地震总输入能量与瞬时输入能量谱的研究
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摘要
现有的抗震设计理论大多是基于承载力或强度的设计方法,与其相应的反应谱理论最大的缺陷是无法反映地震动持时的影响,而以地震动能量作为设计参数时就能弥补现有抗震理论的不足。本文按照反应谱理论的思路建立了线性单自由度体系的地震动总输入能量谱和瞬时输入能量谱。研究发现,阻尼比为5%时的地震动总输入能量谱和最大瞬时输入能量谱的等价速度谱可以分别用阻尼比为0.5%和10%下的拟速度谱来近似获得;地震波的V/A值大于0.15时,总输入能量谱的Δt谱峰值与地震波的强震持时呈线性增长关系,V/A值小于0.15时,两者间的关系无规律性。最大瞬时输入能量谱的Δt谱峰值基本不受地震波的V/A值与强震持时的影响;输入能量谱(总输入能量谱与最大瞬时输入能量谱)的特征周期随地震波V/A值的增大而增大,根据分析结果本文提出了线性单自由度体系输入能量谱的简化计算方法,方法简便,计算结果偏安全。
Most of current methods in seismic design of structures require the provision of sufficient strength against anticipated seismic effects.The corresponding design response spectra can't reflect the effect of duration.Energy-based seismic design is known as an alternative design methodology.A parameter study is carried out on input energy and momentary input energy spectra of linear single degree of freedom(SDOF) system under 42 earthquake ground motions in this paper.It is found that the input energy and momentary input energy spectra with a damping factor of 5% can be estimated from the pseudo-velocity spectra with damping factors of 0.5% and 10%.The maximum of momentary input energy spectra is insensitive to the ratio of peak ground velocity to acceleration(V/A)and effective duration(Δt),the maximum of input energy spectra is linearly increased with Δt when the V/A ratio of ground motions is more than 1.5.The characteristic period of input energy and momentary input energy spectra is increased with the V/A ratio of ground motions.A simple analytical procedure is developed for calculating the input energy and momentary input energy spectra of linear SDOF system.It can be employed in an energy-based seismic design procedure for determining the required energy dissipation capacity of a structural system.
Most of current methods in seismic design of structures require the provision of sufficient strength against anticipated seismic effects.The corresponding design response spectra can't reflect the effect of duration.Energy-based seismic design is known as an alternative design methodology.A parameter study is carried out on input energy and momentary input energy spectra of linear single degree of freedom(SDOF) system under 42 earthquake ground motions in this paper.It is found that the input energy and momentary input energy spectra with a damping factor of 5% can be estimated from the pseudo-velocity spectra with damping factors of 0.5% and 10%.The maximum of momentary input energy spectra is insensitive to the ratio of peak ground velocity to acceleration(V/A)and effective duration(Δt),the maximum of input energy spectra is linearly increased with Δt when the V/A ratio of ground motions is more than 1.5.The characteristic period of input energy and momentary input energy spectra is increased with the V/A ratio of ground motions.A simple analytical procedure is developed for calculating the input energy and momentary input energy spectra of linear SDOF system.It can be employed in an energy-based seismic design procedure for determining the required energy dissipation capacity of a structural system.
引文
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[5]胡冗冗,王亚勇.地震动瞬时输入能量谱探讨[J].工程抗震,2004,(1):9~13.
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[7]Trifunac MD,rady A G.A study on the duration of strong earthquake ground motion[J].Bull.sism.soc.Am,1975,65:581~626.
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[9]周云,徐彤,周福霖.抗震与减震结构的能量分析方法研究与应用[J].地震工程与工程震动,1999,19(4):133~139.
[10]蒋立志,林荫琦,朱镜清.阻尼耗能在结构弹塑性地震反应中的作用[J].地震工程与工程震动,1996,16(3):30~38.
[2]Fajfar P,Vidic T,Fischinger M.Seismic demand in medium and long period structures[J].Earthquake Engineering&Structural Dynamics.1989,18:1133~1144.
[3]Uang C M,Bertero V V.Evaluation of seismic energy in structures[J].Earthquake Engineering&Structural Dynamics,1990,19:77~90.
[4]胡冗冗,王亚勇.地震动瞬时能量与结构最大位移反应关系研究[J].建筑结构学报,2000,(1):71~76.
[5]胡冗冗,王亚勇.地震动瞬时输入能量谱探讨[J].工程抗震,2004,(1):9~13.
[6]朱伯龙,张琨联.建筑结构抗震设计原理[M].上海:同济大学出版社,1994.
[7]Trifunac MD,rady A G.A study on the duration of strong earthquake ground motion[J].Bull.sism.soc.Am,1975,65:581~626.
[8]Sucuoglu H,Nurtug A.Earthquake ground motion characteristics and seismic energy dissipation[J].Earthquake Engineering&Structural Dy-namics,1995,24:1195~1213.
[9]周云,徐彤,周福霖.抗震与减震结构的能量分析方法研究与应用[J].地震工程与工程震动,1999,19(4):133~139.
[10]蒋立志,林荫琦,朱镜清.阻尼耗能在结构弹塑性地震反应中的作用[J].地震工程与工程震动,1996,16(3):30~38.
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