ENVS10003 -Constructing Environments
Francesca Soler TUTOR: MARK IRVING Semester 2, 2014
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Materials used in construction include: timber, steel, concrete and bricks
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Timber -> wood
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Softwood (SW) which comes from plantations, e.g. pine Kill dried hardwood ((kd)hw) which comes from old forest plantation Other abbreviations include: laminated veneer timber (lvl) and medium density fibreboard (mdf)
STANDARD BRICK DIMENSIONS
Steel -> Iron + carbon (as ordinary iron can be brittle) Universal beam (ub) and universal column (uc) o o
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Bricks -> require a bond Extruded bricks vs. pressed bricks
Channel Flange Other abbreviations: parallel flange channel(pfc), square/circular/rectangular hollow section (shs/chs/rhs), ua/ea (unequal angle/ equal angle)
Concrete -> cement
Types of structures include: mass structures, column + beam structures, and tensile structures Mass construction -> compression o
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(Portland) + water + course aggregate (crushed rock) + fine aggregate Reo = reinforcement Reinforcement includes: trench mesh and m12 TRENCH MESH
Materials involved in small mass construction include: clay bricks, concrete, mortar (sand+ cement+ water) Materials involved in large mass construction include: precast concrete panels Precast vs. in situ (on site) The usage of precast materials allows for quality assurance, less on-site labour which decreases the time for construction, allows larger panels to be produced
Week 1’s studio task was to create the tallest possible tower using the smallest amount of materials that was able to accommodate for an elephant/dinosaur to fit into, as well as having a roof. This activity allowed for the observation of compression forces acting upon the structures constructed. The ideas and knowledge gained from this task are able to be applied to much larger structures, such as actual buildings or houses, which allows for a deeper understanding of the forces that must be taken into account during their construction and completion.
The materials used in this activity were wooden blocks as well as slightly larger, pressed bricks. The bricks were noticeably heavier in comparison to the wooden blocks due to the size as well as the composition of both materials. In terms of strength, the bricks were considerably heavier, but both were still relatively strong. The strength and weight of the bricks are two factors on which we based the decision that they would comprise the foundation of our tower as well as another layer of the bricks approximately mid-way through constructing. The shape and stiffness of both materials allowed for relatively easy construction and design. They were both rectangular in shape as well as being quite stiff which meant they were study enough to continuously build open whilst also allowing us to assemble them without difficulty.
Commencing the activity, the group decided that the structure would be circular in shape as to be able to accommodate the elephant/dinosaur whilst utilising a smaller amount of bricks in comparison to a more square or rectangular structure. In real world applications, this shape would also affect the path of wind flow and therefore the wind load. Compression, opposed to tension, is a force that pushing upon an object so in this activity and other mass structures, the weight and the load paths of a structure are ultimately being directed in a downwards. Therefore, The chosen material for the foundation layer were the larger and stronger pressed bricks so that the compression forces acting upon the structure would be directed on to bricks which are better suited to carrying weight in comparison to the blocks. As seen in the second photograph of the structure, the load path ultimately ends at the ground. The placement of the wooden blocks allows the load acting upon it to be directed in opposite directions horizontally before acting vertically downwards where the forces acting on the next wooden block act similarly.
In addition to the other requirements, there was also an entrance needed to allow for the dinosaur/elephant to enter through. The dimensions of the dinosaur/elephant had to be taken into account when constructing the entrance. As my group had constructed a fully enclosed base we had to open up the structure without compromising the structural integrity and losing all the progress we had made. We removed a few blocks from a section of the circle then continued to build upwards until certain that the entrance was tall enough to accommodate for the dinosaur/elephant.
To close the entrance we added a beam which then also acted as a support of the blocks placed on top of it. There would be a large load acting on that beam during to the compression forces being directed vertically downwards. However, it was thought that these loads would be distributed horizontally along the beams then directed downwards into the blocks on either side of the entrance. We also added some more pressed bricks along the same layer as the beam. It was intended that this would add additional support and alleviate some of the compression loads on the wooden blocks and direct them onto the bricks. This also created some more stability within the structure.
