Seismic Behavioural study of A-Shaped Pylon Cable-stayed Bridge through Seismic Fragility Assessment

Abstract

The global acceptance of cable-stayed bridges (CSB) has increased due to their aesthetic appearance and suitability for relatively longer spans. CSBs are the most flexible structure. The behavioural study of CSB under natural disasters i.e. earthquake is a new frontier of research. The current research focused on seismic fragility assessment (SFA) of an A-shaped pylon CSB for Indian seismic zone-V using 25 ground motions. Spectral acceleration 𝑠𝑎(𝑔) is the best IM for a CSB. For the four performance criteria, the fragility curves (FC) have been built using incremental dynamic analysis (IDA). Developed seismic FC illustrates the damage probability of CSB as a function of strong ground motions. It can be used to assess the probability of damage for a specific ground motion index. The pylon drift ratio and bearing displacement have been adopted to produce component FCs. The traditional IDA approach is adopted which involves linear regression. The overall system fragility of CSB has been derived using the Riemannian Manifold Hamiltonian Monte Carlo-based subset simulation (RMHMC-SS). The bound limits exemplify the bridge behaviour under different LSs. Analysis results prove that bearings are the most fragile component; their placements and hinge formulations govern the overall bridge performance.