Efficient Algorithm Proposed to Generate Non-Uniform Ground Motion on Canyon Sites

Many huge structures such as dams, plants and bridges located in canyon sites, are subjected to non-uniform ground motions and so their conventional type of analysis (assuming uniform ground motion) may lead to unreasonable responses. There is noticeable difference between the responses of huge structures to uniform and non-uniform ground motions. In order to conduct non-uniform dynamic analysis of this kind of structures, definition of seismic loading is a main challenge. In this research an efficient algorithm based on the numerical analysis of seismic wave components (P, SH and SV) and their combination is proposed using a single point given accelerogram record of the site. Thus, non-uniform seismic acceleration time series could be generated in different points of the site. Special purpose Boundary element code (TDASC) is developed in order to conduct seismic body waves scattering analysis at a canyon of arbitrary shape. Efficiency of this algorithm has been shown by re-generating the 24 October earthquake free-field accelerograms recorded at the Shafaroud dam site canyon in northern Iran. Comparison of the recorded and generated accelerograms for three different components along the canyon shows a good conformity.