Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can b...Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.展开更多
traditional In this paper, two drawbacks pseudo-static method （vertical of the slice method） in the slope stability evaluation have been studied. First, the sliding mass is divided into vertical slices according to...traditional In this paper, two drawbacks pseudo-static method （vertical of the slice method） in the slope stability evaluation have been studied. First, the sliding mass is divided into vertical slices according to this method, which is irrational to some extent in the seismic design of slope. Second, only peak ground acceleration （PGA） is considered, and the effects of shaking frequency and duration on slope stability are neglected. And then, based on the theory of elastic wave and the summarized geological model, this paper put forwards an improved method of pseudo-method by using the theory of elastic wave and Hilbert-Huang transform. The improved pseudostatic method gives reasonable considerations to the time-frequency effects of seismic wave and its rationality has been verified by the shaking table test. This method can evaluate the safety of a slope, the happening time and the scale of landslides. At the same time, this method also can improve the high accuracy of the evaluation of the safety of the slope.展开更多
Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ens...Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.展开更多
Seismic design should quantitatively evaluate and control the risk of earthquake-induced collapse that a building structure may experience during its design service life. This requires taking into consideration both t...Seismic design should quantitatively evaluate and control the risk of earthquake-induced collapse that a building structure may experience during its design service life. This requires taking into consideration both the collapse resistant capacity of the building and the earthquake ground motion demand. The fundamental concept of uniform-risk-targeted seismic design and its relevant assessment process are presented in this paper. The risks of earthquake-induced collapse for buildings located in three seismic regions with the same prescribed seismic fortification intensity but different actual seismic hazards are analyzed to il- lustrate the engineering significance of uniform-risk-targeted seismic design. The results show that with China＇s current seis- mic design method, the risk of earthquake-induced collapse of buildings varies greatly from site to site. Additional research is needed to further develop and implement the uniform-risk-targeted seismic design aoDroach oronnsed in thi~ nnner展开更多
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.
基金supported in part by National Science Foundation of China (Contract NO. 41030742)Guangxi Science Foundation and the Program for Science & Technology of Henan Province in China (Grant No. 142300410200)
文摘traditional In this paper, two drawbacks pseudo-static method （vertical of the slice method） in the slope stability evaluation have been studied. First, the sliding mass is divided into vertical slices according to this method, which is irrational to some extent in the seismic design of slope. Second, only peak ground acceleration （PGA） is considered, and the effects of shaking frequency and duration on slope stability are neglected. And then, based on the theory of elastic wave and the summarized geological model, this paper put forwards an improved method of pseudo-method by using the theory of elastic wave and Hilbert-Huang transform. The improved pseudostatic method gives reasonable considerations to the time-frequency effects of seismic wave and its rationality has been verified by the shaking table test. This method can evaluate the safety of a slope, the happening time and the scale of landslides. At the same time, this method also can improve the high accuracy of the evaluation of the safety of the slope.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90815021,50725826)
文摘Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90815025,51178249)the Tsinghua University Research Funds (Grant Nos. 2010THZ02-1,2010Z01001)the Program for New Century Excellent Talents in University (Grant No. NCET-10-0528)
文摘Seismic design should quantitatively evaluate and control the risk of earthquake-induced collapse that a building structure may experience during its design service life. This requires taking into consideration both the collapse resistant capacity of the building and the earthquake ground motion demand. The fundamental concept of uniform-risk-targeted seismic design and its relevant assessment process are presented in this paper. The risks of earthquake-induced collapse for buildings located in three seismic regions with the same prescribed seismic fortification intensity but different actual seismic hazards are analyzed to il- lustrate the engineering significance of uniform-risk-targeted seismic design. The results show that with China＇s current seis- mic design method, the risk of earthquake-induced collapse of buildings varies greatly from site to site. Additional research is needed to further develop and implement the uniform-risk-targeted seismic design aoDroach oronnsed in thi~ nnner
