Local soil conditions can significantly modify the seismic motion expected on the soil surface.In most cases,the indications concerning the influence of the underlying soil provided by the in-force European and Italia...Local soil conditions can significantly modify the seismic motion expected on the soil surface.In most cases,the indications concerning the influence of the underlying soil provided by the in-force European and Italian Building Codes underestimate the real seismic amplification effects.For this reason,numerical analyses of the local seismic response(LSR)have been encouraged to estimate the soil filtering effects.These analyses are generally performed in free-field conditions,ignoring the presence of superstructures and,therefore,the effects of dynamic soil-structure interaction(DSSI).Moreover,many studies on DSSI are characterised by a sophisticated modelling of the structure and an approximate modelling of the soil(using springs and dashpots at the foundation level);while others are characterised by a sophisticated modelling of the soil and an approximate modelling of the structure(considered as a simple linear elastic structure or a single degree of freedom system).This paper presents a set of finite element method(FEM)analyses on a fully-coupled soil-structure system for a reinforced concrete building located in Fleri(Catania,Italy).The building,designed for gravity loads only,was severely damaged during the 26 December 2018 earthquake.The soil was modelled considering an equivalent visco-elastic behaviour,while the structure was modelled assuming both the visco-elastic and visco-inelastic behaviours.The comparison made between the results of the FEM analyses and the observed damage is valuable.展开更多
In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a lar...In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a large number of shear-wave velocity profiles from the Kiban-Kyoshin network(KiK-net)and the Kyoshin network(K-NET)to construct the one-dimensional(1D)numerical models.The strong-motion records from rock-sites in Japan with different earthquake categories and taken from the Pacific Earthquake Engineering Research Center dataset were used in this study.We fit a set of 1D site amplification models using the spectral amplification ratios derived from 1D equivalent linear analyses.Parameters of site impedance ratios for both linear and nonlinear site response were included in the 1D model.The 1D model could be implemented into GMPEs using a new proposed adjustment method.The adjusted site amplification ratios retain the nonlinear characteristics of the 1D model for strong motions and match the linear amplification ratio in GMPE for weak motions.The nonlinearity of the present site model is reasonably similar to that of the historical models,and the present site model could satisfactorily capture the nonlinear site response in empirical data.展开更多
In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data an...In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol＇s subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain, using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to 0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran＇s 2800 （earthquake） code.展开更多
国内外规范中推荐或强制规定竖向地震动取为剪切反应谱的1/2～2/3,但该规定如何改进使其更合理已成为一重要课题。首先,对其研究现状简单总结,给出了可处理辐射阻尼、地震动相位特性、计算高效的二维波动显式有限元等效线性化程序 ELPSV...国内外规范中推荐或强制规定竖向地震动取为剪切反应谱的1/2～2/3,但该规定如何改进使其更合理已成为一重要课题。首先,对其研究现状简单总结,给出了可处理辐射阻尼、地震动相位特性、计算高效的二维波动显式有限元等效线性化程序 ELPSV 编制的必要性,然后进行了分析。初步研究表明,竖向地震动强度对周期在0.3 s 以下的地表剪切反应谱有一定的影响,而高于0.3 s 部分影响轻微。竖向地震动强度对斜坡场地的竖向地震反应及地表竖向反应谱影响显著,按规范的取值将偏于不安全。受地形条件影响,坡顶剪切地震反应会比坡脚反应要大,而竖向地震反应并不明显。土层边界面的地震反应要比周围反应要低,交界面效应明显。软斜坡场地地震反应特性除场地竖向地震反应自下而上先增加后减小的规律外,其他情形与硬斜坡场地的规律基本一致。该结果定量反映了竖向地震动的影响程度,为斜坡场地上考虑竖向地震动的建(构)筑结构的抗震设计提供了有益的基础。展开更多
基金Financial support provided by the Dipartimento di Protezione Civile/Rete Laboratori Universitari Ingegneria Sismica e Strutturale,in Italian(DPC/ReLUIS)2019-2021 Research Project,funded by the Civil Protection Department,allowed the authors to achieve the results reported in this paper.
