This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to ...This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity(VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.展开更多
Additional displacement of the building foundations over old goaf are prone to happen under the addi- tional loads induced by new buildings, weakening-rock mass by mining and seismic actions, which will cause serious ...Additional displacement of the building foundations over old goaf are prone to happen under the addi- tional loads induced by new buildings, weakening-rock mass by mining and seismic actions, which will cause serious damage to the buildings. In order to analyze the safety of the building foundations safety over the old goaf. the structure characteristics of the strata over the old goaf was investigated and the instability conditions of overhanging rocks upon old goaf were also analyzed in this paper. The results indicate that the stability of overhanging rocks is remarkably decreased by the interactions of mining fractures, earthquake force and building load, in addition, the settlement of the foundations over old goal is increased by the instability of overhanging rocks. According to the location of a new power plant in Yima Mine and its ambient conditions, we defined the influence scope of old goal via resistivity tomography. Based on the seismic parameters of the construction site, a numerical FLAC3d model of the building foundation under the seismic actions and building load was developed. The numerical results are obtained as follows: the foundation of the main power house meets the requirement of 6° seismic fortification intensity: however, under 7° seismic fortification intensity, the maximum differential settlement of foundation between the neighboring pillars is close to the maximum allowable value, while the seismic fortification intensity reaches 8°, but the safety requirements will not be satisfied.展开更多
In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these building...In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these buildings are seismically vulnerable and should be considered for retrofitting. Different conventional and unconventional retrofitting techniques are available to increase the strength and/or ductility of unreinforced masonry (URM) walls. This paper reviews and discusses seismic retrofitting of masonry walls with emphasis on the conventional techniques. Retrofitting procedures are discussed with regard to a case study: a stone masonry building in lrpinia region, damaged by the 1980 earthquake. The interventions are evaluated by means of finite elements with a macroelement obtained with a homogenization technique. Linear and nonlinear procedures are compared, and peculiarities of each procedure are shown.展开更多
This paper studies and analyzes the response and behavior of regular and irregular building structures in earthquake zones. The non-linear dynamic response of tall buildings structures were obtained using five simulat...This paper studies and analyzes the response and behavior of regular and irregular building structures in earthquake zones. The non-linear dynamic response of tall buildings structures were obtained using five simulated models, which were subjected to UBC code dynamic and static equivalent earthquake loads. The maximum response of the structural models were computed and analyzed in order to verify the effects of building configuration on drift results. Drift results agreed with codes recommendations regarding building configuration and showed that regular buildings performance in resisting earthquake forces is better than that of irregular buildings.展开更多
Debris flow is one of the major secondary mountain hazards following the earthquake. This study explores the dynamic initiation mechanism of debris flows based on the strength reduction of soils through static and dyn...Debris flow is one of the major secondary mountain hazards following the earthquake. This study explores the dynamic initiation mechanism of debris flows based on the strength reduction of soils through static and dynamic triaxial tests. A series of static and dynamic triaxial tests were conducted on samples in the lab. The samples were prepared according to different grain size distribution, degree of saturation and earthquake magnitudes. The relations of dynamic shear strength, degree of saturation, and number of cycles are summarized through analyzing experimental results. The findings show that the gravelly soil with a wide and continuous gradation has a critical degree of saturation of approximately 87%, above which debris flows will be triggered by rainfall, while the debris flow will be triggered at a critical degree of saturation of about 73% under the effect of rainfall and earthquake(M>6.5). Debris flow initiation is developed in the humidification process, and the earthquake provides energy for triggering debris flows. Debris flows are more likely to be triggered at the relatively low saturation under dynamic loading than under static loading. The resistance of debris flow triggering relies more on internal frication angle than soil cohesion under the effect of rainfall and earthquake. The conclusions provide an experimental analysis method for dynamic initiation mechanism of debris flows.展开更多
