Comparison of various procedures for progressive collapse analysis of cable-stayed bridges

Alternate path (AP) method is the most widely used method for the progressive collapse analysis, and its application in frame structures has been well proved. However, the application of AP method for other structures, especially for cable-stayed structures, should be further developed. The four analytical procedures, i.e., linear static, nonlinear static, linear dynamic, and nonlinear dynamic were firstly improved by taking into account the initial state. Then a cable-stayed structure was studied using the four improved methods. Furthermore, the losses of both one cable and two cables were discussed. The results show that for static and dynamic analyses of the cable-stayed bridges, there is large difference between the results obtained from simulations starting with either a deformed or a nondeformed configuration at the time of cable loss. The static results are conservative in the vicinity of the ruptured cable, but the dynamic effect of the cable loss in the area farther away from the loss-cable cannot be considered. Moreover, the dynamic amplification factor of 2.0 is found to be a good estimate for static analysis procedures, since linear static and linear dynamic procedures yield approximately the same maximum vertical deflection. The results of the comprehensive evaluation of the cable failure show that the tread of the progressive failure of the cable-stayed bridges decreases when the location of the failed cables is closer to the pylon.