The bridge is made of steel, and the beam cross sections are 0.1 m wide and 0.15 m high.
The x and y displacements of nodes 1 and 5 are constrained to be zero.
Find the first seven natural frequencies and mode shapes.
Removing the center diagonal members, find the first seven natural frequencies and mode shapes again.
What is the most significant result of removing the center diagonal members? Can you explain why the seventh natural frequency and mode shape do not change?