Scaling of ductility and damage‐based strength reduction factors for horizontal motions

Earthquake Engineering & Structural DynamicsVolume 29, Issue 7 p. 969-987 Research Article Scaling of ductility and damage-based strength reduction factors for horizontal motions Arun K. Tiwari, Arun K. Tiwari Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India Formerly Graduate StudentSearch for more papers by this authorVinay K. Gupta, Corresponding Author Vinay K. Gupta [email protected] Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India ProfessorDepartment of Civil Engineering, Indian Institute of Technology, Kanpur 208016, IndiaSearch for more papers by this author Arun K. Tiwari, Arun K. Tiwari Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India Formerly Graduate StudentSearch for more papers by this authorVinay K. Gupta, Corresponding Author Vinay K. Gupta [email protected] Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India ProfessorDepartment of Civil Engineering, Indian Institute of Technology, Kanpur 208016, IndiaSearch for more papers by this author First published: 19 June 2000 https://doi.org/10.1002/1096-9845(200007)29:7<969::AID-EQE948>3.0.CO;2-NCitations: 36 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract The conventional approach of obtaining the inelastic response spectra for the aseismic design of structures involves the reduction of elastic spectra via response modification factors. A response modification factor is usually taken as a product of (i) strength factor, RS, (ii) ductility factor, Rμ, and (iii) redundancy factor, RR. Ductility factor, also known as strength reduction factor (SRF), is considered to primarily depend on the initial time period of the single-degree-of-freedom (SDOF) oscillator and the displacement ductility demand ratio for the ground motion. This study proposes a preliminary scaling model for estimating the SRFs of horizontal ground motions in terms of earthquake magnitude, strong motion duration and predominant period of the ground motion, geological site conditions, and ductility demand ratio, with a given level of confidence. The earlier models have not considered the simultaneous dependence of the SRFs on various governing parameters. Since the ductility demand ratio is not a complete measure of the cumulative damage in the structure during the earthquake-induced vibrations, the existing definition of the SRF is sought to be modified with the introduction of damage-based SRF (in place of ductility-based SRF). A parallel scaling model has been proposed for estimating the damage-based SRFs. This model considers damage and ductility supply ratio as parameters instead of ductility demand ratio. Through a parametric study on ductility-based SRFs, it has been shown that the hitherto assumed insensitivity of earthquake magnitude and strong motion duration may not be always justified and that the initial time period of the oscillator plays an important role in the dependence of SRF on these parameters. 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