricity
Durability/ life span: typically very durable Reusability/ recyclability: medium. Sometimes reused with no change but more often crushed to be used as aggregate in other concrete products Sustainability& carbon footprint: inclusion of recycled and waste products from other processes is allowing a positive reduction in carbon footprint and increase in sustainability for many concrete products Cost: generally cost effective but labour penalties are often applied as the larger format units mean construction usually progresses at a faster rate
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Activity: on site 1. Lot 6 café The building is supported by concrete column and concrete slabs. And the structure of the building is a solid structure.
Figure 48 Lot 6 café
2. Underground carpark & south lawn Underground car park had been designed by engineering practice and its placed under south lawn. All the columns of underground car park are hollow type and it is designed as water can be drained through column. Also, there are steel inside of the concrete column its called In situ. The following photos are showing the cracks on concrete columns.
3. Arts west centre
Figure 50 Arts west centre
Figure 47 load transfer from concrete column to I beam
Figure 51 load transfer diagram for figure 50
Figure 49 Concrete cracks in column
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4. Stairs on west end of union house It is designed membrane structure. It looks like the wires are holding the stairs like a cable storey bridge. However, in fact, it is not actually holding it. These wires are for just visualization.
5. North court Union house There is a hole for the water to drain.
6. Beaurepaire centre pool The structure is visible for this building. And the window has a steel portal frame. There is no resistance to lateral load like wind and the brick walls are holding the structure at the back.
Figure 54 northcourt
Figure 52 stairs
Figure 55 water drained diagram
Figure 53 visual designed stairs with wire
Figure 56 window steel frame and the brick wall
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Figure 58 running the construction
Figure 57 visible structure
8. New Melbourne school of design under construction New architecture building is in-‐ situ steel and it has two types of governised.
7. Oval pavilion It will be more discussed in the other activities.
Figure 59 New architecture building
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LOGBOOK Glossary 1. Moment -‐ In physics, moment relates to the perpendicular distance from a point to a line or a surface, and is derived from the mathematical concept of moments. It is frequently used in combination with other physical quantities as in moment of inertia, moment of force, moment of momentum, magnetic moment and so on. 2. Retaining wall -‐ Retaining walls are structures designed to restrain soil to unnatural slopes. They are used to bound soils between two different elevations often in areas of terrain possessing undesirable slopes. 3. Pad footing -‐ This carries point loads where the columns come down and is used a lot in portal frames. Piles can be placed on problem sites under the pad. This system allows the portal frame to be put up quickly with the slab able to be placed after.
4. Strip footing -‐ This runs under load bearing walls, which need supporting along their whole length. Strip footing would be used for example under precast concrete panels. 5. Slab on ground The slab on the ground is constructed similar to the stiffened raft, however, it does not require internal stiffening beams and can only be constructed on class A or class S sites. 6. Substructure -‐ The supporting part of a structure; the foundation -‐ The earth bank or bed supporting railroad tracks -‐ A structure forming a foundation or framework for a building or other construction
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Span and spacing Span is the distance measured between two structural supports. It can be measured between vertical supports (horizontal member) or between horizontal supports (vertical member). It is not necessarily the same as the length of a member. Spacing is the repeating distance between a series of like or similar elements. It is often associated with supporting elements (such as beams, columns etc.) and can be measured horizontally or vertically. Spacing is generally measured center-‐line to center-‐line.
Figure 60 Span and Spacing in structure (nationalvetcontent.edu.au)
Figure 61 Span & Spacing in structure
Floor system: Concrete, steel & timber Concrete systems-‐slabs of various types are used to span between structural supports. These can be one-‐way or two-‐ way spans. Steel systems: Steel framing systems take various forms; with some utilising heavy gauge structural steel members & other using light gauge steel framing. In many instances a combination of member types & materials are combined depending on their structural function. Steel framing systems sometimes combine with concrete slab systems to
where the particular benefits of steel framing & shallow depth floor slab systems are desired. The spanning capabilities of the particular materials help to determine the spacing requirements of the supports. Timber systems: traditional timber floor framing systems use a combination of bearers (primary beams) & joists (secondary beams). The span of the bearers determines the spacing of the piers of stumps & the spacing of the bearers equals the span of the joists.
