ENVS10003
Constructing Environments Logbook
Paige Collett 698753 pcollett@student.unimelb.edu.au Bachelor of Environments
Lecturer: Clare Newton Senior Tutor: Rebecca Cameron Tutor: Jullian Tuckett Semester 1, 2014
Materials: an Introduction
The modern construction industry has vast option when it comes to materials, different execution methods with those materials, and the different components and features that can effect the properties of a certain material. Some of the key basic principles of construction materials are stated, defined and examples are given:
Strength
Different materials have different strength properties - and those different properties also vary based on the ‘type’ of strength being measured a material can have different variations of strength in the context of structural forces such as compression and tension.
Stiffness
Impartial to ‘strength’ - simply an appraisal of flexibility and stiffness
MDF - Medium Density Fibreboard. Made of very fine wood dust particles, glued and compressed together with resin under heat and pressure. - economic - even density - vast availability - good workability
Shape
Can effect all other material properties. Certain materials are Monodimensional, Bidimensional and Tridimensional (Newton, 2014)
Material Behaviours The behabviour of a material in responce to forces. A material is typically Isotropic or Anisotropic (Ref. Glossary for definition)
Economy
Is it economically viable to ascertian that particular material?
Sustainability
The environmental impact of a material is very important in the 21st century. This encompasses not only how the material will last and perform over time, but also the impact of sourcing that particular material The embodied energy (ref. Glossary for definition). The materials long term performance is the longituidy of itslife, the recyclability of it, and how it minimises other services that cause environmentalimpact; such as the required heating/cooling/lighting of a structure. Images: MDF Block Tower displaying compressionpowers, approx. 1700mm tall, balancing a weight of approx 4kg at peak; Paige Collett (2014)
1.
Basic Structural Forces Tension and Compression
The Power of Compression
The two most common and basic structural forces one must familarise themselves with are Tension and Compression. Tension describes a pulling force, in which the material or structure experiences elongation to a certain degree. A common structural example of where tension is evident is in the construction of bridges, where steel wiring under a great deal of tension is often used as a key part of the structure.
Image: Ching ‘Building Construction Illustrated p2.11 (2008)
Compression is the opposite force, in which the material or structure is compressed often due to weight and gravity. Brick structures are a
COMPRESSION
Forces and Scale
TENSION
Images: Stages of MDF block tower construction and destruction; Paige Collett (2014)
Forces and scale can be expressed in the mathematical term of ‘Vectors’. They can represent compression, tension or any other form of ‘movement’ - as is the definition of ‘force’. They also depict the measurable scale of that force. (UOM Department of Mathematics and Statistics, 2014)
2.
Loads: Depiction, measurements and types Dead Load is the load of a structure itself; its materials and permenant structure in order for a Structure to stand there must be a balance of equal and opposite forces the earth must be able to support and push up, the weight of the structure being pushed down. The Dead load must also be balanced or able to counterbalance through strength or some other property - this is shown in the sketch of a floating bench:
Dead Load
Image: MDF Block Tower midway through distruction; Paige Collett (2014)
Load Path Above is an image of the MDF block tower built in W1 of Constructing Environments. The image shows a section that was partially destroyed to test the power of compression. The arrows show how the load is distributed throughout the tower and how that distribution changes around the void in the tower. Tarrows show where the load is not spread evenly, however it can be seen that very quickly, the load levels out again throughout the MDF blocks. The more evenly spaced the building materials, (MDF blocks) the more evenly spread the load will be.
Live/Static Load Live load is the applied and often changing load that a structure endures, it is often unbalanced in the structure so the structure must be designed to withstand this change, a bridge is an excellent example with cars as the ‘live’ load.
Image: Bloukrans Bridge, South Africa; ‘Fiona in Monbulk (2012)
3.
The Sytem Breakdown:
Structural Systems
Structural Solid Systems
Compression is the key structural force present in this building method, a very early method of construction. E.g. stone, bricks
The Great Pyrimid of Giza, Egypt; Nina (2005)
Enclosure
Shell/Surface Systems
A planar structure relying on compression tension and tensile forces. Typically construced of steel reinforced concrete, coming to popularity post WWII (Encyclopaedia Britannica Inc. 2014)
Sydney Opera House, Australia; Unknown (2011)
This is not simply the aesthetic of a structure but also the protective outer layer. The facade, exterior walls, entrance points and roof all make up the external envelope system. It must form a divide creating an internal and external space where the two environments can opperate independent of one another. Weather control, light flooding, temperature control, security and privacy are just some of the systems a building enclosure can effect and regulate.
