ENVS10003 CONSTRUCTING ENVIRONMENTS WEEK 05 LOGBOOK
CONTENTS
01_ Studio Report
02_Constrction Workshop
03_Learning Loop
04_Grossary Appendix
Image: Steel Framing Isometric – Roof Skylight Resource: Oval Pavilion Construction drawings, p. S03.10
05_Reference List
01_Studio Report
Report Activity ‘Structural Consepts’ Develop a working understanding of the structural system of a building through analysis of architectural and structural documentation and detailed model making.
Report
Report
Image: Function room upper roof framing plan Resource: Oval Pavilion Construction drawings, p. S03.01
Image: Section through roof skylight & fireplace Resource: Oval Pavilion Construction drawings, p. S03.10
Image: Steel Framing Isometric – Roof Skylight Resource: Oval Pavilion Construction drawings, p. S03.10
In this activirty, we ought to use varitey of materials referred to the structural drawings to construct a 1:20 scale model of the structual system of the chosen part of Oval Pavilion. Our group chose the Roof Skylight structure (the roof system) which is mainly constructed by steel frameing. Referred to the chosen scale, in the structural function drawings, or the section drawing above, the scale usually is 1:100. Therefore, when we tried to measure the length of the trusses, we used the scale ruler to transfer the scale to 1:20 in metres to make the physical structural model.
STRUCTUAL MODEL MAKING Material been used: - Foam board (cutting mat) - UHU glue - Cutter - Steel Ruler - Scale ruler - Balsa Wood - Wood stick
From the function elevation North drawing, the material of the offset is Plaster cement render (large scale of brickwork). However, the structure is mainly similar to the canopy which is constructed by the grid and spine truss. The trusses can transfer the load through into the ground. The truss and the framing are mainly made of steel which is stiff, strong, and hard and enable to carry the compression load. Besides, the structure of the truss and grid used pin joints.
Image: Function elevation North & South Resource: Oval Pavilion Construction drawings, p. A51-04
Activity ‘Structural Consepts’ STRUCTURAL ANALYSIS From the section through roof skylight drawing underneath, the trusses are joined together pin joints.Although in the drawing, it seems like the trusses are joined in point connector, the trusses are nailed together in pin joints.
From the section detail drawings as shown on the left, it illustrates that the open-web joists are used in part of the structural steel framing. The joists have a web consisting of a singel bent bar, running in the zigzag pattern between the upper and lower chords. They are abele to support the ceiling. Besides, as the main structure of the Roof skylight is steel framing. It typically uses a grid of stell columns connected to steel girders and beams. As the section of the skylight shown underneath, the offset from face of the cladding to outside face of steel is thicker than the trusses. Therefore, we used thinner balsa wood stick to make the truss.
As the dead load transferred through the truss in different direction, the horizontal joists underneath them are able to carry the compression to the ground.
02_Construction Workshop Activity 1 ‘Contruction Phase’ Construct a structure that must span 1100mm by using a range of tools and fixings.
Comparision between working with actual construction materials as opposed to working with scale model making materials.
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Difference of the material (balsa wood for model making/ pine wood &plywood for acural construction) Efficience of the material (basa wood –weak, not be able to carry much compressive load/ Pine wood which is very stiff and strong- very good in compression but not good in tension/ plywood- good in tension, engineered sheet product Joints&Fixing (model making, using tape &pin to join the wood sticks together- weak / actual construction, using screw driver or hammer to create point connector:bolt - stronger ,but Nails will create weakness too, wood would crack sometimes.
NAILS
As shown on the left hand side, our group’s plan is to build a bridge strucuture to span 1100mm by using the existing materials. As we have three pieces of pine wood and a plywood sheet. We planned to use the plywood to band as a arch on the top of the two pieces of pine wood. To stable the two sides, we cut the part of the pine wood to four wood cubes and nailed them to the basement. However, as we were run out of time, we only made one vertical wood as support to hold the arch in the middle instead of two. Therefore, there was a risk for the structure not being able to hold the compressive load. If the load transferred to the middle of the arch, the single piece of wood was not going to hold much compression.
Activity 2 ‘Destrucutive Testing Phase’ Place the completed structure in the testing cradle. Consider whether the structure meets the span and height requirements of the brief.
Before we placed our completed structure in the testing cradle, we knew that our structure was not be able to hold very heavy compressive load, as our structure was missing a supporting post under the arch on the left hand side. The tweo pine wood on the bottom carried the tension, and the single column under the arch plywood carried the most compression. Therefore, the pine wood underneath was not be able to hold the load and had nowhere to transfer in order to collapse. Our structure held the 120Kg compressive load. It’s the weakest structure comparing to other gorup’s. Moreover, when we turen the pine wood over, there was a knot in the wood. As we know that the knot is a weak point of the wood. So at the time, the other reason that the strucuture would collapse was partly due to the knot.
CANTILEVER
KNOT
The other group’s structure collapsed when the testing crable reached 217 kg, the structure it self was actually strong and flexible to transfer the load through in horizontal and vertical way. However, the cantilever of the beam on the top was a bit too long, thus the middle of the beam held the compression and bended towards the ground. On the other hand, there was also a knot in the middle of the wood beam, so it created a weakness of the structure.
