Seismic ground motions at a site are greatly affected by nearby many factors, such as strong heterogeneity, irregular interface, topographic relief, and large attenuation. To consider such factors, a simple triangular mesh grading technique is proposed for the efficient simulation of viscoelastic wave bidirectional propagation at irregular interface of large velocity-contrast earth media with rugged topography. The ground motions from finite-fault seismic source of a M_w 5.2 hypothetical earthquake are simulated. The simulation results showed that the existence of soil basin and interlayer can impact greatly ground motions, and should be considered in studying ground motions.

Earthquakes often lead to severe earthquake disasters in cities near fault zones, especially in cities on the surface of basins. To study the basin edge effects on seismic responses of near-fault building-structure groups, an integrated numerical method is adopted and two identical structure clusters inside and outside the basin edge are considered. The seismic responses of two near-fault building-structure groups in the vicinity of basin edge are modelled during an earthquake of M_w 6.0. Comparing to the structures outside the basin edge, the bending moments of plane frame structures inside the basin edge are increased significantly, and the basin edge effect changes earthquake risk positions of the structures. The vertical displacements of the structures are increased and the horizontal displacements of the structures are decreased slightly. The detailed geological structure of basin needs to be considered when modelling seismic responses of near-fault structure groups.

An integrated numerical method is proposed for analyzing the nonlinear seismic response of near-fault building clusters, comprising three algorithms: (1) a structural investigated lump algorithm for elastoplastic dynamic response of structure; (2) a connecting investigated lump algorithm for bidirectional wave propagation between the site and elastoplastic building clusters; (3) a geomedia investigated lump algorithm for seismic wave propagation with an improved viscoelastic constitutive model, which allows independent definition of P/S-wave quality factors to characterize geomedia attenuation. Validated for its capability in simulating site-city dynamic interaction problems via a shaking table test, the method is applied to study the seismic response of near-fault building clusters in Xichang City under a hypothetical M_w6.8 earthquake. It is shown that irrespective of whether shallow geological structures are considered, clusters (c2–c4) situated in rupture-forward surface area within ~1.5 km of the fault trace entered the elastoplastic stage, while others (c1, c5) remained elastic. Shallow geological structures may reverse locally hanging-wall/footwall effects of both near-fault structural seismic response and ground motion. A notable seismic-response characteristic of near-fault structures undergoing the elastoplastic stage is that the permanent structural motion displacement (PSMD) at the slab of a specific floor incorporates not only the non-zero permanent ground motion displacement (PGMD) but also the non-zero final structural residual displacement (FSRD) relative to the supporting ground. The developed method could provide support for seismic damage assessment, site selection, and structural optimization design of near-fault building clusters.