Impact Analysis Of The Spatial Variation Effect Of The Ground Motion On Seismic Vulnerability Of The Urban Road Network

The urban road infrastructure network is an integral passageway for the post-earthquake emergency rescue of the injured and the post-earthquake transportation of rescue materials,and it needs to have good seismic performance.The urban road network covers the whole urban area and the spatial span is large,so the seismic input has the spatial variation effect obviously,which leads to different seismic input intensity of road structures.On the other hand,the urban road network includes different types of road structures.Due to the different vulnerability of each structure,the seismic damage probability is also different,and it is related to the intensity of the ground motion.It is essential to carry out a study on the impact of the spatial variation effect of the ground motion on the overall seismic vulnerability of the urban road network.Based on the seismic vulnerability assessment framework of the urban road network,this study analyzes the impact of the spatial variation effect of the ground motion on the post-earthquake performance and the vulnerability of the urban road network.Firstly,considering the seismic failure of roads and bridges,the simulation method of the seismic damage state of the urban road network is improved.The four performance indicators of the damage ratio of edges,the piece number,the normalized node number of the maximum piece,and the normalized diameter of the maximum piece are used to classify the post-earthquake performance of the urban road network.Later,a seismic vulnerability analysis method of the urban road network considering the spatial variation effect of the ground motion is developed.The spectral representation method is used to simulate spatially varying ground motions of of road structures in the urban road network,and a large number of spatially varying ground motion time-history samples are obtained.Based on the ground motion intensity obtained by spatially varying ground motion time-history samples and the vulnerability function of each road structure,Monte-Carlo simulation method is used to simulate the seismic damage of the urban road network,and the statistical results of the damage states of the post-earthquake road network are obtained.Based on the statistical results,the vulnerability curves are obtained by the curve fitting method.Finally,Taking the road infrastructure system in the city of Datong,China,as an engineering example,comparing the seismic failure probability and seismic vulnerability curves of the road network under three kinds of ground motion excitations of spatial variation input,uniform input and random input,the influences of different seismic input methods are analyzed.The analysis consequences indicate that ignoring the spatial variation effect of the ground motion will underestimate the seismic damage degree and the vulnerability of the road network.Hence,the impact of the spatial variation effect of the ground motion should be considered when evaluating the seismic vulnerability of the urban road network.