[WEEK 2] 7 E-‐Learning Structural Systems Skeletal system: just bare engineering (frame). Membrane: for covering large areas cheaply Construction Systems Environmentally Sustainable Design -‐Performance Requirements -‐Use nature (sun, shadow wind etc..) -‐Aesthetic Qualities -‐ Embodied energy and water needs to -‐Economic Efficiencies be considered not just for the build but -‐Environmental Impacts also the ongoing maintenance. -‐ Using Recycled material, however recycling is energy intensive! This image shows the volume of material that can be produced with one tonne of C02. As green star ratings are becoming more common and even expected in modern designs this is an important factor to consider within environmentally sustainable design (E.S.D). Source: http://www.inthescaleofcarbon.com/
Framework for analyzing form -‐What are the constraints? -‐ Point To Plane: 1 dimension (point) to 2 dimensions (plane). This can then lead onto volume (3 dimensions) -‐ Typical house made up of Large planes (The structure) Smaller planes (Division) and lines (Division)
8 [WEEK 2] Structural Joints -‐ Roller joints allow for horizontal movement for example allowing for the expansion of structures due to heat. -‐ Pin joints allow for the structure to be unbolted making it flexible in use. -‐ Fixed joints are rigid allowing no horizontal or vertical movement. W.R.C: Western red cedar (picture). After being dressed and cut from it’s original wood state W.R.C is highly impervious and good for both exterior and interior use. Sources from left to right: http://www.altiusdirectory.com/Shopping/tree-‐images/western-‐red-‐cedar.jpg http://www.bearcreeklumber.com/ORIGINALS/Photogallery/wrc/wrc_8x8_selappRC_16236_LR G.jpg http://www.forestproducts.com.au/images/timber-‐veneers/large/western_red_cedar.jpg
[WEEK 2] 7 gt L.V.L: Laminated veneer lumber. L.V.L is an engineered timber designed for strength by interchanging the direction of the grains with each layer and then laminating the block. (http://www.woodsolutions.com.au/Wood-‐Product-‐ Categories/Laminated-‐Veneer-‐Lumber-‐LVL) Sources (Left to Right): http://internationalbeams.com/static/upload/galeries_photos/LVL_Closeup_(1).jpg http://www.calco.com.au/Images/lvl2.jpg
On Site Terms S.M.P: Safety management plan J.S.A: Job safety analysis Truss Strengthening Span and spacing are the terms used for the x and y directions of the beams. The ‘flange’ refers to the ends of a steel ‘H’ beam. The truss hole allows for a reduction in the weight of a steel beam (or other such material) whilst still maintain the structural integrity of the beam and force above it. The rectangular shape with the cross allows for maximum strength by creating 4 triangles the most structurally stable shape.
8 [WEEK 2] Plywood shear placed over brace on the wall for additional strength, by adding the diagonal member it created two triangles, which can provide more reinforcement than a rectangular frame. Whilst choosing a design we kept in mind the strength of triangles and attempted a brace of our own. From no pressure till breaking point the brace triangle stayed strong kept down by counter weights at either end. The downward force in the middle was absorbed and distributed evenly through the member.
As the downward force was applied the beam buckled under the pressure and rotated. This meant that the thinner weaker side of the beam was exposed and broke easily. The depth originally in the beam was weak when horizontal force was applied. This could have been avoided with a thicker beam.
[WEEK 2] 7 As the beam buckled under the force it experienced tension, as there was no counter acting upward force to hold the bridge equilibrium. The tension forces stretched the beam, weakening it as each end held strong under the pressure. This made the middle the weakest part, which rotated exposing the thinner side.
In the bridge design there were a couple of successes in resistance. The first was the ends (left). They were able to with hold the force from each end. The weight of the wooden bricks held in place with the sticky tape was enough to stop the end from coming up, keeping it in equilibrium. The second success came from our ability to recognize the joints as a weakness. By reinforcing the joints we were able to stop the bridge from breaking at another spot.
8 [WEEK 2] Structural Joint: the place at which two members meet and are joined. Column: The vertical member used to support the beam or other horizontal member. Tension: Two forces acting in opposite directions on an object causing the object to stretch. Frame: The rigid outer shell or ‘skeleton’ of an object or building Bracing: Reinforcing a frame or structure to improve the load it can withstand. Span: The distance required for a beam to join two columns