This seismic rehabilitation work involved the complete replacement of an existing seismic joint on the San Mateo Bridge, consisting of two 32-feet long bridge spans with steel cover plates. The work location bridged the main channel high-rise structure and the bridge’s trestle section, approximately two miles from the Foster City abutment. This specific retrofit work included strengthening existing steel and concrete bearing surfaces, the jacking and temporary supporting of existing concrete bridge girders under live traffic, and the demolition and replacement of existing girders and seismic joint plates under complete closure of the bridge. The new seismic joint is comprised of 12 separate precast, pre-stressed girders erected in an overlapping configuration to create a 3-feet seismic gap.
The contract initially allowed for two separate complete 55-hour weekend closures of the bridge to replace the deck girders and complete the seismic joint. Shimmick and Caltrans collaborated to develop and successfully execute a plan to complete the project with a single complete closure.
Other work included removal and reinstallation of electrical conductors that pass through the seismic gap, installing permanent access structures, and installing changeable message signs above the roadway.