The response of Veteran's Hospital building 41 in the San Fernando earthquake

Structures which collapse or are heavily damaged in destructive earthquakes are analyzed by engineers to determine why they performed so poorly and to find out how their design could have been improved. However, it is equally important for buildings that survived exceptionally strong shaking to be analyzed and an explanation given as to why they were able to do so. During the San Fernando, California earthquake of February 9, 1971 buildings in the strongly shaken region showed both types of performance. For example, the new Olive View Hospital main building was severely damaged, and another major building collapsed whereas two buildings at the Veteran's Administration (VA) Hospital survived with no significant damage. These two hospitals were located just north of the major surface faulting, and the VA buildings were only V-, miles southwest of Pacoima Dam. The Dam was effectively over the center of energy release of the magnitude of 6.4 earthquake and the well-known Pacoima Dam accelerogram, with peak accelerations over 1g, was recorded on a steep ridge near the abutment of the Dam. The ground shaking at the VA hospital is thought to have been less severe than that recorded at Pacoima Dam, but more severe than that recorded at the Holiday Inn, which was approximately five miles south of the nearest point on the causative fault. Two major structures collapsed at the Veteran's Administrative Hospital killing 46 persons, which accounted for most of the casualties in the earthquake. These buildings were constructed in the 1920's and were not designed to resist earthquakes. Within the immediate neighborhood of these collapsed buildings were two other major structures that were built in the 1930's and the 1940's in accordance with building codes requiring earthquake resistance, and these survived the San Fernando earthquake without significant damage. One of these structures is the subject of this report