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Week 1
Bricks -> require a bond Extruded bricks vs. pressed bricks
Introduction to construction Materials o
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)
Structures o o o o o
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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
Studio Activity
The Task
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.
Materials 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.
The Base of the Structure 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.
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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.
Opening up the Structure
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.
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Closing the Entrance 4
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.
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Building Upwards
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. 6 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.
Wind Loads: Kinetic moving mass of air, assumed to come from any horizontal direction
Live Loads: Any
Occupancy loads:
Snow And Rain loads:
moving or movable loads
Weight of people, stored material, furniture, etc. in a building
Weight of snow or rain accumulating on roof
Dead loads: Acting vertically downward on a structure = self-weight of structure + weight of building elements, fixtures & equipment permanently attached
Loads Static Loads Dynamic Loads
Settlement loads:
Earthquake Loads: Any moving or movable loads
Imposed by structure -> subsidence of portion of supporting soil => differential settlement of its foundation
Impact loads: Kinetic loads, short duration. From moving vehicles, equipment, machinery etc.
Water pressure: Hydraulic force groundwater exerts on foundation system
Ground pressure: Horizontal force soil mass exerts on vertical retaining structure
Forces
Non-concurrent forces: vector sum= single force cause same translation + rotation of body as set of original forces
Glossary
References
Load path: Direction load will pass through connected members. Both, A., Reiss, E., Manning, T., & Mears, D. (1999). Greenhouse Engineering Pictures. Retrieved August 7, 2014, from http://aesop.rutgers.edu/~horteng/conspics.htm
Masonry: Work done using stone, brick or concrete :Compression: external forces pushing on a material. The shortening of a material.
Reaction force: A force which is equal and opposite to a force being applied.
Point load: Load which is localised to a specific location on a structure
Beam: Rigid structural members designed to carry and transfer transverse loads across spaces to supporting elements.
Ching, F. D. K. (2008). Building Construction Illustrated. (4th ed.). Hoboken: Wiley.