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ORMOND COLLEGE CTM DRAWINGS 1. DESCRIPTIONS AND CLASSIFICATION OF STRUCTURAL SYSTEMS a) Foundations and Footings The footing plan and schedule drawing conveys a structural system involving both tension and compression. A series of bored piers and strip footings in blinded trenches are shown supporting a reinforced concrete slab. The concrete itself offers resistance to compressive forces while the steel reinforcing bars within it absorb tensile forces. b) Primary Structure Horizontally, the primary structure consists of beams and trusses that distribute a load to vertical members. These include columns, which allow the force to safely reach the ground. c) Secondary Structure The secondary structure includes minor members that connect and support the load bearing abilities of those in the primary structure. For example, battens can be used as vertical supports to a wall while lintels are used horizontally to support the weight of the wall above it. 2. GRAPHC STRUCTURAL DIAGRAMS a) Foundations and Footings
Blinded Trench
Pad Footing
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Strip Footing b) Primary Structure
Vertical aluminium beam
PFC frame fixed to slab
Concrete column and beam beyond c) Secondary Structure
Lintel
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Purlins
Cladding 3. IDENTIFYING, DESCRIBING AND LOCATING STRUCTURAL MATERIALS Floor Carpet tile Stone floor tile Ceramic tile Sealed concrete Timber lining Concrete slab Precast concrete pavers Walls
Steel frame Copper cladding Cement rendering on exterior brickwork Metal Panel Spandrel Glass blocks as part of faรงade Translucent glass for windows Masonry concrete walls Cement sheet for external soffit Plasterboard Plywood particleboard
Roof Colourbond roofing
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4. IDENTIFYING THREE STRUCTURAL JOINTS a) Mitred joint The joining of two members at an angle where each is cut at an angle equal to half of the angle of junction.
b) Butt joint The square fitting of two members whose contact surfaces have been cut at right angles to the faces of the pieces.
c) Caulked joint The joining of a pipe with hub and spigot ends whereby the spigot end of one is placed inside the hub end of another, then a rope is packed into the annular space around the spigot before molten lead is poured over it. Additional lead is poured into the joint with a caulking iron.
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5. IDENTIFYING AND EXPLAINING THE USE OF DIFFERENT STRUCTURAL FIXINGS
a) Weld Structural fixing that joins metals or thermoplastics through coalescence, which involves melting the materials at their joining and allowing it to cool. Welding is generally used in the making of shear-resisting steel connections and rigid connections. Some examples include welding flanges to a girder of beam, connecting stiffener plates or a shear tab to a column and welded web stiffeners. b) Concrete Concrete fixings are rigid joints, generally precast and involve grouting or high-density plastic bearing strips at their connections for support bearing compressive forces.
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In precast slabs, grout voids of hollow core units are used at the ends of members to tie them into concrete masonry support. Additionally, precast concrete members can be connected to site cast concrete toppings when through reinforcing bars when they protrude upwards from the underlying member. In precast structural tees, the ends of connecting concrete members rest the edges of the inverted tee beams with a separating synthetic rubber bearing bad. They are further secured through steel plates welded to their angles as in the case of precast beams. c) Bolt Bolted fixings are pinned joints that allow rotation but resist translation in any direction. Bolts can be used instead of welding in seated connections and framed connections in steel beam connections. d) Screw
A screw joint uses threads on the ends of two pipes to draw the two pieces together and form a pinned joint. e) Nail A nail is a straight, small, rigid, slender shaft of metal, one end of which is usually pointed; the other end has a head that may be driven with a hammer; usually used as a fastener to join separate pieces of wood. Nails may become loose once the materials they connect expand and shrink over time 6. SUSTAINABILITY AND ENVIRONMENTAL ANALYSIS a) Carbon footprint The design is mainly composed of steel, concrete and glass. 1.8 tonnes of CO2 are produced per tonne of steel 150kg of CO2 are produced per tonne of concrete 185kg of CO2 are produced per tonne of glass However, these materials are not used in the same ratio across the design. b) Embodied energy Steel: 19.8 MJ/kg Concrete: 1.11 MJ/kg Glass block: 142.5 MJ/sf c) Recyclability Steel can be recycled without losing its properties or reducing performance. Almost 100% of concrete can be recycled.
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7. ECONOMICAL IMPLICATIONS OF DECISIONS • •
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The design decision to achieve the effect of copper cladding was a costly one and has subsequently been strategically and sparingly applied. The desire for a complete glass facade may have been unattainable for the span or height of the building as well as very expensive if customized glass sheets were to be made. As a result, cheaper, glass blocks were used however; they produce a significantly different aesthetic to that of thin, translucent glass panels. In using glass blocks, a timber frame would not have withstood the load of these; hence a steel frame was selected. Steel is widely used in framework, second to timber, and although it is more expensive, it is more durable and can support greater loads. The use of cement sheets for walls as opposed to masonry would have been cheaper as they are manufactured on a production like. Thus, the installation costs would have been reduced. The choice of a Colorbond roof may have been influenced by a desire for a modern appeal. This material is more expensive than shingles for example, however, being coated in alloys and plastics to improve durability, it may be more cost effective in the long term. Some walls are prefabricated concrete while others were made in situ, the later being more expensive, however, tis technique may have been employed in making intricate shapes that could not be accurately measured for prefabrication offsite.
Resources Ching, F 2008, Building Construction Illustrated, John Wiley & Sons, Inc., Canada. Harris, C 2006, Dictionary of Architecture and Construction, The McGraw-Hill Companies, Inc., USA. http://media.cannondesign.com/uploads/files/MaterialLife-9-6.pdf