Lateral seismic performance analysis of diamond-shaped pylon based on equivalent single-tower model

Abstract

To study the lateral elastic-plastic seismic performance and failure mechanism of diamond-shaped pylon in long span cable-stayed bridges under extreme seismic excitation, a typical long span cable-stayed bridge was taken as the prototype and its finite element model was established using SAP2000. According to the principle of self-weight effect, lateral stiffness and lateral mode equivalence, a simplified method of diamond-shaped pylon is proposed. The entire bridge model is simplified into an equivalent single-tower model. Two fiber finite element models were established in OpenSees. Comparative analyses of static characteristics and related results were conducted to assess the applicability of single-towers with different material property. The reliability of the models was verified by comparing quasi-static test results. A systematic investigation of the lateral seismic performance of diamond-shaped pylon was carried out at three hierarchical levels: the structure, cross-section, and material. The analysis identified the yielding sequence and damage mechanisms. An in-depth analysis of material damage in diamond-shaped pylon offers essential data to support the investigation of their failure mechanisms under severe seismic excitations. The analysis results reveal that the lower area of the middle crossbeam is the most vulnerable region in the diamond-shaped pylon. The failure mechanisms consist of tensile yielding of the steel reinforcement, subsequent cracking compressive strain in the concrete, and final concrete crushing failure.