Dynamic behaviour of steel pile wall for port-structures in high-seismicity zones: Simple vs. full dynamic analysis

ABSTRACT: Earthquake resiliency of major port structures in high seismicity zones is a major design objective due to their economic and strategic importance. Structural failure or severe damage may cause downtime that leads to potential disruptions in port activities, shipping operations and vessel navigation, causing far-reaching consequences to both the economy and, potentially, national security. This paper examines the seismic design of the steel sheet pile wall for a vital port structure. The sheet pile was designed for the A-jetty at Esquimalt Canadian Forces Base (CFB) located in western Canada in Victoria, British Columbia. The wall supports a 17.6 m high rockfill backfill. The wall's design criteria required a 300 mm gap between the sheet pile wall and the A-jetty wharf structure to isolate differential movement between the structures during an earthquake. The sheet pile wall was top anchored using bulkhead anchors in a way that produces enough movement to induce an active earth pressure on the wall. The design was completed using two approaches: (i) pseudo-static limit equilibrium method (PLEM), which works in conjunction with the Mononobe-Okabe (MO) method, and (ii) full dynamic finite element (FE) analysis using a commercially available code (PLAXIS, 2020). The study shows the advantage of performing detailed FE analysis for analyzing such complex soil-structure interactions in high seismicity zones. The study also clearly indicates that the simplified methodology of PLEM is unable to estimate the structural internal forces and deformations in high seismicity zones.