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An improved multidimensional MPA procedure for bidirectional earthquake excitations.

Wang F, Sun JG, Zhang N - ScientificWorldJournal (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Architecture & Civil Engineering, Dalian Nationalities University, Dalian 116600, China.

ABSTRACT
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.

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Analysis of modification coefficient α.
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Related In: Results  -  Collection


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fig3: Analysis of modification coefficient α.

Mentions: Through the above analysis, the regularity of Rb/Rs along with period change is not very significant, so it is suggested to take the same Rb/Rs spectra value within the entire period. In addition, for the reason of disadvantage in Rb/Rs < 1, “mean value − 1.65 × standard deviation” of Rb/Rs within 0.05~5.0 seconds is defined as modification coefficient, α, of traditional Rs. The distribution curves of modification coefficient, α, along with ductility factor changes are shown in Figure 3. The following can be drawn from Figure 3. (1) For all kinds of soil sites, the minimum value of α is 0.910 and the maximum value is 0.985, which shows that the influence of the analysis variables on Rs spectra is little. (2) For γ > 0, α decreases while γ increases; for γ < 0, α decreases while γ decreases (it is not so significant for γ < 0 at hard soil site and for γ < 0 at intermediate soil site). (3) For hard soil site, α is maximized while μ = 1.5; α decreases and does not change significantly along with increase of ductility factor while μ⩾2; for intermediate soil site, α increases along with increase of the ductility factor while μ⩾2; for soft soil site, α decreases along with increase of ductility factor.


An improved multidimensional MPA procedure for bidirectional earthquake excitations.

Wang F, Sun JG, Zhang N - ScientificWorldJournal (2014)

Analysis of modification coefficient α.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4129155&req=5

fig3: Analysis of modification coefficient α.
Mentions: Through the above analysis, the regularity of Rb/Rs along with period change is not very significant, so it is suggested to take the same Rb/Rs spectra value within the entire period. In addition, for the reason of disadvantage in Rb/Rs < 1, “mean value − 1.65 × standard deviation” of Rb/Rs within 0.05~5.0 seconds is defined as modification coefficient, α, of traditional Rs. The distribution curves of modification coefficient, α, along with ductility factor changes are shown in Figure 3. The following can be drawn from Figure 3. (1) For all kinds of soil sites, the minimum value of α is 0.910 and the maximum value is 0.985, which shows that the influence of the analysis variables on Rs spectra is little. (2) For γ > 0, α decreases while γ increases; for γ < 0, α decreases while γ decreases (it is not so significant for γ < 0 at hard soil site and for γ < 0 at intermediate soil site). (3) For hard soil site, α is maximized while μ = 1.5; α decreases and does not change significantly along with increase of ductility factor while μ⩾2; for intermediate soil site, α increases along with increase of the ductility factor while μ⩾2; for soft soil site, α decreases along with increase of ductility factor.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Architecture & Civil Engineering, Dalian Nationalities University, Dalian 116600, China.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus