For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new ty...For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new type floating bridge, the pontoon-separated floating bridge, under the effect of a moving load. In the paper, a brief summary of the dynamic analysis of the floating bridge is first introduced. The motion equations for a pontoon-separated floating bridge, considering the nonlinear properties of connectors and vehicles＇ inertia effects, are proposed. The super-element method is applied to reduce the numerical analysis scale to solve the reduced equations. Based on the static analysis, the dynamic features of the new type floating bridge subjected to a moving load are investigated. It is found that the dynamie behavior of the pontoon-separated floating bridge is superior to that of the ribbon bridge by taking the nonlinearity of eonneetors into account.展开更多
The floating bridge bears the dead weight and live load with buoyancy,and has wide application prospect in deep-water transportation infrastructure.The structural analysis of floating bridge is challenging due to the ...The floating bridge bears the dead weight and live load with buoyancy,and has wide application prospect in deep-water transportation infrastructure.The structural analysis of floating bridge is challenging due to the complicated fluid-solid coupling effects of wind and wave.In this research,a novel time domain approach combining dynamic finite element method and state-space model(SSM)is established for the refined analysis of floating bridges.The dynamic coupled effects induced by wave excitation load,radiation load and buffeting load are carefully simulated.High-precision fitted SSMs for pontoons are established to enhance the calculation efficiency of hydrodynamic radiation forces in time domain.The dispersion relation is also introduced in the analysis model to appropriately consider the phase differences of wave loads on pontoons.The proposed approach is then employed to simulate the dynamic responses of a scaled floating bridge model which has been tested under real wind and wave loads in laboratory.The numerical results are found to agree well with the test data regarding the structural responses of floating bridge under the considered environmental conditions.The proposed time domain approach is considered to be accurate and effective in simulating the structural behaviors of floating bridge under typical environmental conditions.展开更多
When high voltage is applied to distilled water filled into two beakers close to each other, a watery connection forms spontaneously, giving the impression of a floating water bridge [1-8]. In this work we present the...When high voltage is applied to distilled water filled into two beakers close to each other, a watery connection forms spontaneously, giving the impression of a floating water bridge [1-8]. In this work we present the first inelastic ultraviolet scattering data of such an electrohydrodynamic bridge revealing radial gradients of Stokes- and Anti-Stokes shifts and their intensity profiles. Interpretations including density and temperature changes within the bridge are discussed. The obtained data can be satisfactorily explained by the introduction of a second phase consisting of nano bubbles. Results and interpretation are discussed in relation to similar phenomena.展开更多
A mathematical model of a ribbon pontoon bridge subjected to moving loads was formulated using the theory of simply supported beams.Two types of moving load models were used, the first a moving-constant-force model an...A mathematical model of a ribbon pontoon bridge subjected to moving loads was formulated using the theory of simply supported beams.Two types of moving load models were used, the first a moving-constant-force model and the second a moving-mass model.Using both types of loads, the dynamic behavior of a ribbon pontoon bridge was simulated while subjected to a single moving load and then multiple moving loads.Modeling was done with the Simulink package in MATLAB software.Results indicated that the model is correct.The two types of moving load models made little difference to the response ranges when loads moved on the bridge, but made some difference to the response phases.When loads left, the amplitude of the dynamic responses induced by the moving-constant-force model load were larger than those induced by the moving-mass model.There was a great deal more difference when there were more loads.展开更多
In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the trans...In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the transverse direction of bridges.When adding longitudinal ductile diaphragms,a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge’s longitudinal and transverse axes.This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces（BRBs）in straight multi-span bridge with simply supported floating spans.The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered.Design procedures for the bidirectional ductile diaphragms are first proposed.An analytical model of the example bridge with bidirectional ductile diaphragms,designed based on the proposed methodology,is then built in SAP2000.Pushover and nonlinear time history analyses are performed on the bridge model,and corresponding results are presented.The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated,in order to better understand the impact on the bridge’s dynamic performance.展开更多
