Using the bridge repair system in Problem P5.15, develop two additional two dimensional configurations that utilize different suspension arrangements. The following design requirements must be met: Two-level access to the bridge must be provided with the top platform at 90 in. below the road and the lower level 185 in. below the road; each level must accommodate no more than two 200-lb workers; standard structural steel cables (S_y = 250 Mpa) of 0.50-in. diameter with varying lengths are to be used. Evaluate the three designs (your two and the one from Problem P5.15) with respect to their factor of safety in worst-case loading conditions and identify which configuration has the highest factor of safety.

Problem P5.15

A two-tier system to repair bridge infrastructures is supported by two steel cables for each platform (Figure P5.15). All the support cables have a diameter of 0.50 in. Assume the applied loads are at the midpoint of each platform. Determine how much each cable stretches at points A–D.

Figure P5.15

Transcribed Image Text:

140 in. 90 in. 250 lb 185 in. A 190 in. 400 lb D