Modeling viscous damping in nonlinear response history analysis of steel moment‐frame buildings: Design‐plus ground motions

Author(s):  
Xin Qian ◽  
Anil K. Chopra ◽  
Frank McKenna
2018 ◽  
Vol 8 (6) ◽  
pp. 3565-3569
Author(s):  
M. S. Masmoum ◽  
M. S. A. Alama

This research discusses the feasibility of using the required minimum separation distance based on SBC 301-2007. Moment resistance frames were designed with expansion joints requiring 400mm separation distance. Nonlinear response history analysis was conducted with four ground motions selected and scaled to match the risk-targeted response spectrum of NEOM city based on ASCE 7-16 provisions. An equivalent spring constant value based on floor lateral stiffness was selected as a gap link stiffness. Finally, an evaluation for the pounding response of adjacent blocks is presented along with the conclusions.


2018 ◽  
Vol 34 (4) ◽  
pp. 1931-1954 ◽  
Author(s):  
N. Simon Kwong ◽  
Anil K. Chopra

The current practice for selecting bidirectional ground motions (GM pairs) to conduct nonlinear response history analysis (RHA) of multistory buildings is restricted to those with a symmetric plan. To overcome such limitations, we propose selecting GM pairs to be consistent with a pair of target spectra defined along the structural axes, enabling a unique azimuth to be determined for each GM pair. We develop two new target spectra: (1) the s-GCMS for two horizontal components of GM and (2) the CMS-UHS Composite Spectrum. Based on nonlinear RHAs of buildings with both symmetric and unsymmetric plans, the CMS-UHS Composite Spectrum is shown to be the best alternative to the current practice of utilizing multiple CMSs, because it provides accurate demands with minimal computational effort and can be easily constructed using existing PSHA tools.


2017 ◽  
Vol 33 (2) ◽  
pp. 449-468 ◽  
Author(s):  
Jordan A. Jarrett ◽  
Reid B. Zimmerman ◽  
Finley A. Charney ◽  
Afshar Jalalian

The accuracy of several assumptions made when developing the methodology for nonlinear response history analysis of Chapter 16 of ASCE/SEI 7 is investigated. The major findings of this work include: (1) Modeling the gravity system's lateral influence can have a significant effect on system behavior, but it is generally conservative to neglect its contribution. (2) Exclusion of a residual drift check is acceptable when collapse prevention is the primary objective. (3) Spectrally matched ground motions should cautiously be used for near-field sites. (4) The effects of nonlinear accidental torsion can be influential, and should be considered for the analysis of torsionally irregular buildings. (5) When analyzed using FEMA P-695, a structure designed per ASCE/SEI 7 Chapter 16 may have a probability of collapse that is different than the target value associated with the system's risk category.


2021 ◽  
pp. 107754632110482
Author(s):  
Hamed Keikha ◽  
Gholamreza Ghodrati Amiri

Simplified analysis methods for seismically isolated structures proposed in recent structural codes and specifications are frequently used to reduce the computational effort and to simplify the design procedure, either directly for special cases or for checking the results of nonlinear response history analysis. Of the approximate methods, the equivalent lateral force procedure using the effective stiffness and effective damping is one of the best known. In this study, the simplified method is developed by combining the equivalent lateral force procedure with the capacity spectrum method and evaluated in terms of maximum isolator displacements and base shears for isolated structures with recently invented quintuple friction pendulum isolators , with different geometrical and frictional properties, under two different response spectra with corresponding two different sets of bidirectional near-field ground motions for stiff and soft soils site classes. In order to assess the accuracy of the simplified method, the delivered results of the ELF procedure are compared to those of nonlinear response history analysis, by modelling the quintuple friction pendulum isolator 3D element in OpenSees. Eventually, comments on the accuracy of the simplified method are given to make its applications more appropriate in practical design of base isolation systems.


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