The Design of Earthquake Damage Repairs to Wharves Before the Earthquake Occurs

The issue with the design of a new container wharf is not whether or not it will be damaged in an earthquake, but rather how to manage the damage when it occurs. Currently, wharves on the West coast are designed according to criteria that establish acceptable damage levels for earthquake design based on probabilities, e.g. 10% chance of exceedence in 50 years. In some cases a vulnerability analysis is performed. This vulnerability analysis follows the methods described in the ASCE Seismic Guidelines for Ports and includes estimates of repair costs. The vulnerability analysis does not, however, include the development of detailed designs of the expected repairs. This paper presents an anticipatory approach to the design of repairs and proposes both the development of design criteria for typical repairs and the preparation of detailed designs for select repairs that would be expected after an earthquake. With established criteria, the design of the repairs may proceed immediately after the earthquake. When the detailed design has been prepared, construction can proceed immediately after the earthquake. This approach expedites restoring the wharves to a safe operating condition. Considering future repairs during the design of a new wharf encourages the designer to incorporate features that make repairs easier and less costly. This approach also encourages a cost benefit ratio analysis to justify the cost of the added features. This paper demonstrates the approach with the following case studies of wharves at the Port of Oakland: repairs to the Matson wharf, Berths 32 and 33 after the Loma Prieta Earthquake; repairs to the Ben E. Nutter Terminal wharf, Berths 35 - 37 after the Loma Prieta Earthquake; and the design features of the new Berth 57 - 59 wharves, which are repair friendly. This paper includes suggestions for improving the ease of repair of new wharves. Discussions of slope stability are beyond the scope of this paper.