均质土坝非平稳随机地震反应分析
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摘要
考虑地震荷载的随机性及强度、频率的非平稳性,基于作者提出的适用于非平稳随机过程的一般随机地震动模型,采用虚拟激励法,建立了非平稳随机地震反应分析方法,并将其应用于某实际均质土坝动力分析中。土石坝及坝基体系采用整体有限元离散,坝体和坝基材料的动力非线性性能以等效线性化方法考虑。首先,基于目标加速度时程的强度和能量信息,确定了作为输入的加速度时—频演变功率谱密度;其次,比较了确定性时程动力分析和非平稳随机分析的结果,探讨了频率非平稳随机地震激励下的土石坝地震反应特性;最后,比较了2种不同坝基条件下的土石坝非平稳随机地震反应,探讨了频率非平稳随机激励下的土石—坝基动力相互作用。分析结果表明:地震动的频率非平稳性对土石坝动力反应有一定影响;坝体—坝基动力相互作用在地震过程中的不同阶段表现有所不同,主震阶段的相互作用显著。
A method for the non-stationary stochastic seismic analysis is developed on basis of the general stochastic seismic motion model proposed by the first author to account for the randomness of the seismic loading as well as the non-stationarity of the stochastic process in the aspects of its intensity and frequency spectrum,and has been applied in a dynamic analysis of a homogeneous earth dam with the pseudo excitation method.The dam-foundation system is discretized by the finite element method,and its material nonlinearity is considered with the method of equivalent linearization.Firstly,the input time-frequency evolutionary power spectrum is defined according to the intensity and energy information of target acceleration history.Secondly,the seismic performances of the earth dam during the frequency non-stationary seismic excitations are discussed through comparing the results from determinate time-history analysis and stochastic analysis.Finally,the dynamic dam-foundation interaction is discussed through comparing the seismic responses of the dam under two different conditions of the foundation.The analysis results indicate that the frequency non-stationarity of the seismic motion has some influence on the dynamic response of the dam.In different phases of the earthquake process,effects of the dynamic dam-foundation interaction are different.The interaction is rather prominent in the main shock phase.
A method for the non-stationary stochastic seismic analysis is developed on basis of the general stochastic seismic motion model proposed by the first author to account for the randomness of the seismic loading as well as the non-stationarity of the stochastic process in the aspects of its intensity and frequency spectrum,and has been applied in a dynamic analysis of a homogeneous earth dam with the pseudo excitation method.The dam-foundation system is discretized by the finite element method,and its material nonlinearity is considered with the method of equivalent linearization.Firstly,the input time-frequency evolutionary power spectrum is defined according to the intensity and energy information of target acceleration history.Secondly,the seismic performances of the earth dam during the frequency non-stationary seismic excitations are discussed through comparing the results from determinate time-history analysis and stochastic analysis.Finally,the dynamic dam-foundation interaction is discussed through comparing the seismic responses of the dam under two different conditions of the foundation.The analysis results indicate that the frequency non-stationarity of the seismic motion has some influence on the dynamic response of the dam.In different phases of the earthquake process,effects of the dynamic dam-foundation interaction are different.The interaction is rather prominent in the main shock phase.
引文
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[15]Papadimitriou C.Stochastic characterization of strongground motion and applications to structural response[R].Pasadena:California Institute of Technology,1990.
[16]王君杰,周晶.地震动频率非平稳性对结构非线性反应的影响[J].地震工程与工程振动,1997,17(2):16-20.Wang J J,Zhou J.Effects of frequency nonstationar-ity of seismic ground motion on inelastic response ofstructures[J].Earthquake Engineering and Engineer-ing Vibration,1997,17(2):16-20.
[17]王志华,陈国兴,刘汉龙.基于强度和能量控制的随机地震动模型研究[J].地震工程与工程振动,2006,26(6):37-43.Wang Z H,Chen G X,Liu H L.Stochastic seismicground motion based on intensity and energy control[J].Earthquake Engineering and Engineering Vibra-tion,2006,26(6):37-43.
[2]Kanai K.Semi-empirical formula for the seismic cha-racteristics of the ground[J].Bulletin of EarthquakeResearch Institute,University of Tokyo,1957,(35):309-325.
[3]Tajimi H.A statistical method of determining themaximum response of a building structure during anearthquake[C]∥Proceeding 2ndWorld Conference onEarthquake Engineering,Japan:Tokyo and Kyoto,1960.781-798.
[4]Clough R W,Penzien J.Dynamics of Structures[M].New York:McGraw-Hill,Inc.,1993.
[5]杜修力,胡晓,陈厚群.强震地运动随机过程模拟[J].地震学报,1995,17(1):103-109.Du X L,Hu X,Chen H Q.The stochastic processmodeling of strong ground motion[J].Acta Seismo-logica Sinica,1995,17(1):103-109.
[6]Bogdanoff J I,Goldberg J E,Bernard M C.Responseof a simple structure to a random earthquake-type dis-turbance[J].Bulletin of the Seismological Society ofAmerica,1961,51(2):293-310.
[7]Levy R,Kozin F,Moorman R B B.Random process-es for earthquake simulation[J].Journal of Engineer-ing Mechanics,ASCE,1971,97(2):495-517.
[8]Shinozuka M,Sato Y.Simulation of nonstationaryrandom processes[J].Journal of Engineering Mecha-nics,ASCE,1967,93(1):11-40.
[9]Iyengar R N,Iyengar K T S R.A nonstationary ran-dom process model for earthquake accelerograms[J].Bulletin of the Seismological Society of America,1969,59(3):1163-1188.
[10]Saragoni G R,Hart G C.Nonstationary analysis andsimulation of earthquake ground motions[R].Califor-nia:University of California,1972.
[11]Kubo T,Penzien J.Simulation of three-dimensionalstrong ground motions along principle axes,San Fer-nando Earthquake[J].Engineering and Structure Dy-namics,1979,(7):279-294.
[12]Lin Y K,Yong Y.Evolutionary Kanai-Tajini earth-quake models[J].Journal of Engineering Mechanics,ASCE,1987,113(8):1119-1137.
[13]Yeh C H,Wen Y K.Modeling of nonstationaryground motion and analysis of inelastic structural re-sponse[J].Structural Safety,1990,8(1-4):281-298.
[14]Der Kiureghian,Crempien A,Crempien J.An evolu-tionary model for earthquake ground motion[J].Structural Safety,1989,6(2-4):235-246.
[15]Papadimitriou C.Stochastic characterization of strongground motion and applications to structural response[R].Pasadena:California Institute of Technology,1990.
[16]王君杰,周晶.地震动频率非平稳性对结构非线性反应的影响[J].地震工程与工程振动,1997,17(2):16-20.Wang J J,Zhou J.Effects of frequency nonstationar-ity of seismic ground motion on inelastic response ofstructures[J].Earthquake Engineering and Engineer-ing Vibration,1997,17(2):16-20.
[17]王志华,陈国兴,刘汉龙.基于强度和能量控制的随机地震动模型研究[J].地震工程与工程振动,2006,26(6):37-43.Wang Z H,Chen G X,Liu H L.Stochastic seismicground motion based on intensity and energy control[J].Earthquake Engineering and Engineering Vibra-tion,2006,26(6):37-43.
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