Lecture activity: Use material provided by tutor to construct a foundation to hold a brick stably. (The material provided is a piece of green paper )
Bricks are really strong to compression. There are several kinds of ways to lay bricks. And the following diagrams show two kinds of them, one is stretcher bond and the other is stack bond.
Task in tutorial: Use material provided by tutor to construct a building as tall as possible. The building should be stable and has a door for toy dinosaur to walk in. The following pictures show the works of each group in an order of our group, square group, boys group and tallest group. (The material provided is called Medium Density Fiberboard - MDF)
Ching, F. 2008, Building Construction Illustrated, 4th edn, John Wiley & Sons, INC, hoboken, New Jersey.
Environmental Sustainable Design - ESD Structural systems:
Solid system - use bricks (ancient Egypt & China) Surface system Skeletal system - most commonly used today Membrane system - cheaply cover large area Hybrid system - most commonly used today With the material called ETFA (e.g. Beijing Olympic Buildings) The concerning things during construction:
Performance requirements - the needs of people who use it Aesthetic qualities Economic efficiences - budget, cost, future cost, etc. Environmental impacts - materials
Examples in lecture:
3 types of structural joints: Roller joints - when using it the structure is flexible to reply the changing external forces. Pinned joints - when using it the structure is flexible to reply the changing external forces. Fixed joints - not easy to keep balance, the flexibility of the structure is not as good as those use roller joints or pinned joints.
Examples in lecture:
Enclosure system - The facade of a building, which includes the roof, exterior walls, windows and doors. Structural system - This system is designed and constructed to support and transmit loads to the ground. (e.g. The following diagram shows how it works)
Service system (Mechanical system) - This system provides essential services to buildings, which includes the water supply system, the sewage disposal system, the heating, ventilating, and air-conditioning system, the electric system, vertical transportation systems, fire-fighting systems and waste disposal and recycling systems(maybe). â—?There is no load forcing on this part. So why dose it exist? And how dose this part work?
The right vertical part (b) of this structure receives compression. If only existing this part, this structure will lose balance and fall down. So to keep balance, the left vertical part (a) provides the whole structure with tension. Compressional part and tensional part work together to avoid deformation of the whole structure and keep balance. The pressure points has a scale of 2:1 as it is showing in the picture. (The following example shows how this kind of combine works in normal constructing.)
Task in tutorial: Use material provided by tutor to construct a building as tall as possible. The building should be stable. The following pictures show the works of my group. (The material provided is called Fiber Cement Sheet - FC Sheet - Compressed Sheet )
Properties of Bricks: Hardness - Medium ~ light Fragility - Medium (cannot be broken with trowel) Ductility - Very low Flexibility / Plasticity - Very low Porosity / Permeability - Only if placed in prolonged contact with water will become soaked Cost - labour cost Durability - Durable Sustainability - easy to be reused
Advantages: *It reduces the weight and increase the insulation ability of the block. *If it is needed to increase the strength, concrete and cement can be put into the holes. *Different shapes of blocks can fit different size and shapes of columns - used in walls and place columns in to fix the columns.
Advantages: Can be joined with water based mortar Disadvantages: It absorb moisture and will expand in long term, thus expansion joints are required. Properties of Concrete Blocks: Density - Medium Cost - Generally cost effective but labour penalties are often applied Durability - Durable Porosity / Permeability - Only if placed in prolonged contact with water will become soaked *The holes in the middle of the blocks allows reinforcement rods to be installed within the blocks & The air pocket decreases the insulation performance of the blocks.
Moment: Moment=Force x S (the length between moment joint and the force point) The Unit: KNm
Strut: E.g. Steel column
Shallow Foundations & Deep Foundations:
Guided Campus Tour
The lowest part of a shallow foundation is spread footings.
Purpose of floor system: Span - a measure of the distance between two Transfer dead loads and live loads through the structural supports horizontal members to supports.
