Berth Deepening in a High Seismic Environment: erth 35–37, Port of Oakland

The Port of Oakland is in the process of upgrading a number of existing berths to meet the increasing draft requirements of current and future container shipping vessels. This is called the Wharf and Embankment Strengthening Program (WESP) and includes crane beam strengthening and a seismic evaluation of the existing wharf and embankment systems to ensure that the deepened wharf structure is at least as strong seismically as the existing structure. This paper concentrates on the seismic design issues using Performance Based Design for Berths 35 – 37, which were constructed in the early 1970s and repaired following substantial damage caused by the 1989 Loma Prieta Earthquake. Performance Based Design has developed significantly in its application to marine structures in the last 20 years. The original design performed poorly under seismic loads. The repair approach used many aspects of technology improvements developed in the 1980s, but the design followed typical building code requirements that have since been improved upon for marine structures, as generally discussed in the 1998 publication by ASCE entitled Seismic Guidelines for Ports. The resulting facility is more capable than it was originally, both in its functional use and its design strength. The owner has increased confidence in its future performance and longevity, the shippers have capability to handle the largest vessels using larger cranes, and the regulatory agencies have a clear understanding of its adherence to code requirements and safety.