Loma Linda University Medical Center is in the process of constructing a new state of the art hospital facility. The hospital is part of what is known as the Campus Transformation Project. The new hospital will be almost 800,000 square feet in size and will replace the existing hospital. It will be a general acute care facility and will meet OSHPD-1 requirements. The hospital itself will consist of two hospital towers; University Hospital (UH) Adult Care Tower and the Children’s Hospital Tower, built on top of a shared interventional podium. The hospital building will be supported on a base isolation system that is below the basement. The seismic lateral force resisting system above the isolation plane will be a combination of steel intermediate moment-resisting frames in an east-west direction and steel ordinary concentric braced frames in a north-south direction. The foundation system is a mat foundation and there are permanent shored retaining walls surrounding the building and seismic moat. This will be the first vertically base isolated facility in the world.
CHJ Consultants provided Loma Linda University Medical Center the Geotechnical Investigation and Report to accommodate the revised plans for the design and construction of the University Hospital Adult Care Tower and the Children’s Hospital Tower. The Report included recommendations for design acceleration parameters, site grading and fill placement, foundation design to reduce seismic settlement to acceptable levels, a 4-foot-thick mat foundation, seismic earth pressures and design parameters for permanent shoring accommodate the 30+ foot deep excavation necessary to construct the hospital.
The bottom of the base-isolated foundation is approximately 30 feet below the existing ground surface (bgs). The total footprint area at the base of the new towers will be approximately 100,000 square feet. In addition, new landscaping, hardscape, some possible low retaining walls and free-standing walls, and shoring are anticipated.
Information furnished to us by Arup, the structural engineer (SEOR) indicates that the expected dead-plus-live column loads are approximately 1,000 kips for perimeter columns of the shorter tower and 3,000 kips for interior columns of the taller tower, excluding foundation weight. The final project grading plan should be reviewed by the geotechnical engineer.
The building site is located immediately adjacent and east of the existing main medical center building. The medical center entry drive bounds the site on the north, with Anderson Street to the east and Barton Road to the south. The site is currently developed with asphalt-paved surface parking with planters. The ground surface of the site slopes down from southeast to northwest, with a difference in elevation of approximately 20 feet across the site of the proposed hospital towers. A low, turf-covered slope descends from Barton Road to the existing on-site parking area. Various underground utilities cross the site.