The damage evolution in steel reinforced high strength concrete(SRHSC) frame columns was studied based on the test results of cyclic reversed loading experiment of 12 frame column specimens with various axial compress...The damage evolution in steel reinforced high strength concrete(SRHSC) frame columns was studied based on the test results of cyclic reversed loading experiment of 12 frame column specimens with various axial compression rations,stirrups ratios,steel rations and loading histories.The variation law of the ultimate bearing capacity,ultimate deformation and ultimate hysteretic energy dissipation of specimens under different loading protocols was obtained.The seismic damage characteristics,as well as strength and stiffness degradation,of SRHSC frame columns were analyzed.Based on the analysis of the nonlinear double parameters combination of deformation and energy,a damage model that can well reflect the mechanical characteristics of members subjected to a horizontal earthquake action was established by considering the effects of the number of the loading cycles on the ultimate resistance capacity(ultimate deformation and ultimate energy dissipation capacity) of members,and the loading history on damage,etc.According to the test results,the related parameters of the damage model were proposed.Finally,the damage model proposed was validated by the test results.Results indicated that the proposed damage model is theoretically more reasonable and can accurately describe the seismic damage evolution of the SRHSC frame columns.The results also can be used as a new theoretic reference for the establishment of damage-based earthquake-resistant design method of SRHSC members.展开更多
基金Project(5141001028)supported by International Cooperation and Exchanges of NSFC,ChinaProjects(51308566,51308565,51409025)supported by the National Natural Science Foundation of ChinaProject(CDJZR12200002)supported by the Fundamental Research Funds for the Central Universities,China
文摘This work investigates the correlation between a large number of widely used ground motion intensity measures(IMs) and the corresponding liquefaction potential of a soil deposit during earthquake loading. In order to accomplish this purpose the seismic responses of 32 sloping liquefiable site models consisting of layered cohesionless soil were subjected to 139 earthquake ground motions. Two sets of ground motions, consisting of 80 ordinary records and 59 pulse-like near-fault records are used in the dynamic analyses. The liquefaction potential of the site is expressed in terms of the the mean pore pressure ratio, the maximum ground settlement, the maximum ground horizontal displacement and the maximum ground horizontal acceleration. For each individual accelerogram, the values of the aforementioned liquefaction potential measures are determined. Then, the correlation between the liquefaction potential measures and the IMs is evaluated. The results reveal that the velocity spectrum intensity(VSI) shows the strongest correlation with the liquefaction potential of sloping site. VSI is also proven to be a sufficient intensity measure with respect to earthquake magnitude and source-to-site distance, and has a good predictability, thus making it a prime candidate for the seismic liquefaction hazard evaluation.
基金the Funds of the State Key Development Program for Basic Research of China (Nos. 2013CB227900, 2010CB226800)the National Natural Science Foundation of China (Nos. 51108161, 51374201)+2 种基金the Open Laboratory Foundation for Deep Mine Construction of Henan Province of China (No. 2011KF-09)the Doctor Foundation in Henan Polytechnic University of China (No. Q2013-065)the Key Program for Science and Technology Research of Henan Province of China (Nos. 14A560002, 14B560021).
文摘Additional displacement of the building foundations over old goaf are prone to happen under the addi- tional loads induced by new buildings, weakening-rock mass by mining and seismic actions, which will cause serious damage to the buildings. In order to analyze the safety of the building foundations safety over the old goaf. the structure characteristics of the strata over the old goaf was investigated and the instability conditions of overhanging rocks upon old goaf were also analyzed in this paper. The results indicate that the stability of overhanging rocks is remarkably decreased by the interactions of mining fractures, earthquake force and building load, in addition, the settlement of the foundations over old goal is increased by the instability of overhanging rocks. According to the location of a new power plant in Yima Mine and its ambient conditions, we defined the influence scope of old goal via resistivity tomography. Based on the seismic parameters of the construction site, a numerical FLAC3d model of the building foundation under the seismic actions and building load was developed. The numerical results are obtained as follows: the foundation of the main power house meets the requirement of 6° seismic fortification intensity: however, under 7° seismic fortification intensity, the maximum differential settlement of foundation between the neighboring pillars is close to the maximum allowable value, while the seismic fortification intensity reaches 8°, but the safety requirements will not be satisfied.
