深厚场地地震响应中阻尼矩阵形式的影响分析
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摘要
深厚覆盖土层地震响应时域分析中阻尼矩阵形式的选取十分重要。本文基于滞后阻尼比和振型阻尼比构造了6种不同的比例阻尼矩阵形式,研究其对深覆盖土层地震响应的影响。以上海某一实际深厚覆盖土层为算例,分别以人工合成基岩地震波、汶川地震时上海佘山记录的基岩地震波为输入,得到6种阻尼矩阵形式下不同深度处的土层地震响应,并以频域解为基准解进行比较。研究结果表明,阻尼矩阵形式对加速度结果的影响程度比位移结果要大,运用同一种阻尼矩阵形式所得结果误差和输入地震波频谱特性有关。地震波自身的频谱特征对阻尼矩阵形式的选取有一定影响,建议综合考虑地震波的频谱特征和场地土层特性来构建合适的阻尼矩阵以获得合理的结果。
Seismic response analysis of soil plays a major role in the seismic safety assessment of engineering sites;it reflects the influence of the characteristics of engineering sites on the input ground motion parameters of a structure.Seismic analysis can either be performed in the time or frequency domains.The dynamic analysis of soil is based on the principle of soil dynamics and the viscous damping model,and the Rayleigh proportional damping matrix is built on the assumption that the vibration modes are orthogonal about the damping matrix;therefore,two structural vibration modes can be chosen to obtain the proportion coefficient of the damping matrix.The selection of viable damping models is important for seismic response analysis of deep soil layers in the time domain,and in this paper,the influence is discussed using six different damping matrices formed by the hysteretic damping ratio and modal damping ratio.The paper first introduces two damping matrices based on the hysteretic damping ratio and Rayleigh damping,which is based on the viscous damping ratio.Then,six different damping matrices are constructed for the seismic response analysis of a deep soil site:the first and second frequencies,the first frequency and the frequency closest to the predominant frequency of the seismic wave,the first frequency and third frequencies,a common model based on the first frequency used in soil dynamics,and other forms,such as equivalent damping matrices based on the first frequency and the translation frequency.The damping frequency can be considered as independent in the frequency domain and an accurate solution can be obtained.The time domain solution is obtained using ANSYS,which uses a onedimensional soil column for the simulation.Using a deep soil site as an example,the influence of the different damping matrices on the seismic response is analyzed under an input of synthetic bedrock seismic waves and a natural seismic wave,the Shanghai Sheshan bedrock seismic wave,recorded in the Wenchuan earthquake.The seismic response results at different depths of the soil are compared with the frequency domain solution.The results show that the influence of the damping matrix is greater on the accelerations than on the displacements.The peak ground acceleration is most overvalued by 47.28%,and most undervalued by 32.53% compared to the frequency domain solution.The cause for the different influences of these damping matrices is investigated.The chosen wave spectrum characteristics are different,and the degree of influence of a damping matrix also varies depending on the input wave spectrum characteristics.The spectrum characteristics of a seismic wave should be considered during the selection of a damping matrix.The frequency information of actual bedrock seismic records are generally abundant and due to the frequency correlation of the selected damping in the time domain,using only one frequency is often not sufficient to reasonably reflect the characteristics of a seismic wave.Therefore,both the spectrum of a seismic wave and the actual soil condition at the site should be considered to determine an appropriate damping matrix to obtain more accurate and reasonable results.
Seismic response analysis of soil plays a major role in the seismic safety assessment of engineering sites;it reflects the influence of the characteristics of engineering sites on the input ground motion parameters of a structure.Seismic analysis can either be performed in the time or frequency domains.The dynamic analysis of soil is based on the principle of soil dynamics and the viscous damping model,and the Rayleigh proportional damping matrix is built on the assumption that the vibration modes are orthogonal about the damping matrix;therefore,two structural vibration modes can be chosen to obtain the proportion coefficient of the damping matrix.The selection of viable damping models is important for seismic response analysis of deep soil layers in the time domain,and in this paper,the influence is discussed using six different damping matrices formed by the hysteretic damping ratio and modal damping ratio.The paper first introduces two damping matrices based on the hysteretic damping ratio and Rayleigh damping,which is based on the viscous damping ratio.Then,six different damping matrices are constructed for the seismic response analysis of a deep soil site:the first and second frequencies,the first frequency and the frequency closest to the predominant frequency of the seismic wave,the first frequency and third frequencies,a common model based on the first frequency used in soil dynamics,and other forms,such as equivalent damping matrices based on the first frequency and the translation frequency.The damping frequency can be considered as independent in the frequency domain and an accurate solution can be obtained.The time domain solution is obtained using ANSYS,which uses a onedimensional soil column for the simulation.Using a deep soil site as an example,the influence of the different damping matrices on the seismic response is analyzed under an input of synthetic bedrock seismic waves and a natural seismic wave,the Shanghai Sheshan bedrock seismic wave,recorded in the Wenchuan earthquake.The seismic response results at different depths of the soil are compared with the frequency domain solution.The results show that the influence of the damping matrix is greater on the accelerations than on the displacements.The peak ground acceleration is most overvalued by 47.28%,and most undervalued by 32.53% compared to the frequency domain solution.The cause for the different influences of these damping matrices is investigated.The chosen wave spectrum characteristics are different,and the degree of influence of a damping matrix also varies depending on the input wave spectrum characteristics.The spectrum characteristics of a seismic wave should be considered during the selection of a damping matrix.The frequency information of actual bedrock seismic records are generally abundant and due to the frequency correlation of the selected damping in the time domain,using only one frequency is often not sufficient to reasonably reflect the characteristics of a seismic wave.Therefore,both the spectrum of a seismic wave and the actual soil condition at the site should be considered to determine an appropriate damping matrix to obtain more accurate and reasonable results.
