Evaluation of Seismic Safety of Buildings. Report No. 1. Frequency Content of Ground Motions During the 1971San Fernando Earthquake.

摘要

Description of the site ground motion is an important step in the process of designing a structure subject to strong earthquake ground shaking. Both the intensity and frequency content of ground motions are important in the evaluation of structural response. As a part of an overall effort to demonstrate the application of random vibration analysis to evaluate structural response to earthquake excitation,measurements made during the San Fernando,California earthquake of 1971have been used to study extensively ground motion characteristics. The estimated power spectral density (PSD) function is used as the primary tool for studying ground motion characteristics,but comparisons based on peak acceleration,peak velocity,the ratio of peak values of velocity and acceleration,and selected response spectral values are also briefly reviewed. Observations are made on the variations in ground motion characteristics,followed by a tentative examination of the possible causes of these variations.