土-结构动力相互作用问题分析中地震动输入的一种新方法
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摘要
为实现地震作用下土-结构动力相互作用问题的有限元模拟,需要在人工边界上完成地震动的有效输入,目前工程和科研中常用的地震动输入方法有两种:波动输入方法和振动输入方法。波动输入方法的模拟精度高,但实施上相对复杂且耗时,而振动输入方法处理简单,但模拟精度较低。针对应力型人工边界提出一种在人工边界上实现地震动输入的新方法,该方法通过对土-结构有限元模型中由人工边界节点及相邻节点组成的局部子结构施加自由波场位移时程并进行动力分析,从而直接获得可实现地震波动有效输入的等效地震荷载,然后在土-结构有限元模型的人工边界节点上施加等效输入地震荷载并完成动力计算,由此完成土-结构动力相互作用问题的地震动输入和地震反应计算。与原有波动输入方法相比,新方法避免了原方法需分别计算人工边界上自由场应力和由引入人工边界条件引起的附加力,以及需要根据不同人工边界面的外法线方向确定荷载作用方向等较为复杂的处理过程,具有等效地震荷载计算简便、地震动输入过程更易于实施的特点。采用均匀弹性半空间和成层弹性半空间一维地震反应算例初步验证新方法的正确性和可靠性。
It is necessary to effectively input seismic motion on artificial boundaries to accomplish finite element simulation of the soil-structure dynamic interaction model subjected to seismic load. There are two kinds of seismic motion input methods commonly used in engineering and scientific research, including the wave input method and the vibration input method. The wave input method exhibits high simulation accuracy; however, its implementation is relatively complicated and is time-consuming. Further, the vibration input method is simple to process even though it exhibits low accuracy. In this study, a new method is proposed to provide the seismic motion input on stress-type artificial boundaries. By imposing the displacement-time history of the free field to the local substructure, containing nodes on the artificial boundaries and adjacent nodes in the soil-structure interaction finite element model, and by performing dynamic analysis, the equivalent seismic loads used to accomplish the effective input of the seismic load were directly obtained. The equivalent seismic loads were imposed on the nodes of the artificial boundaries for performing dynamic analysis. At this point, the seismic motion input and seismic response analysis of the soil-structure dynamic interaction problem were completed. When compared with the original wave input method, the proposed method avoids the complex calculation processes associated with the free field stress on the artificial boundaries and the additional forces caused by the artificial boundaries; further, it also does not require to define the directions of the loads based on the external normal directions of the artificial boundaries. The new method concisely determined the equivalent seismic loads and provided the seismic motion as input. The validity and reliability of the new method were preliminarily verified using the one-dimensional seismic response examples of homogenous elastic half-space and layered half-space.
It is necessary to effectively input seismic motion on artificial boundaries to accomplish finite element simulation of the soil-structure dynamic interaction model subjected to seismic load. There are two kinds of seismic motion input methods commonly used in engineering and scientific research, including the wave input method and the vibration input method. The wave input method exhibits high simulation accuracy; however, its implementation is relatively complicated and is time-consuming. Further, the vibration input method is simple to process even though it exhibits low accuracy. In this study, a new method is proposed to provide the seismic motion input on stress-type artificial boundaries. By imposing the displacement-time history of the free field to the local substructure, containing nodes on the artificial boundaries and adjacent nodes in the soil-structure interaction finite element model, and by performing dynamic analysis, the equivalent seismic loads used to accomplish the effective input of the seismic load were directly obtained. The equivalent seismic loads were imposed on the nodes of the artificial boundaries for performing dynamic analysis. At this point, the seismic motion input and seismic response analysis of the soil-structure dynamic interaction problem were completed. When compared with the original wave input method, the proposed method avoids the complex calculation processes associated with the free field stress on the artificial boundaries and the additional forces caused by the artificial boundaries; further, it also does not require to define the directions of the loads based on the external normal directions of the artificial boundaries. The new method concisely determined the equivalent seismic loads and provided the seismic motion as input. The validity and reliability of the new method were preliminarily verified using the one-dimensional seismic response examples of homogenous elastic half-space and layered half-space.
引文
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[13] 黄胜,陈卫忠,伍国军,等.地下工程抗震分析中地震动输入方法研究[J].岩石力学与工程学报,2010,29(6):1254-1262.HUANG Sheng,CHEN Weizhong,WU Guojun,et al.Study of Method of Earthqukae Input in Aseismic Analysis for Underground Engineering[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(6):1254-1262.
[14] 赵武胜,陈卫忠,郑朋强,等.地下工程数值计算中地震动输入方法选择及实现[J].岩石力学与工程学报,2013,32(8):1579-1587.ZHAO Wusheng,CHEN Weizhong,ZHENG Pengqiang,et al.Choice and Implementation of Seismic Wave Input Method in Numerical Calculation for Underground Engineering [J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1579-1587.