Figure 62 concrete floor slab (http://www.tn173.com/)
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Figure 63 Steel framing system ( http://www.steelframingsystems.com.au/)
Figure 64 Timber framing system (http://steelmax.com.au/)
Concrete: Component When cement is mixed with water it binds the sand and gravel aggregates together to make the hard, solid material we call concrete. A common concrete mix is: -‐ Part cement: Portland, Lime -‐ Parts fine aggregate: Sand -‐ Parts coarse aggregate: Crushed rock -‐ 0.4-‐0.5 part water
Figure 65 concrete components (e-‐learning)
Concrete: Provenance When the cement powder and water are mixed, a chemical reaction takes place and heat is released. This process is called hydration. During this process crystals are formed that interlock and bind the sand, crushed rock and cement/water paste together. If too much water is added to the concrete mix, the final concrete will not be strong enough (weak). If too little water is added, the concrete mixture will be too stiff and it will be very difficult to work with (unworkable).
Figure 66 materials of cast concrete provenance ( http://www.examiner.com/article/experience-‐ the-‐nature-‐of-‐sculpture-‐the-‐nathan-‐manilow-‐ sculpture-‐park)
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Concrete: Process One of the great advantages of concrete is fluid and shapeless before it hardens. It can be formed in to any shape we desire. Formwork is the term used for the temporary support or a mould used to hold the liquid concrete in place unit it becomes hard. It can be built at the building site as IN SITU/ PRE-‐CAST with a range of different materials such as timber, metal, plastic, form-‐ply etc. Wall formwork process: -‐ Spreaders: keep formwork apart -‐ Formwork ties -‐ Plywood sheating -‐ Inner surface of panels leaves an impression on concrete -‐ Timber studs -‐ Horizontal walers reinforce the vertical members -‐ Sill plate -‐ Bracing
Figure 67 wall formwork process ( ching)
During the curing process the formwork needs to be supported as the weight of the wet concrete is very heavy. Props and bracings of various types could be used to achieve. Concrete generally reaches 75% of its compressive strength in approximately 7days by testing for the require strength causing 28 days. The formwork can be removed carefully since the concrete is hardened and strong enough.
Figure 68 Examples of concrete ( www.brighthubengineering.com)
Figure 69 Concrete finishes (e-‐learning)
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Concrete: Reinforcement Concrete is also known as ‘artificial stone’. It is showing that the concrete and stone are the similar materials. It is very strong in compression but it is weak in tension. To improve tension forces, steel reinforcement is required in the form of mesh or bars. Properties of concrete: -‐ Hardness: High, can be scratched with a metallic object -‐ Fragility: Low, can be chipped with a hammer -‐ Ductility: Very low ductility -‐ Flexibility/ Plasticity: Low flexibility and plasticity -‐ Porosity/ Permeability: Med, Depending on proportions and components (aerated or high water ratio concrete has a high porosity vs waterproof concrete that is created when permeability reducing admixtures are included in the concrete mix -‐ Density: Med to High, Approximately 2.5 more dense that water -‐ Conductivity: Poor conductor of heat and electricity
Durability/ Life span: Typically very durable Reusability/ Recyclability: Med to Low. Can be partially re-‐used when crushed to be used as aggregate for new concrete elements Sustainability & carbon footpring: High embodied energy. Non-‐renewable. Long Lasting Cost: generally cost effective. Labor dependent for formwork & pouring
Figure 70 Process of reinforcement concrete (dspace.jorum.ac.uk)
Concrete: Considerations One of the main issues is that the concrete is permeable material but it is not completely waterproof. Therefore, the steel bars cannot be protected from moisture and oxidation if it is close to the surface. It can occur both aesthetic and structural degradation of the concrete. Another issue is poor vibration of the concrete while the pouring is processing. Bubbles can compromise the structural performance of the element and, in a worst case scenario will result in the element failing.
