Uncertainties in Establishing Design Earthquakes

Abstract

Many uncertainties are associated with the selection of the design earthquake for a particular structure. In an attempt to address such problems, a ten‐story steel frame is designed for the lateral force requirements in current building codes. Two variations of the designed frame are subjected to representative ground motions recorded during the 1979 Imperial Valley earthquake. Evaluation of the nonlinear dynamic response of the designed frames indicates that ground motions resulting from the same earthquake may have significant variations in dynamic characteristics. One of the more significant of these are long‐duration acceleration pulses. Results indicate that the nonlinear response of structures to this type of motion is particularly sensitive to the pulse duration relative to the fundamental period of the structure and to the pulse acceleration relative to the yield resistance seismic coefficient of the designed structure.