LOG BOOK RACHAEL MCVEA 636656
CONSTRUCTION MATERIALS Considerations:
Strength- weak or strong Stiffness- stiff, flexible, stretchy or floppy Shape- mono dimensional, bi dimensional or tri dimensional. Material behaviours- isotropic or anisotropic. Economy and sustainability- travel, efficiency.
Structural Forces Force- Any influence that produces a change in the shape or movement of a body. (Newton, Clare, Basic Structural Forces, 12/03/2014) Tension Forces- Stretch and elongate the material. Compression Forces- Shortens the material, opposite to tension. Load Paths- The path a load takes to distribute the force evenly to the receptors. This is the most direct route and is met with a reaction force that is equal and opposite. (Newton, Clare, Load Path Diagrams, 11/03/2014) 3 FORMS OF CONSTRUCTION 1: MASS CONSTRUCTION 2: FRAME CONSTRUCTION 3: TENSILE CONSTRUCTION MASS CONSTRUCTION Static structures, supported by the foundation of the Earth, built with generally heavy duty materials. Two types of Mass Construction:
Small Module- Concrete blocks, bricks, mud/clay, adobe, rammed earth. Large Module- Precast concrete.
Figure 1: Irving, Mark, 8/03/2014
Strengths Small Module
Creates a bond, which in turn spreads the load of the mass, this bond makes the structure stronger. Allows shape to be developed in the structure by use of smaller materials. Create patterns, ultimately the smaller module materials allow for more flexible creativity and design.
Faster in the sense of putting the building together. Cheaper; reducing construction time on site as more trades can work at the one time and are not held up by time consuming materials. Quicker to make and erect. Made off site and brought to site ready to be used.
Limitations Small Module
Time consuming, slow process to put a wall of bricks up. Requires scaffolding and ladders once the height of the construction exceeds a human. Holds up other trades on site, hence costing more money. Hard to transport large loads of them around the site without needing special equipment
Very limited designs, curves are difficult and expensive. Incredibly heavy, requiring special transport to site as well as a crane on site to erect.
Site Analysis- Process of studying contextual forces that may influence the construction of the land and the building to which will be erected there, its shape, lay out, orientation. (Ching, Frances D.K, Building Constructed Illustrated, 2008) Important definitions DDA- Disability and discrimination act. PPE- Personal protection equipment. UB- Universal beam UC- Universal column Pfc- Parallel flange channel
Bricks Pressed Clay pressed into moulds and placed in an oven, this however created variations in the bricks because of the different temperatures within the oven. E.g. a brick in the middle would be baked more thoroughly than a brick towards the edge. “Frog,” divot in the middle, helps to increase the depth of the mortar, assisting with the joining process.
Fig 2: Irving, Mark, 07/03/2014
Extruded Made by forcing a bar through the clay, which reduces the amount of clay used to produce the bricks, therefore they’re not just cheaper but create a cohesive bond between bricks when mortared in. (Readers Digest, 11/03/2014) Forces Considered in Construction Dead - Static, e.g. furniture. Live- Humans
Gravity Wind Water in the ground Seismic
CLASS TASK DESCRIPTION: BUILD A TOWER AS HIGH AS POSSIBLE , MUST HAVE A DOORWAY FOR THE PLASTIC DINOSAUR TO FIT THROUGH AND AN ENCLOSED CEILING .
MATERIALS: SMALL MDF BLOCKS .
As a group we figured out how many blocks high the dinosaur was, telling us how high our door would need to be. Our group discussed the possible shape and structure, and after dismissing a square base, as we were not sure how we would enclose the roof, and dismissing a pyramid as that would not give us the height we desired, we all agreed on a round cylindrical shape. We began construction, creating that cohesive “bond” of bricks by laying them via Stretcher bond, as this creates the best bend strength (Boral). We left a space for the doorway to fit and figured further up in our construction we would be able to slowly bring the bricks in closer till they eventually met.
As we reached about 7 bricks high we came to realise that a single layered wall would be very unstable and could easily topple over. We needed a firm foundation for the tower to gain the required height we wanted. Therefore, we began again, this time creating a double layered wall, with that same bond however. However, we did aim in the future to slowly bring the bricks in, not just to close the doorway but to allow us to enclose the roof also. We knew if we did this procedure too early the tower wouldn’t reach the height we desired and wouldn’t have a stable base to sit upon.
As we got higher we very slowly brought the entrance bricks closer together, inching them a few millimetres inwards every new layer. We were easily able to slip a few individual bricks in the cracks to finally join the doorway together. This needed to be strengthened above the doorway before we could bring the bricks in to create our roof; therefore we made sure there were at least 10 layers of bricks above the doorway, so it would not weaken under the above weight. The tower started reaching higher and higher and we began to now slowly inch the bricks inwards in order to be able to conceal the roof. As was done with the doorway, we slowly each row brought the bricks in, only millimetres, to allow the cylinder to get smaller.
