Evaluation of the MPA Procedure for Estimating Seismic Demands: RC-SMRF Buildings

2008 ◽  
Vol 24 (4) ◽  
pp. 827-845 ◽  
Author(s):  
Hugo Bobadilla ◽  
Anil K. Chopra
Keyword(s):  
Ground Motions ◽  
Pushover Analysis ◽  
Cyclic Behavior ◽  
Hysteretic Model ◽  
Practical Application ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Special Moment Resisting Frame

The modal pushover analysis (MPA) procedure is extended for analysis of reinforced concrete special moment resisting frame (RC-SMRF) buildings, after demonstrating that the theory, assumptions, and approximations underlying this procedure are valid for such systems. The principal extension of the procedure is in the hysteretic model for modal SDF systems, chosen as the peak-oriented model to represent the global monotonic and cyclic behavior of such buildings, characterized by deterioration of stiffness and strength under cyclic deformation. The median seismic demands for 4-, 8-, 12-, and 20-story RC-SMRF buildings—designed to comply with current codes—due to an ensemble of 78 ground motions scaled to four intensity levels were computed by MPA and nonlinear RHA, and compared. It is demonstrated that, even for the most intense ground motions that deform the buildings far into the inelastic range, the MPA procedure demonstrates an adequate degree of accuracy that should make it useful for practical application in estimating seismic demands for RC-SMRF buildings. In contrast the FEMA-356 force distributions are inadequate in estimating seismic demands for the 8-, 12-, and 20-story buildings at all excitation intensities, from the weakest that causes response essentially within the linearly elastic range, to the strongest that drives the buildings far into the inelastic range.

scholarly journals Evaluation of Modified Fish-Bone Model for Estimating Seismic Demands of Irregular MRF Structures

2018 ◽  
Author(s):  
Amin Haghighat ◽  
Ashkan Sharifi
Keyword(s):  
Ground Motions ◽  
Fish Bone ◽  
Seismic Demands ◽  
Error Measure ◽  
Ductility Demand ◽  
Earthquake Records ◽  
Moment Resisting Frame ◽  
Different Types ◽  
Story Drift ◽  
Moment Resisting

This paper evaluates the accuracy of the Modified Fish-Bone (MFB) model for estimating the maximum inter-story drift ratio of irregular moment resisting frame (MRF) structures. To make this model applicable to irregular MRF structures, some modifications are made to the MFB formula. In order to evaluate the accuracy of the MFB model, several irregular frames with different types of irregularities are considered when subjected to different ground motions with different intensities. A local and a global error measure are defined and they are calculated for different frame models subjected to different earthquake records. The effects of different irregularities, ductility demand and frame height on the accuracy of the MFB model are investigated. Based on the results obtained from this evaluation, two simple and effective approaches are suggested to improve the MFB models.

scholarly journals Characterizing Ground Motions that Collapse Steel Special Moment-Resisting Frames or Make Them Unrepairable

2015 ◽  
Vol 31 (2) ◽  
pp. 813-840 ◽  
Author(s):  
Anna H. Olsen ◽  
Thomas H. Heaton ◽  
John F. Hall
Keyword(s):  
Regression Models ◽  
Ground Motions ◽  
Spectral Acceleration ◽  
Ground Displacement ◽  
Intensity Measures ◽  
Moment Resisting Frame ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Equivalent Frame ◽  
Special Moment Resisting Frame

This work applies 64,765 simulated seismic ground motions to four models each of 6- or 20-story, steel special moment-resisting frame buildings. We consider two vector intensity measures and categorize the building response as “collapsed,” “unrepairable,” or “repairable.” We then propose regression models to predict the building responses from the intensity measures. The best models for “collapse” or “unrepairable” use peak ground displacement and velocity as intensity measures, and the best models predicting peak interstory drift ratio, given that the frame model is “repairable,” use spectral acceleration and epsilon ( ∊) as intensity measures. The more flexible frame is always more likely than the stiffer frame to “collapse” or be “unrepairable.” A frame with fracture-prone welds is substantially more susceptible to “collapse” or “unrepairable” damage than the equivalent frame with sound welds. The 20-story frames with fracture-prone welds are more vulnerable to P-delta instability and have a much higher probability of collapse than do any of the 6-story frames.

scholarly journals FEMA P695 methodology for safety margin evaluation of steel moment resisting frames subjected to near-field and far-field records

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mahdi Heshmati ◽  
Alireza Khatami ◽  
Hamzeh Shakib
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Near Field ◽  
Safety Margin ◽  
Far Field ◽  
Performance Factors ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Nonlinear Static ◽  
Special Moment Resisting Frame