Figure 71 reinforcement concrete failing (inhabitat.com)
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Beams A Beam is mostly horizontal structural element. A beam can carry loads along the length of the beam and transfer the load to the columns. A beam normally can process: -‐ Supported at both ends of the beam -‐ Supported at numerous points along the length of beam -‐ Supported at points away from the ends of the beam -‐ Supported at only one end of the beam
Figure 72 force tramsfer along the beam (ching)
Figure 73 Beam and column joints (www.condor-‐ rebar.com)
Cantilevers A cantilever is created when a structural element is supported at only one end. The function of a cantilever is: -‐ Carrying loads along the length of the member and transfer these loads to the support. -‐ Horizontal -‐ Vertical -‐ Angled
Figure 74 Examples of cantilever (Ching)
Figure 75 Cantilever beam load transfer to column
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IN SITU CONCRETE It has been poured into formwork and cured on the building site. This process includes: -‐ Fabrication and assembly of the formwork -‐ Placing any required reinforcement -‐ Pouring -‐ Vibration and the curing of the concrete There is a limited time to harden the concrete to become unworkable to ensure that the concrete is placed in the proper position since the concrete has been poured. (Note: the air bubbles removed and the desire finish applied)
Figure 76 Uses of IN SITU CONCRETE (e-‐learning)
Uses of IN SITU In situ concrete is a great many applications. It is generally used for structural purposes: -‐ Footings -‐ Retaining walls -‐ Bespoke (nonstandard) -‐ Structural element Sometimes it is used as: -‐ Landscapes -‐ Swimming pools -‐ Basement walls between piers or overhead surfaces.
Figure 77 Examples of insitu concrete uses (e-‐ learning)
Joints There are construction joints and control joints: -‐ Construction joints are used to divide the construction into smaller and more manageable sections of work. -‐ Control joints are required to absorb the expansions and contractions that thermal variations cause and the long term tendency of concrete to shrink over time. The elongation/shrinkage is proportional to the temperature differential, the material coefficient and the dimensions of the piece. These joints are potential weak points and must ensure that be detailed appropriately, expecially in terms of water and moisture control
Figure 78insitu concrete joints (www.praton.com)
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PRE-‐CAST CONCRETE The concrete has been fabricated in a controlled environment and then transported to site for installation can be called as pre-‐cast concrete. It may avoid many of the quality control issues associated with in situ concrete. These elements also allow work on site to progress at a much faster rate.
Figure 81 uses of pre-‐cast concrete (e-‐learning)
Figure 80Pre-‐cast concrete processing (www.mhmarketingsalesmanagement.com419)
Figure 79 process of pre-‐cast concrete (Ching)
Uses of Pre-‐cast concrete It is widely used in many different applications such as: -‐ The structure of a building -‐ Bridge or civil works -‐ Forming part of the primary -‐ Rarely used in footings -‐ Common in retaining walls, walls and columns
Joints-‐pre-‐cast concrete There are two types of joints for pre-‐cast concrete such as: -‐ Construction joints: the panel/element nature of pre-‐cast concrete mean that joints naturally occur when on precast element meets another -‐ Structural joints: the type and performance of the structural connections joining the precast elements to each other and to other parts of the structure are critical for the overall performance of the building. It depends on the desired aesthetic outcome.
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Figure 83 Pre cast concrete finishes (e-‐learning)
Figure 82 Pre cast concrete panel (gsacriteria.tpub.com)
Activity: Oval pavilion will be discussed more in later week.
Considerations of Pre-‐cast concrete These elements can be limited in size due to transport. It is very difficult to incorporate on site changes.
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LOGBOOK Glossary 1. Joist -‐ In architecture and engineering, a joist is one of the horizontal supporting members that run between foundations, walls, or beam to support a ceiling or floor. They may be made of wood, engineered wood, steel, or concrete. Typically, a beam is bigger than a joist and beams lay out in repetitive patterns often support joists. 2. Steel decking -‐ A structural steel deck plate is stiffened either longitudinally or transversely, or in both directions. This allows the deck both to directly bear vehicular loads and to contribute to the bridge structure’s overall load-‐ bearing behavior. 3. Span Span is the distance between two intermediate supports for a structure, e.g. a beam or a bridge. A span can be closed by a solid beam or by a rope. The first kind
is used for bridges, the second one for power lines. 4. Girder -‐ A girder is a support beam used in construction. Girders often have an I-‐beam cross section for strength, but may also have a box shape, Z shape or other forms. 5. Concrete plank -‐ is a precast slab or pre-‐stressed concrete typically used in the construction of floors in multi-‐ storey apartment buildings. 6. Spacing -‐ In architecture and structural engineering, a space frame or spacing is a truss-‐like, lightweight rigid structure constructed from interlocking struts in a geometric pattern. Spacing can be used to span large areas with few interior supports.