Time began to run out on us so we quickly worked to ensure our tower had a roof upon it. This meant bringing the blocks in and getting it as high as possible. If time had not have been a restraint, I believe the solid base of our structure wouldâ€™ve allowed us to extend our tower to the ceiling, however it became thin when we needed to create height and enclose the roof and this section would not have been able to extend to the ceiling. By the end our tower reached to about my chest and was incredibly stable because of the foundations we had created. The only reason it became a thin tower was to get that roof on top that the brief had asked for, otherwise the thick solid beginnings couldâ€™ve taken us to all sorts of heights. OTHER GROUPS WORK Other groups in the Constructing Environments class took quite different approaches. Some were similar to our group in a round structure; others however chose square foundations and aimed for high and skinny. Some just went for the artistic approach, however all stood up. The square
structure had an incredibly solid base, but as the tower was tall and thin, it was vulnerable to the forces. The artistic structure looked quite weak and fragile and didnâ€™t quite get the height required or achieve a closed ceiling. And the structure of similar stature to ours stood firm, creating height as well as a closed ceiling. DEMOLITION Our solid structure allowed us to pull of huge amounts of blocks without the structure collapsing, literally like a game of Jenga, we were able to remove blocks from all areas and our structure still stood up. We removed that whole outer wall and were left with another, thinner, but still quite sturdy structure.
WEEK 2 14/03/2014 CONSTRUCTION SYSTEMS A building is a combination of a number of systems and subsystems that must coordinate with one another as well as with the building as a whole. These physical systems organise the ordering and construction of a building. (Ching, Frances D.K, Building Construction Illustrated, 2008)
Enclosure system- how you protect a building from the elements. Structural System - Frame, column & beam, mass construction. Service system- Anything providing amenity to the building; electrical, mechanical, hydraulics
ENCLOSURE SYSTEM Shell or envelope of a building, consisting of the roof, exterior walls, windows and doors. (Ching, Frances D.K, Building Construction Illustrated, 2008) SERVICE SYSTEMS Provide essential services to the building; water supply, sewage disposal, heating and airconditioning, electrical system controls, vertical transportation systems (lifts), fire-fighting systems and perhaps recycle and waste disposal systems. (Ching, Frances D.K, Building Construction Illustrated, 2008) STRUCTURAL SYSTEMS
SOLID- Early buildings, mud, bricks, stone. Compression arches. SURFACE- Sydney Opera House. SKELETAL- Frames, efficient. MEMBRANE- Tension, shade sails, sports stadiums. HYBRID- Structural frames covered in different materials.
(Newton, Clare, Structural Systems and Forms, 14/03/2014) Structural Systems: Primary member- large beam which spans the shortest distance. Secondary member- Rafters, run perpendicular to primary member. The more distance you cover with a beam the wider and heavier the beam needs to become, this can cause issues of being too heavy. To overcome this you turn the beam into a truss to lighten it. Considerations
Performance requirements- structural, fire resistance, comfort, protection from elements, compatibility, easy maintenance. Aesthetic qualities- proportion, colour, surface qualities. Economic efficiencies- budget, affordability (initial cost and maintaining cost) Environmental impacts- embodied energy, constructability efficiency.
(Newton, Clare, Structural Systems and Forms, 14/03/2014) ESD= Environmental Sustainable Design Examples:
Recyclability- Reduce, reuse, recycle. Carbon footprint- Measure of greenhouse gases used. Local materials Thermal mass -Use of a material to store energy. Eg. Concrete slab. Water harvesting -Collection and use of rain water. Insulation Wind energy Solar power Material efficiency Night air purging - bringing outside air inside in the evening to remove stale air
Newton, Clare, ESD and Selecting Materials, 14/03/2014 Structural joins Every load must have a responding force of equal strength.
Roller joint- Only resists vertical forces Pin joint- resists both vertical and horizontal Fixed joint- Resists vertical, horizontal and rotational forces. (Cantilever- one point of support. E.g. a tree or wing of a plane.
Embodied Energy= How much energy is in the item. Moving it, maintaining it, running of it, getting rid of it.
Base Metals- Elemental (periodic) E.g. aluminium. Alloy metals- Combinations. E.g. bronze= copper + zinc
Aluminium is stronger than steel and lighter but is expensive and requires a lot of embodied energy.
Fig 3: Newton, Clare, Structural Connections, 14/03/2014
CLASS TASK DESCRIPTION: BUILD A TOWER OUT OF SELF-CUT BALSA WOOD STRIPS .
Using our 43 strips of balsa wood to develop the highest tower possible proved harder than first thought. The balsa is flimsy and easily bent and snapped, this lead us to choose a triangle based design that would allow us to have a sturdier structure and high structure.
As we had just learnt that day, trussing was an effective way of stabilising a building, thus we implemented this into our design, to reduce those bends and snapping of the balsa. The use of masking tape to join the balsa led to many difficulties also, it was heavy and difficult to use on such small pieces of balsa, leading to breaks and messy joins. The base developed strongly, however as we began to run out of balsa we came to realise the higher we got the more unstable it would become after we triangulated the roof, leaving us not much room for movement.
In a last bid attempt to extend our tower to the ceiling we created a very long and very thin piece of balsa which was stuck to the top of our building and extended almost to the ceiling. If we had not of finished the base off so soon by adding a triangular roof we may have been able to create a sturdier structure that stood as high as it did as an actual structure. In the end our structure did extend quite high but officially the singular pieces of balsa don’t count as a structure, next time a higher and sturdier foundation would’ve enabled us to continue building a “structure” as high as the thin balsa. The thin balsa also didn’t prove strong, swaying in the slightest of movement. Out in the elements it would’ve snapped off very quickly.
OTHER GROUPS A common theme of most groups was the idea of trussing their structures to strengthen them. The group with thicker balsa was more successful in this. The group with short and thick balsa however created a very unstable structure that wouldnâ€™t stand on the floor.
RESOURCES www.readersdigest.com.au http://www.boral.com.au/images/common/clay_bricks_pavers/pdfs/1_307.pdf Ching, Frances D.K, Building Construction Illustrated, 2008 Newton, Clare, Constructing Environments ELearning, 2014.