WEEK 2 CONSTRUCTION JOURNAL: FRAMES CHRISTOPHER DEBONO 640177 SEMESTER 2 2013
Geometrically speaking, triangles are one of the strongest shapes in framework, so we opted to use triangles as much as we could, this is where we derived our overall shape.
Because materials were limited, we did the bracing to half way so that there was still ample rigidity in the structure to go verticle. There was also bracing along the outside and along the corners to transfere lateral forces down to the base.
We built it in modules, adding on each section which was identicle to the last. This made it quick to build up to a decent height. During this process we tried to use the thicker pieces as our columns so that there was more material to resist lateral forces.
We tried to make a rigid fixed joint so that it would assist the bracing, however we did experiment with pinned joints aswell. By taping them it allowed some flexibility to absorb the forces acting on the structure and if utilised correctly, resulted in the structure performing better.
When we reached a substantial height we used the rest of our materials to strengthen the tower further,. adding bracing to the larger spans between joints
Adding ribs of tape assisted in reducing the deflection the balsa wood had when we needed rigidity in our columns.
The flexibility is directly proportional to the cross sectional area and its orientation to the acting forces.
We concluded that it was the flexibility in the balsa wood that resulted in the towers destruction. It reached a point where the wood would deflect no more and at this point, it failed. The joints proved to be suffient in taking the weight but because of there distance appart and some being pinned, it allowed it to be flexible. Material selection is vital to success
Refference List: Ching, F.C, 2008. Building Constructing Illustrated. 4th ed. New Jersey: John Wiley & Sons. Chapter 2 Construction & Working Drawings - Discussion • SketchUcation Community Forums. 2013. Construction & Working Drawings - Discussion • SketchUcation Community Forums. [ONLINE] Available at: http://sketchucation.com/forums/ viewtopic.php?f=12&t=15911&start=300. [Accessed 22 August 2013].