Mechanical/Services
Frame/Skeletal Systems
The most common form of construction in the 21st century. An efficient way of transfering loads (Newton, 2014) and the structure can be made out of a vast range of materials E.g. wood, steel
The purely practical side to a structure: the mathematics, the physics, the backbone to everything else. Superstructure is the above ground structure of a building, the beams, the columns, loadbearing walls etc. Substructure encompasses is the underground aspect of the structure, the foundations whether it be reinforced concrete slabs, piles, etc.
Vodafone Headquarters, Portugal; Unknown (2014)
The mechanical systems of a structure are the ones that are regarded as necessary for a ‘comfortable’ dwelling - however the sustainability and environmental aspects of a structure can realistically impact the services required, or altar the ‘way’ in which those systems are required. Some of the systems are: water, electricity, heating/cooling, ventilation, sewage (Ching 2014)
Membrane Systems
Efficient and economic. Able to cover large surfaces of area, with the primary force being tension. The membrane is typically thin and flexible such as fabric (Encyclopaedia Britannica Inc. 2014)
National Aquatics Centre, Beijing; Unknown (2008)
Hybrid Systems
Newest system to the Construction Industry, a combination of structural systems are used E.g. Skeletal and Membrane Sports Park Stozice, Slovenia; Unknown
4.
Key Considerations in Construction NEED
WANT
It all starts with... and An individual or company requires a building
Aesthetic
Performance
Wanted performances can be things that must fit a use, such as an area to accomodate a certain quantity of people. Need performances tend to be based on location and also building use - fire escape, natural disaster considerations, soil types, sound resistence, ongoing maintenance
Tend to be solely ‘want’. But also effect the way a building can be used. Environmental and neighbourhood context should be taken into consideration
Environmental
Will the Structure be sustainable not only now, but over time? Will the building materials assist in minimal electricity usage? What is the embodied energy of the materials?
Economic
Does it fit the Budget?
It should be noted that this process does not stop when the construction begins, this is a circular processes that will continue to change and evolve throughout the entire construction
Construction Limitations
What are the building codes and regulations? What is the material availability? Are their labourers available with the appropriate qualifications?
5.
Structural Joints Week 2 brought the experimentation of structural joints. A structure is only as strong as its weakest joint. Regardless of the materials used, the joint type, and strength has a paramount effect on the stability and strength of a structure this was first shown in the demonstration of a ‘water tank’ built with straws for columns and pins for joints - although the columns were weak, it must be noted that the failing point in the experiment occurred at the ‘pin’ joints. Following this, students were asked to construct towers with a skeletal frame using balsa wood - A major flaw observed was the lack of stability and support in the footings - at a certain point of height the structure would fail due to becoming unbalanced
Roller Joint
Allows horisontal movement Ideal for structures with a moving load E.g. bridges
Pin Joint
Allows rotational movement Often found within a truss system
images to be inserted
Fixed Joint
A complex joint that allows no movement, because of this a lot of pressure can be put on the joint and columns/structure when a load is applied and result in bending (Newton, 2014)
6.
Glossary Tension: the degree to which something such as a wire, string, thread, or muscle is stretched Physics; the stress resulting from a force of tension, or a measure of it Compression: the reduction of the volume or mass of something by applying pressure, or the state of having been treated in this way Isotropic: having physical properties that do not vary with direction Anisotropic: describes something with physical properties that are different in different directions, e.g. crystals that measure differently along each of two or more axes Torque: force that causes twisting or turning, e.g. the force generated by an internal-combustion engine to turn a vehicle's drive shaft Faรงade: the face of a building, especially the principal or front face showing its most prominent architectural features Dead Load: the permanent weight of a structure such as a bridge, exclusive of its load Live/Static Load: the permanent weight of a structure such as a bridge, exclusive of its load
References Ching, F. (2008). Building Construction Illustrated (4th Ed.). USA. John Wiley & Sons, Inc. Encyclopaedia Britannica Inc. (2014). Shell Structure. Retrieved from http://www.britannica.com/EBchecked/topic/1385998/shell-structure Encyclopaedia Britannica Inc. (2014). Membrane Structure. Retrieved From http://www.britannica.com/EBchecked/topic/1382569/membrane-structure' Newton, C. (Producer). (2014, March). W01 m1 Introduction to Materials. Retrieved from https://www.youtube.com/watch?v=s4CJ8o_lJbg&feature=youtu.be Newton, C. (Producer). (2014, March). W02 s1 Structural Joints. Retrieved from https://www.youtube.com/watch?v=kxRdY0jSoJo&feature=youtu.be Newton, C. (Producer). (2014, March). W02 s1 Structural Systems. Retrieved from https://www.youtube.com/watch?v=l--JtPpI8uw&feature=youtu.be The University of Melbourne, Department of Mathematics and Statistics. (2014). MAST10005 Calculus 1: Lecture Slides. Melbourne, University of Melbourne.