Earthquake Retrofit Strengthens Hospital Against Seismic Peril

Challenge
A structural analysis of one of the hospital’s buildings indicated that it was vulnerable to severe damage during a significant seismic event. The retrofit design called for installation of new footings and large diameter piers around the perimeter of the foundation. The new footings as well as the existing interior footings required a series of tiedowns locking them down against uplift.

Action
In order to install the exterior footings and tiedowns, first it was necessary to construct soldier beam and wood lagging shoring to a depth to 30 ft. An opening was cut into the basement area from the shoring pit. Finally a small track rig was lowered into the pit to perform the exterior and interior tiedown drilling. The 36” diameter piers needed to be installed 40 ft. deep directly against the existing foundation, while avoiding damaging the building.

Results
The work was completed successfully. This San Francisco General Hospital building now stands reinforced against the possibility of a devastating earthquake. San Francisco General Hospital Earthquake Retrofit Strengthens Hospital Against Seismic Peril.