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SHORT AND LONG COLUMNS Columns are vertical structural members designed to transfer axial compressive loads. It can be divided into Short and long column. Short columns: -‐ The ratio of effective column length to the smallest cross section dimension is less than 12:1 -‐ Structurally adequate if the load applied to the column cross section does not exceed the compressive strength of the material. -‐ Become shorter when a compressive load is applied. It can be failed by crushing when the compressive strength is exceeded
Figure 84 crushed by compressive strength (e-‐ learning)
Figure 85 illustration of short column
Long column When the ratio of effective column length to the smallest cross section dimension is greater than 12:1, it considers as a long column. The characteristics of long columns are: -‐ Unstable and fail by buckling -‐ The actual length is between the fixed point at the top and bottom of the column -‐ Column changes by different fixing methods
Figure 86 long column illustration (Ching)
Figure 87 long column buckling(www.civildb.com)
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Wall systems There are three types of wall systems. 1. Structural Frames -‐ Concrete frames -‐ Steel frames -‐ Timber frames 2. Load bearing walls -‐ Concrete -‐ Masonry 3. Stud walls -‐ Light gauge steel framing -‐ Timber framing
Figure 89 Examples of wall systems ( www.neslo.com)
Figure 88 3 different types of wall system (ching)
Structural Frames 1. Concrete frames-‐typically use a grid of columns with concrete beams connecting the columns together 2. Steel frames-‐typically use a grid of steel columns connected to steel girders and beams. 3. Timber frame (post and beam)-‐ typically uses a grid of timber posts or poles connected to timber beams. Bracing of members are required.
Figure 90 Examples of steel frame ( buildipedia.com)
Figure 91 Examples of timber frame (www.strandsystems.com)
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LOGBOOK Load bearing walls 1. Concrete -‐ In situ/precast element -‐ Supporting spandrel panels over and link into other strucgtural elements 2. Reinforced masonry -‐ Constructed from core filled hollow concrete blocks or grout filled cavity masonry -‐ Bond beams creates special concrete blocks-‐filled with concrete to bond the individual units together -‐ Propping can be removed after concrete has cured -‐ Bond beams can be used as steel or concrete lintels 3. Solid masonry -‐ Can be created with single or multiple skins of concrete masonry units or clay bricks -‐ Skins of masonry joined together using a brick or with metal wall ties placed within the mortar bed 4. Cavity masonry -‐ Walls formed from 2 skins of masonry
Advantage: better thermal performance, better opportunities for insulation within the cavity, better waterproofing and the better opportunity to run services within the wall cavity DAMP PROOF COURSE/WEEP HOLES in a wall are indicators that the wall is a cavity wall rather than a solid wall
Figure 92 examples of concrete and reinforced masonry bearing walls (e-‐learning
Figure 93 solid masonry & cavity masonry examples (ching)
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Stud framing Metal and timber stud framed walls use smaller sections of framing timber or light gauge framing steel to meet the structural demands of the construction. -‐ Smaller sections: repeated at smaller intervals and require restraining along their lengths with rows of NOGGINGS to prevent the long thin members from buckling -‐ It consists of: top and bottom plates, vertical studs, noggins, cross bracing and ply bracing
Figure 95 ply bracing illustration
Brick veneer construction Combinations of 1skin of non-‐structural masonry and 1 skin of structural frame wall are widely used in the construction industry.
