Study On Mechanical Behavior Of Long-span Steel Truss Arch Bridge With Transverse Asymmetric Dead Load

In this thesis,a steel truss arch bridge with transverse asymmetric dead load is taken as the research object.By establishing the finite element model of the bridge,the mechanical behavior of the structure with transverse asymmetric dead load is studied,and the structural response of operation stage and construction stage is analyzed.Finally,the seismic response of structures with transverse asymmetric dead load is studied.The main research contents are as follows:(1)The finite element software MIDAS/CIVIL was used to establish the bridge model,and the structural stress and deformation under the four design stages were calculated and compared.The results show that under the condition of asymmetric dead load,the asymmetric arch rib structure and asymmetric tension of suspenders can eliminate the height difference between the arch crown and the two sides of the main beam under the action of dead load,to make the bridge structure achieve a good bridge structural alignment,achieving the purpose of "beam flat,arch upright ".(2)Under the ideal bridge state,the internal force,stress and displacement of the structure under the dead load,the main force load and the main force+ attached force load combination were analyzed by the one-time drop-frame bridge model.It shows that the structural strength meets the requirements of the specification.The deformation characteristics of bridge main beam and arch rib under dead load and live load were further analyzed,the pre-camber setting value of main girder was proposed,and then the internal force and structural alignment in the ideal bridge state were discussed.(3)The finite element model of the construction stage was established,the internal force and deformation of the structure in each construction stage were analyzed,and the key processes in the construction process were studied and corresponding prevention and control measures were put forward,and proper adjustment scheme of bridge internal force is determined through comparative analysis.(4)The natural vibration characteristics of the structure were calculated and analyzed,and the vibration mode characteristics of the bridge were analyzed.The response spectrum method and the time-history analysis method were used to analyze the seismic response law of the transverse asymmetric dead load structure of the bridge under different seismic excitations.