Static And Dynamic Analysis And Security Evaluation Of Trestle Bridge Under High Flow Velocity And Mass Peddles Condition

Construction environment with high flow velocity and mass peddles explains the existing of complex forces on temporary trestle bridge.However,present researches rarely focus on studying on this surrounding environment that high velocity of water flow accompanies with mass peddles.Thanks to the absence of relevant regulations and rules,traditional strategies generally refer to similar engineering construction experience in the static calculation of bridge,which missed the significant influence caused by flow and peddles dynamics.In order to find out the extent of impact that dynamic load of water flow and peddles work on bridge.This thesis,based on an empirical analysis of the Xi Gu Yellow River Bridge Project,will consider flow load and impact load of peddles and both static and dynamic forces on bridge's foundation will be analyzed under the very condition of high water flow and mass peddles.Moreover,bearing capacity and security might decrease due to the complexity stress,thus,security evaluation are needed on this situation.This thesis,firstly focus on the static analysis of trestle bridge,which follows the traditional calculation methods ignoring the effects of hydrodynamic force and peddles.Secondly,we calculated the hydrodynamic load and peddles' impact load based on Morison Equation and Hertz Theory.Once the length of time is given,a function equation of the action range and effort of water flow about time will be deduced.Then,we measured the diameters and impact force of peddles under different water flow conditions.As a periodic force,approximate curve diagram of impact forces and time has been gained.Thirdly,we analyze the dynamic force of trestle bridge concerning the hydrodynamic force and peddles' impact.Finally,there comes out a comparing between the static and dynamic force analyses,which shows the effect law and influencing degree of water current and peddles work on trestle bridge.Security evaluation is made on the basis of the specific project.When flood spreads,the flow velocity and depth of water will change all the time,thus the action range and effort of water flow that bridge's foundation experienced is dynamic changed.As the water flow speed up,peddles will move with the stream,which might dash on trestle bridge's foundations as a result.Therefore,it is clearly that the trestle bridge's foundation is affected by the combined action of hydrodynamic force and peddles on the very condition.According to the research,our study objects are highly qualified with security satisfaction,but its security coefficient will descend by the effects of hydrodynamic force and peddles' impact which might cause the vibration of bridge's foundation and increase both axial stress and transverse displacement.That is to say,the effect of hydrodynamic force and peddles' impact should not be ignored when conduct projects on the Yellow River or others with similar construction environment.Also,much attention should be attached by the government to perfect relevant regulations or standards.