After adding the beam and the layer of pressed bricks, we continued to build upwards with the completion of the structure in mind. At this point of construction the structure appears to be taking the form of shape similar to a horseshoe rather than a circle as previously intended. The structure also became slightly more unstable in comparison to the earlier stages of construction. This could possibly be due to the greater amount of load acting upon the lower areas of the structure in addition to the hastiness whilst placing the blocks due to time constraints. However, after a certain point the structure began to form a circle once again and less blocks were beginning to be utilised every few layers with purpose of closing the structure at its maximum height. This activity allowed my group and me to observe compression acting upon a structure and how the design and construction of a structure affected these forces in various ways. The design of our structure varied to other groups in addition to the placement of blocks. Other groups also chose to use less or more bricks than my group and the way in which they used these bricks also impacted on their design and the stability of their structures. Most groups chose a more circular design similar to my group’s, however the approaches in continuing to build upwards varied from group to group. The amount of spaces between the blocks also varied which allowed certain groups to use less materials than others.
Kinetic moving mass of air, assumed to come from any horizontal direction
Any moving or movable loads
Weight of people, stored material, furniture, etc. in a building
Weight of snow or rain accumulating on roof
Acting vertically downward on a structure = self-weight of structure + weight of building elements, fixtures & equipment permanently attached
Any moving or movable loads
Kinetic loads, short duration. From moving vehicles, equipment, machinery etc.
Imposed by structure -> subsidence of portion of supporting soil => differential settlement of its foundation
Hydraulic force groundwater exerts on foundation system
Horizontal force soil mass exerts on vertical retaining structure
Non-concurrent forces: vector sum= single force cause same translation + rotation of body as set of original forces
Both, A., Reiss, E., Manning, T., & Mears, D. (1999). Greenhouse Engineering Pictures. Retrieved August 7, 2014, from http://aesop.rutgers.edu/~horteng/conspics.htm Ching, F. D. K. (2008). Building Construction Illustrated. (4th ed.). Hoboken: Wiley.
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Cellulose fibres -> FC (fibre cement)-Waterproof to some degree -> CFC (compressed fibre cement)
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Processed Timber a.k.a dressed
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LVL (Laminated Veneer Lumber) -> change direction of grain => stronger (e.g. beams, floor joints) Oregon -> window frames Put holes in beams to make them lighter
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1990s Statutory law -> enforced OH+S regulation -> found in workplace JSA, WMS => written methodology on how they are going to do something Also, builders given legal possession of the site/land when building
Bracing/ triangulation => essence of bracing => increases rigidity Brace in both directions for stability For rigidity => brace, sheer panel (plywood), knee joint, portal frames
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To create a structure from the provided balsa wood that would span 1500mm (1.5m) which would then be able to carry a load. o
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Initial idea to create a triangular truss type span for increased rigidity Ideas of being able to transfer and distribute load evenly across the structure This truss system is seen in many bridges in Australia and internationally Could be considered as a skeletal system as it is frame and has ability to efficiently transfer loads down The piece of wood provided was only 600mm in length and therefore it was decided that the material had to be divided into a minimum of three parts As there needed to be a top and bottom there needed to be a minimum of six pieces It was decided that the pieces would be 1cm in length to allow for enough wood for the top and bottom of the truss in addition to the triangles within the truss
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The bottom and top of the trusses were constructed to be able to span the 1500mm which allowed for some overlap of the materials on the actual structure To construct the top and bottom three 10mm x 600mm pieces of balsa wood were glued and taped together The structure was able to span the require length, however the deflection of the structure was clear visible The compression forces acting above the span and the tension forces acting below the span where creating this noticeable deflection which would give way if extra loads where placed on it
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To increase rigidity of the structure and reduce the amount of deflection the initial truss idea was looked at However, due to inexperience and time constraints the triangular trusses were not able to be constructed To brace the system we added vertical trusses between the top and bottom This also reduced the amount of deflection evident in the structure Upon observing the decrease in deflection, more pieces were added to brace the structure These pieces were also larger in length, but smaller in width in comparison to earlier pieces used It was noted that this also further decreased the deflection Whilst there was still a small amount of deflection, it was less significant in comparison to earlier stages of the process
