Influence of Batter Piles on the Dynamic Behavior of Pile-Supported Wharf Structures

Recent experience has demonstrated that waterfront structures are highly susceptible to earthquake-induced damage. In the western United States, port waterfront structures are commonly constructed using pile-supported wharves in combination with rock dike structures retaining hydraulically placed fills. Many ports use batter piles to limit deflections from lateral loads, such as ship berthing and seismic loads. Extensive earthquake-induced damage to batter piles has been observed at several ports worldwide. Consequently, batter piles are now used cautiously in the design of new wharves in seismically active regions even though many wharves with batter piles have performed adequately. They have also been used as part of the unique “structural fuse” concept that has been adopted on major projects in the western United States. The continued use of batter piles combined with the significant number of existing wharves supported with batter piles creates the need for a better understanding of their seismic performance. In order to augment the limited number of instrumented earthquake case studies for modern wharves and evaluate the performance of the soil-foundation-structure system, a series of large-scale centrifuge models have been constructed and tested with typical pile-supported wharf configurations. This paper presents the results of the final two models where batter piles were incorporated. Tests were carried out with and without the batter piles attached for each model at identical input accelerations. To the authors’ knowledge, the tests provide the first recording and quantification of seismic force distribution for pile-supported wharf structures with batter piles. This paper summarizes 1) quantification of seismic lateral loads on vertical and batter piles, 2) pile shear and moment data with emphasis on the wharf deck connection, 3) embankment displacements with comments regarding their influence on pile loading.