Analysis of transient wave scattering and its applications to site response analysis using the scaled boundary finite-element method

In this paper, the problem of scattering and amplification of seismic waves by topographical and geological irregularities is addressed directly in the time domain through the scaled boundary finite-element method (SBFEM). The quadtree domain decomposition technique is utilized for the SBFEM discretization of the near field. The far field is rigorously modeled by the displacement unit-impulse response matrix. The computational cost of analyses is reduced through using local formulations in space and time. Considering incident fields of obliquely plane waves coming from far field, the seismic wave inputs are formulated as boundary tractions applied to the near field. Implementing all these aspects in the SBFEM, leads to an elegant technique for time domain modeling of seismic wave propagation in heterogeneous media with topographical irregularities. Four numerical examples considering various site effects and wave patterns demonstrate the accuracy, versatility and applicability of the approach. The approach is straightforwardly applicable to nonlinear and 3D wave scattering problems with complex site effects.