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The bracing/support of the structure differed from the initial idea, however the idea of concept of bracing was still looked in to This allowed the structure to become more rigid and utilise less materials
o When the structure was tested using a weight being applied on top of it, it failed o The structure began to deflect greatly in the centre of the span due to the weight o The ends of the span also gave way as they were not sturdy enough to support
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the structure in addition to the added load There should have been more focus on making the centre of the span more rigid as well as focussing on how to strengthen the ends of the structure which were anchoring the span in place
In comparison to other groups, our design greatly differed Many groups decided to not include a truss system, but to stiffen and make their structure more rigid in different ways Some groups strengthened their spans by layering the wood on each other to provide a deeper depth The way load was transferred on these structures also differed due to their different design However, a common factor in most groups was the failure of their structure during testing Most failed due to the same reasons as my group -> the weakness of the ends of their span
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Think about embodied energy Recyclability and carbon footprint Common ESD strategies: local materials, material efficiency, thermal mass, night air purging, solar energy, wind energy, cross ventilation, smart sun design, insulation, water harvesting
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E.g. Council House 2
Roller joints: loads only transferred in one direction, but only when pushed in any other direction, roller just moves -> Vertical loads Pin joints: modes of action can be in 2 directions -> planar Fixed joints: bending can occur
Enclosure/ Envelope System
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Structural System
Green building strategies -> reduce consumption
Service/Mechanical System
Structural Systems
Solid -> compression; early buildings e.g. Great Wall of China Surface -> e.g. Sydney Opera House
Skeletal -> frame, efficient way of transferring load Membrane -> e.g. sail, sports stadiums Most are hybrid
Structural Joint: Connectors used to join structural elements Span: Distance between two points of support
Column: Rigid, relatively slender structural members designed primarily to support axial compressive loads applied to the ends of the members
Ching, F. D. K. (2008). Building Construction Illustrated. (4th ed.). Hoboken: Wiley. Specifier Magazine (2014). Council house 2. Retrieved from http://www.specifier.com.au/projects/offices/34523/Council-House-2.html Tension: External forces pulling on a material. Stretch and elongate the material
Frame: A rigid structure that surrounds something. The skeleton of a building.
Bracing: Adding support to a structure to strengthen and stiffen it.
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Masonry
Cantilever o o
Anchored only at one point Eg. Trees, canopies, diving boards and plane wings
Foundations o
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Agricultural drain Drain excess water Takes away some of the hyrdrostatic pressure Efflorescence Salt in ground eg. white salt on wall
o One of the first buildings we came across our guided tour was situated near the Sidney Myer Asia Centre and Doug McDonell Building o The structure is a steel frame structure o Materials used on structure are mainly steel, zinc (pre-weathered), hardwood, timber and concrete o Zinc for cladding, protective coating for base metal -> self annealing o The flooring of structure is timber o Bolted connections, as to not to have to weld in situ o Welded steel beams o Discolouration of concrete o Timber beams also used support
Sports Centre
Architecture Building o
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Materials included reinforced concrete, glass, white cement (some panels polished In situ concrete columns within building Structural steel Zinc screens and frames
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Mass brick construction Bricks have different dimensions -> metric bricks compared to traditional brick buildings Unusual material in buildings, did not last long
Sports Pavilion Redmond Barry Building o o o
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Mass construction building Made up of bricks Various colours of the bricks could suggest that the bricks are pressed No obvious signs of weep holes which could mean that it is not brick cavity construction
o Hybrid of structures and includes a cantilever o Timber, steel and concrete used in structure o Timber used for aesthetics and warmth o Steel used for spans and cantilevers o In-situ concrete present, blow holes presents suggesting not properly vibrated o Vinyl sheeting for non-slip on floor o Ponding -> where mud is collecting o Most roof slabs tend to be in-situ o Back walls are concrete blocks and acoustic treatment to reduce noise
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Another issue is the staining of the concrete from the timber Unable to be removed
North Court o
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The larger sheet like material is being pulled on leaving the cable members on the ground in tension Creates an umbrella-like structure Cables also appear to be anchoring the structure to one central area As these elements are in tension they can be thought of as ties instead of struts
Cables being pulled = tension Uniting Church Centre for Theology and Ministry o o o o
Pre-cast concrete, trench mesh and glass blocks Glass blocks used for noise Air pockets are good for insulation, noise and heat Need to reduce noise from road for prayer rooms etc.
