Damage-based inelastic response spectra for seismic design incorporating performance considerations

Modern seismic design allows a structure to develop inelastic response during moderate to severe earthquakes. The emerging performance-based design requires more clearly defined levels of inelastic response, or damage, to be targeted for different earthquake hazard levels. While there are a range of factors that could influence the level of damage and hence the performance, the design strength remains to be a fundamental design parameter that is inherently related to the structural performance. In this paper, the response reduction factor, which is a normalized form of the design strength, is investigated on a direct damage basis. The implications of the damage-based strength reduction factor (SRF), denoted as R-D factor, on multiple performance targets are discussed. A series of R-D spectra are generated from a large set of ground motions in different groupings to examine the effects of local site condition, earthquake magnitude and distance to rupture on the R-D spectra. The overall mean and standard deviation of the R-D spectra for different levels of damage are obtained, and simple empirical formulas are proposed. (C) 2007 Elsevier Ltd. All rights reserved.