Damage spatial distribution and its influential factors in Dujiangyan City subjected to Wenchuan earthquake

Base on the outcomes of seismic damage assesment in Dujiangyan City, spatial distribution of building seismic damage subjected to Wenchuan earthquake was investigated and the possible causes were analyzed with the two key factors of the spatial evolution of urban area and the spatial earthquake inputs taken into account. Firstly, urban layout and characteristics of seismic damage in Dujiangyan City were considered along the direction normal to the mountains, and the city was divided into two regions spatially by the inner ring road and the outer ring road. Then, considering that the evolution of seismic codes would cause remarkable changes on seismic performance of buildings, buildings were divided into groups in chronological order, and the seismic damages of building groups were compared spatially by each period. Finally, the influential factors of spatial urban evolvement, topographical condition, site condition and distance to fault on the spatial distribution of seismic damage were discussed. It is found that the spatial evolution of urban area is the key cause to the spatial seismic damage distribution. From the analysis, early-age buildings has up to 6.5 times higher average damage level than the new buildings. And the spatial ground motion input is also an important cause for the damage distribution. In Dujiangyan City, seismic damage in inner ring road part is significantly higher than that of the outer ring road part, with the amount of up to 1.88 times higher than the latter. This study will provide solid references for future aseismic design and damage prediction.