Beam - carry loads along the length of beams and transfer them to vertical supports Spacing - a measure of the distance between a series of like or similar elements (beams & columns) *It depends on the spanning capability Cantilever - transfer loads to the supports
Concrete system: One-way slab - uniformly thick, reinforced in one direction, and cast integrally with parallel supporting beams Two-way slab and beams - uniformly thick, reinforced in two direction, cast integrally with supporting beams and columns on all four sides of square or nearly square bays. Two-way slab and beam construction is effective for medium spans and heavy loads. For economy, two-way slabs are usually constructed as flat slabs and plates without beams.
The properties of Concrete: *Concrete is strong in compression and weak in tension. So reinforcement is required. Such as steel, which usually in the form of mesh and bars. Hardness - High Fragility - Low Ductility - Very low Flexibility / Plasticity - Low Density - Medium~high Durability - Very durable Conductivity - Poor conductor of heat and electricity Cost - Generally cost effective. Labour dependent for formwork and pouring. *The amount of water added during producing influences the strength and shaping ability of concrete. *Formwork is used to hold the liquid concrete in place. It will be taken away later and often be reused. *The steel bars inside should not be too close to surface. Because they are easy to get oxidation. Pre-cast Concrete: *Be manufactured in factories and transferred to the site, which ensure a more standardised quality and more faster to be made.
In Situ Concrete: *Formworks and reinforcement are settled and then concrete is poured in. It has a limited time to start to harden so the process should be quick. And it needs hand work to get the air bubbles removed. *Sometimes concrete is sprayed into place using a pressure hose (Shotcrete) E.g. concrete wall
*Uses of In Situ Concrete: Footings, retaining walls and all bespoke structural elements. *Joints: Construction Joints Control Joints Both are potential weak points and need to make sure the details are appropriate in terms of water and moisture control.
*Uses of Pre-cast Concrete: Rarely used in footings, and commonly used in retaining walls, walls and columns. *Joints: Construction Joints Structural Joints Joints can be made Into different look for the appearance of buildings. *Pre-cast Concrete elements can be limited in *If the site plan change, it is not easy to adjust size due to transport limit. the shape and size of Pre-cast Concrete.
Steels: Steel beams connection - different shapes of steel beams are easier to be fixed and decrease their dead loads.
Wood â€” Prefabricated Joists & Trusses:
Workshop Task: Design and construct a structure that must span 1000mm in 45 minutes Materials: One 1200 x 3.2 x 90mm PLYwood Three 1200 x 35 x 35mm Pine Tools: Sundry nails, screws, hammers, saws, and screwdrivers.
Two projects we thought: As PLYwood is easy to bond, it cannot be set horizontally on the surface of pines’ top. It is better to place it vertically, which will enrich the compressive ability.
So the design will then be Outcome: The second highest load tolerant
BUT another group has chosen to do it... Set a framework structure to transfer loads
It broke at the middle part and the crack started from the bottom side - because the bottom side provides tension support and it will earlier get to limit.
The most load was held by this groupâ€™s bridge:
Their project was the first project we designed. *Crack always firstly comes into being around the nails.
After changing the position and making the PLYwood vertically stand, it could hold more loads.
