近场脉冲型地震动作用下TMD-基础隔震混合控制结构的减震效果分析
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摘要
近场地震动具有很高的加速度峰值和长周期的速度脉冲,因此能够对结构造成严重的破坏。基础隔震是一种有效的减震技术,然而这种单一的减震手段在低频具有很高能量的近场脉冲型地震动作用下已不能确保结构的安全,必须寻求新的减震策略。本文将速度脉冲模型与随机地震地面运动模型联合来生成近场脉冲型地震动,并以此作为激励,用MATLAB对近场脉冲型地震动作用下TMD-基础隔震混合控制结构及独立基础隔震结构的地震响应进行求解,比较研究该混合控制结构的减震效果。结果表明该混合控制方式可以有效地控制结构的位移,而对加速度的控制效果不明显。
Near-fault ground motions can cause severe damage to structures because of its high peak accelerations and macrocyclic velocity pulses.In the last two decades,the seismic isolation technique,which was proved to be very effective for the seismic protection of new constructions and the seismic retrofitting of existing ones,had been applied for buildings,bridges,industrial facilities,and structures of historical value as well.As a consequence,design guidelines for seismically isolated structures have been developed in many countries with a high seismic hazard.The insertion of an isolation system at the base of a building structure allows the horizontal seismic loads to be reduced through a decoupling of the structure motion from that of the soil;moreover,the superstructure behaves like a fixed or base isolated structure along the vertical direction,depending on the value,respectively very high or very low,of the ratio between the vertical stiffness of the isolator and the horizontal one.Base isolation technique,taken as an effective method to control structure's vibration that is induced by earthquake ground motions,has been widely accepted,however,only such an approach can not ensure structure's safety under near-fault pulse-like ground motions with high energy in low frequency band,because strong near-fault ground motions are characterized by long-duration horizontal pulses and very large displacements,which can lead to an oversizing of the isolation system and an amplification of the response of a base isolated structure.Specifically,the frequency content of the motion transmitted by the isolators to the superstructure can become critical when the pulse intensity is so strong that the superstructure undergoes plastic deformations.Moreover,the structural response can be amplified due to the long duration of the pulse.To overcome these problems,many authors have proposed a lot of solutions based on different kinds of isolators and dampers.Nevertheless,some problems remain unsettled if additional damping is adopted,because the displacements at the top of the isolators can be substantially reduced,but the contribution of the higher vibration modes of the superstructure increases,if this contribution becomes too large,it can give rise to significant increase in inter-story drifts and floor accelerations,so it is necessary to find more effective vibration control strategies.A pulse model and a stochastic ground motion model are combined to simulate the near-fault ground motions.The simulation of directivity pulse type ground motions through superimposition of modeled directivity pulse on a non-pulse type motion is a possible approach to meet the scarcity of such motions in studying the structural response.Typically,pulse duration or period,pulse amplitude,and the number and phase of half cycles constituting the pulse have been considered as the parameters which are necessary for such a characterization. The structure dynamic responses are solved by using MATLAB under these artificial ground motions.The effectiveness of TMD-Base isolation hybrid control method is studied through the comparisons of response time histories of a base isolated structure with and without TMD.The results show that this hybrid control method is capable of controlling isolation layer's displacement effectively.
Near-fault ground motions can cause severe damage to structures because of its high peak accelerations and macrocyclic velocity pulses.In the last two decades,the seismic isolation technique,which was proved to be very effective for the seismic protection of new constructions and the seismic retrofitting of existing ones,had been applied for buildings,bridges,industrial facilities,and structures of historical value as well.As a consequence,design guidelines for seismically isolated structures have been developed in many countries with a high seismic hazard.The insertion of an isolation system at the base of a building structure allows the horizontal seismic loads to be reduced through a decoupling of the structure motion from that of the soil;moreover,the superstructure behaves like a fixed or base isolated structure along the vertical direction,depending on the value,respectively very high or very low,of the ratio between the vertical stiffness of the isolator and the horizontal one.Base isolation technique,taken as an effective method to control structure's vibration that is induced by earthquake ground motions,has been widely accepted,however,only such an approach can not ensure structure's safety under near-fault pulse-like ground motions with high energy in low frequency band,because strong near-fault ground motions are characterized by long-duration horizontal pulses and very large displacements,which can lead to an oversizing of the isolation system and an amplification of the response of a base isolated structure.Specifically,the frequency content of the motion transmitted by the isolators to the superstructure can become critical when the pulse intensity is so strong that the superstructure undergoes plastic deformations.Moreover,the structural response can be amplified due to the long duration of the pulse.To overcome these problems,many authors have proposed a lot of solutions based on different kinds of isolators and dampers.Nevertheless,some problems remain unsettled if additional damping is adopted,because the displacements at the top of the isolators can be substantially reduced,but the contribution of the higher vibration modes of the superstructure increases,if this contribution becomes too large,it can give rise to significant increase in inter-story drifts and floor accelerations,so it is necessary to find more effective vibration control strategies.A pulse model and a stochastic ground motion model are combined to simulate the near-fault ground motions.The simulation of directivity pulse type ground motions through superimposition of modeled directivity pulse on a non-pulse type motion is a possible approach to meet the scarcity of such motions in studying the structural response.Typically,pulse duration or period,pulse amplitude,and the number and phase of half cycles constituting the pulse have been considered as the parameters which are necessary for such a characterization. The structure dynamic responses are solved by using MATLAB under these artificial ground motions.The effectiveness of TMD-Base isolation hybrid control method is studied through the comparisons of response time histories of a base isolated structure with and without TMD.The results show that this hybrid control method is capable of controlling isolation layer's displacement effectively.
