Selection of Optimal Intensity Measures in Seismic Damage Analysis of Cable-Stayed Bridges Subjected to Far-Fault Ground Motions

The intensity measures of ground motions are closely related to the damage of bridge structures. However, it is difficult for engineers to select these parameters to predict the potential damage of cable-stayed bridges under earthquakes. This paper investigated the correlation between the intensity measures of far-fault ground motions and the damage of cable-stayed bridges. 322 far-fault ground motions were selected, and 26 available intensity measures in the literatures were chosen to carry out comparative analysis on a cable-stayed bridge with a single pylon. The nonlinear finite element model of this bridge was built, considering the stiffness degradation of concrete and low-cycle fatigue effect of steel. It is concluded in this study that velocity spectral intensity (VSI) is the optimal intensity measure for seismic damage analysis of cable-stayed bridges subjected to far-fault ground motions, followed by spectral acceleration at fundamental period and Housner intensity. Five commonly used intensity measures, namely peak ground acceleration (PGA), the ratio of PGA to peak ground velocity (PGA/PGV), specific energy density (SED), predominant period (T-p) and mean period (T-m), demonstrate low correlations with the bridge damage. In particular, there is very weak correlation between the conventionally used PGA and the seismic damage of cable-stayed bridges.