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

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.

Author(s):  
Gareth J. Morris ◽  
Andrew J. Thompson ◽  
James N. Dismuke ◽  
Brendon A. Bradley

Nonlinear response history analysis (NLRHA), or so-called “nonlinear time history analysis”, is adopted by practicing structural engineers who implement performance-based seismic design and/or assessment procedures. One important aspect in obtaining reliable output from the NLRHA procedure is the input ground motion records. The underlying intention of ground motion selection and amplitude-scaling procedures is to ensure the input for NLRHA is representative of the ground shaking hazard level, for a given site and structure. The purpose of this paper is to highlight the salient limitations of the ground motion selection and scaling requirements in Sections 5.5 and 6.4 of the New Zealand (NZ) loading standard NZS 1170.5 (2004). From a NZ regulatory perspective; there is no specific framework for seismic hazard analysis and ground motion selection (thus self-regulation is the current norm). In contrast, NZS 1170.5 contains many prescriptive requirements for scaling and applying records which are challenging to satisfy in practice. Also discussed within, there are implications for more modern guidance documents in NZ, such as the 2017 “Assessment Guidelines” for existing buildings, which cite NZS 1170.5, a standard which is at least 16 years old (draft issued in 2002). To emphasize the above issues with NZS 1170.5, this paper presents a summary of the more contemporary approaches in the US standards ASCE 7-16 (new buildings) and ASCE 41-17 (existing buildings), along with some examples of the more stringent US requirements for Tall Buildings.


2012 ◽  
Vol 28 (4) ◽  
pp. 1469-1493 ◽  
Author(s):  
Erol Kalkan ◽  
Anil K. Chopra

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.


Author(s):  
Michalis Fragiadakis ◽  
Nikos D. Lagaros ◽  
Yiannis Tsompanakis ◽  
Manolis Papadrakakis

Four alternative analytical procedures are recommended by the design codes for the structural analysis of buildings under earthquake loading. The objective of this chapter is to assess these procedures by integrating them in the framework of structural optimization. The evaluation is based on the European seismic design code, where procedures based on both linear and nonlinear response history analysis are adopted. In order to realistically simulate seismic actions, suites of both natural and artificial ground-motion records are used. For the solution of the optimization problem an evolutionary algorithm is adopted. The results obtained demonstrate the advantages of using more elaborate seismic design procedures, based on a detailed simulation of the structural behaviour and the applied seismic loading, as opposed to the commonly used simplified design methodologies. Designs with less material cost combined with better seismic performance are obtained when nonlinear response history analysis is performed.


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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