UC San Diego, York Hall

Surgical retrofit preserves historic complex on UC San Diego campus.

The York Hall seismic rehabilitation extended the life of a historically significant four-building laboratory and educational complex designed by Neptune & Thomas Associates, while preserving its unique architectural character. The integrated design team developed an innovative approach to saving the minimalist mid-century complex’s iconic columns that reduced costs, preserved programming space and helped the University of California system set new technical standards for its seismic retrofit program.

York West, part of the historically recognized Revelle Plaza, is supported by a 300-foot-long arcade of thin, hexagonal fan-vaulted columns that made the building vulnerable to major damage or even collapse in a strong earthquake. Additionally, nearly 75% of the 800 precast concrete fins on the complex’s façade were in various states of disrepair after decades of exposure to salty ocean air. Design teams were challenged to keep the classrooms, labs and lecture halls open during the retrofit, requiring careful coordination between educators, the builder and a multidiscipline team of architects, engineers, and landscape architects.

The design team eventually settled on an approach that replaced four columns, reducing the embodied carbon impact of the retrofit by 40% compared to initial plans. The four critical columns were replaced with tightly tied rebar cages with new high-strength concrete cast into custom-built fiberglass molds, preserving the historic dimensions and the colonnade’s clean lines. A combination of foundation beams and piers was used to bridge over and around a 10-foot-diameter utility tunnel that housed the main power supply for a large portion of the campus. Each 500-pound fin was analyzed to develop a uniform repair strategy that contractors used in the field to save time and avoid mistakes.

The surgical approach delivered the retrofit on time and 10% under budget and serves as a model for future seismic retrofits on the campus.