Plywood: An engineered sheet product that used for structural bracing Brick veneer walls: Timber stud frame and brick skin
Structural Frames - made in concrete steel or timber Concrete Frames: Use a grid of columns with concrete beams connecting the columns together Steel frames: Use a grid of steel columns together connecting steel grids and beams Timber Frames: use timber posts or poles connected to timber beams Stud Walls - made in timber or light gauge steel framing
Timber Properties: Hardness - Medium~low - Most can be reasonably easily marked Fragility - Medium~low Ductility - Low Flexibility / Plasticity - High / Medium Porosity / Permeability - High Density - depending on timber type Conductivity - Poor conductor of heat and electricity Durability - Very durable Reusability - Very high Sustainability - Very low embodied energy Cost - Generally cost effective and labour dependent for on-site work. It can be manufactured in factories Seasoned Timber: Typically used for furniture and floor Water <15% Unseasoned Timber: Used as frame materials Timber can be attacked by fire & insect (termites and borer)
Timber Products: LVL (Laminated Veneer Lumber) Uses: Mainly structural (Beams, posts, portal frames) Glulam (Glue Laminated Timber) Uses: Mainly structural (Beams, posts, portal frames) CLT (Cross Laminated Timber) Uses: Structural panels (horizontal and vertical) Engineered Timber: I Beams Uses: Floor joists / rafters Box Beams Uses: Floor joists / rafters Timber Flanged Steel Web Joists Uses: Floor joists / rafters
Tutorial Task Make a module of the roof level of kitchen
Materials we used: Cardboard Fibreboard Super glue Masking tape
*Purlins are supported by beams *The walls and roofs are usually finished with sheet metal Flat Roofs & Pitched and sloping roofs
Sloping structural steel roofs - Roof beams and purlins for lighter sheet metal roofing
Concrete roofs: *Used where the space has high safety requirements Flat structural steel roofs - Primary and secondary roof beams for heavier roof finishes - Roof beams and purlins for lighter sheet metal roofing
Portal Frames - A series of rigid frames (two columns and a beam) with purlins for the roof and girts for the walls
Steel Truss: - Timber / Steel This kind of structure is about compression and tension supports Space Frames: - Column sections or pipes Useful for big roofing space and when big top glazing is required
Light framed roofs: - Timber, cold-formed steel sections (or heavier steel) Gable roofs - consists of common rafters, ridge beams and ceiling joists ceiling joists
Hip roofs: Legend in site drawings: Characterised by a vertical, triangular section of wall at one or both ends of the roof
Metal: Properties: Hardness - depending on type Fragility - Low Ductility - High Flexibility - Medium Conductivity - Very good conductors of heat and electricity Permeability - Used for guttering, flashing, etc Durability - depending on type (Can be very durable) Reusability - High Sustainability - Very high embodied energy, recycled and renewable if correctly managed Ferrous metals and alloys: Iron - good compressive strength Very reactive chemically Meganetic properties
Galvanic actions & Oxidation and Corrosion
See Week 10 Protection: (1)Avoid prolonged exposure to moisture (2)Seal against moisture (3)Chemical treatment Iron alloy & carbon steel: Very strong and resistant to fracture Uses: Structural Steel - Framing (Column, beams, purlins, stud frames ...) Steel sheeting - cladding and roofings Stainless steel alloys *Stainless steel is very very rarely used as primary structure due to cost
Eaves: Help protect buildings’ wall services Window: Has high risk to let water come into the building Keep water away from openings: (1) Set Grading (sloping) roof so that water will be collected in gutters (2) Set overlapping cladding and roof elements (e.g. Weatherboards and roof tiles)
(3) Set sloping window and door sills and roof / wall flashings Use slops and overlaps to carry water out. (4) Sloping ground surface away from walls
Air pressure differential strategies: Typically used for high-rise buildings
3 methods to avoid water come in: Remove openings Keep water away from openings Neutralise the forces that move water through the openings *forces includes - gravity - surface tension and capillary action - momentum - air pressure differential Remove openings: Use sealants or gaskets *Both rely heavily on correct insallation and will deteriorate over time due to weathering.
How to stop Air Leakage: - Sarking Used to provide an air barrier - Weather Stripping around doors and windows and other openings
Thermal Protection Controlling heat can save energy for adjusting the temperature of inside buildings (1)Thermal Insulation (2)Thermal Breaks - reduce the amount of conduction (3)Double Glazing
Radiation can be controlled by using - reflective surface - Shading systems Materials used for thermal mass: Masonry, concrete and water bodies Rubber: Natural rubber Uses: seals, flooring, insulation, hosing and piping Synthetic rubber Uses: epum neoprene silicone Properties: Hardness - Harder rubbers resist abrasion Softer rubbers provide better seals Ductility - High Flexibility / Plasticity - High Fragility - Low Reusability - High Cost - Effective *Rubbers should be protected from sun exposure
Plastic: not renewable! The thermoplastics Can be recycled - Polyethelyne (Water pipes going through ) - PVC (pipes) - Polycarbonate The thermosetting plastics Can be only shaped once - Melamide Formaldehyde (Laminex) Widely used for finishing surfaces - Polystyrene (Styrene) Mostly used in insulation panels Elastomers Properties: Hardness - Medium~low Fragility - Low~medium Ductility - High in heated state, varied in cold state Flexibility / Plasticity - High Fragility - Low Conductivity - Very poor conductor of heat and electricity
Windows: Frames (Metal / wood)
Strategies that could be used to stop water entering a building: - Sarking - Weatherstrip - Cladding - Roof - Flashing - Drip detail
Glass Consists of formers, fluxes and stabilizers. Fluxes are quite cheap.
