Residual Axial and Lateral Load Carrying Capacity of Pile Supported Marine Terminal Exhibiting Seismically-induced Local Buckling in Inground Plastic Hinges

Steel pipe piles have been increasingly used to support new marine terminals along the seismically active west coast of the US. The first generation of performance-based seismic design requirements incorporated into the ASCE-COPRI 61 “Seismic Design of Piers and Wharves” Standards is commonly referenced for the design of seismically prone marine structures. These structures are essential to the regional economy, post-event recovery response, or require a level of seismic performance beyond life-safety protection. The standard prescribes performance-level checks for three seismic hazards and provides strain limit-states to design these piles. These limit-states were borne-out using engineering judgment. Minimal to no physical testing or computational simulation has ever been conducted on marine piles specific to verify the critical life-protection performance level that could occur when a pile loses the gravity load-carrying capacity after the pile develops an inertia loading-induced inground plastic hinge and exhibits local buckling. This research evaluates the in-ground hinge performance of steel pipe piles commonly used in marine applications. The overall test program was divided into two phases, funded by three agencies: (i) the joint research program between the National Institute of Standards and Technology (NIST) and the National Science Foundation (NSF); (ii) the Naval Facilities Engineering Systems Command (NAVFAC) via the ASCE-COPRI Institute; and (iii) the Port of Long Beach. The analytical portion of the research was supported by the Pacific Earthquake Engineering Research Center (PEER). The Port of Long Beach provided test specimens, the Port of Los Angeles supplied material testing samples, and Earth Mechanics Inc. (EMI) offered geotechnical support services. Guidance for the project was provided by an Advisory Board comprising industry experts. The test program was executed at the Soil-Structure Interaction (SSI) Test Facility’s North Soil Pit at the University of California, San Diego Englekirk Structural Engineering Center. Four steel pipe piles underwent reversed cyclic lateral loading using an increasing amplitude displacement loading protocol to achieve very large lateral displacements.