Is Modal Pushover Analysis accurate in estimating seismic demands for unreinforced masonry buildings with flexible diaphragms?

2016 ◽  
pp. 269-274
Author(s):  
Y Nakamura ◽  
H. Derakhshan ◽  
M.C. Griffith ◽  
G. Magenes
Keyword(s):  
Pushover Analysis ◽  
Unreinforced Masonry ◽  
Masonry Buildings ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
Flexible Diaphragms ◽  
Modal Pushover

Applicability of Modal Pushover Analysis on Bridges

2011 ◽  
Vol 255-260 ◽  
pp. 806-810
Author(s):  
Biao Wei ◽  
Qing Yuan Zeng ◽  
Wei An Liu
Keyword(s):  
Seismic Analysis ◽  
Pushover Analysis ◽  
Time History ◽  
Seismic Demand ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
History Analysis ◽  
Bridge Structures ◽  
Scope Of Application ◽  
Modal Pushover

Taking one irregular continuous bridge as an example, modal pushover analysis (MPA) has been conducted to judge whether it would be applicable for seismic analysis of irregular bridge structures. The bridge’s seismic demand in the transverse direction has been determined through two different methods, inelastic time history analysis (ITHA) and MPA respectively. The comparison between those two results indicates that MPA would be suitable only for bridges under elastic or slightly damaged state. Finally, some modifications are used to improve the MPA’s scope of application, and the results illustrate that the adapted MPA will be able to estimate bridges’ seismic demands to some extent.

scholarly journals Seismic analysis of in-plane loaded walls in unreinforced masonry buildings with flexible diaphragms

2014 ◽  
Vol 47 (4) ◽  
pp. 275-289
Author(s):  
Yasuto Nakamura ◽  
Hossein Derakhshan ◽  
Jason M. Ingham ◽  
Michael C. Griffith
Keyword(s):  
Seismic Analysis ◽  
Unreinforced Masonry ◽  
Mode Analysis ◽  
Analysis Approach ◽  
Masonry Buildings ◽  
Alternative Analysis ◽  
Response Modification Factor ◽  
Seismic Demands ◽  
Flexible Diaphragms ◽  
Modification Factor

It is well recognised that the dynamic response of unreinforced masonry buildings with flexible timber diaphragms typically contains multiple dominant modes associated with the excitations of the diaphragms and the in-plane walls. Existing linear analysis methods for this type of structure commonly account for the multi-mode behaviour by assuming the independent vibrations of the in-plane loaded walls (in-plane walls) and the diaphragms. Specifically, the in-plane walls are considered to be rigid and the unmodified ground motion is assumed to be transmitted up the walls to the diaphragm ends. While this assumption may be appropriate for many low-rise unreinforced masonry buildings, neglecting the dynamic interaction between the diaphragms and the in-plane walls can lead to unreliable predictions of seismic demands. An alternative analysis approach is proposed in this paper, based on the mode properties of a system in which (1) the mass ratios between the diaphragms and the in-plane wall are the same at all levels, and (2) the periods of the diaphragms are the same at all levels. It is proposed that under these conditions, two modes are typically sufficient to obtain the peak seismic demands of the in-plane walls in elastically responding low-rise regular buildings. The applicability of the two-mode analysis approach is assessed for more general diaphragm configurations by sensitivity analysis, and the limitations are identified. The two-mode approach is then used to derive a response modification factor, which may be used in conjunction with a linear static procedure in the seismic assessment of buildings with flexible diaphragms.

scholarly journals An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Feng Wang ◽  
Jian-Gang Sun ◽  
Ning Zhang
Keyword(s):  
Pushover Analysis ◽  
Structural Response ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Multidimensional Analysis ◽  
Strength Reduction Factor ◽  
Earthquake Excitation ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
Modal Pushover

Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1) the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2) Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3) Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase.

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.

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