Acceleration Response Spectra– Bridging the gap between geotechnical and structural engineers

ABSTRACT: Acceleration response spectra are primarily used by structural engineers but have become an important part of geotechnical earthquake engineering particularly in site response analysis and in interpreting building code requirements. The objective of this paper is to assist geotechnical engineers by providing a geotechnical perspective on a concept that was formulated, developed and implemented into building codes by structural engineers. This paper provides a basic background on how response spectra were developed and explains how structural engineers commonly idealize buildings primarily as a “single degree of freedom” system. Response spectra and their relationship with Seismic Hazard Analysis is then discussed followed by an explanation on why geotechnical engineers should have a basic understanding of response spectrum concepts. The paper finishes by providing an example of how an acceleration time history can be converted into a Response Spectrum using a Northridge Earthquake 1994 acceleration time history. It is thought using an example with real values will help to demonstrate the process by which the Response Spectra is constructed.