The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed...The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed Floating Two-stage Buffer Collision-Prevention System(FTBCPS).The actual anti-collision effect of the current designed FTBCPS can be evaluated by the dynamic simulation.The construction method of 3D model is introduced,and the system initial state is defined.The transformation matrix and the basic kinematics vector are given,and the system basic dynamics equation is then created.The mechanical analysis on each component is carried out,and the detailed process of numerical simulation is also given.The simulation results indicate that collision direction and collision position have a great influence on the system kinematic response.Bridge pier faces the greatest threat when a ship hits the floater on the front beam in a nearly vertical direction,or on the side beam in a larger course angle.The study shows that the current designed FTBCPS can make full use of the fracture tensile property of polyester ropes and keep the tensile force acted on pier within its bearable range at the same time.The collision direction has a significant effect on the dynamic response of the colliding bodies,but no failure appeared in the simulations,which indicates that the current designed FTBCPS can protect bridge piers of all cases for the 5000-t ship with a velocity smaller than 5 m/s in navigable waters.展开更多
A NFFP HVI structure which implements high breakdown voltage without using additional FFP and process steps is proposed in this paper. An 850 V high voltage half bridge gate drive IC with the NFFP HVI structure is exp...A NFFP HVI structure which implements high breakdown voltage without using additional FFP and process steps is proposed in this paper. An 850 V high voltage half bridge gate drive IC with the NFFP HVI structure is experimentally realized using a thin epitaxial BCD process. Compared with the MFFP HVI structure, the proposed NFFP HVI structure shows simpler process and lower cost. The high side offset voltage in the half bridge gate drive IC with the NFFP HVI structure is almost as same as that with the self-shielding structure.展开更多
There are two types of floating bridge such as discrete-pontoon floating bridges and continuous-pontoon floating bridges. Analytical models of both floating bridges subjected by raoving loads are presented to study th...There are two types of floating bridge such as discrete-pontoon floating bridges and continuous-pontoon floating bridges. Analytical models of both floating bridges subjected by raoving loads are presented to study the dynamic responses with hydrodynamic influence coefficients for different water depths. The beam theory and potential theory are introduced to produce the models. The hydrodynamic coefficients and dynamic responses of bridges are evaluated by the boundary element method and by the Galerkin method of weighted residuals, respectively. Considering causal relationship between the frequencies of the oscillation of floating bridges and the added mass coefficients, an iteration method is introduced to compute hydrodynamic frequencies. The results indicate that water depth has little influence upon the dynamic responses of both types of floating bridges, so that the effect of water depth can be neglected during the course of designing floating bridges.展开更多
基金This project was supported by the Commission of Science Technology and Industry for National Defense .
文摘For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new type floating bridge, the pontoon-separated floating bridge, under the effect of a moving load. In the paper, a brief summary of the dynamic analysis of the floating bridge is first introduced. The motion equations for a pontoon-separated floating bridge, considering the nonlinear properties of connectors and vehicles＇ inertia effects, are proposed. The super-element method is applied to reduce the numerical analysis scale to solve the reduced equations. Based on the static analysis, the dynamic features of the new type floating bridge subjected to a moving load are investigated. It is found that the dynamie behavior of the pontoon-separated floating bridge is superior to that of the ribbon bridge by taking the nonlinearity of eonneetors into account.
基金financially supported by the Program of Science and Technology Innovation Action Plan,Shanghai,China(Grant No.20200741600).
文摘The floating bridge bears the dead weight and live load with buoyancy,and has wide application prospect in deep-water transportation infrastructure.The structural analysis of floating bridge is challenging due to the complicated fluid-solid coupling effects of wind and wave.In this research,a novel time domain approach combining dynamic finite element method and state-space model(SSM)is established for the refined analysis of floating bridges.The dynamic coupled effects induced by wave excitation load,radiation load and buffeting load are carefully simulated.High-precision fitted SSMs for pontoons are established to enhance the calculation efficiency of hydrodynamic radiation forces in time domain.The dispersion relation is also introduced in the analysis model to appropriately consider the phase differences of wave loads on pontoons.The proposed approach is then employed to simulate the dynamic responses of a scaled floating bridge model which has been tested under real wind and wave loads in laboratory.The numerical results are found to agree well with the test data regarding the structural responses of floating bridge under the considered environmental conditions.The proposed time domain approach is considered to be accurate and effective in simulating the structural behaviors of floating bridge under typical environmental conditions.
