Strand7 Software:  Galleries:  Civil:  Suspension Bridge

Suspension bridge

One of the most important design criteria is the response of the bridge to seismic excitation. This type of analysis is normally performed as a spectral response analysis, using a modal superposition technique. The modes included in the spectral response must include the effect of the tension in the main cables. Since the cable behaviour is nonlinear, the nonlinear static solver is used to determine the equilibrium state of the stucture. In Strand7 the results of a nonlinear analysis can be used as initial conditions in eigenvalue analysis (i.e. natural frequency and linear buckling).

The natural frequency analysis of the suspension bridge should consider the tension in the cables. Cable tensions are as a result of both applied pre-tension and the effects of gravity. As the cables exhibit nonlinear behaviour, the equilibrium state of tension is determined using the nonlinear geometric solver. This result is then used as initial conditions by the natural frequency solver.