|Loma Linda, CA, USA
With the construction of a new adult hospital and children’s tower in addition to the existing campus, Loma Linda University Medical Center became the tallest building in San Bernardino County. It is also one of the safest in the state when it comes to earthquakes.
The hospital is made up of 6 main podium levels before the building splits into two towers, a 10 storey children’s hospital and an 18 storey adult’s hospital. This new structure is an extension to an existing hospital which has been built in the seismically active area.
Due to the seismic activity in the area, the project implemented a first-of-its-kind vertical earthquake isolation system. It includes seismic resistant design concepts such as Sideplate technology and Buckling-Restrained Braces as well as an extremely complex base level that has a grand total of zero traditional anchor/holding down bolts to the foundation. The design separates the building from the ground using more than 500 vertical shock absorbers—a large-scale version of a modern car suspension system.
Working hand-in-hand with a lateral earthquake isolation system of sliding bearings and dampers, the system will protect patients and staff from injury while keeping the hospital operational following a potentially catastrophic magnitude 7.9 earthquake on the nearby San Jacinto Fault.
DBM Vircon was involved in detailing the Loma Linda University Medical Center project.
The project consisted of an 18 storey main building split into two towers above the 6th level, along with 3 auxiliary buildings consisting of an entrance structure with architecturally exposed steelwork and two connecting bridges back to the existing hospital.
The base level was a major challenge for the project. All main framing members were built up plate girders, some designed with 4” thick flanges. Due to the size of the plate girders, it created difficulties with available space for the structural nodes above the isolators, splice connections and penetrations to allow for services. Through a highly celebrated effort with detailing the connections, splice locations and penetration locations were fine-tuned to achievable constructible base level.
Another challenging aspect of the project was the interaction of the BRB brace connections and the Sideplate connections. The connection were designed with haunch plates above and below the Sideplate connections creating challenging fabrication and erection clearances that was also resolved through the detailing process.