引文
[1]Agrawal A K,Xu Z,He W L.Ground Motion Pulse-basedActive Control of A Linear Base-isolated Benchmark Building[J].Structural Control and Health Monitoring,2006,13(2):792-808.
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[4]周福霖.工程结构减震控制[M].北京:地震出版社,1997:3-10.ZHOU Fu-lin.Vibration Control of Structural Engineering[M].Beijing:Earthquake Press,1997,3-10.
[5]Palazzo B,Petti L.Seismic Response Control in Base IsolatedSystems Using Tuned Mass Dampers[A]//Proceedings ofFirst World Conference on Structural Control[C].Los Angel-es,California:Proceedings of First World Conference onStructural Control,1994,275:155-165.
[6]De Iuliis M,Petti L,Palazzo B.Combined Control StrategyBase Isolation and Tuned Mass Damper:An Effectiveness A-nalysis of Its Application to Non-linear Benchmark Base Isola-ted Structure[A]//World Conference on Earthquake Engineer-ing[C].Beijing,China:The 14th World Conference on Earth-quake Engineering,2008.
[7]Dickinson Bryce W,P Gavin Heri.Parametric Statistical Gen-eralization of Uniform-Hazard Earthquake Ground Motions[J].Journal of Structural Engineering,2011,137(3):410-422.
[8]LIN Chi-chang,CHEN Chi-lun,WANG Jer-fu.VibrationControl of Structures with Initially Accelerated Passive TunedMass Dampers under Near-fault Earthquake Excitation[J].Computer-Aided Civil and Infrastructure Engeering,2010,25(1):69-75.
[9]He W L,Agrawal A K.Analitical Model of Ground MotionPulses for the Design and Assessment of Seismic ProtectiveSystems[J].Journal of Structural Engineering,2008,134(7):1177-1188.
[10]Tan P,Agrawal A K,Pan Y.Near-field Effects on Seismi-cally Excited Highway Bridge Equipped with Nonlinear Vis-cous Dampers[J].Bridge Structures,2005,1(3):307-318.
[11]刘晶波,杜修力.结构动力学[M].北京:机械工业出版社,2005:262-264.LIU Jing-bo,DU Xiu-li.Dynamics of structure[M].Beijing:Machine Press,2005:262-264.
[12]Sadek Fahim,Mohraz Bijan,Taylor Andrew W,et al.AMethod of Estimating the Parameters of Tuned Mass Damp-ers Fot Seismic Applications[J].Earthquake Engeering andStructural Dynamics,1997,26(6):617-635.
[13]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 Re-sponse Analysis on Multistage Series Non-proportion Damp-ing Isolated Structure[J].Northwestern Seismological Jour-nal,2012,34(4):319-323.
[2]Nagarajaiah S,Ferrell K.Stability of Elastomeric Seismic Iso-lation Bearings[J].Journal of Structural Engineering,1999,125(9):946-954.
[3]Kelly J M.Earthquake-resistant Design with Rubber(2ndEdn).[M].Springer,New York:[s.n.],1997(ISBN:3540761314).
[4]周福霖.工程结构减震控制[M].北京:地震出版社,1997:3-10.ZHOU Fu-lin.Vibration Control of Structural Engineering[M].Beijing:Earthquake Press,1997,3-10.
[5]Palazzo B,Petti L.Seismic Response Control in Base IsolatedSystems Using Tuned Mass Dampers[A]//Proceedings ofFirst World Conference on Structural Control[C].Los Angel-es,California:Proceedings of First World Conference onStructural Control,1994,275:155-165.
[6]De Iuliis M,Petti L,Palazzo B.Combined Control StrategyBase Isolation and Tuned Mass Damper:An Effectiveness A-nalysis of Its Application to Non-linear Benchmark Base Isola-ted Structure[A]//World Conference on Earthquake Engineer-ing[C].Beijing,China:The 14th World Conference on Earth-quake Engineering,2008.
[7]Dickinson Bryce W,P Gavin Heri.Parametric Statistical Gen-eralization of Uniform-Hazard Earthquake Ground Motions[J].Journal of Structural Engineering,2011,137(3):410-422.
[8]LIN Chi-chang,CHEN Chi-lun,WANG Jer-fu.VibrationControl of Structures with Initially Accelerated Passive TunedMass Dampers under Near-fault Earthquake Excitation[J].Computer-Aided Civil and Infrastructure Engeering,2010,25(1):69-75.
[9]He W L,Agrawal A K.Analitical Model of Ground MotionPulses for the Design and Assessment of Seismic ProtectiveSystems[J].Journal of Structural Engineering,2008,134(7):1177-1188.
[10]Tan P,Agrawal A K,Pan Y.Near-field Effects on Seismi-cally Excited Highway Bridge Equipped with Nonlinear Vis-cous Dampers[J].Bridge Structures,2005,1(3):307-318.
[11]刘晶波,杜修力.结构动力学[M].北京:机械工业出版社,2005:262-264.LIU Jing-bo,DU Xiu-li.Dynamics of structure[M].Beijing:Machine Press,2005:262-264.
[12]Sadek Fahim,Mohraz Bijan,Taylor Andrew W,et al.AMethod of Estimating the Parameters of Tuned Mass Damp-ers Fot Seismic Applications[J].Earthquake Engeering andStructural Dynamics,1997,26(6):617-635.
[13]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 Re-sponse Analysis on Multistage Series Non-proportion Damp-ing Isolated Structure[J].Northwestern Seismological Jour-nal,2012,34(4):319-323.
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