In Phase III of the process, SGH provided construction engineering support for the North Anchorage Housing Seismic Upgrade on behalf of the General Contractor. This large reinforced concrete structure at the bridge's Marin County landing provides both anchorage for suspension cables and support for the roadway.
The renovations entailed demolition and roadway replacement. Using a nonlinear static (pushover) procedure, SGH evaluated the structure's service load stability and earthquake resistance during various construction stages and recommended strengthening and temporary bracing/shoring, as necessary. As part of this process, we determined the probability of earthquake closure of the bridge, which carries 40,000 vehicles per day, within the two-year construction period, enabling the contractor and the District to assess the acceptability of risk.