The effect of seismic directionality is crucial for curved bridges,a subject generally overlooked in seismic vulnerability analysis.This paper focuses on seismic fragility development as a function of seismic incidenc...The effect of seismic directionality is crucial for curved bridges,a subject generally overlooked in seismic vulnerability analysis.This paper focuses on seismic fragility development as a function of seismic incidence directions for a geometrically curved bridge.A series of non-linear time history analyses were carried out for a representative finite element model of the bridge by considering actual ground motions.For reliable seismic demand models,a total of eleven intensity measures(IM)were analyzed based on optimality metrics.To quantify the sensitivity of fragility functions to input incidence directions,fragility surfaces were developed throughout the horizontal plane by considering spectral acceleration at one second(Sa_(1.0))as the optimal IM.Results show that the optimal IM ranking is insignificantly influenced by seismic directionality.However,seismic orientation influences fragility,which intensifies in higher damage states,particularly for piers.For a bridge system,the differences in median demand corresponding to the least and most vulnerable direction for slight,moderate,extensive,and collapse states are about 9.0%,7.31%,10.32%,and 11.60%,respectively.These results imply that while evaluating the vulnerability of curved bridges,the optimality of IM in demand estimation and the impact of seismic directionality should not be disregarded.展开更多
This study introduces an advanced community-level resilience analysis methodology integrating 3D fragility sur-faces for combined successive earthquake-tsunami hazard and analysis.The methodology facilitates comprehen...This study introduces an advanced community-level resilience analysis methodology integrating 3D fragility sur-faces for combined successive earthquake-tsunami hazard and analysis.The methodology facilitates comprehen-sive evaluations of spatial damage,economic loss,and risk under multi-hazard conditions.This study compares earthquake-only analysis results to the successive earthquake-tsunami analysis at the community level to reveal-and quantify-significant disparities in damage and loss estimations between the analyses,emphasizing the need to consider both hazards in community planning even at lower seismic intensities.Critical assessment of the FEMA combinational rule demonstrates its limitations in accurately predicting losses and damage patterns at higher hazard intensities,highlighting the necessity for refined models that accurately account for hazard inter-actions.This research advances multi-hazard community-level resilience analysis by offering a robust framework for earthquake and tsunami assessment,underscoring the need for integration of detailed multi-hazard analy-ses into resilience planning.Finally,it suggests future directions for enhancing framework applicability across diverse community settings and structural types,aiming to improve community resilience.展开更多
The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and t...The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and twelve vector-valued IMs for seismic collapse assessment of structures. The vector-valued IMs consist of two components, with S（T1） as the first component and different parameters that are ratios of scalar IMs, as well as the spectral shape proxies εSa and N, as the second component. After investigating the properties of an optimal IM, a new vector-valued IM that includes the ratio of Sa（T1） to the displacement spectrum intensity （DSI） as the second component is proposed. The new IM is more efficient than other IMs for predicting the collapse capacity of structures. It is also sufficient with respect to magnitude, source-to-site distance, and scale factor for collapse capacity prediction of structures. To satisfy the predictability criterion, a ground motion prediction equation （GMPE） is determined for Sa（T1）/DSI by using the existing GMPEs. Furthermore, an empirical equation is proposed for obtaining the correlation between the components of the proposed IM. The results of this study show that using the new vector-valued IM leads to a more reliable seismic collapse assessment of structures.展开更多
Subjected to the coupling action of multiple hazards in hydraulic engineering,hydraulic tunnels may be corroded and damaged to varying degrees during their service lives,which will decrease the seismic performance of ...Subjected to the coupling action of multiple hazards in hydraulic engineering,hydraulic tunnels may be corroded and damaged to varying degrees during their service lives,which will decrease the seismic performance of these structures.However,the research and seismic design of significant hydraulic engineering projects focus on investigating the structural response based on the design material parameters,which may overestimate the seismic capacity of structures during their service lives.In this paper,research is performed to identify the effect of hydro-chemo-mechanical corrosion on the seismic performance of hydraulic tunnels with different burial depths.A plastic damage model of time-varying concrete degradation induced by the hydro-chemo-mechanical