Figure 97 Examples of brick veneer construction (www.workspacetraining.com.au) Figure 94 stud framing (www.architectionary.com)
Figure 96 Brick veneer construction (e-‐learning)
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Wood to Timber Provenance Early wood: -‐ Rapid growth at beginning of growing season -‐ Thin, large cells: light colour Late wood: -‐ Slower growth, often limited by lack of water -‐ Thick small cells: darker colour -‐ Gives the growth ring Growth -‐ One ring per year -‐ Some climates may have more than -‐ One growth season per year -‐ Fires or disease may produce an extra ring
Figure 98 3 different wood type (e-‐learning)
Step2: place the balsa wood into the drawing
Figure 99 Timber (www.diytrade.com)
Activity: Structural concepts Step1: Draw the structure with 1:20 scale
Figure 100 structure drawing
Figure 102 balsa wood used for the structural member
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Figure 101 balsa wood used for the structural member
LOGBOOK Step3: cut the each structural member and connect it together as same shaped as the drawing
Figure 103 1:20 scaled structural member
Our group had used super glue to connect each structural member, however, it wasn’t strong enough to stick together because the structure was pretty big. Also, the balsa wood was too weak. The other group was proper wood and the nails to create the structure member and it was pretty strong.
Figure 105 other group's structure
Figure 104 load path diagram of the structure
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1. Stud A wall stud is a vertical framing member in a building’s wall of smaller cross section than a post. They are a fundamental element in building framing. 2. Nogging An architectural term, it refers to the term used for the filling in between wall framing in buildings. Also it is a horizontal bracing piece used to give rigidity. 3. Lintel A lintel can be a load-‐bearing building component, a decorative architectural element, or a combined ornamented structural item. It is often found over portals, doors, windows, and fireplaces. 4. Axial load -‐ is a force that is exerted along the lines of an axis of a straing structural member. It is an essential mechanical force that is used to determine an ideal column in structural design.
5. Buckling In a compression member or compression portion of a member, the load at which bending progresses without an increase in the load. 6. Seasoned timber Wood drying reduces the moisture content of wood before its use.
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Trusses In engineering process, a truss is a structure comprising five or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes. External forces and reactions to those forces are considered to act only at the nodes and result in forces in the members which are either tensile or compressive forces. Moments are explicitly excluded because, and only because, all the joints in a truss are treated as revolute.
Figure 106 Truss load transfer
Figure 107 Examples of timber trusses (www.eldortrusses.com)\
Roof Systems There are two roof types such as flat roofs and pitched and sloping roofs. Flat roofs are normally consists of concrete slabs, flat trusses/ space frames, beams & decking, joinst & decking and roof sheet. To be pitched roof the angle should be greater than 3degress. It consists of rafters, beams & purlins and trusses. Concrete roofs are generally flat plates of reinforced concrete or precast slabs with a topping of concrete. The top
surface is sloped towards drainage points and the entire roof surface finished with applied waterproof membrane. 1. Flat -‐ Structural steel roofs consist of a combination of primary and secondary roof beams for heavier roof finishes such as metal deck/concrete; or roof beams and purlins for lighter sheet metal roofing. 2. Sloping -‐ Structural steel roofs consist of roof beams and purlins and lighter sheet metal roofing 3. Portal frames -‐ Consist of a series of braced rigid frames (two columns and a beam) with purlins for the roof and girts for the walls. -‐ The walls and roof are usually finished with sheet metal. Ju Hyun Son-‐354978 48
Figure 108Examples of flat roof (alliedroofing.info)
Figure 110 3d drawing of frames of the roof
Figure 109 Examples of sloping roof construction (crate-‐gate.com)
3D plate type structures that are long spanning in two directions Linear steel sections of various cross section types are welded, bolted or threaded together to form matrix-‐like structures.
Trussed roofs -‐ constructed from a series of open web type steel or timber elements -‐ manufactured from steel or timber components -‐ fixed together to form efficient elements able to span long distances Space frames
Figure 111 welded and bolted connections
Figure 112 Examples of space frame (commons.wikimedia.org)
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Light framed roofs There are two types of light framed roofs such as gable roofs and hip roofs Gable roofs: -‐ Characterized by a vertical, triangular section of wall at one or both ends of the roof. -‐ Consists of common rafters, ridge beams and ceiling joists. -‐ Timber, cold-‐formed steel sections are used Hip roofs: -‐ Characterized by a vertical, triangular section of wall at one or both ends of the roof -‐ Consists of common rafters, hip rafters, valley rafters, jack rafters, ridge beams and ceiling joists. -‐ Timber-‐cold-‐formed steel sections are used.
