考虑上部结构非线性的LRB基础隔震建筑结构动力特性研究
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摘要
以两自由度体系的LRB基础隔震建筑结构为对象,在同时考虑LRB隔震系统以及上部结构非线性的基础上,提出综合利用Fourier级数展开、谐波平衡法以及梯度法对该两自由度体系在简谐地震动激励作用下的稳态响应进行求解的方法。以此为基础通过参数分析对考虑上部结构非线性的LRB基础建筑结构的动力特性进行研究并发现:非线性上部结构基底固定时,随着结构延性的增加,结构的耗能能力也随之增加,而且结构自身的频率随之降低,远离发生共振的频率,从而有效地抑制结构延性的快速增加;非线性上部结构自身频率的变化并不会根本改变整个LRB基础隔震建筑结构的频率,由于低频的简谐地震动激励限制非线性上部结构自身的耗能能力,从而导致在激励幅值不断增加的情况下,上部结构的延性需求急剧增加。
In this paper,under harmonic ground excitation,computational method which combines Fourier series expansion,harmonic balancing method and gradient method is proposed to solve two-degree-of-freedom system of LRB base-isolated building structure where the nonlinearity of both LRB isolation system and superstructure are taken into consideration.Dynamic behavior of LRB base-isolated building structure is investigated through parametric study.It is observed that capacity of energy dissipation of fixed-base structure is enhanced with the increase of the ductility,and at the same time its frequency moves away from the resonant excitation frequency due to the significant frequency decrease,which effectively controls the rapid increase of ductility demand.It is shown as well that the change of superstructure frequency dose not fundamentally change the natural frequency of the overall LRB base-isolated system;low excitation frequency has the effect on reducing the capacity of energy dissipation of superstructure,which leads to the rapid increase of ductility demand of superstructure with the increase of low-frequency excitation amplitude.
In this paper,under harmonic ground excitation,computational method which combines Fourier series expansion,harmonic balancing method and gradient method is proposed to solve two-degree-of-freedom system of LRB base-isolated building structure where the nonlinearity of both LRB isolation system and superstructure are taken into consideration.Dynamic behavior of LRB base-isolated building structure is investigated through parametric study.It is observed that capacity of energy dissipation of fixed-base structure is enhanced with the increase of the ductility,and at the same time its frequency moves away from the resonant excitation frequency due to the significant frequency decrease,which effectively controls the rapid increase of ductility demand.It is shown as well that the change of superstructure frequency dose not fundamentally change the natural frequency of the overall LRB base-isolated system;low excitation frequency has the effect on reducing the capacity of energy dissipation of superstructure,which leads to the rapid increase of ductility demand of superstructure with the increase of low-frequency excitation amplitude.
引文
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[4]叶昆,李黎.LRB基础隔震结构在近断层脉冲型地震作用下的动力响应研究[J].工程抗震与加固改造,2009,31(2):32-38(Ye Kun,Li Li.Study on the dynamic responseof LRB base-isolated structure under near-fault pulse-likeground motion[sJ].Earthquake Resistant Engineering andRetroffiting,2009,31(2):32-38(in Chinese))
[5]GB 50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of building[M].Beijing:China Architecture&Building Press,2001(in Chinese))
[6]Ordonez D,Foti D,Bozzo L.Comparative study of theinelastic response of base isolated buildings[J].EarthquakeEngineering and Structural Dynamics,2003,32(1):151-164
[7]Marano G C,Greco R.Efficiency of base isolation systemsin structural seismic protection and energetic assessment[J].Earthquake Engineering and Structural Dynamics,2003,32(10):1505-1531
[8]Kikuchi M,Black C J,Aiken I D.On the response ofyielding seismically isolated structures[J].EarthquakeEngineering and Structural Dynamics,2008,37(5):659-679
[9]张强星,SainsburyMG.干摩擦振动系统的简化[J].振动与冲击,1987,6(1):42-57(Zhang Qiangxing,Sainsbury MG.The linearization of frictional damped vibration system[J].Journal of Shock and Vibration,1987,6(1):42-57(in Chinese))
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[2]Fragiacomo M,Rajgelj S,Cimadom F.Design of bilinearhysteretic isolation system[sJ].Earthquake Engineering andStructural Dynamics,2003,32(9):1333-1352
[3]杨迪雄,李刚,程耿东.近断层脉冲型地震动作用下隔震结构地震反应分析[J].地震工程与工程振动,2005,25(2):119-124(Yang Dixiong,Li Gang,Cheng Gengdong.Seismic analysis of base-isolated structures subjected to near-fault pulse-like ground motion[sJ].Earthquake Engineeringand Engineering Vibration,2005,25(2):119-124(inChinese))
[4]叶昆,李黎.LRB基础隔震结构在近断层脉冲型地震作用下的动力响应研究[J].工程抗震与加固改造,2009,31(2):32-38(Ye Kun,Li Li.Study on the dynamic responseof LRB base-isolated structure under near-fault pulse-likeground motion[sJ].Earthquake Resistant Engineering andRetroffiting,2009,31(2):32-38(in Chinese))
[5]GB 50011—2001建筑抗震设计规范[S].北京:中国建筑工业出版社,2001(GB 50011—2001 Code for seismicdesign of building[M].Beijing:China Architecture&Building Press,2001(in Chinese))
[6]Ordonez D,Foti D,Bozzo L.Comparative study of theinelastic response of base isolated buildings[J].EarthquakeEngineering and Structural Dynamics,2003,32(1):151-164
[7]Marano G C,Greco R.Efficiency of base isolation systemsin structural seismic protection and energetic assessment[J].Earthquake Engineering and Structural Dynamics,2003,32(10):1505-1531
[8]Kikuchi M,Black C J,Aiken I D.On the response ofyielding seismically isolated structures[J].EarthquakeEngineering and Structural Dynamics,2008,37(5):659-679
[9]张强星,SainsburyMG.干摩擦振动系统的简化[J].振动与冲击,1987,6(1):42-57(Zhang Qiangxing,Sainsbury MG.The linearization of frictional damped vibration system[J].Journal of Shock and Vibration,1987,6(1):42-57(in Chinese))
[10]Caughey T K.Sinusoidal excitation of a system withbilinear hysteresis[J].Transactions of the ASME,1960,60-APM-8:640-643
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