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.

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 IMPAβ: Incremental Modal Pushover Analysis for Bridges

2020 ◽  
Vol 10 (12) ◽  
pp. 4287 ◽  
Author(s):  
Alessandro Vittorio Bergami ◽  
Camillo Nuti ◽  
Davide Lavorato ◽  
Gabriele Fiorentino ◽  
Bruno Briseghella
Keyword(s):  
Pushover Analysis ◽  
Structural Response ◽  
Small Contribution ◽  
Base Shear ◽  
Higher Modes ◽  
Modal Pushover Analysis ◽  
Complementary Method ◽  
Incremental Methods ◽  
Total Base ◽  
Modal Pushover

In the present study, the incremental modal pushover analysis (IMPA), a pushover-based approach already proposed and applied to buildings by the same authors, was revised and proposed for bridges (IMPAβ). Pushover analysis considers the effects of higher modes on the structural response. Bridges are structurally very different from multi-story buildings, where multimodal pushover (MPA) has been developed and is currently used. In bridges, consideration for higher modes is often necessary: The responses of some structural elements of the bridge (e.g., piers) influence the overall bridge response. Therefore, the failure of these elements can determine the failure of the whole structure, even if they give a small contribution total base shear. Incremental dynamic analysis (IDA) requires input accelerograms for high intensities, which are rare in the databases, while scaling of generated accelerograms with a simple increment of the scaling acceleration is not appropriate. This fact renders IDA, which is by its nature time-consuming, not straightforward. On the contrary, the change of input spectrum required by IMPA is simple. IMPAβ also utilizes a simple complementary method coupled to MPA, to obtain bounds at very high seismic intensities. Finally, the two incremental methods based on static nonlinear and dynamic nonlinear analyses are compared.

scholarly journals Application of the Incremental Modal Pushover Analysis to Bridges Subjected to Near-Fault Ground Motions

2020 ◽  
Vol 10 (19) ◽  
pp. 6738
Author(s):  
Alessandro Vittorio Bergami ◽  
Gabriele Fiorentino ◽  
Davide Lavorato ◽  
Bruno Briseghella ◽  
Camillo Nuti
Keyword(s):  
Ground Motion ◽  
Pushover Analysis ◽  
Vertical Component ◽  
Structural Response ◽  
Strong Motion ◽  
Seismic Action ◽  
Modal Pushover Analysis ◽  
Near Fault ◽  
Modal Pushover

Near-fault events can cause severe damage to civil structures, including bridges. Many studies have demonstrated that the seismic assessment is not straightforward. Usually, dealing with near-fault ground motion, the structural analysis is performed using Nonlinear Response-History Analysis (NRHA) but in the last years, many authors have tested existing pushover-based procedures originally developed and validated using far-field events. Between those procedures, the Incremental Modal Pushover Analysis (IMPAβ) is a pushover-based procedure specifically developed for bridges that, in this work, was applied to a case study considering near-fault pulse-like ground motion records. The records were analyzed and selected from the European Strong Motion Database. In the paper the results obtained with IMPAβ together with other standard pushover procedures, are compared with NRHA and incremental dynamic analyses; the vertical component of the motion has been also considered. Results obtained with the bridge case study demonstrate that the vertical seismic action has a minor influence on the structural response and that IMPAβ is confirmed as a very effective pushover-based method that can be applied also for near-fault events.

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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