effect is first determined and implemented,and the endurance time acceleration records are generated in MATLAB.Then,a study of the endurance time relationship of hydro-chemomechanical corrosion-affected hydraulic tunnels,considering the fluid–structure-surrounding rock interaction systems throughout the service period,is undertaken to directly associate the structural response with the predefined evaluation index.Moreover,this research constructs 3D time-varying fragility surfaces considering the hydro-chemo-mechanical effect and seismic intensity.The results show that the relative displacement of hydro-chemo-mechanical corrosion-affected hydraulic tunnels is larger than that of nonaffected hydraulic tunnels.Hydro-chemo-mechanical effect-induced material deterioration will lead to an increase in the cumulative damage(crack)area and damage degree of hydraulic tunnels.Additionally,the seismic fragility analysis shows that the longer the service time of hydro-chemo-mechanical corrosion-affected hydraulic tunnels,the more likely they are to collapse.Hence,attention should be given to improving the aseismic capacity of hydro-chemo-mechanical corrosion-affected hydraulic tunnels in future seismic design and performance assessments.展开更多
The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake ri...The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake risks and structural safety.However,the seismic design code(mainly for aboveground structures)and dynamic analysis of underground structures conventionally employ the peak ground acceleration(PGA)as an optimal IM.In this paper,the research is to identify the optimal scalar and vector IMs in the fragility investigation of deep-buried hydraulic arched tunnels using the finite element method.A refinement process was performed to determine the optimal scalar IMs by comprehensively comparing their correlation,efficiency,practicality,proficiency,and sufficiency among the examined IMs.Furtherly,the optimum vector IMs were also developed,followed by the three different scalar IMs.Eventually,the dif-ferences between the fragility curves of the tunnel produced using the optimal scalar and vector IM were compared.The generated vector fragility surface can be used to estimate the seismic fragility of identical hydraulic tunnels in an approximative manner.展开更多
基金financial support from the Ministry of Education,Culture,Sports,Science and Technology (MEXT),Japan
文摘The effect of seismic directionality is crucial for curved bridges,a subject generally overlooked in seismic vulnerability analysis.This paper focuses on seismic fragility development as a function of seismic incidence directions for a geometrically curved bridge.A series of non-linear time history analyses were carried out for a representative finite element model of the bridge by considering actual ground motions.For reliable seismic demand models,a total of eleven intensity measures(IM)were analyzed based on optimality metrics.To quantify the sensitivity of fragility functions to input incidence directions,fragility surfaces were developed throughout the horizontal plane by considering spectral acceleration at one second(Sa_(1.0))as the optimal IM.Results show that the optimal IM ranking is insignificantly influenced by seismic directionality.However,seismic orientation influences fragility,which intensifies in higher damage states,particularly for piers.For a bridge system,the differences in median demand corresponding to the least and most vulnerable direction for slight,moderate,extensive,and collapse states are about 9.0%,7.31%,10.32%,and 11.60%,respectively.These results imply that while evaluating the vulnerability of curved bridges,the optimality of IM in demand estimation and the impact of seismic directionality should not be disregarded.
基金funded through a cooperative agreement between the U.S.National Institute of Standards and Technology and Colorado State University(NIST Financial Assistance Award Numbers:70NANB15H044 and 70NANB20H008).
文摘This study introduces an advanced community-level resilience analysis methodology integrating 3D fragility sur-faces for combined successive earthquake-tsunami hazard and analysis.The methodology facilitates comprehen-sive evaluations of spatial damage,economic loss,and risk under multi-hazard conditions.This study compares earthquake-only analysis results to the successive earthquake-tsunami analysis at the community level to reveal-and quantify-significant disparities in damage and loss estimations between the analyses,emphasizing the need to consider both hazards in community planning even at lower seismic intensities.Critical assessment of the FEMA combinational rule demonstrates its limitations in accurately predicting losses and damage patterns at higher hazard intensities,highlighting the necessity for refined models that accurately account for hazard inter-actions.This research advances multi-hazard community-level resilience analysis by offering a robust framework for earthquake and tsunami assessment,underscoring the need for integration of detailed multi-hazard analy-ses into resilience planning.Finally,it suggests future directions for enhancing framework applicability across diverse community settings and structural types,aiming to improve community resilience.
