RESEARCH ON PROBABILISTIC SEISMIC DEMAND MODEL OF SIMPLY SUPPORTED GIRDER BRIDGE BASED ON GAUSSIAN PROCESS

This paper proposes a new method of probabilistic seismic demand analysis with high accuracy considering heteroscedasticity. For a typical simply supported girder bridge, the spectral acceleration corresponding to the fundamental period of bridge is chosen to reflect the ground motion intensity, and the displacement ductility coefficient of pier is selected as engineering demand parameter. A series of nonlinear dynamic time history analysis was performed on the bridge finite element model using the multiple strip analysis and the seismic demand sample set was established. Based on the Gaussian process regression method, the probabilistic seismic demand models were established for univariate and multivariate cases, and the fitting results were compared with the seismic demand models derived from the traditional linear regression. The seismic fragility models were established based on the two aforementioned seismic demand models by defining the limit values of different damage states of piers. The results show that: The probabilistic seismic demand models based on Gaussian process can reflect the probabilistic characteristics of seismic demand under different ground shaking intensities more accurately and describe the heteroscedasticity of seismic demand in logarithmic space better; there are some differences in the fragility curves of bridge components and system generated by the two models. The probabilistic seismic demand model based on Gaussian process can provide more reasonable and accurate assessment of the seismic performance of the bridge.