文摘In many seismically active regions of the world there are large numbers of masonry buildings. Most of these buildings have not been designed for seismic loads. Recent earthquakes have shown that many of these buildings are seismically vulnerable and should be considered for retrofitting. Different conventional and unconventional retrofitting techniques are available to increase the strength and/or ductility of unreinforced masonry (URM) walls. This paper reviews and discusses seismic retrofitting of masonry walls with emphasis on the conventional techniques. Retrofitting procedures are discussed with regard to a case study: a stone masonry building in lrpinia region, damaged by the 1980 earthquake. The interventions are evaluated by means of finite elements with a macroelement obtained with a homogenization technique. Linear and nonlinear procedures are compared, and peculiarities of each procedure are shown.
文摘This paper studies and analyzes the response and behavior of regular and irregular building structures in earthquake zones. The non-linear dynamic response of tall buildings structures were obtained using five simulated models, which were subjected to UBC code dynamic and static equivalent earthquake loads. The maximum response of the structural models were computed and analyzed in order to verify the effects of building configuration on drift results. Drift results agreed with codes recommendations regarding building configuration and showed that regular buildings performance in resisting earthquake forces is better than that of irregular buildings.
基金sponsored by Natural Science Foundation of China (Grant No. 51269012)Major Projects of Natural Science Foundation of Inner Mongolia Autonomous Region (Grant No. ZD0602)+2 种基金part of National Project 973 "Wenchuan Earthquake Mountain Hazards Formation Mechanism and Risk Control" (Grant No. 2008CB425800)funded by "New Century Excellent Talents" of University of Ministry of Education of China (Grant No. NCET-11-1016)China Scholarship Council
文摘Debris flow is one of the major secondary mountain hazards following the earthquake. This study explores the dynamic initiation mechanism of debris flows based on the strength reduction of soils through static and dynamic triaxial tests. A series of static and dynamic triaxial tests were conducted on samples in the lab. The samples were prepared according to different grain size distribution, degree of saturation and earthquake magnitudes. The relations of dynamic shear strength, degree of saturation, and number of cycles are summarized through analyzing experimental results. The findings show that the gravelly soil with a wide and continuous gradation has a critical degree of saturation of approximately 87%, above which debris flows will be triggered by rainfall, while the debris flow will be triggered at a critical degree of saturation of about 73% under the effect of rainfall and earthquake(M>6.5). Debris flow initiation is developed in the humidification process, and the earthquake provides energy for triggering debris flows. Debris flows are more likely to be triggered at the relatively low saturation under dynamic loading than under static loading. The resistance of debris flow triggering relies more on internal frication angle than soil cohesion under the effect of rainfall and earthquake. The conclusions provide an experimental analysis method for dynamic initiation mechanism of debris flows.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90815005, 50978218)Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20106120110003)the Educational Office of Shan'xi Province in China (Grant No.2010JK633)
文摘The damage evolution in steel reinforced high strength concrete(SRHSC) frame columns was studied based on the test results of cyclic reversed loading experiment of 12 frame column specimens with various axial compression rations,stirrups ratios,steel rations and loading histories.The variation law of the ultimate bearing capacity,ultimate deformation and ultimate hysteretic energy dissipation of specimens under different loading protocols was obtained.The seismic damage characteristics,as well as strength and stiffness degradation,of SRHSC frame columns were analyzed.Based on the analysis of the nonlinear double parameters combination of deformation and energy,a damage model that can well reflect the mechanical characteristics of members subjected to a horizontal earthquake action was established by considering the effects of the number of the loading cycles on the ultimate resistance capacity(ultimate deformation and ultimate energy dissipation capacity) of members,and the loading history on damage,etc.According to the test results,the related parameters of the damage model were proposed.Finally,the damage model proposed was validated by the test results.Results indicated that the proposed damage model is theoretically more reasonable and can accurately describe the seismic damage evolution of the SRHSC frame columns.The results also can be used as a new theoretic reference for the establishment of damage-based earthquake-resistant design method of SRHSC members.