Beaurepaire Centre o o o
Mass construction using bricks and steel Uses steel portal frames instead of braces, trusses etc. Efficiency of materials observed in structure
Union house o o
Cast iron frame stair structure Beams and cables also present, but do not appear to be carrying much load
South Lawn Underground Carpark o
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Concrete columns underground to support roof as well as providing guidelines for parking sports Unusual shape for columns, spanning outwards on top Two connected pieces for one column Efflorescence occurring on some columns
Joining of the two parts to form one column
White salt forming on columns
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In order to support substructure Function = safely transfer all loads acting on building structure to the ground Load on super structure should not exceed bearing capacity of soil Settlement: over time sink into earth Footings and foundations => settlement occurs evenly and bearing capacity of soil not exceeded Differential settlement= settlement uneven which leads to cracks in buildings Shallow footings: soil conditions stable, required soil bearing close to surface of ground, load transferred vertically from foundation to ground Eg. Pad footings
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Deep foundations: load transferred from foundations through unsuitable soil down to levels where bed rock, stiff clay, dense sand/gravel located (geotechnical engineers test soil conditions) Eg. End bearing piles or friction piles
Centre of mass/gravity
o point about which an object is balanced o point where entire weight concentrated Equilibrium o state of balance or rest resulting from the equal action of opposing forces o
Strip footings
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Raft foundations (raft slab) -> increased stability, joining the individual strips together as a single mat
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Moment: The tendency of a force to produce a rotation of a body about a point or line. Acting in a clockwise or anti-clockwise direction. A moment can be described as the product of force multiplied by the moment arm.
Retaining Wall: Structures that are constructed to support almost vertical or vertical slopes of earth masses.
Slab on Ground: Poured directly into excavated trenches in the ground (concrete). Rely on the existing ground for support. Form of foundation.
Substructure: Lower portion of the structure and is usually located below the ground level. Transmits the loads of the superstructure to the supporting soil.
Pad Footing: Isolated footings. Help to spread a point load over a wider area of ground.
Strip Footing: When loads form a wall or a series of columns, is spread in a linear matter.
Build Right. (2014). Ground slabs - Introduction. Retrieve from https://www.dlsweb.rmit.edu.au/toolbox/buildright/content/bcgbc4010a/ 04_struct_members/06_concrete_slabs/
Builder's Engineer. (204). Components of a building: Sub-structure and super-structure. Retrieved from http://www.abuildersengineer.com/2012/10/components-of-building-substructure.html
Hardscape Construction. (2007). Retaining Wall Contractors. Retrieved from http://hardscapeco.com/capabilities.html Idaho Transportation Department. (2011). Retaining Walls. Retrieved from http://itd.idaho.gov/enviro/stormwater/BMP/PDF%20Files%20for%20B MP/Chapter%205/PC-17%20%20Retaining%20Walls.pdf