| The rail-road bridge with simply supported steel truss girder gets widely used for its advantages of lightweight construction,high stiffness,large loading,full use of natural resources,cost saving and excellent span capacity.For the road of steel truss girder bridge,out-of-plane bending of its steel crossbeam gradually dominates bridge design.Against the engineering background of a long span rail-road bridge with simply supported steel truss girder,this paper adopts finite element analysis software MIDAS/Civil2017 to establish the model of rail-road bridge with simply supported steel truss girder,finishes the linear control of top chord camber and road crossbeam lateral bending through comparative analysis of real data during the preloading construction,and completes optimization of road crossbeam lateral bending by means of comparative analysis.The research content of this paper can be divided into the following aspects:(1)This paper expounds the structure system and development of rail-road bridge with steel truss girder at home and abroad,and summarizes the present situation of manufacturing technology of rail-road bridge with steel truss girder.(2)This paper makes a summary of the necessity of preloading technology in bridge construction,and various preloading methods,then compares and analyzes the applicability of different preloading methods in bridge construction as well as their advantages and disadvantages.In addition,the engineering background,overall layout and design parameters of the bridge are introduced.Based on the preloading method of top chord,the pre-loading construction process and measurement scheme are explained in detail with a description of real data of both the top chord camber during different phases of preloading and crossbeam lateral bending during the removal of preloading force.(3)According to the principles of finite element modeling and the requirements of the requirements of top chord preloading construction,simulated-computation analysis model of the simply supported steel truss girder bridge is established on the finite element software MIDAS/Civil2017.Boundary conditions such as general support and elastic link are applied to represent the connection between components of the bridge under actualsituation.This paper elaborates on the content of the preloading construction stage,and analyzes the linear control of top chord camber during different phases of preloading and that of crossbeam lateral bending during the removal of preloading force involved in the deformation monitoring of simply supported steel truss girder bridge.(4)This paper gives an account of optimization purposes and criteria.Based on the theoretical framework of out-of-plane-bending theory during the preloading optimization analysis,it draws out various factors which influence the lateral bending of road crossbeam during construction,including preload value,the distance between longitudinal beam and top chord,welding position,longitudinal beam as well as longitudinal shortening amount in advance.Finally,optimal scheme is concluded under different influencing factors according to the influence of individual factor on crossbeam lateral bending in the process of the preloading construction,with the targeted analysis of finite element software simulated-computation. |
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