Time-dependent spectral analysis of thirty-one strong-motion earthquake records

Velocity response spectral analysis as a function of time for 5 percent critical damping is presented for the horizontal components of thirty-one earthquake records (61 components). A nomograph that allows conversion of the velocity response envelope to a displacement response envelope and a pseudo-absolute acceleration response envelope spectrum is also presented. Included among the records analyzed are such important accelerograms as those from El Centro, 1940, Olympia, 1949, Taft, 1952, San Francisco, 1957, Park-field, 1966, San Fernando, 1971 and Managua, 1972. Time-duration spectra showing the number of cycles for a particular period of the response envelope above different levels are presented. The effects of peak ground acceleration on the response envelope are examined.