Research On Overall Synchro Jacking-up And Translation Technology Of Fabricated Beam Bridge

With the continuous development of bridge construction,many active bridges no longer meet the requirements of the use function,they are badly in need of maintenance modification.For some medium and small span bridges which cross lines or are located in the busy areas,to seek a fast and economical transformation technology becomes a subject of great concern in the bridgework filed.Around a cross line fabricated beam bridge,this article presents a kind of overall transformation technique and uses numerical calculation and theoretical analysis of mechanics to research on the key processes which included synchro jacking-up and translation processes of the main beam of bridge.Besides,the stability of underpinned device is analysed.The main contents of this article are as follows:(1)Becausing of the limited transformation space under the fabricated beam bridge,it designs a rigid and flexible support integral underpinning device and focuses on the research on creep shock impact of moving crossbeam and concrete mainbeam which belonging to device.The structural dynamic equation is established which can reflect the interaction and friction coefficient between two beams.It clears the critical point of the upper slideway static and dynamic friction coefficient ratio that the moving crossbeam can keep up with the beam to be demolished.The numerical analysis is given to verify the results.At the same time,the dynamic stress change rule of concrete beam is presented.It is found that the maximum stress value is related to the relative position of the two beams.When the horizontal distance of moving crossbeam and the bottom beam reaches the minimum,concrete beam hanging point stress reaches the maximum.Besides,two measures are proposed to reduce the shock impact of beam.(2)Analysing the fatigue performance of the suspender which connected the upper moving crossbeam and the main beam,using the rain flow counting method and cumulative fatigue damage criterion to make the stress amplitude equivalent to the constant stress amplitude and obtain the fatigue cycle times of suspender by the fatigue S-N curve.(3)Establishing the space model of concrete beam,using the bending capacity as indicator,a variety of working conditions of horizontal jacking difference is designed and compared.Finally,it determined the the worst condition and gets the maximum allowable jacking difference of the bridge and provides guidance to ensure the safety of the project.(4)The static and dynamic stability of this underpinned device are analysed.The influences of friction coefficient,translation speed of main beam and gravity of main beam on the stability of underpinned device are considered.