RC框架结构连续倒塌动力响应影响因素分析
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摘要
在极端荷载作用下,结构局部会发生初始损伤.由于初始损伤会在不同结构构件间发生传递,可能会引发结构整体的连续倒塌,造成重大经济损失和人员伤亡.为评估结构的抗连续倒塌能力,通常采用拆除构件法对结构在某一构件发生失效后的整体承载能力进行分析.拆除构件法包括非线性静力Pushdown分析方法和非线性动力分析方法.本文对拆除构件法中非线性动力分析方法的主要影响因素进行研究.选择一个按中国规范设计的五层三跨钢筋混凝土框架结构作为研究对象,分析框架柱失效时长、重力荷载分布形式以及动力加载方式对结构在瞬间失柱条件下非线性动力反应的影响.研究结果表明:柱失效时长对结构非线性动力反应影响显著,当失效时长大约为结构自振周期的0.5倍时,结构非线性反应的动力效应几乎消失;采用不同重力荷载分布形式(满跨分布和受损跨分布)对结构的非线性动力反应影响并不明显;与先加载后移柱的动力加载方式相比,采用先移柱再加载的动力加载方式会放大结构的非线性动力反应,但放大效应有限.
Subjected to extreme load actions,local damages will be initiated. Since the initial local damages can be transferred between different elements,global progressive collapse may be occurred and leads to large economic loss and human casualty. To assess structural resistance of progress collapse,the alternate path method,which includes nonlinear static analysis technique and nonlinear dynamic analysis technique,is commonly used to analyze the global resistance of the damaged structure with one element removed. This paper aims to investigate the main influence factors on the nonlinear dynamic analysis technique used in the alternate path method. A reinforced concrete frame structure that was designed according to the current Chinese codes was selected as the study case.The effects due to different failure time of a frame column,different gravity load distributions,and different applying ways of dynamic loads on the structural dynamic responses caused by a sudden removal of column were examined. The results show that the variation of column failure time has a significant effect on structural nonlinear dynamic response. When the column failure time reaches 0.5 times of structural natural period,the corresponding dynamic effects on structural nonlinear responses almost disappear. Different gravity load distributions( i. e.,full bay distribution and damage-bay distribution) do not affect structural nonlinear dynamic responses obviously.Applying dynamic load after column removal consequently amplifies the nonlinear dynamic response of the structure,while the scale of amplification is limited.
Subjected to extreme load actions,local damages will be initiated. Since the initial local damages can be transferred between different elements,global progressive collapse may be occurred and leads to large economic loss and human casualty. To assess structural resistance of progress collapse,the alternate path method,which includes nonlinear static analysis technique and nonlinear dynamic analysis technique,is commonly used to analyze the global resistance of the damaged structure with one element removed. This paper aims to investigate the main influence factors on the nonlinear dynamic analysis technique used in the alternate path method. A reinforced concrete frame structure that was designed according to the current Chinese codes was selected as the study case.The effects due to different failure time of a frame column,different gravity load distributions,and different applying ways of dynamic loads on the structural dynamic responses caused by a sudden removal of column were examined. The results show that the variation of column failure time has a significant effect on structural nonlinear dynamic response. When the column failure time reaches 0.5 times of structural natural period,the corresponding dynamic effects on structural nonlinear responses almost disappear. Different gravity load distributions( i. e.,full bay distribution and damage-bay distribution) do not affect structural nonlinear dynamic responses obviously.Applying dynamic load after column removal consequently amplifies the nonlinear dynamic response of the structure,while the scale of amplification is limited.
引文
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[2]Department of Defense(Do D).Design of structures to resist progressivecollapse[S].Washington DC:Do D,2005.
[3]中国工程建设标准化协会.建筑结构抗倒塌设计规范:CECS392—2010[S].北京:中国计划出版社,2015.China Association for Engineering Construction Standardization.Code for anti-collapse design of building structures:CECS 392—2010[S].Beijing:China Planning Press,2015.
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[5]李易,陆新征,叶列平,等.基于Pushdown分析的RC框架抗连续倒塌承载力研究[J].沈阳建筑大学学报(自然科学版),2011,27(1):10-19.LI Yi,LU Xinzheng,YE Lieping,et al.Study on progressive-collapse resistance capacity of RCframe structures based on pushdown analysis[J].Journal of Shenyang Jianzhu University(Natural Science),2011,27(1):10-19.
[6]马高,李惠,欧进萍.基于构件拆除法的RC框架结构动力反应和抗倒塌能力分析[J].震灾防御技术,2010,5(1):62-72.MA Gao,LI Hui,OU Jinping.Dynamic response and collapse capacity analysis of RC frame buildings based on the element-removal method[J].Technology for Earthquake Disaster Prevention,2010,5(1):62-72.
[7]吕大刚,李雁军,陈志恒.钢筋混凝土框架结构连续倒塌的竖向非线性动力分析[J].土木建筑与环境工程,2012,34(增1):49-53.LYU Dagang,LI Yanjun,CHEN Zhiheng.Progressive collapse analysis of RC frame using vertical nonlinear dynamic analysis.Journal of Civil[J].Architectural&Environmental Engineering,2012,34(Sl):49-53.
