Donahue - 2 Implications of the Observed Seismic Performance of a Pile Supported Wharf for Numerical Modeling Matthew J. Donahue, a) M. EERI, Stephen E. Dickenson, b) M. EERI, Thomas H. Miller, b) M.EERI, Solomon C. Yim, c) M.EERI The seismic response and performance of pile supported wharves on sloping ground is not well documented due to a historical lack of instrumentation on port structures. Although general surface observations have been made at numerous ports following recent earthquakes, much more specific soil-foundation-structure-interaction data could have been obtained with the more wide spread employment of instrumentation. This paper presents the results of an empirical analysis of recorded strong motion data (SMD) from an array of instruments located on a pile supported wharf and in the adjacent free field. The recorded SMD have provided insight into the behavior of wharf backland soils as well as structural response due to seismic wave passage and potential torsional behavior due to the configuration of structural and foundation elements. Presented herein are the results of an investigation of the seismic response of Berth 24/25 at the Port of Oakland, California during the M7.0 Loma Prieta earthquake. The primary objectives of this project were to evaluate SMD from an instrumentation array at Berth 24/25 and to identify the limitations inherent in capturing the complete dynamic character, including soil structure interaction, of a pier or wharf with a structural model. In engineering practice there is ongoing debate concerning the limitations of 3D structural modeling of wharves and piers for seismic analysis. A numerical model of Berth 24/25 was validated using ground motions recorded during the 1989 Loma Prieta earthquake with a twelve channel array placed on and adjacent to the structure. Through a series of simulations, the effect of variation of selected model parameters has been evaluated by comparison to recorded wharf motions. Analyses using design level input motions were performed to evaluate applicability of the full 3D model. The project is expected to serve the professional engineering community by providing guidance in selecting appropriate techniques for seismic analysis and subsequent upgrade of existing port facilities. INTRODUCTION Construction of Berth 24/25 at the Port of Oakland (Port) was completed in 1977. The facility has overall dimensions of 493 m length by 20 m width. Wharf support is provided by 46 cm square prestressed vertical and batter piles arranged in a pattern that repeats itself every fifteen meters, and a steel sheet pile cut-off wall running the length of the in-shore side a) Graduate Student b) Associate Professor c) Professor a-c) Department of Civil, Construction and Environmental Engineering, Oregon State University, 202 Apperson Hall, Corvallis, OR, 97331