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181 Fremont Tower, San Francisco, CA

This tower will be the most resilient tall building on the west coast of the United States

The 181 Fremont Tower project is a mixed-use high-rise building located in the high-density Transbay corridor of the South of Market district in San Francisco, California. The tower will rise over 800ft above street level, with a total of 56 stories including five basement levels. Arup provided structural and geotechnical services and also assessed the potential impact of the 181 Fremont Tower on the adjacent Transbay Transit Center during large earthquakes.

Geotechnical and geoseismic services

Our geotechnical team derived the geotechnical properties of the soils and bedrock and proposed recommendations for the temporary and permanent works of the project, including the design of the drilled shafts, base mat, shoring walls, and basement walls. The geotechnical team also provided services during construction, including monitoring of the shoring wall and adjacent structures during the excavation of the deep basement.

Arup’s geoseismic services included site-specific earthquake hazard and ground motion development, advanced soil-structure interaction analysis to account for the beneficial reduction of earthquake demands due to embedded basements, and advanced structure-soil-structure interaction to prove that the performance of the 181 Fremont Tower does not adversely affect the performance of the Transbay Transit Center.

Structural engineering services

The 181 Fremont Tower will be the most resilient tall building on the west coast of the United States and the second tallest building in San Francisco when complete. Arup’s structural engineers employed a holistic resilience-based seismic design approach to minimise damage in a 500 year earthquake and allow immediate reoccupancy after a seismic event, far exceeding building code criteria. Its iconic tapering form, small footprint, and location in the midst of the Transbay urban regeneration zone presented significant engineering challenges. Arup incorporated groundbreaking design solutions including an innovative viscous damping system within the architecturally expressed steel megabraces and uplifting megacolumns which significantly reduced seismic and wind demands and resulted in a steel material savings of approximately 3,000 tons.

Watch a video of 181 Fremont coming to life.