为研究液化场地桥梁桩基加速度反应特性,采用自编的土-结地震相互作用有限元分析程序,输入三种试验记录工况,进行可液化场地桥梁桩基地震反应振动台试验与数值模拟.结果表明:三种地震输入下,自下而上沿桩-柱墩长度方向,加速度峰值放大...为研究液化场地桥梁桩基加速度反应特性,采用自编的土-结地震相互作用有限元分析程序,输入三种试验记录工况,进行可液化场地桥梁桩基地震反应振动台试验与数值模拟.结果表明:三种地震输入下,自下而上沿桩-柱墩长度方向,加速度峰值放大系数变化基本一致且均出现在10～20s时段内,加速度时程曲线的形状也极其相似;压缩0.15g El Centro波输入下加速度反应在砂土层与黏土层过渡带有增大趋势、在地表则有一定程度减小,且压缩0.15g El Centro波较0.15g El Centro波输入下均偏小,0.15g El Cen-tro波输入下自下而上桩的加速度时程幅值和峰值放大系数的试验值、计算值均一直有较大幅度增大;0.5g El Centro波输入下,加速度时程幅值的计算值和试验值在桩折断位置之下一直增大、至砂土层与黏土层过渡带则大大减小,加速度峰值放大系数的试验值和计算值在砂土层与黏土层过渡带突变增大、而在地表则明显减小,且较0.15g El Centro波输入下桩的峰值放大系数要偏小.展开更多
In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(...In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.展开更多
Based on the data from typical sites in the Jianghuai region,many kinds of soil layer seismic response are modeled by increasing and decreasing the measured values of shear velocity to a certain scale. The seismic res...Based on the data from typical sites in the Jianghuai region,many kinds of soil layer seismic response are modeled by increasing and decreasing the measured values of shear velocity to a certain scale. The seismic response of soil layer sites are calculated using the one-dimensional equivalent linear method in the frequency domain by choosing the Taft,Kobe and El-centro records as the ground motion input. The results show that the impact of shear velocity variability on the surface ground motion is in relation to the soil layer structure and ground motion input parameters such as amplitude and spectral characteristic. With the increase of shear velocity,the PGA( peak ground acceleration)on the surface of site will increase,however,the characteristic period of the acceleration response spectra is decreasing.展开更多
Records of the May 12, 2008 Ms8.0 Wenchuan, Sichuan, earthquake from 27 stations of Shaanxi Digital Strong Motion Network are processed and analyzed, including baseline adjustment of acceleration traces, filtering, an...Records of the May 12, 2008 Ms8.0 Wenchuan, Sichuan, earthquake from 27 stations of Shaanxi Digital Strong Motion Network are processed and analyzed, including baseline adjustment of acceleration traces, filtering, and calculations of velocities, displacements and acceleration response spectra. The results show that direction energy radiation of the large earthquake and horizontal inhomogeneous medium along the wave traveling path might both have some effect on the scattering degree of the attenuation of PGAH, besides influence of local site conditions. For the same intensity, the ratios of PGA/PGV are commonly small, on average about 5, which indicates that long period components are rich in ground motion. Intensities for most sites of the stations are within V -VII. The larger one among PGAE-W and PGAN-S is quite close to their PGAH, which is less than 10 % in relative deviation. The dominated waves are surface waves. The thicker the soil overburden is, the stronger the surface wave will be and the longer the shaking will last. Local site conditions have strong effects on ground motion, especially those of thick sediment filled-in basins, as they can significantly amplify long-period components.展开更多
文摘为研究液化场地桥梁桩基加速度反应特性,采用自编的土-结地震相互作用有限元分析程序,输入三种试验记录工况,进行可液化场地桥梁桩基地震反应振动台试验与数值模拟.结果表明:三种地震输入下,自下而上沿桩-柱墩长度方向,加速度峰值放大系数变化基本一致且均出现在10～20s时段内,加速度时程曲线的形状也极其相似;压缩0.15g El Centro波输入下加速度反应在砂土层与黏土层过渡带有增大趋势、在地表则有一定程度减小,且压缩0.15g El Centro波较0.15g El Centro波输入下均偏小,0.15g El Cen-tro波输入下自下而上桩的加速度时程幅值和峰值放大系数的试验值、计算值均一直有较大幅度增大;0.5g El Centro波输入下,加速度时程幅值的计算值和试验值在桩折断位置之下一直增大、至砂土层与黏土层过渡带则大大减小,加速度峰值放大系数的试验值和计算值在砂土层与黏土层过渡带突变增大、而在地表则明显减小,且较0.15g El Centro波输入下桩的峰值放大系数要偏小.
基金Project(2011CB013605)supported by the National Basic Research Development Program of China(973 Program)Projects(51178071,51008041)supported by the National Natural Science Foundation of ChinaProject(NCET-12-0751)supported by the New Century Excellent Talents Program in University of Ministry of Education of China
文摘In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.
基金sponsored by the Anhui Natural Science Foundation Project(10040606Q24)the Youth Seismic Research Program of Anhui Province,China(20120707)and(20140301)
文摘Based on the data from typical sites in the Jianghuai region,many kinds of soil layer seismic response are modeled by increasing and decreasing the measured values of shear velocity to a certain scale. The seismic response of soil layer sites are calculated using the one-dimensional equivalent linear method in the frequency domain by choosing the Taft,Kobe and El-centro records as the ground motion input. The results show that the impact of shear velocity variability on the surface ground motion is in relation to the soil layer structure and ground motion input parameters such as amplitude and spectral characteristic. With the increase of shear velocity,the PGA( peak ground acceleration)on the surface of site will increase,however,the characteristic period of the acceleration response spectra is decreasing.
文摘Records of the May 12, 2008 Ms8.0 Wenchuan, Sichuan, earthquake from 27 stations of Shaanxi Digital Strong Motion Network are processed and analyzed, including baseline adjustment of acceleration traces, filtering, and calculations of velocities, displacements and acceleration response spectra. The results show that direction energy radiation of the large earthquake and horizontal inhomogeneous medium along the wave traveling path might both have some effect on the scattering degree of the attenuation of PGAH, besides influence of local site conditions. For the same intensity, the ratios of PGA/PGV are commonly small, on average about 5, which indicates that long period components are rich in ground motion. Intensities for most sites of the stations are within V -VII. The larger one among PGAE-W and PGAN-S is quite close to their PGAH, which is less than 10 % in relative deviation. The dominated waves are surface waves. The thicker the soil overburden is, the stronger the surface wave will be and the longer the shaking will last. Local site conditions have strong effects on ground motion, especially those of thick sediment filled-in basins, as they can significantly amplify long-period components.
