New Bay Area hospital is constructed to withstand the most severe earthquake

Safety measures
The release notes that because Stanford is the only designated level-1 trauma center on the Peninsula, it is imperative for the hospital to be up and running in order to receive the brunt of casualties in the event of an emergency. The hospital is recognized by the American College of Surgeons as being capable of providing total care for every aspect of injury — from prevention through rehabilitation — for both adults and children.

Two sizes of base isolators have been custom-made for the hospital: 154 “large” ones each weighing 5,400 pounds (about 2.5 tons) and 52 super-sized ones each weighing 8,900 pounds (4.5 tons). Two years in the making, the steel plates were cast in Texas and manufactured by Earthquake Protection Systems, a design firm in Vallejo.

Hoisted in place by massive cranes, many of the base isolators already have been positioned thirty feet below ground level on supports that have been dug 100 feet into the earth. Their design is so precise that there is only 1/32 of an inch of space around each bolt that holds them in place. The design also allows enough leeway for the building to be jacked up if any of the isolators need to be checked or replaced.

Construction challenges
“The base isolators are only part of the solution,” Hurlbut said. “The building and all its components also have to be able to move and not touch anything.”

That means the hospital’s concrete and steel foundation has to be constructed with a cushion of air around it, and any structural elements that contact the ground have to be flexible as well. Each doorway, staircase, and ambulance bay is designed like a drawbridge so that it can slide back and forth, and all pipes and utility connections — medical gas, diesel, water, electricity, etc. —have to be able to move in any direction as well. The foundation walls, thirty-five feet deep, are shored up with 50-foot steel beams and 70-foot tieback rods placed at an angle to create a kind of bucket in which to position the building.

The pedestrian bridge that will connect the new Stanford Hospital with the existing hospital facility has been a particular challenge, said Hurlbut. The solution was to create pin joints at each end so that it could move almost 5 feet in any direction. “It’s sort of like a jet walkway connecting you from the gate to your plane,” he said.

To facilitate all the ongoing problem-solving needs for such a complex project — and to stay on schedule — the architects, engineers, general contractor and subcontractors work together in an open compound adjacent to the construction site.

“Construction, design and operations all go hand in hand,” Hurlbut said. “We’ve made the process fully integrated.”