To study the ground motion intensity measures(IMs)suitable for the design of seismic performance with a focus on longitudinal resistance in tunnel structures,21 different seismic intensity parameters are selected for ...To study the ground motion intensity measures(IMs)suitable for the design of seismic performance with a focus on longitudinal resistance in tunnel structures,21 different seismic intensity parameters are selected for nonlinear calculation and analysis of tunnel structures,in order to determine the optimal IM for the longitudinal seismic performance of tunnel structures under different site conditions.An improved nonlinear beam-spring model is developed to calculate the longitudinal seismic response of tunnels.The PQ-Fiber model is used to simulate the longitudinal nonlinear behavior of tunnel structures and the tangential interactions between the tunnel and the soil is realized by load in the form of moment.Five different site types are considered and 21 IMs is evaluated against four criteria:effectiveness,practicality,usefulness,and sufficiency.The results indicate that the optimal IMs are significantly influenced by the site conditions.Specifically,sustained maximum velocity(V_(SM))emerges as the optimal IM for circular tunnels in soft soil conditions(CaseⅠsites),peak ground velocity(V PG)is best suited for CaseⅡsites,sustained maximum acceleration(A_(SM))is ideal for both CaseⅢand CaseⅤsites,and peak ground acceleration(A PG)for CaseⅣsites.As site conditions transition from CaseⅠto CaseⅤ,from soft to hard,the applicability of acceleration-type intensity parameters gradually decreases,while the applicability of velocity-type intensity parameters gradually increases.展开更多
Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese C...Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.展开更多
Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelin...Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelines suggest several confi gurations, they are diff erent from the designs that have been proven in practice, e.g., Japanese styles, and extensive experimental investigation into their seismic performance is required. Three types of seals, rubber-, metal- and asbestinebased, were tested quasi-statically with infi lled pressurized water at 2.5 MPa. The asbestine-based seal leaked at a smaller deformation than the other two types of seals. Based on the test results, three damage states were defi ned and the deformation capacity was estimated. To evaluate their performance, a three-dimensional model of a base-isolated medical building was developed using OpenSees, with the fl exible pipelines simulated by a mechanical model calibrated from the experimental data. A probabilistic seismic demand model and the fragility function of the fl exible pipelines were then developed to evaluate the seismic performance.展开更多
Performance-based seismic design can generate predictable structure damage result with given seismic hazard.However,there are multiple sources of uncertainties in the seismic design process that can affect desired per...Performance-based seismic design can generate predictable structure damage result with given seismic hazard.However,there are multiple sources of uncertainties in the seismic design process that can affect desired performance predictability.This paper mainly focuses on the effects of near-fault pulse-like ground motions and the uncertainties in bridge modeling on the seismic demands of regular continuous highway bridges.By modeling a regular continuous bridge with OpenSees software,a series of nonlinear dynamic time-history analysis of the bridge at three different site conditions under near-fault pulse-like ground motions are carried out.The relationships between different Intensity Measure(IM)parameters and the Engineering Demand Parameter(EDP)are discussed.After selecting the peak ground acceleration as the most correlated IM parameter and the drift ratio of the bridge column as the EDP parameter,a probabilistic seismic demand model is developed for near-fault earthquake ground motions for 3 different site conditions.On this basis,the uncertainty analysis is conducted with the key sources of uncertainty during the finite element modeling.All the results are quantified by the"swing"base on the specific distribution range of each uncertainty parameter both in near-fault and far-fault cases.All the ground motions are selected from PEER database,while the bridge case study is a typical regular highway bridge designed in accordance with the Chinese Guidelines for Seismic Design of Highway Bridges.The results show that PGA is a proper IM parameter for setting up a linear probabilistic seismic demand model;damping ratio,pier diameter and concrete strength are the main uncertainty parameters during bridge modeling,which should be considered both in near-fault and far-fault ground motion cases.展开更多
基金National Key Research and Development Program of China(No.2022YFC3004300)the National Natural Science Foundation of China(No.52378475).
