Time-domain analysis of wave propagation in 3-D unbounded domains by the scaled boundary finite element method

• An efficient method for modeling elastic waves in 3D unbounded media is proposed.
• The displacement unit-impulse response matrix is derived using SBFEM, which can be truncated.
• Spatial decoupling is achieved by dividing the unbounded domain into multiple subdomains.
• Based on two extensive parameter studies, a guideline for choosing appropriate spatial decoupling schemes is provided.

Transient wave propagation in three-dimensional unbounded domains is studied. An efficient numerical approach is proposed, which is based on using the displacement unit-impulse response matrix representing the interaction force–displacement relationship on the near field/far field interface. Spatially, an approximation is used to reduce the computational effort associated with the large size of three-dimensional problems. It is based on subdividing the fully coupled unbounded domain into multiple subdomains. The displacement unit-impulse response matrices of all subdomains are calculated separately. The error associated with this spatial decoupling can be reduced by placing the near field/far field interface further away from the domain of interest. Detailed parameter studies have been conducted using numerical examples, in order to provide guidelines for the proposed spatially local schemes, and to demonstrate the accuracy and high efficiency of the proposed method for three-dimensional soil–structure interaction problems.