On a Process of Rapid Estimation of Seismic Demands for Generic Steel Frame Structures

2005 ◽  
Author(s):  
Chiung-Yueh Lin ◽  
Wei-Zhi Chen ◽  
Tysh-Shang Jan
Keyword(s):  
Pushover Analysis ◽  
Tall Buildings ◽  
Frame Structures ◽  
Seismic Demands ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
History Analysis ◽  
Story Drift ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis

The seismic demands of tall buildings can be evaluated by nonlinear response history analysis with some more representative, site-dependent, earthquakes, or by pushover analysis. However, the process of the evaluation is tedious and time consuming. Therefore, it is desirable to have a simplified process that provides quick and reasonable estimates of seismic demands, especially in the stage of conceptual (preliminary) design. Gupta & Krawinkler (2000) has reached on a process in the estimation of roof and story drift demands for frame structures from the spectral displacement at the first period of the structure, through a series of modification factors, accounting for MDOF effects, inelasticity effects, and P-delta effects. It is found that this process can estimate seismic demands reasonably, provided that no negative post-yield story stiffness exists. Also, the modification factors are uniform or with reasonable dispersion, except for structures dominated by higher mode effects. This study has conducted a similar research by performing simulations on Taiwan code–compliant structures of different heights (2,5,10,20 and 30 stories), located in different seismic zones and subjected to sets of local ground motions. The feature of this study is that the seismic demands are estimated from the SRSS of the elastic, modal roof displacements of the structure, instead of the first mode spectral displacement. The simulation results have shown that the modification factors are more promising — uniform or with more reasonable dispersion — even the structure is dominated by high mode effects. Therefore, it is concluded that the process proposed in this study is a feasible method and the modification factors obtained in this study are useful for local engineer in engineering applications.

scholarly journals Extension of Modal Pushover Analysis to Compute Member Forces

2005 ◽  
Vol 21 (1) ◽  
pp. 125-139 ◽  
Author(s):  
Rakesh K. Goel ◽  
Anil K. Chopra
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
History Analysis ◽  
Response History Analysis ◽  
Standard Response ◽  
Nonlinear Response History Analysis ◽  
Seismic Deformation ◽  
Modal Pushover

This paper extends the modal pushover analysis (MPA) procedure for estimating seismic deformation demands for buildings to compute member forces. Seismic demands are computed for six buildings, each analyzed for 20 ground motions. A comparison of seismic demands computed by the MPA and nonlinear response history analysis (RHA) demonstrates that the MPA procedure provides good estimates of the member forces. The bias (or error) in forces is generally less than that noted in earlier investigations of story drifts and is comparable to the error in the standard response spectrum analysis (RSA) for elastic buildings. The four FEMA-356 force distributions, on the other hand, provide estimates of member forces that may be one-half to one-fourth of the value from nonlinear RHA.

scholarly journals Evaluation of a Modified MPA Procedure Assuming Higher Modes as Elastic to Estimate Seismic Demands

2004 ◽  
Vol 20 (3) ◽  
pp. 757-778 ◽  
Author(s):  
Anil K. Chopra ◽  
Rakesh K. Goel ◽  
Chatpan Chintanapakdee
Keyword(s):  
Structural Engineering ◽  
Pushover Analysis ◽  
Computational Effort ◽  
Attractive Alternative ◽  
Engineering Practice ◽  
Seismic Demands ◽  
History Analysis ◽  
Modes Of Vibration ◽  
Response History Analysis ◽  
Damped Systems

The modal pushover analysis (MPA) procedure, which includes the contributions of all significant modes of vibration, estimates seismic demands much more accurately than current pushover procedures used in structural engineering practice. Outlined in this paper is a modified MPA (MMPA) procedure wherein the response contributions of higher vibration modes are computed by assuming the building to be linearly elastic, thus reducing the computational effort. After outlining such a modified procedure, its accuracy is evaluated for a variety of frame buildings and ground motion ensembles. Although it is not necessarily more accurate than the MPA procedure, the MMPA procedure is an attractive alternative for practical application because it leads to a larger estimate of seismic demands, improving the accuracy of the MPA results in some cases (relative to nonlinear response history analysis) and increasing their conservatism in others. However, such conservatism is unacceptably large for lightly damped systems, with damping significantly less than 5%. Thus the MMPA procedure is not recommended for such systems.