Figure 114 Examples of hip roofs (www.tecotested.com)
Figure 113 Gable roofs (Ching)
Metal atoms as being like ball bearings to understand why metals are malleable and ductile and not brittle Subject to any stress the metal atoms slide past each other and the mobile electrons rearrange Packed together in layers and these layers stacked one upon another copper atoms can easily slide over or past one another hence copper is malleable and ductile
Figure 115 Examples of metal (wiki)
Figure 116metal atom sketches
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Metal-‐types -‐ Ferrous: iron is the 4th most common element in the earth (relatively cheap) -‐ Non-‐Ferrous: all other metals generally more expensive (less common). Less likely to react with oxygen and superior working qualities -‐ Alloys: combinations of two or more metals
Figure 118 different metal shapes for construction (www.spartanmechanics.net)
Figure 117 different metal types and used(www.handsmetals.co.uk)
Metal-‐properties -‐ Hardness: varied. Depending on type -‐ Fragility: low. Generally will not shatter or break -‐ Ductility: high -‐ Flexibility/plasticity: med to high. Flexibility and high plasticity while heated -‐ Porosity/ permeability: generally impermeable/ used for guttering, flashing etc -‐ Density: high (3times greater than water for aluminium to
19times greater than water for gold Conductivity: very good conductors of heat and electricity. Can be advantage/disadvantage Durability/ life span: can very durable. Varies depending on type, treatment, finishing and fixing Reusability/ recyclability: high Sustainability & carbon footprint: very high embodied energy, recyclable and renewable if correctly managed Cost: generally cost effective
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Metal consideration -‐ React with other metals by giving up/taking on another metal’s ions. -‐ Galvanic series lists the metals in order of their tendency to give up ions to other metals and corrode -‐ Ion transfer caused by contacting two different metals
Figure 119 different type of metals corrosion order (e-‐learning)
Water related damage Oxidation and corrosion: ions can react with oxygen forming an oxide which can sometimes protects the metal but in other instances it can result in the corrosion of the metal. Aluminum oxidizes to form a protective layer. Rusty steel is an example of undesirable corrosion. Protect against water to reduce corrosion: 1. Avoid prolonged exposure to moisture 2. Seal against moisture 3. Chemical treatment.
Figure 120 metal corrosion (www.uotechnology.edu.iq)
Ferrous metals Iron alloys -‐ Steel is an alloy of iron with carbon being the primary additional alloy element -‐ Including manganese, chromium, boron and titanium among others -‐ Different proportions and combinations result in different types of steel Steel property -‐ Very strong and resistant to fracture -‐ Transfer heat and electricity -‐ Can be formed into many different shapes -‐ Long lasting and resistant to wear
Figure 121 iron steel (e-‐learning)
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Steel-‐types and uses 1. Framing -‐ Columns, beams, purlins, stud frames -‐ Hot rolled steel: elements are shaped while metal is hot. More materials is required for this type or process -‐ Cold formed steel: elements are folded from sheets that have been previously produced and cooled down. Used as secondary structure (protected by hot dip process: galvanization)-‐joints are bolted or screwed -‐ Reinforcing bars: due to its good tensile resistance, steel is used in conjunction with concrete to produce reinforced concrete. Deformations on the bars assists bonding with the concrete 2. Sheeting -‐ Cladding and roofing: protected from weather exposure (paint, enameled finishes, galvanization)
3. Stainless steel alloys -‐ Chromium is the main alloying element -‐ Alloy is miled into coils, sheets, plates, bars, wire, and tubing -‐ Generally used harsh environments or where specific inert finishes are required -‐ Wall ties in cavity walls are often made from stainless steel due to its corrosion resistance -‐ Very rarely used as primary structure due to cost
Figure 122 stainless steel (www.thomasnet.com)
Figure 123 different shapes of steel (www.stainlesssteelblog.com)
Figure 124 steel framed structure (chinaprefabhouse.en.made-‐in-‐china.com)
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Nonferrous metals Aluminium -‐ Very light compared to other metals -‐ Non-‐magnetic and non-‐ sparking -‐ Easily formed, machined and cost -‐ Pure aluminium is soft and lacks strength, but alloys with small amount copper, magnesium, silicon, manganese, and other elements have very useful properties