2 Traditional types of glass: Flat glass and shaped glass
Float glass is commonly used today: Clear float glass Laminated glass - provide high safety Because this kind of glass has a piece of plastic between two glass boards. And when the glass get crushed, the particles will be hold by the plastic rather than falling apart. Tempered glass very tough Good for used as curtain wall
Loads are carried around windows but not through windows. Actually windows transfer loads to columns inside. Double and Triple glazing: Properties: - Decrease heat transfer Porosity - None-porous - Decrease sound Density - Medium~high transmission Conductivity - Transmits heat and light but - Decrease visibility electricity Hardness - High Fragility - High (depending on types) Ductility - Very low Durability - Typically very durable (chemical, rust and rot resistant) Reusability - Very high Cost - Generally expensive to produce and transport
Site Visit Location: 567 Collins Street, Melbourne
Tower Crane Carry columns, steels and all the heavy materials in construction site
Mud pipe Transport the liquid concrete and pour them into reinforcement module
Temporary bracing beams - the above levelâ€™s flooring concrete slab has not shaped and strong yet Composite Materials: Composite materials are those combine two or more materials and individual material remains easily distinguishable. However, Monothic Materials are of single material or combined material so that components are distinguishable (e.g. Metal alloys) 4 Main types: - Fibrous - Laminar - Particulate - Hybrid
What to consider while choosing materials:
Welded wire fabric - a kind of steel reinforcement to provide tension. Because concrete is relatively weak in tension. Villain materials: Steel, Hardwood, Timber, oil based paints, Aluminum window, Treated PWE, MDF. Hero materials: Recycled steel, Softwood pine, bamboo, water based paints, Timber window, Cypress PWE, EO MDF or Z MDF.
â‘ĽThe density or hardness of a material - its resistance to wear and abrasion, its durability in use, and the costs for maintaining it. â‘ŚElasticity & Stiffness - ductile (elastic limit) Low elastic limit is not suitable for structural purpose. - stiffness is important factor when considering the relationship between span and deflection under loading. Crushed stone - used as aggregate in concrete products.
*Bamboo - grows faster (about 7 years) *MDF - Medium Density Fibre Board *Cypress PWE - more healthy for human body *EO MDF or Z MDF - not use raw wood material but bonding small wood particles under heat and pressure Trait of 3 main nonferrous metals: Alumium - natural resistance to corrosion & easy to have galvanic action with other metals Uses: windows, doors, roofing, flashing, trim and hardware. Copper - corrode aluminum, steel, stainless steel and zinc. Uses: electric wiring, water piping and use as roofing and flashing material. Lead - heavy, soft Uses: its pliability makes it desirable for application over uneven surface)
Galvanic action: Two metals which are respectively close to each side are easily to have galvanic action. Closing metals set together for construction use can prevent corrosion. For roofing and gutter combinations - choose closing metals such as zinc roof sheet & galvanised steel gutter. And the metals for roof must be more anodic.
Different shapes of steel and their names:
How to use wood in right grain direction:
4 main wood panel products: *PLYwood - bond veneers together
Set the wood materials to support the force when the grain is horizontal. Because the force will be sent passing around the whole wood and it can stand more compressive force.
*Particleboard - bond small wood particles Uses: decorative panels and cabinetwork and underlayment for floor. *Oriented Strandboard (OSB) - bond layers of long, thin wood strands strength and stiffness work as directions showed in picture *Waferboard - bond large, thin wood flakes Equal strength and stiffness in all directions
Plasterboard: Set at the interior wall. As it needs time to be burned out in fire, it is set as a safety equipment. There are different types of burning time (60 minutes, 120 minutes, 180 minutes...)
The gap between external wall and form drip edge is for water draining to prevent water flowing into the room.
Published on May 18, 2014