- 摘 要
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（1 上海市建筑科學研究院有限公司 上海市工程結(jié)構(gòu)安全重點實驗室， 上海 200032；2 同濟大學土木工程學院， 上海 200092）
［摘要］基于性態(tài)的結(jié)構(gòu)抗震設(shè)計理論中的強度折減系數(shù)是確定結(jié)構(gòu)非彈性反應譜的重要依據(jù)。主要研究了主余震序列型地震作用下單自由度體系的基于延性的強度折減系數(shù)譜。首先收集實測的主余震序列型地震記錄并按中國《建筑抗震設(shè)計規(guī)范》（GB 50011—2010）要求進行場地類別劃分，對余震峰值加速度進行調(diào)幅后，再進行單自由度結(jié)構(gòu)彈塑性動力時程分析，研究了結(jié)構(gòu)周期、延性系數(shù)、余震和場地類別等因素對強度折減系數(shù)的影響。結(jié)果表明，強余震對基于延性的強度折減系數(shù)影響顯著，尤其是在短周期階段，余震相對強度系數(shù)為1.5時，主余震序列型地震作用下的強度折減系數(shù)是僅受主震作用下的0.8倍。最后，經(jīng)過統(tǒng)計平均和回歸分析，建立了強度折減系數(shù)譜的簡化公式。
［關(guān)鍵詞］非彈性譜； 序列型地震動； 強度折減系數(shù)； 余震； 場地條件
中圖分類號：P315-9， TU318文獻標識碼：A文章編號：1002-848X(2020)14-0097-07
Ductility-based strength reduction factor for main aftershock sequence-type ground motions
ZHANG Yongqun1,2
(1 Shanghai Key Laboratory of Engineering Structure Safety, Shanghai Research Institute of Building Sciences Co., Ltd., Shanghai 200032, China; 2 College of Civil Engineering, Tongji University, Shanghai 200092, China)
Abstract:The strength reduction factors are the key parameters to derive the inelastic response spectra for performance-based structural seismic design. The ductility-based strength reduction factors of single-degree-of-freedom (SDOF) system subjected to main aftershock sequence-type ground motions were investigated. Firstly, records of main aftershock sequence-type ground motions were collected and the site categories were divided according to the requirements of Code for seismic design of buildings (GB 50011—2010) in China. After amplitude adjustment of the peak acceleration of aftershocks, the elastoplastic dynamic time history analysis of SDOF structure was conducted to study the effects of structural period, ductility coefficient, aftershocks and site types on the strength reduction factor. The results indicate that strong aftershocks have a significant effect on the ductility-based strength reduction factor especially in the short-period stage，the strength reduction factor under main aftershock sequence-type ground motions was 0.80 times that under mainshock ground motions when relative intensity of aftershock ground motion was 1.5. Finally, a simplified formula of strength reduction factor spectrum was established after statistical average and regression analysis.
Keywords:inelastic response spectra; sequence-type ground motion; strength reduction factor; aftershock; site condition
*國家重點研發(fā)計劃（2018YFC0704800），上海市青年科技啟明星計劃（20QB1404700）。
作者簡介：張永群，博士，工程師，Email: zyq2007yh@163.com。