Activity 2 ‘Destrucutive Testing Phase’
This group’s structure was pretty strong as they turned over the pine wood and joined them together in parallel direction.And they nailed them together on both sides and the middle to keep them stable. For instance, in their way, even if one pine wood beam collapsed, the other two would share the compressive load. However, their weakness was the fixing nail. As they have nailed 6 different parts of the wood, when the wood carried the load, the fixing part could easily cracked. This structure held 250 Kg load, it was strong but still has weakness.
When we are working with wood, we need to know about the material, its process, efficiency and weakness. Grain- the changing regions of relatively darker and lighter wood which can result from the differing growth parameters occurring in different
seasons. Knots - a particular disadvantage in the wood that would cause weaknesss -cause slope of grain. Other weakness – sunlight /heat/fire/termites/borer
03_Learning Loop Wall, Grids &ColumnsE-learning, 2014
Frame E-learning, 2014
Walls - structural component of building system - protect exterior and interior - carry the loads from the rood to the ground Wall system - stud wall members can be timber or steel - structual frames can be constructed using timber/steel /concrete. Structural frames -concrete frames (big building in the city) -steel frames (fire proofing/industrial) -timber frames (post&beam) -steel &concrete frame->span greater distance&carry heavier loads
Fixed Frame - rigid frame connected to its support with fixed joints (more resistant to deflection than a hinged frame, but more sentitive to support settlements&thermaal expansion&contraction). Hinged Frame -rigid frame connected to its supports with pin joints. Three-hinged Frame -High frame (structure assembly of two rigid sections connected to each other and to its support with pin joints.
Load bearing walls- concrete/Mansonry ->noncombustible Concrete Frames -typically use a GRID of columns with concrete beams connectiong the columns together. Steel Frames - typically use a grid of stell columns connected to steel girders and beams
Timber Frames -Use a grid of timber ‘posts’ or ‘poles’ connected to timber beams. -Bracing of members between bays or at the corner of post/beam junction’s required to stablise the structure. -a lot faster than concrete building
Short and long columns Ching, 2014 Short Columns - ratio of effective columns length to the smallest cross section dimension is less than 12:1 - Fail by crushing (shear) when a compressive load’s applied - shorter when compressive length is exceeded (apply too great load or if cross-section is small) Long Columns - ratio of effective columns length to the smallest cross section dimension is greater than 12:1 -Fail by buckling ( slenderness ratio of column increase, the corner critical stress ->buckle.\ Effective length – distance between infuction joints.
Solid Mansonry- load bearing walls –created with single/ multiple skins of concrete masonry units or clay bricks
Wood to Timber E-learning, 2014
Solid Cavity Cavirty Masonry- typically formed for two skins of masonry(allow water to run outside, concrete inside- insalation) Reinforced Masonry- build from concrete block, ‘core filled’hollow concrete blocks or ‘grout filled’cavity masonry. Bond beams- alternative to steel or concrete lintels. Knots- weak pints /cause slope of grain Risk- sunlight/heat/fire/termites/borer/water-damage Plywood -engineered sheet product -made from timber chips,wax and resin
Heartwood->Sapwood->cambium cell layer->iner bark->outer bark Early Wood-rapid growth at beginning (thin/large celllighter colour Later Wood-slower growth, limited by lack of water (thick/small cells- darker colour) Growth- growth ring (one ring per year) Quarter sawn -best grain shows on face (furniture, floor) -less splitting when nailing Back Sawn -season more rapidly Radial Sawn -used as buildings ,fenses -less wastage in milling
04_Glossary Appendix 1. Stud- an upright timber in the wall of a building to which lath and plasterboard are nailed. Stud framing accept variety of interior and extension wall finishes, some of the require a nail base sheathing (light guade steel framing/timber framing). 2. Nogging- a short horizontal timber member used between the studs of a framed partition.
3. Buckling- ‘the sudden lateral or torsional instability of a slender strucutral member induced by the action of axial load before the yield stress of the material is reached’ (Ching, 2014, p. 2.13).
Length
4. Axial Load- an axial load is a force administered along the lines of the axis.
Column supporting axial compressive loads applies to the end of the members
5. Lintel- a load-bearing building component, a decorative architectural element. It is often used as windows and fireplaces.
6. Seasoned Timber- the seasong (drying) timber, in which, the moisture is removed (removing the water from the cell wood) - Air- 6months to 2years per 50mm thickness - Kiln- 20-40 hours to dry to 12% - Solar Slan- less expensive to run
7. Grain- the changing regions of relatively darker and lighter wood which can result from the differing growth parameters occurring in different seasons.
8. Knots - a particular disadvantage in the wood that would cause weaknesss -cause slope of grain.
05_Reference List Ching, F. (2014). Building construction illustrated / Francis D. K. Ching. Hoboken, New Jersey: John Wiley & Sons, Inc., 2014, p. 5.01- 5.50 Engineered timber products, e-learning, 2014, viewed 27th August 2014. Retrieved From, http://www.youtube.com/watch?v=0YrYOGSwtVc&feature=youtu.be From wood to timber, e-learning, 2014, viewed 27th August 2014. Retrieved from, http://www.youtube.com/watch?v=YJL0vCwM0zg&feature=youtu.be
Short and long columns, e-learning, 2014, viewed 27th August 2014, Retrieved from, https://app.lms.unimelb.edu.au/bbcswebdav/courses/ENVS10003_2014_SM2/WEE K%2005/SHORT%20AND%20LONG%20COLUMNS.pdf
Walls, grids and columns, e-learning, 2014, viewed 27th August 2014. Retrieved from http://www.youtube.com/watch?v=tIe6txNIO58&feature=youtu.be