a) Draw a free body diagram of the truss and obtain expressions for the external reaction forces at A and G as a function of P and a.

b) Identify all zero-force members.

c) Use the method of joints to find the internal forces in each truss member (indicating if it is compressive or tensile). Hint: the truss has a symmetric geometry and symmetric loading.

d) Take a look again at the bridge picture. Do you see anything different when comparing tensile vs. compressive members? Are all members the same size? Explain.

e) What would happen if you remove the two circled truss members from the bridge? Explain.

 

TAM 210/211 Written Assignment 6 (due on October 9th) Consider the bridge below, where all vertical and horizontal members have a fixed length a, with a vertical load P at each of the joints in the support along the deck and at the pylons. This load P corresponds to the load from the deck. For everything ahead, we will simplify the problem by considering it in 2D. The figure below models the supporting side truss of the bridge. K B E F P P P P P