Simulation of Spatially Variable Artificial Earthquake: A Case Study of Different Site Conditions

The dynamic analysis of structures under seismic ground motions is a major issue in earthquake engineering. The seismic ground motions observed at the surface are variables in space and time. The main causes of this variability come from seismic waves propagation between the source and the site, and in particular the local geological site conditions. For this purpose, it is essential to consider all these factors of the spatial variability of seismic ground motion when representing seismic loading to be applied to any structure. Given the scarcity of real seismic records, many researchers suggest the use of artificial or synthetic seismic motions. The main objective of this study is the simulation of spatially variable artificial seismic motions by considering all fact of factors of the seismic spatial variability, especially site local conditions. In this sense, a simulation technique of spatially variable seismic motions is developed using the spectral representation method. By adopting the unconditional simulation approach, the target seismic motion in bedrock is defined by the Clough-Penzien spectral model and a specified coherency loss model. Then, the simulated ground motions in the bedrock are projected on the surface by considering amplification site effect. The results showed that the simulated artificial seismic motions are strongly conditioned by the local site conditions.