Energy-based sidesway collapse fragilities for ductile structural frames under earthquake loadings. (1st November 2018)

• Record Type: Journal Article
• Authors: Deniz, Derya; Song, Junho; Hajjar, Jerome F.
• Is Part Of: Engineering structures. Volume 174(2018)
• Page Start: 282
• Page End: 294
• Publication Date: 2018-11-01
• Subjects: Incremental dynamic analysis -- Probabilistic seismic collapse assessment -- Collapse descriptor -- Collapse criterion -- Energy-based analysis -- Ductile structural frames; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2018.07.019
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: A new descriptor's been proposed for seismic performance of ductile moment frames. New seismic demand models and collapse fragility relations are obtained for frames. The new collapse fragility relations are compared with the traditional approaches. The developed techniques help achieve reliable prediction of structural collapse. Abstract: In assessing the likelihood of structural collapse under strong earthquake motions, uncertainties in structural properties and ground motions can be incorporated by use of a probabilistic analysis framework in conjunction with analysis methods such as incremental dynamic analysis (IDA). Maximum inter-story drift ratio ( IDR ) is typically selected as the key descriptor to characterize the global behavior of structural system in such a probabilistic assessment. The structural collapse capacity is often defined in terms of a threshold value of IDR or a reduced slope of the IDA curve between a selected seismic intensity measure and the corresponding IDR . However, collapse assessment approaches based on IDR may not accurately represent the overall structural collapse behavior due to redistribution and variation of local damage within the structure. Moreover, results of collapse predictions are found to be sensitive to variability in such drift measures, and assumed threshold values used in the collapse criterion. Recently, an energy-based seismic collapse criterion has been developed to describe collapse in terms of dynamic instability of the whole structural system caused by gravity loads. Using the energy-based collapse criterion, this paper proposes a more effective sidesway collapse risk assessment approach of ductile planar frames subjected to horizontal seismic loadings based on a new key descriptor of structural performance. The key descriptor, designated as the equivalent-velocity ratio, is related to the ratio of the energy dissipated through structural degradation to the seismic input energy. Using the equivalent-velocity ratio, a probabilistic collapse assessment method is developed for systematic treatment of uncertainties in the ground motions.