文摘To study the ground motion intensity measures(IMs)suitable for the design of seismic performance with a focus on longitudinal resistance in tunnel structures,21 different seismic intensity parameters are selected for nonlinear calculation and analysis of tunnel structures,in order to determine the optimal IM for the longitudinal seismic performance of tunnel structures under different site conditions.An improved nonlinear beam-spring model is developed to calculate the longitudinal seismic response of tunnels.The PQ-Fiber model is used to simulate the longitudinal nonlinear behavior of tunnel structures and the tangential interactions between the tunnel and the soil is realized by load in the form of moment.Five different site types are considered and 21 IMs is evaluated against four criteria:effectiveness,practicality,usefulness,and sufficiency.The results indicate that the optimal IMs are significantly influenced by the site conditions.Specifically,sustained maximum velocity(V_(SM))emerges as the optimal IM for circular tunnels in soft soil conditions(CaseⅠsites),peak ground velocity(V PG)is best suited for CaseⅡsites,sustained maximum acceleration(A_(SM))is ideal for both CaseⅢand CaseⅤsites,and peak ground acceleration(A PG)for CaseⅣsites.As site conditions transition from CaseⅠto CaseⅤ,from soft to hard,the applicability of acceleration-type intensity parameters gradually decreases,while the applicability of velocity-type intensity parameters gradually increases.
基金National Natural Science Foundation of China Under Grant No.51108105,90815029,50938006 Research Fund for the Doctoral Program of Higher Education of China Under Grant No.20094410120002+3 种基金 Major Program of National Natural Science Foundation of China Under Grant No.90815027Key Projects in the National Science&Technology Pillar Program during the Eleventh Five-Year Plan Period Under Grant No.2009BAJ28B03Fund for High School in Guangzhou (10A057)the Open Foundation of State Key Laboratory of Subtropical Building Science(2011KB15)
文摘Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.
基金Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant Nos.2016A05 and 2016A06the International Science and Technology Cooperation Program of China under Grant No.2014DFA70950the National Natural Science Foundation of China under Grant No.51378478
文摘Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelines suggest several confi gurations, they are diff erent from the designs that have been proven in practice, e.g., Japanese styles, and extensive experimental investigation into their seismic performance is required. Three types of seals, rubber-, metal- and asbestinebased, were tested quasi-statically with infi lled pressurized water at 2.5 MPa. The asbestine-based seal leaked at a smaller deformation than the other two types of seals. Based on the test results, three damage states were defi ned and the deformation capacity was estimated. To evaluate their performance, a three-dimensional model of a base-isolated medical building was developed using OpenSees, with the fl exible pipelines simulated by a mechanical model calibrated from the experimental data. A probabilistic seismic demand model and the fragility function of the fl exible pipelines were then developed to evaluate the seismic performance.
基金This work was supported by the Poliba2China Project Funding(Italy Code Number:CUPD96D17000110002)and the National Natural Science Foundation of China(Grant No.51878180)and the Transportation Science and Technology Development Project of Fujian Province(No.201803).
文摘Performance-based seismic design can generate predictable structure damage result with given seismic hazard.However,there are multiple sources of uncertainties in the seismic design process that can affect desired performance predictability.This paper mainly focuses on the effects of near-fault pulse-like ground motions and the uncertainties in bridge modeling on the seismic demands of regular continuous highway bridges.By modeling a regular continuous bridge with OpenSees software,a series of nonlinear dynamic time-history analysis of the bridge at three different site conditions under near-fault pulse-like ground motions are carried out.The relationships between different Intensity Measure(IM)parameters and the Engineering Demand Parameter(EDP)are discussed.After selecting the peak ground acceleration as the most correlated IM parameter and the drift ratio of the bridge column as the EDP parameter,a probabilistic seismic demand model is developed for near-fault earthquake ground motions for 3 different site conditions.On this basis,the uncertainty analysis is conducted with the key sources of uncertainty during the finite element modeling.All the results are quantified by the"swing"base on the specific distribution range of each uncertainty parameter both in near-fault and far-fault cases.All the ground motions are selected from PEER database,while the bridge case study is a typical regular highway bridge designed in accordance with the Chinese Guidelines for Seismic Design of Highway Bridges.The results show that PGA is a proper IM parameter for setting up a linear probabilistic seismic demand model;damping ratio,pier diameter and concrete strength are the main uncertainty parameters during bridge modeling,which should be considered both in near-fault and far-fault ground motion cases.