文摘When high voltage is applied to distilled water filled into two beakers close to each other, a watery connection forms spontaneously, giving the impression of a floating water bridge [1-8]. In this work we present the first inelastic ultraviolet scattering data of such an electrohydrodynamic bridge revealing radial gradients of Stokes- and Anti-Stokes shifts and their intensity profiles. Interpretations including density and temperature changes within the bridge are discussed. The obtained data can be satisfactorily explained by the introduction of a second phase consisting of nano bubbles. Results and interpretation are discussed in relation to similar phenomena.
文摘A mathematical model of a ribbon pontoon bridge subjected to moving loads was formulated using the theory of simply supported beams.Two types of moving load models were used, the first a moving-constant-force model and the second a moving-mass model.Using both types of loads, the dynamic behavior of a ribbon pontoon bridge was simulated while subjected to a single moving load and then multiple moving loads.Modeling was done with the Simulink package in MATLAB software.Results indicated that the model is correct.The two types of moving load models made little difference to the response ranges when loads moved on the bridge, but made some difference to the response phases.When loads left, the amplitude of the dynamic responses induced by the moving-constant-force model load were larger than those induced by the moving-mass model.There was a great deal more difference when there were more loads.
文摘In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the transverse direction of bridges.When adding longitudinal ductile diaphragms,a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge’s longitudinal and transverse axes.This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces（BRBs）in straight multi-span bridge with simply supported floating spans.The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered.Design procedures for the bidirectional ductile diaphragms are first proposed.An analytical model of the example bridge with bidirectional ductile diaphragms,designed based on the proposed methodology,is then built in SAP2000.Pushover and nonlinear time history analyses are performed on the bridge model,and corresponding results are presented.The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated,in order to better understand the impact on the bridge’s dynamic performance.
基金financially supported by the National Natural Science Foundation of China(Grant No.51679250)the High-Tech Ship Research Projects Sponsored by Chinese Ministry of Industry and Information Technology(Grant No.[2019-357]).
文摘The collision of ships poses a great threat to the piers in navigable waters.The kinetic energy of the moving ship can be consumed not only with the structural deformation,but also with tensile force from the proposed Floating Two-stage Buffer Collision-Prevention System(FTBCPS).The actual anti-collision effect of the current designed FTBCPS can be evaluated by the dynamic simulation.The construction method of 3D model is introduced,and the system initial state is defined.The transformation matrix and the basic kinematics vector are given,and the system basic dynamics equation is then created.The mechanical analysis on each component is carried out,and the detailed process of numerical simulation is also given.The simulation results indicate that collision direction and collision position have a great influence on the system kinematic response.Bridge pier faces the greatest threat when a ship hits the floater on the front beam in a nearly vertical direction,or on the side beam in a larger course angle.The study shows that the current designed FTBCPS can make full use of the fracture tensile property of polyester ropes and keep the tensile force acted on pier within its bearable range at the same time.The collision direction has a significant effect on the dynamic response of the colliding bodies,but no failure appeared in the simulations,which indicates that the current designed FTBCPS can protect bridge piers of all cases for the 5000-t ship with a velocity smaller than 5 m/s in navigable waters.
基金This work was supported by the National Nature Science Foundation of China under Grant No.60436030.
文摘A NFFP HVI structure which implements high breakdown voltage without using additional FFP and process steps is proposed in this paper. An 850 V high voltage half bridge gate drive IC with the NFFP HVI structure is experimentally realized using a thin epitaxial BCD process. Compared with the MFFP HVI structure, the proposed NFFP HVI structure shows simpler process and lower cost. The high side offset voltage in the half bridge gate drive IC with the NFFP HVI structure is almost as same as that with the self-shielding structure.
基金the National Natural Science Foundation of China (Grant No. 50379026).
文摘There are two types of floating bridge such as discrete-pontoon floating bridges and continuous-pontoon floating bridges. Analytical models of both floating bridges subjected by raoving loads are presented to study the dynamic responses with hydrodynamic influence coefficients for different water depths. The beam theory and potential theory are introduced to produce the models. The hydrodynamic coefficients and dynamic responses of bridges are evaluated by the boundary element method and by the Galerkin method of weighted residuals, respectively. Considering causal relationship between the frequencies of the oscillation of floating bridges and the added mass coefficients, an iteration method is introduced to compute hydrodynamic frequencies. The results indicate that water depth has little influence upon the dynamic responses of both types of floating bridges, so that the effect of water depth can be neglected during the course of designing floating bridges.