文摘The present study is aimed to investigate the ability of different intensity measures （IMs）, including response spectral acceleration at the fundamental period of the structure, Sa（T1）, as a common scalar IM and twelve vector-valued IMs for seismic collapse assessment of structures. The vector-valued IMs consist of two components, with S（T1） as the first component and different parameters that are ratios of scalar IMs, as well as the spectral shape proxies εSa and N, as the second component. After investigating the properties of an optimal IM, a new vector-valued IM that includes the ratio of Sa（T1） to the displacement spectrum intensity （DSI） as the second component is proposed. The new IM is more efficient than other IMs for predicting the collapse capacity of structures. It is also sufficient with respect to magnitude, source-to-site distance, and scale factor for collapse capacity prediction of structures. To satisfy the predictability criterion, a ground motion prediction equation （GMPE） is determined for Sa（T1）/DSI by using the existing GMPEs. Furthermore, an empirical equation is proposed for obtaining the correlation between the components of the proposed IM. The results of this study show that using the new vector-valued IM leads to a more reliable seismic collapse assessment of structures.
基金support from the National Natural Science Foundation of China(Grant Nos.52209169 and 51508521).
文摘Subjected to the coupling action of multiple hazards in hydraulic engineering,hydraulic tunnels may be corroded and damaged to varying degrees during their service lives,which will decrease the seismic performance of these structures.However,the research and seismic design of significant hydraulic engineering projects focus on investigating the structural response based on the design material parameters,which may overestimate the seismic capacity of structures during their service lives.In this paper,research is performed to identify the effect of hydro-chemo-mechanical corrosion on the seismic performance of hydraulic tunnels with different burial depths.A plastic damage model of time-varying concrete degradation induced by the hydro-chemo-mechanical effect is first determined and implemented,and the endurance time acceleration records are generated in MATLAB.Then,a study of the endurance time relationship of hydro-chemomechanical corrosion-affected hydraulic tunnels,considering the fluid–structure-surrounding rock interaction systems throughout the service period,is undertaken to directly associate the structural response with the predefined evaluation index.Moreover,this research constructs 3D time-varying fragility surfaces considering the hydro-chemo-mechanical effect and seismic intensity.The results show that the relative displacement of hydro-chemo-mechanical corrosion-affected hydraulic tunnels is larger than that of nonaffected hydraulic tunnels.Hydro-chemo-mechanical effect-induced material deterioration will lead to an increase in the cumulative damage(crack)area and damage degree of hydraulic tunnels.Additionally,the seismic fragility analysis shows that the longer the service time of hydro-chemo-mechanical corrosion-affected hydraulic tunnels,the more likely they are to collapse.Hence,attention should be given to improving the aseismic capacity of hydro-chemo-mechanical corrosion-affected hydraulic tunnels in future seismic design and performance assessments.
基金support from the National Natural Science Foundation of China(Grant No.52209169).
文摘The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake risks and structural safety.However,the seismic design code(mainly for aboveground structures)and dynamic analysis of underground structures conventionally employ the peak ground acceleration(PGA)as an optimal IM.In this paper,the research is to identify the optimal scalar and vector IMs in the fragility investigation of deep-buried hydraulic arched tunnels using the finite element method.A refinement process was performed to determine the optimal scalar IMs by comprehensively comparing their correlation,efficiency,practicality,proficiency,and sufficiency among the examined IMs.Furtherly,the optimum vector IMs were also developed,followed by the three different scalar IMs.Eventually,the dif-ferences between the fragility curves of the tunnel produced using the optimal scalar and vector IM were compared.The generated vector fragility surface can be used to estimate the seismic fragility of identical hydraulic tunnels in an approximative manner.
