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Journal of Zhejiang University SCIENCE A 2005 Vol.6 No.8 P.813-825


Seismic force modification factor for ductile structures

Author(s):  TONG Gen-shu, HUANG Jin-qiao

Affiliation(s):  Department of Structural Engineering, Zhejiang University, Hangzhou 310027, China; more

Corresponding email(s):   tonggs@ccea.zju.edu.cn, huangjq@chinacuc.com

Key Words:  Aseismic design, Seismic force modification coefficient, Ductility, Energy-dissipating capacity

TONG Gen-shu, HUANG Jin-qiao. Seismic force modification factor for ductile structures[J]. Journal of Zhejiang University Science A, 2005, 6(8): 813-825.

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%DOI 10.1631/jzus.2005.A0813

T1 - Seismic force modification factor for ductile structures
A1 - TONG Gen-shu
A1 - HUANG Jin-qiao
J0 - Journal of Zhejiang University Science A
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PB - Zhejiang University Press & Springer
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DOI - 10.1631/jzus.2005.A0813

The earthquake forces used in design codes of buildings should be theoretically determinable. This work examines the seismic force modification factor R based on elastic-plastic time-history earthquake analysis of SDOF systems, wherein the hysteresis models are elastic-perfectly-plastic (EPP), elastic-linearly-hardening (ELH), shear-slipped and bilinear-elastic. The latter two models are analysed for separating the effect of the ductility and the energy-dissipating capacity. Three-hundred eighty-eight earthquake records from different site conditions are used in analysis. The ductility is taken to be 2, 3, 4, 5 and 6, with the damping ratio being 0.02, 0.035 and 0.05 respectively. The post-yield stiffness ratios 0.0, 0.1 and 0.2 are used in the analysis. The R spectra are standardized by the characteristic period of the earthquake records, which leads to a much smaller scatter in averaged numerical results. It was found that the most important factor determining R is the ductility. R increases more than linearly with ductility. The energy-dissipating capacity, damping and the post-yield stiffness are the less important factors. The energy dissipating capacity is important only for structures with short period and moderate period (0.3≤T/Tg<5.0). For EPP and ELH models, R for 0.05 damping is 10% to 15% smaller than for 0.02 damping. For EPP and ELH models, greater post-yield stiffness leads to greater R, but the influence of post-yield stiffness is obvious only when the post-yield stiffness is less than 10% of the initial stiffness. By means of statistical regression analysis the relation of the seismic force modification factor R with the natural period of the system and ductility for EPP and ELH models were established for each site and soil condition.

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article


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Open peer comments: Debate/Discuss/Question/Opinion



2014-11-19 19:48:20

This paper interests me and helps me a lot.


2014-11-18 18:01:53

Hi sir.pls mail your research for me.
best regard


2014-08-26 17:25:32

very good.


2014-08-22 01:25:51

i need this paper for my project work


2010-06-24 10:51:22

i´m intersting in the response modification factors

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