Seismic Soil-Structure Interaction Issues for Pile-Supported Piers and Wharves

ASCE 7-05 (ASCE, 2005) was developed as the national standard to provide minimum life-safety standards for designing buildings and other structures. However, it does not address in detail the requirements for seismic design of pile-supported piers and wharves. Piers and wharves are typically built on sloping ground and the evaluation of and designing for kinematic loading on pile foundations and structures due to permanent ground deformation during an earthquake has been a challenge. Performance-based seismic design codes and criteria have been adopted by some local and state jurisdictions on the West Coast for the seismic design and evaluation of piers and wharves to achieve a specific level of performance using a displacement approach based on a minimum of two levels of earthquake motions. ASCE is in the process of developing a national standard for the seismic design of piers and wharves by incorporating salient features from available performance-based seismic design codes and criteria. As a part of this effort, seismic soil-structure interaction associated with piers and wharves are being addressed by a group of structural and geotechnical engineers and owners with interest in seismic design of piers and wharves. This paper discusses lateral soil-structure interaction issues and provides guidelines and suggestions to simplify the evaluation process while maintaining a robust design.