近场多脉冲地震动作用下组合隔震结构抗震性能分析
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摘要
采用速度脉冲分量与宽频分量相结合的方法,拟合了近场多脉冲地震波;构建了组合隔震结构的计算模型和运动方程,对组合隔震结构的动力响应进行仿真分析。结果表明:通过增设黏滞阻尼器可以有效控制结构的地震响应,减小隔震层位移,改善结构的受力。对于提高近场多脉冲地震作用下结构的安全性有显著作用。
In recent years,the base isolation technique has been widely accepted and promoted as one of the most effective approaches for earthquake resistance due to its security and reliability for use with near-field earthquakes.Some researchers have studied and discussed the influence of various parameters including peak ground acceleration/peak ground velocity(PGV/PGA),input energy,peak values,and duration of the near-field earthquakes on the earthquake-resistant performance of constructions.Multi-pulse near-field earthquakes have a larger influence on the base isolation structure than do single-pulse near-field earthquakes;thus,more attention has been paid to the security problems of constructions under this working condition.The focus of this paper,therefore,is an isolation project in the northwest district in which the elastic-plastic response time history of near-field earthquakes was analyzed,and a viscous damper was added to improve the current earthquake-resistant performance of the base isolation structure.In this paper,a multi-pulse seismic wave in a near-field earthquake was simulated and synthesized using a MATLAB procedure and a combination of velocity impulse and broadband components.The design scheme for the X-type symmetrical distributed viscous damper was selected to reduce the additional internal force effect of the energy-dissipating brace on the beam and column construction of the structure.On this basis,a computational model and equation of motion for the composite isolated structure was established.The earthquake response of the base and composite isolated structures was measured under three working conditions including the El Centro wave,the near-field wave of the Chi-chi earthquake recorded at Tcu075observation station,and an artificially fitted multi-pulse wave.Theoretical analysis and numerical simulation revealed the peak valueacceleration of the base isolation structure was larger than that of the composite isolated structure.The input energy of the structure increased progressively.In particular,the input energy of the seismic wave in the multi-pulse near-field earthquake was greater than that of the Chi-chi wave and significantly greater than that of the El Centro wave.When an earthquake occurred,components with many structures entered the plastic stage owing to the input energy factor,which resulted in substantial weakness.However,the time-history curve for energy consumption of the damper revealed that the damper fully exerted its energy consumption under each working condition.The composite isolated structure was able to fully consider the energy consumption of the structure under the action of the near-field earthquake and multi-pulse near-field earthquake to guarantee the security of the structure. Designers and engineering technicians have focused on displacement of the isolation layer and the bottom column axial force.After discussion and analysis,it has been determined that the complex isolation design is more feasible under the action of the near-field earthquake. This study examined the earthquake responses of structures under different working conditions including the function of multi-pulse near-field seismic oscillation on base isolation structures and the damping effect of composite isolated structures after addition of the damper.The results are summarized in the following points:1.The energy consumption of the complex isolation of a composite isolated structure has distinct advantages that can effectively reduce the number of components in the plastic structural system and improve the earthquake resistance ability of the structure in the near-field multi-pulse earthquake process;2.Under the action of a near-field earthquake,the displacement of the base isolation structure in the isolation layer becomes excessively large;and 3.The composite isolated structure can effectively reduce the axial force of the bottom column.
In recent years,the base isolation technique has been widely accepted and promoted as one of the most effective approaches for earthquake resistance due to its security and reliability for use with near-field earthquakes.Some researchers have studied and discussed the influence of various parameters including peak ground acceleration/peak ground velocity(PGV/PGA),input energy,peak values,and duration of the near-field earthquakes on the earthquake-resistant performance of constructions.Multi-pulse near-field earthquakes have a larger influence on the base isolation structure than do single-pulse near-field earthquakes;thus,more attention has been paid to the security problems of constructions under this working condition.The focus of this paper,therefore,is an isolation project in the northwest district in which the elastic-plastic response time history of near-field earthquakes was analyzed,and a viscous damper was added to improve the current earthquake-resistant performance of the base isolation structure.In this paper,a multi-pulse seismic wave in a near-field earthquake was simulated and synthesized using a MATLAB procedure and a combination of velocity impulse and broadband components.The design scheme for the X-type symmetrical distributed viscous damper was selected to reduce the additional internal force effect of the energy-dissipating brace on the beam and column construction of the structure.On this basis,a computational model and equation of motion for the composite isolated structure was established.The earthquake response of the base and composite isolated structures was measured under three working conditions including the El Centro wave,the near-field wave of the Chi-chi earthquake recorded at Tcu075observation station,and an artificially fitted multi-pulse wave.Theoretical analysis and numerical simulation revealed the peak valueacceleration of the base isolation structure was larger than that of the composite isolated structure.The input energy of the structure increased progressively.In particular,the input energy of the seismic wave in the multi-pulse near-field earthquake was greater than that of the Chi-chi wave and significantly greater than that of the El Centro wave.When an earthquake occurred,components with many structures entered the plastic stage owing to the input energy factor,which resulted in substantial weakness.However,the time-history curve for energy consumption of the damper revealed that the damper fully exerted its energy consumption under each working condition.The composite isolated structure was able to fully consider the energy consumption of the structure under the action of the near-field earthquake and multi-pulse near-field earthquake to guarantee the security of the structure. Designers and engineering technicians have focused on displacement of the isolation layer and the bottom column axial force.After discussion and analysis,it has been determined that the complex isolation design is more feasible under the action of the near-field earthquake. This study examined the earthquake responses of structures under different working conditions including the function of multi-pulse near-field seismic oscillation on base isolation structures and the damping effect of composite isolated structures after addition of the damper.The results are summarized in the following points:1.The energy consumption of the complex isolation of a composite isolated structure has distinct advantages that can effectively reduce the number of components in the plastic structural system and improve the earthquake resistance ability of the structure in the near-field multi-pulse earthquake process;2.Under the action of a near-field earthquake,the displacement of the base isolation structure in the isolation layer becomes excessively large;and 3.The composite isolated structure can effectively reduce the axial force of the bottom column.
