The concept of response spectrum was proposed by Biot in 1932 for analysis and design of earthquake-resistant structures. It remained in the academic sphere of research for almost 40 years, finally gaining wide engineering acceptance during the early 1970's. Success in recording large number of excellent accelerograms during the 1971 San Fernando earthquake, and publication of Brune [18] paper marked the beginning of the modern era for the Response Spectrum Method (RSM). This paper outlines the ideas which helped develop the modern RSM and describes the role Brune's Spectrum played in this process.
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