Seismic Design of Port of Los Angeles Pier 400 Container Wharf

This paper addresses the seismic design of a container wharf more than 2130m (7000 ft) long supporting 30.48m (100 ft) gage cranes. The wharf, a reinforced concrete deck on prestressed vertical concrete piles, provides 16m (53 ft) water depth for 6600 TEU vessels. The performance based design uses following limit states: a lower level earthquake (OLE) with a 72 year average return period (peak ground acceleration 0.28g), no interruption of operations after the event is permitted; and an upper lever earthquake (CLE) with a 475 year average return period (peak ground acceleration 0.52g), requiring the structural damage to be repairable. The dike analysis indicates in excess of 0.9m (3.0 ft) deformation at the dike crest for the CLE event without reinforcing effects of the piles, therefore soil-structure interaction analysis was necessary. The results show that the pile moment curvature still meets the limit state strain conditions. Elastic modal analyses were performed to evaluate different computer procedures and wharf geometry. Increasing the clear space between wharf deck and dike crest has the surprising result that pile ductility improves and shear demand on the pile decreases. Inelastic time-history analyses then were performed to evaluate the influence of different soil spring stiffness in the up-slope and down-slope direction and passive pressure on the rear edge of the wharf. Other studies investigate crane-wharf interaction (crane mass is out of phase with the wharf and can be neglected) and the dynamic response of linked wharf units (displacement values for pure transverse response must be amplified by approximately 15% to account for a combination of transverse and longitudinal seismic excitation). Several important detail issues are investigated, such as the dowel development length and detailing of the pile deck connection, use of additional mild steel in prestressed concrete piles, pile shear capacity and others.