Week 8 journal

Week 8- Constructing Environments Journal entry In this weeks tutorial we had our workshop session. In the session we were assigned a task to construct a bridge that had to span 1 metre and withstand a downward force until breaking point. We were given four pieces of wood which were specified on a sheet assigned to our group and with these materials we had to make our creation with the goal of it being able to take as much weight as possible.

When constructing the design we had to use a range of tools, these wooden blocks were essential in holding the structure in place when being nailed, drilled and sawn.

We used our piece of plywood to provide an extra support for the structure. The plywood added tensile force to the structure due to its flexible nature.

We were given 3 pieces of treated pine 35x35mm two of which we used as the main spanning beams to support the structure and create its shape.

The third piece of pine was chopped up into 120mm lengths, which acted and the supporting posts between the larger lengths of timber. These were evenly spaced apart to distribute weight evenly through the structure making it very strong in compression.

Screws were used to fix the timber menbers together.

Week 8- Constructing Environments Journal entry

Each piece of wood was evenly spaced along the 1 metre spanning length.

Woodscrews screws were chosen due to their stronger holding power over nails. This holding power comes from the treads in the shaft of the screw (Ching, 2008).

Creating 12 shorter lengths of timber to space along the spanning beam we created a more solid structure that was not string in tension but very strong in compression as the weight is transferred directly down the beam and into the foundations below (how stuff works, 2013).

Other methods used by the other groups were very different to our own.

The group to the left used a more tensile-based structure that utilized the ply woods flexible properties. On the right the group used a truss like form supported by plywood, however the lack of supporting beams meant it couldn’t hold up to the forces applied.

410kg force.

Deflected 20mm

150kg force.

Deflected 16mm

Week 8- Constructing Environments Journal entry The machine used to measure and apply the force could deliver up to two tones of pressure. We slowly applied the pressure to our bridge and documented its reaction to the force until it gave way. it was really interesting to see the way different structures reacted to the force and how the materials altered to compensate for and support the pressure.

A large crack appeared when our structure gave way. The crack appeared in the lower beamm, as that’s where the pressure was being transferred.

The plywood bent and folded out of shape pulling the fixing nails our and detaching itself from the main structure as the force was applied.

Due the pressure being applied directly over the beam the force was very direct to a single spot where the crack appeared.

The screws may have provided a point of fixing however they also created a point of weakness to the wood and in turn the structure as it results in a ‘split’ in the wood.

605kg force.

Deflected 48mm

Week 8- Constructing Environments Journal entry

After the workshop we went back to our room and were given the plans for our case study building. We were required to redraw one of the details from the plan at a 1:1 scale. The hardest part about this task was the size of the drawing; it was just a difficult size of paper and scale to produce a drawing at.

This helps to define why exactly it is that we produce drawings and smaller scales such as 1:5 or 1:10 and so on to create more practical and convenient instructions to produce and deal with while on site.

REFERENCES Ching, F, 2008, Building construction illustrated, 4th edition. John Wiley & Sons, Inc., Hoboken, New Jersey, Chapter 12, section 12.19.

How stuff works, 2013, how bridges work, viewed 24 September 2013 <http://science. howstuffworks.com/engineering/civil/bridge2.htm> Own images, Glen George, 2013.