Group 5 during a group meeting at the library to work on the incomplete Visual Analysis file.
This week Dan was focused on making progress on the SketchUp CAD representation of the Atomium monument. Seen here are the frontal and top views of the model as of 4/22/14. The model consists of the tilted cube with nine spheres, one located at each corner and one in the center. There are several features still missing, including the base of the building, details on the interior of the spheres, windows, and the three supporting bipods.
For the homework assignment, the bridge was obvious unstable and VisualAnalysis always reported errors "when doing p-delta analysis". Everyone was confused at first until we saw this picture above. (RISA News, http://risanews.com/what-is-p-delta-analysis-risatech-risa3d/) When a model is loaded, the deflection in the members of the model may induce "secondary moments" due to the fact that the ends of the member may no longer be vertical in the deflected postition.
Yiping finally made the bridge work but it still seemed weak. She also tried to reinforce the structure, but due to the weight of the material itself, a dual-layer-bottom for the bridge deck did no help. An additional vertical one seemed help a little. Also, from the lab of last term, we know that Warren Truss is not the best choice. So the direction of the diagonal trusses were also changed.
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