强度需求谱与延性需求谱之比较
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摘要
强度需求谱和延性需求谱是两种常见的弹塑性反应谱,本文比较了二者在概念、计算以及应用方面的不同。在单条地震波作用下,单自由度体系的延性需求并不总是随着强度折减系数的增加而单调增加。本文对产生这一现象的原因进行了分析,并指出当采用迭代计算建立强度需求谱时,必须选择满足指定延性需求的最小强度折减系数。但这会使得在多条地震波作用下,对同一个强度折减系数,由平均强度需求谱反推出的延性需求要比直接由平均延性需求谱获得的偏小。为此,本文建议:当采用改进能力谱法进行结构抗震性能评估时,宜用延性需求谱代替强度需求谱来估计结构的延性需求。
Strength demand spectrum and ductility demand spectrum are two kinds of elastic-plastic response spectrum.Their difference in concept,computation and application is presented in this paper.Ductility demands of single-degreeof-freedom system under an earthquake wave don't always increase as strength reduction factors increase.The reason of this phenomenon is analyzed.Also it is indicated that to develop the strength demand spectrum,the minimum strength reduction factor must be chosen for an appointed ductility demand factor.But this will bring that for the same strength reduction factor,the ductility demand from the average strength demand spectrum is less than that from the average ductility demand spectrum under many earthquake waves.Therefore,it is proposed that the strength demand spectrum should be substituted by the ductility demand spectrum in the improved capacity spectrum method to estimate the seismic performance of a structure.
Strength demand spectrum and ductility demand spectrum are two kinds of elastic-plastic response spectrum.Their difference in concept,computation and application is presented in this paper.Ductility demands of single-degreeof-freedom system under an earthquake wave don't always increase as strength reduction factors increase.The reason of this phenomenon is analyzed.Also it is indicated that to develop the strength demand spectrum,the minimum strength reduction factor must be chosen for an appointed ductility demand factor.But this will bring that for the same strength reduction factor,the ductility demand from the average strength demand spectrum is less than that from the average ductility demand spectrum under many earthquake waves.Therefore,it is proposed that the strength demand spectrum should be substituted by the ductility demand spectrum in the improved capacity spectrum method to estimate the seismic performance of a structure.
引文
[1]Miranda E.Evaluation of site-dependent inelastic seismicdesign spectra[J].Journal of Struct.Engng.,ASCE,1993,119(5):1319~1339
[2]Lee L H,Han S W,Oh Y H.Determination of ductilityfactor considering different hysteretic models[J].EarthquakeEngng.and Sturct.Dyn.,1999,28:957~977
[3]易伟建,张海燕.结构随机延性需求谱的理论研究[J].工程力学,2006,23(5):14~19
[4]Newark N M,Hall W H.Earthquake spectra and design[R].1stedition.Oakland:Earthquake Engineering ResearchInstitute,1982
[5]Nassar A A,Krawinkler H.Seismic demands for SDOF andMDOF systems[R].John A.Blume Earthquake EngineeringCenter Report No.95,Stanford University,CA,1991,2~3
[6]何政,欧进萍.钢筋混凝土结构基于改进能力谱法的地震损伤性能设计[J].地震工程与工程振动,2000,20(2):31~38
[7]易伟建,张海燕.弹塑性反应谱的比较及其应用[J].湖南大学学报,2005,32(2):10~13
[8]Tena-Colunga A.Displacement ductility demand spectra forthe seismic evaluation of structures[J].Engng Struct.,2001,(23):1319~1330
[2]Lee L H,Han S W,Oh Y H.Determination of ductilityfactor considering different hysteretic models[J].EarthquakeEngng.and Sturct.Dyn.,1999,28:957~977
[3]易伟建,张海燕.结构随机延性需求谱的理论研究[J].工程力学,2006,23(5):14~19
[4]Newark N M,Hall W H.Earthquake spectra and design[R].1stedition.Oakland:Earthquake Engineering ResearchInstitute,1982
[5]Nassar A A,Krawinkler H.Seismic demands for SDOF andMDOF systems[R].John A.Blume Earthquake EngineeringCenter Report No.95,Stanford University,CA,1991,2~3
[6]何政,欧进萍.钢筋混凝土结构基于改进能力谱法的地震损伤性能设计[J].地震工程与工程振动,2000,20(2):31~38
[7]易伟建,张海燕.弹塑性反应谱的比较及其应用[J].湖南大学学报,2005,32(2):10~13
[8]Tena-Colunga A.Displacement ductility demand spectra forthe seismic evaluation of structures[J].Engng Struct.,2001,(23):1319~1330
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