引文
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[9]杜永峰,张尚荣,李慧.多级串联非比例阻尼隔震结构地震响应分析[J].西北地震学报,2012,34(4):319-323.DU Yong-feng,ZHANG Shang-rong,LI Hui.Seismic Response Analysis on Multistage Series Non-proportion Damping Isolated Structur[J].Northwestern Seismological Journal,2012,34(4):319-323.(in Chinese)
[10]中华人民共和国住房和城乡建设部.建筑结构抗震设计规范(GB50011-2010)[S].北京:中国建筑工业出版社,2010.Ministry of Housing and Urban-Rural Development of the People's Republic of China.Code for Seismic Design of Buildings(GB50011-2010)[S].Beijing:China Architecture&Building Press,2010.(in Chinese)
[2]杨迪雄,赵岩,李刚.近断层地震动运动特征对长周期结构地震响应的影响分析[J].防灾减灾学报,2007,27(2):133-140.YANG Di-xiong,ZHAO Yan,LI Gang.Influence Analysis of Motion Characteristics of Near-fault Ground Motions on Seismic Responses of Long-period Structures[J].Journal of Disaster Prevention and Mitigation Engineering,2007,27(2):133-140.(in Chinese)
[3]Liao W I,Loh C H,Wan S.Earthquake Response of RC Moment Frame Subjected to Near-fault Ground Motions[J].The Structural Design of Tall Buildings,2001,10(2):219-229.
[4]Malhotra PK.Response of Buildings to Near-field Pulse-like Ground Motions[J].Earthquake Engineering and Structural Dynamics 1999,28:1309-1326.
[5]He W L,Agrawal A K.Analytical Model of Ground Motion Pulses for the Design and Assessment of Seismic Protective Systems[J].J.of Structure Engineering,2008,134(7):1177-1188.
[6]董娣,刘锐,桑向国.随机方法模拟地震动的应用研究[J].西北地震学报,2006,28(4):298-302.DONG Di,LIU Rui,SANG Xiang-guo.Application Research of Simulation of Ground Motion Using the Stochastic Method[J].Northwestern Seismological Journal,2006,28(4):298-302.(in Chinese)
[7]谭平,周云,周福霖.大底盘多塔楼结构的混合隔震控制[J].世界地震工程,2007,23(2):12-19.TAN Ping,ZHOU Yun,ZHOU Fulin.Hybrid Isolation Control for Multi-tower Structures with A Large Podium[J].World Earthquake Engineering,2007,23(2):12-19.(in Chinese)
[8]李春锋,杜永峰,李慧.阻尼连体结构地震响应影响参数研究[J].西北地震学报,2012,34(1):33-38.LI Chun-feng,DU Yong-feng,LI Hui.Study of Seismic Response Influence Parameters on Damping Connective Structure[J].Northwestern Seismological Journal,2012,34(1):33-38.(in Chinese)
[9]杜永峰,张尚荣,李慧.多级串联非比例阻尼隔震结构地震响应分析[J].西北地震学报,2012,34(4):319-323.DU Yong-feng,ZHANG Shang-rong,LI Hui.Seismic Response Analysis on Multistage Series Non-proportion Damping Isolated Structur[J].Northwestern Seismological Journal,2012,34(4):319-323.(in Chinese)
[10]中华人民共和国住房和城乡建设部.建筑结构抗震设计规范(GB50011-2010)[S].北京:中国建筑工业出版社,2010.Ministry of Housing and Urban-Rural Development of the People's Republic of China.Code for Seismic Design of Buildings(GB50011-2010)[S].Beijing:China Architecture&Building Press,2010.(in Chinese)
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