-‐ Copper -‐ -‐ -‐ Uses Figure 126 Aluminium atom shape
Figure 125 Aluminium metal property (www.constellium.com)
Extruded sections are common for window frames and other glazed structures such as balustrades/ handrails Door handles and catches for windows Rolled aluminium is used for cladding panels Reacts with air creating a very fine layer of oxide that keeps it from further
-‐ -‐ -‐
oxidation giving it that matte natural finish Common treatments are power coating and anodisation Reddish with a bright metallic lustre Very malleable and ductile Good conductor of heat and electricity Traditionally roofing material Widely used for hot and cold domestic water and heating pipework Electrical cabling
Figure 127 copper cable (39clues.wikia.com)
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-‐ -‐ -‐
Present use in construction: plating thin layers of zinc on to iron or steel is known as galvanizing and helps to protect the iron from corrosion (roofing material). Cladding material for both roofs and walls Brittle at ambient temperatures but is malleable at 100to 150 degress. Reasonable conductor of electricity
Figure 128 zinc used construction (www.commodityonline.com)
Frequently used for roofs, cornices, tank linings and flashing strips for waterproofing Less commonly used to day because it is now known to be toxic to humans. It occurs high enough doses, lead can be toxic. A bluish-‐white lustrous metal. Very soft, highly malleable, ductile, and a relatively poor conductor of electicity Very resistant to corrosion but tarnishes upon exposure to air
Figure 129 lead material (www.guptametalmart.com)
Very rare today Used in building for lining lead pipes and occasionally as a protective covering for iron plates and for small gas pipes/tubing Tin is a silvery-‐white metal, is malleable, somewhat ductile, and has a highly crystalline structure Resists, distilled, sea, and soft top water, but is attacked by strong acids, alkalis, and acid salts Oxygen in solution accelerates the attack
Figure 130 Tin material (www.proactiveinvestors.com.au)
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Titanium -‐ Used in strong light-‐weight alloys -‐ Making an attractive and durable cladding material, though it is often prohibitively expensive -‐ Well known for its excellent corrosion resistance -‐ High strength to weight ratio -‐ Light, strong, easily fabricated metal with low density
Bronze -‐ -‐
Brass Used for bearings, clips, electrical connectors and springs Often used for external applications, prior to the discovery of aluminium, due to its toughness and resistance to corrosion Corrosion resistant, harder and can be used in engineering and marine applications
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Tough and typically used in elements where friction is required such as locks, gears, screws, valves Commonly cound in fittings such as knobs, lamps, taps Malleable and has a relatively low melting point and is easy to cast Not ferromagnetic
Figure 133 Brass material (brass-‐turned-‐ parts.brass-‐cable-‐glands.co.uk) Figure 131 Titanium material (www.titaniumjoe.com)
Figure 132 Bronze I-‐beam (life.time.com)
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LOGBOOK Activity: continue from week5. We have actually done everything in week5. Glossary 1. Rafter -‐ A rafter is one of a series of sloped structural members (beams) that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof deck and its associated loads. 2. Purlin -‐ A purlin is any longitudinal horizontal, structural member in a roof except a type of framing with what is called a crown plate. 3. Cantilever -‐ A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is forced against by a moment and shear stress. It allows for overhanging structures without external bracing. It can also be constructed with trusses or slabs. 4. Portal frame
-‐ is a method of building and designing structures, primarily using steel or stee-‐reinforced precast concrete although they can also be constructed using laminated timber such as glulam. The connections between the columns and the rafters are designed to be moment-‐resistant, i.e. they can carry bending forces. Eave -‐ is the bottom edge of a roof. The eaves normally project beyond the side of the building forming an overhang to throw water clear. Alloy -‐ is a mixture or solid solution composed of a metal and another element. Soffit -‐ formed as a ceiling. Top chord -‐ is a truss.
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