文摘Local soil conditions can significantly modify the seismic motion expected on the soil surface.In most cases,the indications concerning the influence of the underlying soil provided by the in-force European and Italian Building Codes underestimate the real seismic amplification effects.For this reason,numerical analyses of the local seismic response(LSR)have been encouraged to estimate the soil filtering effects.These analyses are generally performed in free-field conditions,ignoring the presence of superstructures and,therefore,the effects of dynamic soil-structure interaction(DSSI).Moreover,many studies on DSSI are characterised by a sophisticated modelling of the structure and an approximate modelling of the soil(using springs and dashpots at the foundation level);while others are characterised by a sophisticated modelling of the soil and an approximate modelling of the structure(considered as a simple linear elastic structure or a single degree of freedom system).This paper presents a set of finite element method(FEM)analyses on a fully-coupled soil-structure system for a reinforced concrete building located in Fleri(Catania,Italy).The building,designed for gravity loads only,was severely damaged during the 26 December 2018 earthquake.The soil was modelled considering an equivalent visco-elastic behaviour,while the structure was modelled assuming both the visco-elastic and visco-inelastic behaviours.The comparison made between the results of the FEM analyses and the observed damage is valuable.
基金National Science Foundation of China under Grant No.51578470。
文摘In this manuscript we present a nonlinear site amplification model for ground-motion prediction equations(GMPEs)in Japan,using a site period-based site class and a site impedance ratio as site parameters.We used a large number of shear-wave velocity profiles from the Kiban-Kyoshin network(KiK-net)and the Kyoshin network(K-NET)to construct the one-dimensional(1D)numerical models.The strong-motion records from rock-sites in Japan with different earthquake categories and taken from the Pacific Earthquake Engineering Research Center dataset were used in this study.We fit a set of 1D site amplification models using the spectral amplification ratios derived from 1D equivalent linear analyses.Parameters of site impedance ratios for both linear and nonlinear site response were included in the 1D model.The 1D model could be implemented into GMPEs using a new proposed adjustment method.The adjusted site amplification ratios retain the nonlinear characteristics of the 1D model for strong motions and match the linear amplification ratio in GMPE for weak motions.The nonlinearity of the present site model is reasonably similar to that of the historical models,and the present site model could satisfactorily capture the nonlinear site response in empirical data.
文摘In this the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical site characterization in Babol, Iran. Use of geotechnical data and synthesis of drilling data extracted from the Babol＇s subsurface database have enabled authors to determine the geotechnical properties of each site. These data are consisted of twenty five boreholes up to depth of 40 m. Based on the obtained data from geotechnical investigation the study area is divided to five zones. Dynamic analysis was performed in time domain, using fully nonlinear model by PLAXIS. A series of analysis in the study area showed the site period, ranging from 0.4 to 0.8 s. Finally the obtained response spectra from fully nonlinear method were compared with site response spectra of Iran＇s 2800 （earthquake） code.
文摘国内外规范中推荐或强制规定竖向地震动取为剪切反应谱的1/2～2/3,但该规定如何改进使其更合理已成为一重要课题。首先,对其研究现状简单总结,给出了可处理辐射阻尼、地震动相位特性、计算高效的二维波动显式有限元等效线性化程序 ELPSV 编制的必要性,然后进行了分析。初步研究表明,竖向地震动强度对周期在0.3 s 以下的地表剪切反应谱有一定的影响,而高于0.3 s 部分影响轻微。竖向地震动强度对斜坡场地的竖向地震反应及地表竖向反应谱影响显著,按规范的取值将偏于不安全。受地形条件影响,坡顶剪切地震反应会比坡脚反应要大,而竖向地震反应并不明显。土层边界面的地震反应要比周围反应要低,交界面效应明显。软斜坡场地地震反应特性除场地竖向地震反应自下而上先增加后减小的规律外,其他情形与硬斜坡场地的规律基本一致。该结果定量反映了竖向地震动的影响程度,为斜坡场地上考虑竖向地震动的建(构)筑结构的抗震设计提供了有益的基础。