[15] 汪精河,周晓军,毛露露,等.地下结构抗震分析中地震动输入方法的比较研究[J].现代隧道技术,2015,52(3):103-109.WANG Jinghe,ZHOU Xiaojun,MAO Lulu,et al.Comparative Study of Earthquake Input Methods for the Seismic Analysis of Underground Structures[J].Modern Tunnelling Technology,2015,52(3):103-109.
[2] LIAO Z P,WONG H L.A Transmitting Boundary for the Numerical Simulation of Elastic Wave Propagation[J].International Journal of Soil Dynamics and Earthquake Engineering,1984,3(4):174-183.
[3] LYSMER J,KULEMEYER R L.Finite Dynamic Model for Infinite Media[J].Journal of the Engineering Mechanics,ASCE,1969,95(4):859-877.
[4] 刘晶波,王振宇,杜修力,等.波动问题中的三维时域粘弹性人工边界[J].工程力学,2005,22(6):46-51.LIU Jingbo,WANG Zhenyu,DU Xiuli,et al.Three-Dimensional Visco-Elastic Artificial Boundaries in Time Domain for Wave Motion Problems[J].Engineering Mechanics,2005,22(6):46-51.
[5] 赵密.近场波动有限元模拟的应力型时域人工边界条件及其应用[D].北京:北京工业大学,2009.ZHAO Mi.Stress-Type Time-Domain Artificial Boundary Condition for Finite-Element Simulation of Near-Field Wave Motion and Its Engineering Application[D].Beijing:Beijing University of Technology,2009.
[6] 高峰,孙常新,赵冯兵.地下结构波动法与振动法的对比[J].重庆交通大学学报(自然科学版),2012,31(4):764-768.GAO Feng,SUN Changxin,ZHAO Fengbing.Contrast of Wave and Vibration Methods for Underground Structure[J].Journal of Chongqing Jiaotong University (Natural Sciences),2012,31(4):764-768.
[7] 胡世丽,李贵荣.振动力学和波动力学的讨论[J].采矿技术,2010,10(4):115-116.HU Shili,LI Guirong.Discussion on Vibration Mechanics and Wave Mechanics[J].Mining Technology,2010,10(4):115-116.
[8] 田玉基,杨庆山.地震地面运动作用下结构反应的分析模型[J].工程力学,2005,22(6):170-174.TIAN Yuji,YANG Qingshan.AnalysisModels and Methods for Structural Seismic Responses[J].Engineering Mechanics,2005,22(6):170-174.
[9] 王峥峥.跨断层隧道结构非线性地震损伤反应分析[D].成都:西南交通大学,2009.WANG Zhengzheng.Nonlinear Seismic Damage Response of Tunnel Structure Across Fault[D].Chengdu:Southwest Jiaotong University,2009.
[10] 刘晶波,吕彦东.结构-地基动力相互作用问题分析的一种直接方法[J].土木工程学报,1998,31(3):55-64.LIU Jingbo,LU Yandong.A Direct Method for Analysis of Dynamic Soil-Structure Interaction[J].China Civil Engineering Journal,1998,31(3):55-64.
[11] 王振宇,刘晶波.成层地基非线性波动问题人工边界与波动输入研究[J].岩石力学与工程学报.2004,23(7):1169-1173.WANG Zhenyu,LIU Jingbo.Study on Wave Motion Input and Artificial Boundary for Problem of Nonlinear Wave Motion in Layered Soil[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(7):1169-1173.
[12] 赵源,杜修力,赵密,等.地下结构地震响应中的地震动输入探讨[J]:土木建筑与环境工程,2010,32(增刊2):192-197. ZHAO Yuan,DU Xiuli,ZHAO Mi,et al.Discussion on the Seismic Motion Input of the Seismic Response of Underground Structure[J].Journal of Civil,Architectural & Environmental Engineering,2010,32(Supp2):192-197.
[13] 黄胜,陈卫忠,伍国军,等.地下工程抗震分析中地震动输入方法研究[J].岩石力学与工程学报,2010,29(6):1254-1262.HUANG Sheng,CHEN Weizhong,WU Guojun,et al.Study of Method of Earthqukae Input in Aseismic Analysis for Underground Engineering[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(6):1254-1262.
[14] 赵武胜,陈卫忠,郑朋强,等.地下工程数值计算中地震动输入方法选择及实现[J].岩石力学与工程学报,2013,32(8):1579-1587.ZHAO Wusheng,CHEN Weizhong,ZHENG Pengqiang,et al.Choice and Implementation of Seismic Wave Input Method in Numerical Calculation for Underground Engineering [J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1579-1587.
[15] 汪精河,周晓军,毛露露,等.地下结构抗震分析中地震动输入方法的比较研究[J].现代隧道技术,2015,52(3):103-109.WANG Jinghe,ZHOU Xiaojun,MAO Lulu,et al.Comparative Study of Earthquake Input Methods for the Seismic Analysis of Underground Structures[J].Modern Tunnelling Technology,2015,52(3):103-109.