How Many Records Should be used in an ASCE/SEI-7 Ground Motion Scaling Procedure?

2012 ◽  
Vol 28 (3) ◽  
pp. 1223-1242 ◽  
Author(s):  
Juan C. Reyes ◽  
Erol Kalkan
Keyword(s):  
Ground Motions ◽  
Accurate Estimate ◽  
Perfectly Plastic ◽  
History Analysis ◽  
Scaling Procedure ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
Structural Responses ◽  
Ground Motion Scaling ◽  
Elastic Perfectly Plastic

U.S. national building codes refer to the ASCE/SEI-7 provisions for selecting and scaling ground motions for use in nonlinear response history analysis of structures. Because the limiting values for the number of records in the ASCE/SEI-7 are based on engineering experience, this study examines the required number of records statistically, such that the scaled records provide accurate, efficient, and consistent estimates of “true” structural responses. Based on elastic–perfectly plastic and bilinear single-degree-of-freedom systems, the ASCE/SEI-7 scaling procedure is applied to 480 sets of ground motions; the number of records in these sets varies from three to ten. As compared to benchmark responses, it is demonstrated that the ASCE/SEI-7 scaling procedure is conservative if fewer than seven ground motions are employed. Utilizing seven or more randomly selected records provides more accurate estimate of the responses. Selecting records based on their spectral shape and design spectral acceleration increases the accuracy and efficiency of the procedure.

Evaluation of Modal Pushover–Based Scaling of One Component of Ground Motion: Tall Buildings

2012 ◽  
Vol 28 (4) ◽  
pp. 1469-1493 ◽  
Author(s):  
Erol Kalkan ◽  
Anil K. Chopra
Keyword(s):  
Ground Motions ◽  
Tall Buildings ◽  
Accurate Estimate ◽  
Existing Structures ◽  
History Analysis ◽  
Scaling Procedure ◽  
Response History Analysis ◽  
Performance Based Seismic Design ◽  
Nonlinear Response History Analysis ◽  
Modal Pushover

Nonlinear response history analysis (RHA) is now increasingly used for performance-based seismic design of tall buildings. Required for nonlinear RHAs is a set of ground motions selected and scaled appropriately so that analysis results would be accurate (unbiased) and efficient (having relatively small dispersion). This paper evaluates accuracy and efficiency of recently developed modal pushover– based scaling (MPS) method to scale ground motions for tall buildings. The procedure presented explicitly considers structural strength and is based on the standard intensity measure (IM) of spectral acceleration in a form convenient for evaluating existing structures or proposed designs for new structures. Based on results presented for two actual buildings (19 and 52 stories, respectively), it is demonstrated that the MPS procedure provided a highly accurate estimate of the engineering demand parameters (EDPs), accompanied by significantly reduced record-to-record variability of the responses. In addition, the MPS procedure is shown to be superior to the scaling procedure specified in the ASCE/SEI 7-05 document.

scholarly journals Required Separation to Mitigate Pounding of Adjacent Building Blocks

2018 ◽  
Vol 8 (6) ◽  
pp. 3565-3569
Author(s):  
M. S. Masmoum ◽  
M. S. A. Alama
Keyword(s):  
Nonlinear Response ◽  
Response Spectrum ◽  
Ground Motions ◽  
Building Blocks ◽  
Separation Distance ◽  
Expansion Joints ◽  
History Analysis ◽  
Adjacent Building ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

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.

Determining Bidirectional Ground Motions for Nonlinear Response History Analysis of Buildings at Far-Field Sites

2018 ◽  
Vol 34 (4) ◽  
pp. 1931-1954 ◽  
Author(s):  
N. Simon Kwong ◽  
Anil K. Chopra
Keyword(s):  
Nonlinear Response ◽  
Current Practice ◽  
Ground Motions ◽  
Computational Effort ◽  
Far Field ◽  
Composite Spectrum ◽  
Multistory Buildings ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

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.

Incorporation of Velocity Pulses in Design Ground Motions for Response History Analysis Using a Probabilistic Framework

2015 ◽  
Vol 31 (3) ◽  
pp. 1647-1666 ◽  
Author(s):  
Ibrahim Almufti ◽  
Ramin Motamed ◽  
Damian N. Grant ◽  
Michael Willford
Keyword(s):  
San Francisco ◽  
Structural Damage ◽  
Peer Review Process ◽  
Ground Motions ◽  
Pulse Amplitude ◽  
Intensity Level ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
The Time Domain

Ground motions that contain velocity pulses may cause greater structural damage than ground motions that do not contain pulses. The effects of pulse-like motions are best approximated in the time domain using nonlinear response history analysis. Current approaches for incorporating pulse effects are not reproducible since they largely rely on engineering judgment and often result in unrealistic representation of the hazard. This study extends a method by Shahi and Baker (2011) that incorporates the effects of pulse-like motions in probabilistic seismic hazard analyses (PSHA). It uses disaggregation information from the PSHA to construct suites of target spectra that are used for matching an appropriate proportion of pulse-like motions with characteristics (pulse amplitude and pulse period) representative of a desired hazard intensity level. The methodology has been successfully employed for several high-profile projects in California that were subjected to a rigorous peer review process, including the Transbay Tower in San Francisco.

Response-History Analysis for the Design of New Buildings in the NEHRP Provisions and ASCE/SEI 7 Standard: Part IV - A Study of Assumptions

2017 ◽  
Vol 33 (2) ◽  
pp. 449-468 ◽  
Author(s):  
Jordan A. Jarrett ◽  
Reid B. Zimmerman ◽  
Finley A. Charney ◽  
Afshar Jalalian
Keyword(s):  
Nonlinear Response ◽  
Ground Motions ◽  
Near Field ◽  
Primary Objective ◽  
Risk Category ◽  
Residual Drift ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
New Buildings

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.

Modal Pushover-Based Scaling of Two Components of Ground Motion Records for Nonlinear RHA of Structures

2012 ◽  
Vol 28 (3) ◽  
pp. 1243-1267 ◽  
Author(s):  
Juan C. Reyes ◽  
Anil K. Chopra
Keyword(s):  
Ground Motion ◽  
Nonlinear Response ◽  
Accurate Estimate ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
Small Set ◽  
Ground Motion Records ◽  
Story Building ◽  
Modal Pushover

The modal-pushover-based-scaling (MPS) procedure, currently restricted to scale one component of ground motion records, is extended herein to scale two horizontal components. The accuracy and efficiency of the MPS procedure is evaluated here by applying it to an existing nine-story building, symmetric in plan. The computer model developed for the building is validated against motions of the building recorded during the Chino Hills earthquake (2008). It is demonstrated that nonlinear response history analysis (RHA) of the building for a small set of records scaled by the MPS procedure provided a highly accurate estimate of the engineering demand parameters (EDPs), accompanied by significantly reduced record-to-record variability of the responses. Furthermore, the MPS procedure is shown to be much superior to the procedure specified in the ASCE/SEI 7-05 standard for scaling two components of ground motion records.

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