A numerical framework for underground structures in layered ground under inclined P-SV waves using stiffness matrix and domain reduction methods

A numerical framework was proposed for the seismic analysis of underground structures in layered ground under inclined P-SV waves.The free-field responses are first obtained using the stiffness matrix method based on plane-wave assumptions.Then,the domain reduction method was employed to reproduce the wavefield in the numerical model of the soil–structure system.The proposed numerical framework was verified by providing comparisons with analytical solutions for cases involving free-field responses of homogeneous ground,layered ground,and pressure-dependent heterogeneous ground,as well as for an example of a soil–structure interaction simulation.Compared with the viscous and viscous-spring boundary methods adopted in previous studies,the proposed framework exhibits the advantage of incorporating oblique incident waves in a nonlinear heterogeneous ground.Numerical results show that SV-waves are more destructive to underground structures than P-waves,and the responses of underground structures are significantly affected by the incident angles.

Physics-based seismic analysis of ancient wood structure:fault-to-structure simulation

Based on the domain reduction method,this study employs an SEM-FEM hybrid workflow which integrates the advantages of the spectral element method(SEM)for flexible and highly efficient simulation of seismic wave propagation in a three-dimensional(3D)regional-scale geophysics model and the finite element method(FEM)for fine simulation of structural response including soil-structure interaction,and performs a physics-based simulation from initial fault rupture on an ancient wood structure.After verification of the hybrid workflow,a large-scale model of an ancient wood structure in the Beijing area,The Tower of Buddhist Incense,is established and its responses under the 1665 Tongxian earthquake and the 1730 Yiheyuan earthquake are simulated.The results from the simulated ground motion and seismic response of the wood structure under the two earthquakes demonstrate that this hybrid workflow can be employed to efficiently provide insight into the relationships between geophysical parameters and the structural response,and is of great significance toward accurate input for seismic simulation of structures under specific site and fault conditions.

Space–time finite element method with domain reduction techniques for dynamic soil–structure interaction problems

Design of earth structures,such as dams,tunnels,and embankments,against the vibrational loading caused by high-speed trains,road traffic,underground explosions,and,more importantly,earthquake motion,demands solutions of the dynamic soil–structure Interaction(SSI)problem.This paper presents a velocity-based space–time finite element procedure,v-ST/finite element method(FEM),to solve dynamic SSI problems.The main goal of this study is to present the computation details of implementing viscous boundary conditions of Lysmer–Kuhlemeyer to truncate the unbounded soil domain.Furthermore,additional time-dependent boundary conditions,in terms of the free-field response,are included to facilitate energy flow from the far field to the computation domain at the vertical truncated boundaries.In the FEM,seismic input motion is applied to an effective nodal force vector,which can be obtained explicitly in the numerical simulations.Finally,the response of a concrete gravity dam resting on an elastic half-space to the horizontal component of earthquake motion is computed and successfully compared with the results of semidiscrete FEM using the Newmark-βmethod.