Practical Implementation of Generalized Force Vectors for the Multimodal Pushover Analysis of Building Structures

2015 ◽  
Vol 31 (2) ◽  
pp. 1043-1067 ◽  
Author(s):  
F. Soner Alıcı ◽  
HalÛk Sucuoğlu
Keyword(s):  
Nonlinear Response ◽  
Pushover Analysis ◽  
Practical Implementation ◽  
Building Structures ◽  
Design Spectrum ◽  
History Analysis ◽  
Response History Analysis ◽  
Generalized Force ◽  
Nonlinear Response History Analysis ◽  
The Mean

A practical implementation of generalized multimodal pushover analysis is presented in this study, where the number of pushovers is reduced significantly in view of the number of modes contributing to seismic response. It has been demonstrated in two case studies that the reduced procedure for generalized push-over analysis is equally successful in estimating the maximum member deformations and forces under a ground excitation with reference to nonlinear response history analysis. It is further shown that the results obtained by using the mean spectrum of a set of ground motions are almost identical to the mean of the results obtained from separate generalized pushover analyses. These results are also very close to the mean results of the nonlinear response history analyses, hence motivating the implementation of generalized pushover analysis with design spectrum.

Developing a simplified method for analysis and design of isolated structures with the novel quintuple friction pendulum system under bidirectional near-field excitations

2021 ◽  
pp. 107754632110482
Author(s):  
Hamed Keikha ◽  
Gholamreza Ghodrati Amiri
Keyword(s):  
Nonlinear Response ◽  
Near Field ◽  
Lateral Force ◽  
History Analysis ◽  
Special Cases ◽  
Simplified Method ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
Isolated Structures ◽  
Friction Pendulum

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.

scholarly journals Evaluation of a Substitute Structure Method to Estimate Seismic Displacement Demand in Piers and Wharves

2018 ◽  
Vol 34 (2) ◽  
pp. 759-772 ◽  
Author(s):  
Rakesh K. Goel
Keyword(s):  
Spectral Acceleration ◽  
Design Spectrum ◽  
Seismic Displacement ◽  
Long Period ◽  
History Analysis ◽  
Short Period ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
Displacement Demand ◽  
Spectral Velocity

This paper compares seismic displacement from the MOTEMS and the ASCE/COPRI 61-14 substitute structure method (SSM) with results from the nonlinear response history analysis (NLRHA). It is found that the SSM is biased toward overpredicting displacement demand for short-period systems and under-predicting displacement demand for long-period systems. The overprediction was found to be excessive for very-short period systems (i.e., systems with periods shorter than the period at which the design spectrum transitions from linearly increasing spectral acceleration to constant spectral acceleration). It is recommended that the SSM not be used for such systems. It is also recommended that the SSM not be used for long-period systems (i.e., systems with periods longer than the period at which the design spectrum transitions from constant spectral acceleration to constant spectral velocity), where it underpredicts displacement demand and may lead to unconservative design. The SSM provides reasonable results (within 20% of results from NLRHA) for systems with periods in the constant spectral acceleration region of the design spectrum.

scholarly journals Ground motion input for nonlinear response history analysis

2019 ◽  
Vol 52 (3) ◽  
pp. 119-133
Author(s):  
Gareth J. Morris ◽  
Andrew J. Thompson ◽  
James N. Dismuke ◽  
Brendon A. Bradley
Keyword(s):  
Ground Motion ◽  
Nonlinear Response ◽  
Time History ◽  
Tall Buildings ◽  
Nonlinear Time History Analysis ◽  
Existing Buildings ◽  
Ground Motion Selection ◽  
History Analysis ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

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.

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