二质点模型在Pushover分析中的应用
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摘要
对常见的主要失效模式为下部破坏型结构在强烈地震作用下的位移需求估计,常规的Pushover方法和模态Pushover方法不能得到满意的结果。为此,本文提出等效成二自由度体系的Pushover分析方法,并推导了多自由度体系等效成二自由度体系的计算公式。分别采用常规Pushover方法、模态Pushover方法、等效成二自由度体系的Pushover方法以及时程分析法对8个7层平面框架结构进行了强烈地震作用下的位移反应分析,同时还对其中的一个结构进行了不同地震动强度水平下的位移反应分析。结果表明,等效成二自由度体系的Pushover分析方法能够较好地估计下部破坏型结构的位移需求。
The seismic displacement demands under strong earthquake excitation of a multi-story structure with the main failure mode of local damage at the lower story can not be well estimated by conventional Pushover analysis and Modal Pushover analysis.In this paper,this kind of structur is equivalent to two-degree-of-freedom(TDOF) systems in Pushover analysis.The relationships of a multi-degree-of-freedom(MDOF) structure with its equivalent TDOF system are derived.Then the proposed seismic demand estimation procedure by using TDOF model is developed.Seismic response of seven planar frames with failure modes of damage at the lower stories and one with beam hinge damage mechanism is analyzed by conventional Pushover analysis,Modal Pushover analysis,proposed Pushover analysis procedure and time history analysis.The precision and applicability of three Pushover analysis methods are compared.The results indicat that the seismic displacement demands under strong earthquake excitation of a structure with the failure mode of damage at the lower stories will be underestimated by conventional Pushover analysis and Modal Pushover analysis,but well estimated by proposed procedure.
The seismic displacement demands under strong earthquake excitation of a multi-story structure with the main failure mode of local damage at the lower story can not be well estimated by conventional Pushover analysis and Modal Pushover analysis.In this paper,this kind of structur is equivalent to two-degree-of-freedom(TDOF) systems in Pushover analysis.The relationships of a multi-degree-of-freedom(MDOF) structure with its equivalent TDOF system are derived.Then the proposed seismic demand estimation procedure by using TDOF model is developed.Seismic response of seven planar frames with failure modes of damage at the lower stories and one with beam hinge damage mechanism is analyzed by conventional Pushover analysis,Modal Pushover analysis,proposed Pushover analysis procedure and time history analysis.The precision and applicability of three Pushover analysis methods are compared.The results indicat that the seismic displacement demands under strong earthquake excitation of a structure with the failure mode of damage at the lower stories will be underestimated by conventional Pushover analysis and Modal Pushover analysis,but well estimated by proposed procedure.
引文
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[8]张海燕.基于位移的概率地震需求分析与结构抗震设计研究[D].长沙:湖南大学土木工程学院,2005Zhang H Y.Displacement-based probabilistic seismicdemand analysis and design[D].Changsha:HunanUniversity,2005(in Chinese)
[9]Chopra A K,Goel R K.A modal pushover analysisprocedure for estimating seismic demands for building[J].Earthquake Engineering and Structure Dynamics,2002,31:561～582
[2]清华大学、西南交通大学、北京交通大学土木工程结构专家组.汶川地震建筑震害分析[J].建筑结构学报,2008,29(4):1～9Civil and Structural Groups of Tsinghua University,Xinan Jiaotong University and Beijing JiaotongUniversity.Analysis on seismic damage of buildings inthe Wenchuan earthquake[J].Journal of BuildingStructures,2008,29(4):1～9(in Chinese)
[3]叶列平,曲哲,马千里,等.从汶川地震中框架结构震害谈“强柱弱梁”屈服机制的实现[J].建筑结构,2008,38(11):52～59Ye L P,Qu Z,Ma Q L,et al.Study on ensuring thestrong column-weak beam mechanism for RC framesbased on the damage analysis in the Wenchuanearthquake[J].Building Structure,2008,38(11):52～59(in Chinese)
[4]Faella G.Evaluation of the R/C structures seismicresponse by means of nonlinear static push-over analysis[A].In:11th WCEE[C].1996,1～8,No.1146
[5]Bracci J,Kunnath S K,Reinhorn A M.Seismicperformance and retrofit evaluation of reinforced concretestructures[J].Journal of Structural Engineering,1997,123(1):3～10
[6]李中锡,周锡元.规则型隔震房屋的自振特性和地震反应分析方法[J].地震工程与工程振动.2002,22(2):33～41Li Z X,Zhou X Y.Simplified analysis method ofseismically isolated regular building.EarthquakeEngineering and Engineering Vibration,2002,22(2):33～41(in Chinese)
[7]张海燕,易伟建.等效成二自由度体系的规则梁式桥概率地震需求分析[J].中国公路学报,2008,21(2):61～67Zhang H Y,Yi W J.Probabilistic seismic demandanalysis of regular beam bridges equivalent to Two-degree-of-freedom systems[J].China Journal ofHighway and Transport,2008,21(2):61～67(inChinese)
[8]张海燕.基于位移的概率地震需求分析与结构抗震设计研究[D].长沙:湖南大学土木工程学院,2005Zhang H Y.Displacement-based probabilistic seismicdemand analysis and design[D].Changsha:HunanUniversity,2005(in Chinese)
[9]Chopra A K,Goel R K.A modal pushover analysisprocedure for estimating seismic demands for building[J].Earthquake Engineering and Structure Dynamics,2002,31:561～582
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