The paper summarizes an empirical investigation of damage to low-rise buildings in two selected control areas within Glendale, California, caused by the ground motion precipitated there by the San Fernando earthquake of February 9, 1971. The procedures for obtaining the appropriate data and the methodology used in deriving ground motion-damage relationships are described. Motion-damage relationships are derived for overall damage and for the most frequently damaged building components. Overall motion-damage relationships are expressed in terms of damage incidence (damage ratio) and damage cost (damage cost factor).
The motion-damage relationships derived from the earthquake data are compared with similar data obtained for low-rise buildings subjected to ground motion generated by an underground nuclear explosion. Overall comparison results show that for the same spectral acceleration, the earthquake caused slightly more damage. Differences in ground-motion characteristics for the two types of disturbances provide the most probable explanation for this discrepancy.