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.

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.

scholarly journals Accuracy of Advanced Methods for Nonlinear Static Analysis of Steel Moment-Resisting Frames

2014 ◽  
Vol 8 (1) ◽  
pp. 310-323 ◽  
Author(s):  
Massimiliano Ferraioli ◽  
Alberto M. Avossa ◽  
Angelo Lavino ◽  
Alberto Mandara
Keyword(s):  
Pushover Analysis ◽  
Nonlinear Static Analysis ◽  
Seismic Demands ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Capacity Spectrum ◽  
History Analysis ◽  
Moment Resisting ◽  
Response History Analysis ◽  
Nonlinear Static

The reliability of advanced nonlinear static procedures to estimate deformation demands of steel momentresisting frames under seismic loads is investigated. The advantages of refined adaptive and multimodal pushover procedures over conventional methods based on invariant lateral load patterns are evaluated. In particular, their computational attractiveness and capability of providing satisfactory predictions of seismic demands in comparison with those obtained by conventional force-based methods are examined. The results obtained by the static advanced methods, used in the form of different variants of the original Capacity Spectrum Method and Modal Pushover Analysis, are compared with the results of nonlinear response history analysis. Both effectiveness and accuracy of these approximated methods are verified through an extensive comparative study involving both regular and irregular steel moment resisting frames subjected to different acceleration records.

3D Continuum Model for Nonlinear Dynamic Analysis of Wall-Frame Structures with Uniform Stiffness and Yield Strength

2012 ◽  
Vol 594-597 ◽  
pp. 662-665
Author(s):  
Kai Huang ◽  
Li Hua Zou ◽  
Jian Mei Chen
Keyword(s):  
Nonlinear Response ◽  
Nonlinear Dynamic Analysis ◽  
Frame Structures ◽  
Hysteretic Model ◽  
Concrete Wall ◽  
History Analysis ◽  
Reinforced Concrete Wall ◽  
Response History Analysis ◽  
Nonlinear Response History Analysis ◽  
The Continuum

A simplified 3D multi-degree-of-freedom (MDOF) model for estimation of seismic response of reinforced concrete wall-frame structures with uniform stiffness along the height are proposed in this paper. This model is aimed at reducing the computation demand in the nonlinear response history analysis (RHA). By employing the continuum technique for the structure and adopting the bilinear hysteretic model for material properties, the procedure for the development of a simplified MDOF model, called continuum MDOF model is developed. The proposed continuum MDOF model is shown to provide a simple and efficient for computation of nonlinear response of tall wall-frame structures.

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.

Approximate Quantification of Higher-Mode Effects on Seismic Demands of Buildings

2019 ◽  
Vol 19 (03) ◽  
pp. 1950023 ◽  
Author(s):  
Jui-Liang Lin
Keyword(s):  
Vibration Mode ◽  
Full Range ◽  
Beam Model ◽  
Strength Ratio ◽  
Site Class ◽  
Seismic Demands ◽  
Higher Mode Effects ◽  
Building Model ◽  
Mode Effects ◽  
Story Drift

Quantifying the higher-mode effects on the seismic demands of buildings may benefit not only the awareness of characteristics of the seismic responses of buildings, but also the development of rapid/simplified methods for the seismic assessment of buildings. This study proposes an approach that is applicable for quantifying the aforementioned effects, covering the full range of building heights and deformation types. The vehicle used in this proposed approach is the generalized building model, which has been modified from the conventional cantilever beam model. In addition to building height and deformation type, the strength ratio of each vibration mode and the site class of buildings are the parameters considered in this study. The higher-mode effects on floor displacements, inter-story drift ratios, floor accelerations, and base shears with relation to the aforementioned parameters are investigated. Finally, the proposed approach is verified via the investigation of the higher-mode effects of a 20-story exemplar building.

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