The collapse margin ratio of steel frames considering the vertical component of earthquake ground motions. (January 2022)

• Record Type: Journal Article
• Authors: Hamidia, Mohammadjavad; Shokrollahi, Nima; Rasti Ardakani, Reza
• Is Part Of: Journal of constructional steel research. Volume 188(2022)
• Publication Date: 2022-01
• Subjects: Collapse margin ratio (CMR) -- FEMA P695 -- Steel moment frame -- Vertical earthquake -- Nonlinear response history dynamic analysis -- Vertical fundamental period; Steel, Structural -- Periodicals; Building, Iron and steel -- Periodicals; Acier de construction -- Périodiques; Construction métallique -- Périodiques; 624.1821
• DOI: 10.1016/j.jcsr.2021.107054
• Languages: English
• ISSNs: 0143-974X

Abstract

Abstract: The FEMA P695 methodology does not consider the application of the vertical component of ground motions in nonlinear response history dynamic analyses for obtaining collapse margin ratios. The vertical component of earthquake affects the demand on the steel moment frame and flexural capacity of the columns in interaction with the fluctuating axial load. This paper investigates the effect of the vertical component of far- and near-field ground motions on the seismic collapse capacity of low-, mid-, and high-rise buildings. Various span lengths, story heights, and seismic mass ratios have been taken into account to cover the significant parameters in amplifying vertical earthquake damages. More than 50, 000 nonlinear response history dynamic analyses are performed to obtain seismic collapse margin ratios considering (1) the horizontal components of ground motion, (2) the horizontal plus vertical components of the earthquake, (3) the horizontal components of ground motion along with dead load factors suggested by ASCE7–16 to represent the vertical earthquake loading. Results are compared numerically, and the robustness of the procedure suggested by ASCE7–16 is assessed. It is shown that the adverse effect of the vertical component of the earthquake on the collapse capacity of the considered archetype buildings increases with the increase in the fundamental vertical period of buildings. Finally, adjusting equations using dimensionless parameters are developed for estimating the seismic collapse margin ratio of structures considering the vertical component of the ground motion. The proposed equations adjust the corresponding collapse margin ratio obtained using the horizontal components of ground motion. Graphical abstract: Unlabelled Image Highlights: The effect of the vertical component of earthquake on the CMR is investigated. More than 50, 000 nonlinear response history dynamic analyses are conducted. The effect of vertical earthquake increases with the increase in the vertical period. Adjusting equations are developed for estimating the seismic collapse margin ratio. The equations adjust the collapse margin ratio obtained using FEMA P695 methodology.