SOM

SOM

Superior Court of California - San Diego – Structural Engineering

The new Superior Court of California building in San Diego consolidates the county's criminal trial, family, and civil courts into a single downtown high-rise. Comprising a full city block, the 704,000-square-foot building consists of a 25-story tower and 4-story podium clad in glass and precast concrete, with two below grade basement levels. It replaces an adjacent, obsolete courthouse facility that was built in 1961 over an active earthquake fault line.

SOM designed the new courthouse to achieve the enhanced seismic performance criteria defined in the Judicial Court of California (JCC)'s 2011 Trial Court Facility Standards. Early in the design process, SOM performed seismic risk assessment and life-cycle analysis for a variety of structural systems. This analysis supported the client's decision-making process to meet the JCC design standards and 25-year lifecycle objectives.

Based on site-specific seismic data, the design team selected a steel special moment frame (SMF) system, combined with 106 supplemental viscous damping devices (VDD). The devices are distributed on levels 6 to 25 in the narrow transverse direction to protect the building from seismic shocks. The team evaluated the design using nonlinear response history analysis subjected to peak Maximum Considered Earthquake (MCE) site-specific ground motions. Based on this analysis, the VDD energy dissipating system reduces seismically-induced building story shears, story drifts, floor accelerations, and inelastic rotational demands on the steel SMF beam-column joints with reduced beam section (RBS) connections. The VDDs are also intended to resist the resonant portion of wind load with effective linear damping greater than 10 percent—a goal that the design team substantiated through both analytical methods and a damper prototype testing program.

The 400-foot-tall building integrates a cost-effective steel framed superstructure with two-way lateral resisting special moment frames, resting on a continuous 8-by-6-foot deep mat foundation. At the third level, a pedestrian bridge connects the courthouse to the adjacent Hall of Justice. The bridge required complicated planning, engineering, and logistics, as it passes over the catenary lines for the San Diego metro. The bridge, with its 85-foot cantilever span and 80-foot back span, is supported at the center by a single tapered column. The building design also accommodates a future underground tunnel planned to connect the courthouse with the county jail facility.

At the top of the building, a dramatic cantilevered steel cornice supports precast and suspended articulated louver panels. By filtering light and providing solar shading for the glazed east exterior wall, the cornice design enhances the building's energy performance.

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