The performance of public school plants during the San Fernando earthquake

Abstract

The epicenter of the San Fernando earthquake was just 25 miles from the Earthquake Engineering Research Laboratory of the California Institute of Technology, which has been for some 50 years actively studying the problem of earthquake resistant design. It was therefore most natural that the EERL was very quickly involved in a number of major investigations growing out of the event. Several Earthquake Engineering research grants from the National Science Foundation to the EERL were in effect at the time and provided the framework for an expanded NSF sponsorship of additional special studies. These expanded NSF assignments included a responsibility to investigate those aspects of earthquake damage for which important evidence might quickly disappear through demolition, repairs, etc., and also those for which significant studies might otherwise not be made because of a lack of adequate resources. Both of these aspects were involved in the important matter of the earthquake behavior of school buildings. The whole question of the earthquake safety of the schools very quickly came to the attention of the EERL staff, through service on the Los Angeles County Earthquake Commission, as consultants to the Los Angeles Unified School District in evaluating the postearthquake safety of schools, and a natural historical consequence of past studies of the Long Beach 1933 earthquake. Since it became apparent that detailed studies of the school situation were not likely to be made by existing public agencies, it was decided that a portion of the NSF emergency grant resources should be used for this purpose. These resources were later expanded by NSF through a supplemental research grant for the particular objective of completing a comprehensive report on the behavior of school buildings during the San Fernando Earthquake. The San Fernando earthquake was an unusually valuable test of school safety because: (1) there were several hundred schools having structures of all types in the heavily-shaken area, including 10 schools within 5 miles of the epicenter; (Z) the severity of ground motion is believed to have been near the maximum to be expected for an earthquake of any size--a number of campuses were subjected to major ground cracking and deformation; (3) since there were many instruments in the area, the details of the earthquake ground motion are better known than for any other earthquake. On some campuses, pre-Field Act buildings, renovated pre-Field Act buildings, and new buildings existed side by side, and direct comparisons show the efficacy of the Field Act and the associated plan check and field inspection procedures in reducing the earthquake hazard to an acceptably low level. The study became feasible through the cooperation of the California State Office of Architecture and Construction in making available as a consultant the services of Mr. Donald K. Jephcott, Principal Structural Engineer in charge of the Structural Safety Section (formerly Schoolhouse Section) of the Los Angeles office. Two members of Mr. Jephcott's staff, Mr. Leon Stein and Mr. Byrne Eggenburger, assisted as consultants in the preparation of several of the detailed descriptions of the school plants. We are also much indebted to the Los Angeles Unified School District for making available much information and many drawings which simplified our task. We are pleased to acknowledge also the assistance of the Earthquake Research Affiliates program of the California Institute of Technology in providing financial support for portions of this study.

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