引文
[1]文雯,陈宇军,王珏,等.地震安全性评价中地震动衰减关系的类型及其选取[J].地震工程学报,2013,35(3):709-714.WEN Wen,CHEN Yu-jun,WANG Jue.Type and Selection of the Ground Motion Attenuation Relations During Seismic Safety Evaluation[J].China Earthquake Engineering Journal,2013,35(3):709-714.(in Chinese)
[2]盛志强,卢育霞,石玉成,等.河谷地形的地震反应分析[J].地震工程学报,2013,35(1):126-132.SHENG Zhi-qiang,LU Yu-xia,SHI Yu-cheng.Seismic Response Analysis of Valley Topography[J].China Earthquake Engineering Journal,2013,35(1):126-132.(in Chinese)
[3]Rathje E M,Bray J D.One-and two-dimensional Seismic Analysis of Solid-waste Landfills[J].Canadian Geotechnical Journal,2001,38(4):850-862.
[4]楼梦麟,潘旦光.滞后阻尼在土层时域分析中的应用[J].同济大学学报:自然科学版,2004,32(3):281-285.LOU Meng-lin,PAN Dan-guang.Hysteretic Damping Application in Time Domain Analysis of Soil layer[J].Journal of Tongji University:Natural Science,2004,32(3):281-285.(in Chinese)
[5]楼梦麟,殷琳.关于高土坝地震反应分析中阻尼模型的讨论[J].水力发电学报,2009,28(5):103-107.LOU Meng-lin,YIN Lin.Discussion on Damping Models for Seismic Response Analysis of High Earth Dams[J].Journal of Hydroelectric Engineering,2009,28(5):103-107.(in Chinese)
[6]邹德高,徐斌,孔宪京.瑞利阻尼系数确定方法对高土石坝地震反应的影响研究[J].岩土力学,2011,32(3):797-803.ZOU De-gao,XU Bin,KONG Xian-jing.Study of Influence of Different Methods for Calculating Rayleigh Damping Coefficient on High Earth-Rock Dam Seismic Response[J].rock and Soil Mechanics,2011,32(3):797-803.(in Chinese)
[7]杨燕,楼梦麟.汶川地震中远场深覆盖土层动力反应分析[J].防灾减灾学报,2011,31(4):462-468.YANG Yan,LOU Meng-lin.Dynamic Response Analysis of Far-field Soil Layer with Deep Deposit during Wenchuan Earthquake[J].Journal of Disaster Prevention and Mitigation Engineering,2011,31(4):462-468.(in Chinese)
[8]邬都,楼梦麟.水平成层土层地震响应分析的一维有限元方法[J].震灾防御技术,2008,3(1):45-52.WU Du,LOU Meng-lin.Seismic Response Analysis in Horizontal Layer with 1-D Finite Element Method[J].Technology for Earthquake Disaster Prevention.2008,3(1):45-52.(in Chinese)
[2]盛志强,卢育霞,石玉成,等.河谷地形的地震反应分析[J].地震工程学报,2013,35(1):126-132.SHENG Zhi-qiang,LU Yu-xia,SHI Yu-cheng.Seismic Response Analysis of Valley Topography[J].China Earthquake Engineering Journal,2013,35(1):126-132.(in Chinese)
[3]Rathje E M,Bray J D.One-and two-dimensional Seismic Analysis of Solid-waste Landfills[J].Canadian Geotechnical Journal,2001,38(4):850-862.
[4]楼梦麟,潘旦光.滞后阻尼在土层时域分析中的应用[J].同济大学学报:自然科学版,2004,32(3):281-285.LOU Meng-lin,PAN Dan-guang.Hysteretic Damping Application in Time Domain Analysis of Soil layer[J].Journal of Tongji University:Natural Science,2004,32(3):281-285.(in Chinese)
[5]楼梦麟,殷琳.关于高土坝地震反应分析中阻尼模型的讨论[J].水力发电学报,2009,28(5):103-107.LOU Meng-lin,YIN Lin.Discussion on Damping Models for Seismic Response Analysis of High Earth Dams[J].Journal of Hydroelectric Engineering,2009,28(5):103-107.(in Chinese)
[6]邹德高,徐斌,孔宪京.瑞利阻尼系数确定方法对高土石坝地震反应的影响研究[J].岩土力学,2011,32(3):797-803.ZOU De-gao,XU Bin,KONG Xian-jing.Study of Influence of Different Methods for Calculating Rayleigh Damping Coefficient on High Earth-Rock Dam Seismic Response[J].rock and Soil Mechanics,2011,32(3):797-803.(in Chinese)
[7]杨燕,楼梦麟.汶川地震中远场深覆盖土层动力反应分析[J].防灾减灾学报,2011,31(4):462-468.YANG Yan,LOU Meng-lin.Dynamic Response Analysis of Far-field Soil Layer with Deep Deposit during Wenchuan Earthquake[J].Journal of Disaster Prevention and Mitigation Engineering,2011,31(4):462-468.(in Chinese)
[8]邬都,楼梦麟.水平成层土层地震响应分析的一维有限元方法[J].震灾防御技术,2008,3(1):45-52.WU Du,LOU Meng-lin.Seismic Response Analysis in Horizontal Layer with 1-D Finite Element Method[J].Technology for Earthquake Disaster Prevention.2008,3(1):45-52.(in Chinese)
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