ENVS10003 CONSTRUCTING ENVIRONMENTS A01 LOGBOOK CONSTRUCTION WORKSHOP This construction workshop provides opportunities for us to learn how to use construction tools and full size material in the real practice. The content was mainly about building a structure that span 1000 mm and withstand maximum load. Every group was given different types of material to build. Our group got 2 pieces of plywood (1200×90×3.2mm), 2 pieces of pines (1200×35×35mm).
All the lengths were 1200 mm, we decided to cut pines into two parts because the materials are long enough, smaller part can be used to strengthen the structure. We used nails to combine two longer pines together vertically, pines were set to mainly withstand loads therefore combined pines may be much stronger. There were three nails at the top and three nails at the bottom. Due to the time limit, it was hard to add more nails to strengthen the structure. These pines were combined vertically and but were placed horizontally, spread surface may share horizontal forces better. Two pieces of plywood were added to top and bottom of pines through nails. To make it more stable, we used more nails to combine them both at top and bottom. It was supposed to add two small cut pines at two ends of the structure to make it stronger and more stable, however we only had time to add one, therefore it may tend to shake when adding load to it. We finally decided to cancel these two small pines.
Steps of design are shown above (red means nails). They were all uniformly distributed however some unexpected things happened such as nails were not absolutely vertically put into materials. Lack of enough joints and not strong joints may be the weak points.
What it supposed to be
218 kg
What it actually was
Final presentation
433 kg
It can be seen that there were just some slight changes when the loads became heavier. Some nails flies out in the process but the basic shape was well kept, because there is strong compression force at the top and tension force at the bottom. Plywood share horizontal force quite well.
This was the last moment that the structure survived. It finally withstood 539 kilograms, which was as good result. However it expected to suffer from larger forces if the nails would be all vertically and the number of nails would increase, then the structure would be improved to be better.
Load path and free body diagram is shown above.
Group 1 design is based on a triangle shape which is quite strong, it withstood 393 kg. The reason of failure is because of the unstable corner, the nail cannot tide the three pieces timber together. If the joints would be stronger, the structure would be stronger.
This structure only withstood less than 100 kg. It is quite weak due the design although it looks creative, but it cannot share forces well because there is empty space. The plywood here shares the vertical force so it bends in vertical direction. This structure failed due to weak joints.