Collapse Pattern Identification for Cable-stayed Bridges Based on Ultimate Limit Analysis

A method based on ultimate limit analysis (ULA) was proposed to identify collapse pattern for cable-stayed bridges. The proposed method had no need to model the whole process of structural progressive failure, but assumed plastic hinge model of cable-stayed bridges, which had two sets of variables describing plastic hinges' positions and rotational angles. By a two-stage sequential optimization, the variables could be solved to reveal the bridge collapse pattern. Parametric studies could be further conducted to identify the bridge critical components, and explore the effects of some design parameters on collapse pattern and ultimate load-carrying capacity (ULC). The proposed technique was illustrated on a twin-pylon cable-stayed bridge. Comparing with the results of nonlinear finite element analysis (FEA), the yielded components forming collapse pattern can be correctly extracted from the plastic hinge model. This technique results in small errors (less than 3.1%) for estimating the ULCs.