Week 5 Anita Nicholls 698556
STUDIO ACTIVITY Task: Construct an assigned sec8on of the Oval pavilion on groups using the Construc8on drawings. Sec*on Assigned: Canopy Materials used: Balsa wood s8cks, cuTng blade, cuTng mat, pins, glue, Tape
We firstly iden8fied the canopy’s steel frame. Steel frames use a grid of steel columns connected to steel girders and beams. Flipping through the construc8on drawings, the architectural drawings helped us to see the canopy in context to the whole pavilion and its exterior elements however the engineering drawings helped us to see the structure in detail.Drawing S04.01 was especially useful as it showed us the grid spine truss eleva8on and its subsequent components.
The S04.01 drawings were scaled as 1:100 yet our task was to build a 1:20 model. Thus we measured from the page and converted to a 1:20 scale recording the measurements of each member on paper.
STUDIO ACTIVITY Our group of four split up into two groups of twos and each group aWempted to complete a sec8on of the canopy which would later join up. From our length of balsa wood, we measured individual subsequent members that replicated the measurements we had gathered from the drawings. Star8ng from the spine we connected each member with pins. The actual canopy’s steel framing comprised welding, nuts and bolts. The holes we created in the balsa wood from pinning allowed rota8onal movement which was not as adequate for fixed joints, and so the use of tape and glue helped to replicate welding and fixed joints not allowing rota8on. We ran out of thicker balsa wood and had to make do with with lengths of a smaller cross sec8onal area for some sec8ons of the spine which was quite difficult as the pins kept slipping out of the holes. And the use of tape and glue created addi8onal bulkiness to some edges. Our class could not combine all our components as some were made to a different scale. However, most of the groups had u8lised the same materials of strip balsa wood.
This groups sec8on was at too large a scale in comparison and could not be linked with the rest.
LEARNING LOOP WALL SYSTEMS STRUCTURAL FRAMES -‐CONCRETE STRUCTURAL FRAMES use a grid of columns with concrete beams connec8ng the columns together -‐STEEL FRAMES use a grid of steel columns connected to steel girders and beams e.g. The can8levered sec8on of the MSD is constructed in steel -‐TIMBER FRAMES (Post and Beam) use a grid of 8mber posts or poles usually connected to 8mber beams. Bracing of members between bays or at post-‐ beam joining point is usually required to stabilize the structure. Oval pavilion uses 8mber posts, steel beams. LOAD BEARING WALLS: -‐CONCRETE (pre cast or in situ.. the load bearing panels can also provide support for SPANDREL PANELS) -‐reinforced masonry (reinforcement placed through the core of the blocks, then filled with grout) SOLID MASONRY -‐single or mul8ple skins of brickwork together (concrete masonry or concrete block) -‐The skins of masonry are joined together using a brick (with Header showing in face of wall) or with metal WALL TIES placed within the mortar bed -‐If waterproofing is necessary a cavity of about 50ml is usually constructed between the two leaves of brickwork -‐over openings, steel lintels are commonly used CAVITY MASONRY WALLS are formed from two skins of masonry. (gap in middle) +ves: beWer thermal performance and opportuni8es for insula8on or to run services within the cavity, beWer waterproofing. Presence of a DAMP PROOF COURSE and WEEP HOLES in a wall indicate that the wall is a cavity wall rather than a solid wall -‐at intervals, the ver8cal mortar joint (called a perpend) is leg open and becomes a weep hole to allow any water that seeps in to run outside STUD FRAMING -‐Metal and 8mber stud framed walls use smaller sec8ons of framing 8mber or light gauge framing steel to meet the structural demands of the construc8on. Common in Australia. Horizontal noggings prevent each stud from buckling. Stud framing generally consists of top plates, boWom plates, ver8cal studs, noggings, cross bracing and ply bracing. (DIAGRAM) -‐Brick veneer construc8on: Combina8ons of 1 skin of non-‐structural masonry and 1 skin of structural frame wall are widely used in the construc8on industry. Structural system is 8mber or steel rather than brick. The brickwork is a cladding system that is 8ed to the stud work. Roof and floor (if its a 2 story building) loads are carried down through the studs through the boWom plates onto the joists, onto the bearers, onto the piers, then onto the building stumps. Effec8vely the brickwork is a non structural skin. Combina8ons of 1 skin of non-‐structural masonry and 1 skin of structural frame wall are widely used in the construc8on industry
FROM WOOD TO TIMBER Grain direc8on helps us understand the strength and performance of 8mber -‐Strong and s8ff parallel to the grain -‐Weak perpendicular to the grain Seasoning is the process of removing water from the cells and the cell walls so that there is less than 15% of its 100% growing tree moisture content Why? To prove increased dimensional stability and to adjust the moisture content to suit needs How? By Air seasoning (cheap but slow-‐ 6-‐24months per 50mm thickness ), Kiln seasoning (20-‐40 hours to get to a moisture level of about 12% below what is at a living material) or Solar kiln seasoning (less expensive to run) Wood Types (biologically categorised) SoMwoods (in Australia common sogwoods include all conifer species): Radiata pine, Cypress pine, Hoop pine, Douglas fir Hardwoods (Na8ve Australian hardwoods include all Eucalyptus species): Victorian Ash, Brown Box, SpoWed Gum, Jarrah, Tasmanian Oak, Balsawood (neither a eucalypt nor Australian 8mber ) Common sawing strategies: Quarter Sawn, Back Sawn, Radial Sawn (see addi*onal terminology) ENGINEERED TIMBER PRODUCTS SOLID PRODUCTS (LVL) Laminated veneer lumber: A lamina8on of