By Jessica Grafton
This semester in Arc 362 – Structures II, we have been working on a wood design project. The project objective was to design and build a small scale structure that would hold both a concentrated load and a uniform load of 150lbs. in teams of two. At the start of the semester we explored, with our teammate, the calculations that would allow us to discern whether or not our structure would indeed support the given weight. After learning the methods for doing this, we then started to play with design.
The parameters for the project were as follows:
The structure was made from one 2 x 4 lumber, supporting columns must sit outside the limits of a 48” diameter circle, while uniform load of 150lbs.(27 bricks) must not exceed the limits of a 36” diameter circle, both load types must pass deflection minimum of 4” above ground, total weight of structure must not exceed 5lbs.
After sketching and debating a suitable design, we then had to make sure that our members would indeed allow for the uniform distribution of bricks to sit in one layer across the structure, within the 36” dia. Circle. Likewise the point load would have to be supported, but stacked centrally two bricks wide. Once each we knew that both of these requirements were met, we went on to analyze the calculations that would tell us what size each member would need to be in order to support both scenarios.
Then the fun part! We built the structure using the school wood shop and then presented it in class by actually applying these loads. Each team stacked bricks on their structure in both load types to see if in actuality it could hold the loads. If the structure collapsed the team automatically received a C for the grade, this was the case also if it exceeded the specified 5lb. weight limit. Points were also deducted for exceeding the min. 4” deflection.
I’m happy to say that my partner and I passed on all accounts despite a lot of nervousness prior to the testing.