An assessment of the domain reduction method as an advanced boundary condition and some pitfalls in the use of conventional absorbing boundaries

This paper assesses the performance of two commonly used absorbing boundaries in dynamic finite element analysis of geotechnical problems in conjunction with the domain reduction method (DRM). The DRM was originally developed by Bielak et al . ( Bull. Seismol. Soc. Am. 2003; 93 (2):817–824) to reduce the computational cost of seismological applications, whereas Yoshimura et al . ( Bull. Seismol. Soc. Am. 2003; 93 (2):825–840) showed that it can be effectively used as a boundary condition. In this study a practical methodology is proposed, which employs the cone boundary of Kellezi ( Soil Dyn. Earthq. Eng. 2000; 19 :533–547) on the outer boundary of the reduced (step II) model of the DRM. To verify the applicability of the proposed methodology, the results using both the cone boundary and the standard viscous boundary are compared with those using an extended mesh. Finally, results using the DRM as a boundary condition are compared with those using conventional boundary conditions. Some common pitfalls in the use of absorbing boundaries are highlighted and guidance for their correct use in engineering practice is given.