thin sheets of 8mber with the grain aligned to longitudinal direc8on. (Useful for structural beams and posts). Uses (mainly structural: beams, posts and portal frames) GLULAM: Made from gluing pieces of dressed sawn 8mber together to form a deep member. Uses (mainly structural: beams, posts and portal frames) CLT: Made by gluing and pressing thin laminates together to form a sheet, laminate grain laid in alternate direc8ons (90 degrees), provides strength in two direc8on. Used in structural panels SHEET PRODUCTS: -‐Plywood (gluing 8mber laminated to form a sheet) -‐MDF (medium density fiberboard) -‐Chipboard and Strandboard OTHER MANUFACTURED PRODUCTS: Examples of *mber manufactured products formed into beams and joints -‐I beams, Box beams (a varia8on of two ply webs), Timber flanged steel web joints -‐Hybrid use of materials (composite structure where the 8mber is joined together with steel structure or sheet material)
Timber Proper*es and Considera*ons Timber is a living material. Proper8es can greatly differ depending on type. Generally: Proper*es: Medium-‐Low hardness, medium-‐low fragility (geometry dependent), low duc8lity (although in its green-‐state 8mbers can be manipulated into a range of shapes), high flexibility and medium plas8city, high porosity and permeability ( depending on seasoning, finishing (protec8on), extremely varied density depending on 8mber type, poor conductors of heat and electricity, insulates well, can be durable, high reusability and recyclability, correctly sourced can be sustainable, generally cost effec8ve Consider: size, strength grade, moisture content, species of wood, treatment, availability Graded according to strength, determines the size of the load allowed Seasoned 8mber used in furniture and flooring Knots: Weak points, cause slope of grain Strength across knot weaker than strength across the grain Place knots on top of beams to reduce weakness, as 8mber tends to bend under loads (boWom under tension so you want the knot in the top of the beam.. A load compressing on the knot wont be a point of weakness) Durability-‐ Good prac*ce Timber should be detailed for longevity Water related damage: Fungal aWack, ogen occurs when moisture content of wood is more than 20%, swelling or shrinkage can cause cracks Protec8on against water: avoid exposure (When possible), Seal against moisture movement-‐paint, par8cular care is needed with end grain (seal before assembly) Ends of grains should be protected from water: through detailing or pain8ng etc. Water ingress greater at end grain. Timber can be damaged by fire, insect aWack (use chemical and physical barriers between ground and 8mber) and chemical exposure. Light coloured paints are best in regards to protec8on against sun and heat.
Glossary Stud: A ver8cal framing member Noggings: Masonry units used to fill the spaces between framing members, or a horizontal 8mber frame placed between two studs used to strengthen the frame. Lintel: A horizontal beam spanning above an opening of a door or window (see addi8onal terminology for alterna8ve: Bond Beams) Axial load: A load that carries a force parallel to an objects axis. Buckling: Bending of originally straight members due to load forces. Seasoned Timber: Timber that has been dried out with a resultant lower water percentage. ‘Seasoning’ is the process of removing water from the cells and the cell walls so that there is less than 15% of its 100% growing tree moisture content
Addi8onal Terminology Reinforced masonry load bearing walls can be constructed from CORE FILLED hollow concrete blocks or GROUT FILLED cavity masonry Bond beams over openings can be created using special concrete blocks which are filled with concrete to bond the individual units together. Ager the concrete has cure, the temporary propping can be removed, leaving only the appearance of the concrete block wall. Bond beams are used as an alterna8ve to steel or concrete LINTELS UC, CHS, RHS (universal symbols) SAWING STRATEGIES Quarter Sawn: Timber sawn across the rings, less common in structural 8mber +ve: best grain shows on face, good wearing surface for floors and furniture, lower width shrinkage on drying, less cupping and warp than other cups, can be successfully recondi8oned, radial face preferred for coa8ngs. -‐ve: slower seasoning, nailing on face more prone to spliTng Back sawn: Rings parallel to long edge of piece, more common in structural 8mber +ve: season more rapidly, less prone to spliTng when nailing, wide sec8ons possible, few knots on edge -‐ve: shrink more across width when drying, more likely to warp and cup, collapsed 8mber more difficult to recondi8on Radial sawn: face is always a radial cut (weather board cladding system +ve: dimensional stability, less prone to warping and cupping, efficient use of 8mer -‐ve: wedge shaped cross sec8on, difficult to detail and stack Columns: Ver8cal structural members that carry axial loads. All columns re considered slender members. For axial loads they are considered as either: Short columns: (thicker and shorter), ra8o of effec8ve column length to the smallest cross sec8on dimension less than 12:1. They become shorter when compressive load is applied and fail by crushing (shear). They are structurally adequate if the load applied to the cross sec8on does not exceed the compressive strength of the material Compressive Strength (Pa) = Load (N) / area (mm2) Long columns: (thinner and longer), ra8o of effec8ve column length to the smallest cross sec8on dimension more than 12:1. E.g. a 8000mm tall column with a 450mm x 400mm cross-‐sec9on will have a ra9o of 20:1 and is considered a long column. Become unstable and fail by buckling. The length of a long column and it’s fixings ( which change it’s effec8ve length-‐which is measured between the points of contraflexure ) at the boWom and top determine how it buckles and how much load it can carry.