[8]陈志恒.钢筋混凝土框架结构倒塌失效模式、风险与鲁棒性分析[D].哈尔滨:哈尔滨工业大学,2008.CHEN Zhiheng.Collapse modes,risk and robustness analysis of RC frame structures[D].Harbin:Harbin Institute of Technology,2008.
[9]SCOTT B D,PARK R,PRIESTLEY M J N.Stress-strain behavior of concrete confined by overlapping hoops at low and high strain rates[J].ACI Journal proceedings,1982,79(2):13-27.
[10]MANDER J B,PRIESTLEY M J N,PARK R.Theoretical stressstrain model for confined concrete[J].ASCE Journal of Structural Engineering,1998,114(8):1804-1826.DOI:10.1061/(ASCE)0733-9445(1988)114:8(1804).
[11]MENEGOTTO M,PINTO P E.Method of analysis of cyclically loaded RC plane frames including changes in geometry and non-elastic behavior of elements under normal force and bending[C]//Proceedings of IABSE Symposium on Resistance and Ultimate Deformability of Structures Acted on by Well-Defined Repeated Loads.Lisbon,Portugal:International Association for Bridge and Structural Engineering,1973:15-22.
[12]SPACONE E,FILIPPOU F C,TAUCER F F.Fiber beam-column model for nonlinear analysis of R/C frames:part 1:formulation[J].Earthquake Engineering and Structural Dynamics,1996,25(7):711-725.DOI:10.1002/(SICI)1096-9845(199607)25:7<711:AID-EQE576>3.0.CO;2-9.
[2]Department of Defense(Do D).Design of structures to resist progressivecollapse[S].Washington DC:Do D,2005.
[3]中国工程建设标准化协会.建筑结构抗倒塌设计规范:CECS392—2010[S].北京:中国计划出版社,2015.China Association for Engineering Construction Standardization.Code for anti-collapse design of building structures:CECS 392—2010[S].Beijing:China Planning Press,2015.
[4]KAPIL K,SHERIF EI-TAWIL.Pushdown resistance as a measure of robustness in progressivecollapse analysis[J].Engineering Structures,2011,33(9):2653-2661.DOI:10.1016/j.engstruct.2011.05.013.
[5]李易,陆新征,叶列平,等.基于Pushdown分析的RC框架抗连续倒塌承载力研究[J].沈阳建筑大学学报(自然科学版),2011,27(1):10-19.LI Yi,LU Xinzheng,YE Lieping,et al.Study on progressive-collapse resistance capacity of RCframe structures based on pushdown analysis[J].Journal of Shenyang Jianzhu University(Natural Science),2011,27(1):10-19.
[6]马高,李惠,欧进萍.基于构件拆除法的RC框架结构动力反应和抗倒塌能力分析[J].震灾防御技术,2010,5(1):62-72.MA Gao,LI Hui,OU Jinping.Dynamic response and collapse capacity analysis of RC frame buildings based on the element-removal method[J].Technology for Earthquake Disaster Prevention,2010,5(1):62-72.
[7]吕大刚,李雁军,陈志恒.钢筋混凝土框架结构连续倒塌的竖向非线性动力分析[J].土木建筑与环境工程,2012,34(增1):49-53.LYU Dagang,LI Yanjun,CHEN Zhiheng.Progressive collapse analysis of RC frame using vertical nonlinear dynamic analysis.Journal of Civil[J].Architectural&Environmental Engineering,2012,34(Sl):49-53.
[8]陈志恒.钢筋混凝土框架结构倒塌失效模式、风险与鲁棒性分析[D].哈尔滨:哈尔滨工业大学,2008.CHEN Zhiheng.Collapse modes,risk and robustness analysis of RC frame structures[D].Harbin:Harbin Institute of Technology,2008.
[9]SCOTT B D,PARK R,PRIESTLEY M J N.Stress-strain behavior of concrete confined by overlapping hoops at low and high strain rates[J].ACI Journal proceedings,1982,79(2):13-27.
[10]MANDER J B,PRIESTLEY M J N,PARK R.Theoretical stressstrain model for confined concrete[J].ASCE Journal of Structural Engineering,1998,114(8):1804-1826.DOI:10.1061/(ASCE)0733-9445(1988)114:8(1804).
[11]MENEGOTTO M,PINTO P E.Method of analysis of cyclically loaded RC plane frames including changes in geometry and non-elastic behavior of elements under normal force and bending[C]//Proceedings of IABSE Symposium on Resistance and Ultimate Deformability of Structures Acted on by Well-Defined Repeated Loads.Lisbon,Portugal:International Association for Bridge and Structural Engineering,1973:15-22.
[12]SPACONE E,FILIPPOU F C,TAUCER F F.Fiber beam-column model for nonlinear analysis of R/C frames:part 1:formulation[J].Earthquake Engineering and Structural Dynamics,1996,25(7):711-725.DOI:10.1002/(SICI)1096-9845(199607)25:7<711:AID-EQE576>3.0.CO;2-9.