AbstractThis study presents the impact of near-field and far-field earthquakes on the seismic design of Intermediate Moment Resisting Frame (IMRF) and Special Moment Resisting Frame (SMRF) structures through FEMA (Federal Emergency Management Agency) P695 methodology to highlight the importance of probabilistic collapse as well as seismic performance factors of these structures. The purpose of this study is to investigate the collapse performance of steel intermediate and special moment resisting frame systems as the most common structural systems in urban areas in order to assess the seismic performance factors used for the design using nonlinear static and dynamic analysis methods. In this regard, as the representatives of low-rise to high-rise buildings, archetypes with 5-, 10- and 15- story of intermediate and special moment resisting frames are designed and then the nonlinear models are developed in OpenSees software. Nonlinear static analyses are performed to assess the overstrength and ductility of these systems. The effects of near-field and far-field ground motions on these frames are investigated through incremental dynamic analysis. These analyses are performed with 22 far-field and 20 near-field ground motion records using FEMA P695 methodology. The results show that near-field earthquakes have serious impacts on the collapse probability of structures. The superiority of special moment resisting frame over intermediate moment resisting frame is quantified in terms of safety margin and median collapse capacity under both near-field and far-field earthquakes. Finally, the results indicate that the response modification factors introduced in seismic design code are acceptable for intermediate moment resisting frame and special moment resisting frame under far-field ground motions. However, in the near-field sites while SMRF system meets the requirements of FEMA P695 methodology, the IMRF system does not satisfy these criteria.

Applicability of Modal Pushover Analysis on Bridges

2011 ◽  
Vol 255-260 ◽  
pp. 806-810
Author(s):  
Biao Wei ◽  
Qing Yuan Zeng ◽  
Wei An Liu
Keyword(s):  
Seismic Analysis ◽  
Pushover Analysis ◽  
Time History ◽  
Seismic Demand ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
History Analysis ◽  
Bridge Structures ◽  
Scope Of Application ◽  
Modal Pushover

Taking one irregular continuous bridge as an example, modal pushover analysis (MPA) has been conducted to judge whether it would be applicable for seismic analysis of irregular bridge structures. The bridge’s seismic demand in the transverse direction has been determined through two different methods, inelastic time history analysis (ITHA) and MPA respectively. The comparison between those two results indicates that MPA would be suitable only for bridges under elastic or slightly damaged state. Finally, some modifications are used to improve the MPA’s scope of application, and the results illustrate that the adapted MPA will be able to estimate bridges’ seismic demands to some extent.

An evaluation ofP-Δ amplification factors in multistorey steel moment resisting frames

1999 ◽  
Vol 26 (5) ◽  
pp. 535-548 ◽  
Author(s):  
R Tremblay ◽  
B Côté ◽  
P Léger
Keyword(s):  
Amplification Factor ◽  
Ground Motions ◽  
Beam Model ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frame ◽  
Dynamic Analyses ◽  
Moment Resisting ◽  
Shear Beam ◽  
Nonlinear Dynamic Analyses ◽  
Shear Beam Model

Three different amplification factors that have been proposed to account for P-Δ effects in the seismic design of multistorey building structures are described and compared. Nonlinear dynamic analyses of a typical 20-storey steel moment resisting frame are carried out under earthquake ground motions typical of eastern and western Canada to evaluate the gravity load effects and to assess the effectiveness of each type of amplification factor in accounting for these effects. All three approaches maintain the ductility demand within the level computed without P-Δ effects, but lateral deformations are generally larger than those obtained neglecting the gravity loads. Nonlinear dynamic analyses are also performed on a shear-beam (stick) model of the same building to examine the possibility of using such simple models for studying the dynamic stability of buildings subjected to ground motions. The shear-beam model does not predict adequately the seismic behaviour of steel moment resisting frames for which P-Δ effects are significant.Key words: ductility, earthquake, ground motion, lateral deformation, moment resisting frame, P-Δ effects, push-over analysis, seismic, shear-beam model, stability coefficient, amplification factor.

scholarly journals Comparison of Scaling Ground Motions Using Arithmetic with Logarithm Values for Spectral Matching Procedure

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Rui Zhang ◽  
Dong-sheng Wang ◽  
Xiao-yu Chen ◽  
Hong-nan Li
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Response Spectra ◽  
Time History Analysis ◽  
Spectral Matching ◽  
Moment Resisting Frame ◽  
History Analysis ◽  
Moment Resisting ◽  
Structural Responses ◽  
Structural Time

In recent studies, spectral matching is the most commonly proposed method for selecting earthquake records for time-history analysis of structures. However, until now, there have been no serious investigations of the effects of coordinate values on the scaling of ground motions. This paper investigated the influence of using arithmetic and logarithmic values of response spectra in spectral matching procedures (i.e., ASM and LSM methods) on the results of nonlinear structural time-history analysis. Steel moment resisting frame structures of the 3-, 9-, and 20-stories, which represent low-, medium-, and high-rise buildings, respectively, were used as examples. Structural benchmark responses were determined by calculating the arithmetic mean and median of peak interstory drift ratio (PIDR) demands based on the three record sets developed by the American SAC Steel Project. The three record sets represent seismic hazard levels with 50%, 10%, and 2% probabilities exceeded in 50 years, and their average acceleration spectra were also taken as the target spectrum. Moreover, another 40 record components for selection were scaled both by ASM and LSM methods. The seven components whose spectra were best compatible with the target spectra were selected for the structural time-history analysis. The scale factors obtained by the LSM method are nearly larger than that of the ASM method, and their ranking and selection of records are different. The estimation accuracies of structural mean (median) responses by both methods can be controlled within an engineering acceptable range (±20%), but the LSM method may cause larger structural responses than the ASM method. The LSM method has a better capacity for reducing the variability of structural responses than the ASM method, and this advantage is more significant for longer-period structures (e.g., 20-story structure) with more severe nonlinear responses.

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