Abstract
In this paper, various moment‐resisting steel frames (MRSFs) are subjected to 30 narrow‐band motions scaled at different ground motion intensity levels in terms of spectral acceleration at first mode of vibration Sa(T1) in order to perform incremental dynamic analysis for peak and residual interstory drift demands. The results are used to compute the structural reliability of the steel frames by means of hazard curves for peak and residual drifts. It is observed that the structures exceed the threshold residual drift of 0.5%, which is perceptible to human occupants, and it could lead to human discomfort according to recent investigations. For this reason, posttensioned connections (PTCs) are incorporated into the steel frames in order to improve the structural reliability. The results suggest that the annual rate of exceedance of peak and residual interstory drift demands are reduced with the use of PTC. Thus, the structural reliability of the steel frames with PTC is superior to that of the MRSFs. In particular, the residual drift demands tend to be smaller when PTCs are incorporated in the steel structures.
Highlights
Most of the seismic design regulations recommend the use of maximum interstory drift as the main engineering demand parameter
Two groups of four structural steel frame models are selected for the study. e first group of structures corresponding to moment-resisting steel frames was designed according to the Mexico City Building Design Provisions (MCSDPs) [28]. e buildings are assumed to be for office occupancy. ey have 4, 6, 8, and 10 stories, and 3 bays, hereafter indicated as F4, F6, F8, and F10, respectively. e dimensions of the frames are shown in Figure 1. e beams and columns are A36 steel W sections
The well-known seismic performance-based assessment procedure suggested by the Pacific Earthquake Engineering Center [37] in the United States was employed in this study, which indicates that the mean annual frequency of exceedance of an engineering demand parameter (EDP) of interest exceeding a certain level EDP can be computed as follows: λ(EDP > edp) P[EDP > edp | IM im] · dλIM(im), IM
Summary
Most of the seismic design regulations recommend the use of maximum interstory drift as the main engineering demand parameter. In the present study, motivated by the need to reduce peak and residual interstory drift demands, PTCs are incorporated into various MRSFs. Posttensioned steel moment-resisting frames are structural systems proposed in recent years as an appropriate alternative to welded connections of momentresisting frames in seismic zones [14,15,16,17,18,19,20,21,22,23,24,25,26,27]. E structural performance of the selected MRSFs is compared with the structures with PTC through incremental dynamic analysis and the estimation of the structural reliability of the frames in terms of peak and residual interstory drift demands With this aim, four MRSFs and the same structures with PTC (here named FPTC frames with posttensioned connections) are subjected to 30 long-duration ground motions recorded at the lake zone of Mexico City where most of the damages were found in buildings as a consequence of the 1985 Michoacan earthquake. The residual drift demands tend to be smaller than 0.5% (which is perceptible for building occupants) when PTCs are incorporated into the steel structures
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