The Corrosion Analysis Of Large-span Three-storey Steel Pipe Rhombic Truss Roof

With the wide application of large-span steel pipe truss structure, insiders realize that environmental corrosion leads to the destruction of the steel structure, and especially, the steel rust exerts great influence on the carrying capacity, stability and durability of steel structure. Many scholars at home and abroad have devoted themselves to the research of the steel rust’s influence on the steel properties. They hold that the corrosion of the steel pipe truss structure member can lead to the reallocation of its stress, and the corresponding change of the structure forced state causes the destruction of the structure. Based on Su Zhou Railway Station’s large-span three-storey steel pipe rhombic truss structure roof, the thesis sets up finite element model, set this roof as its research object, and analyze the static force and component force of the roof in the condition that the influence of atmospheric corrosion on section area of the roof truss member reduces gradually.1. According to the project background and engineering design instruction, the thesis employs afinite element software called "ansys" to build the roof model of dense drainage rhombic truss structure, analyze the dead weight of the roof structure and the finite element static force under the effect of a certain node, and compare the node displacement of the member.2. In view of the truss structure member section area due to different corroded degree such as1%、5%、10%、15%、30%, and finite element software "ansys", the thesis will carry out comparative analysis of the roof member node displacement in the direction of X,Y, Z and determine the relations between the reduction of the member section area and the member displacement to determine the influence of corroded degree on the deflection of the large-span dense drainage rhombic truss structure.3. In view of the truss structure member section area due to different corroded degree such as1%、5%、10%、15%、30%, and finite element software "ansys", the thesis will also carry out comparative analyses on internal forces of the middle chord, the lower chord and the bearing member, calculate the member stress, determine the relations between the member section area reduction and the member stress in order to determine corroded degree’s influence on reallocation of the internal force of large-span dense drainage rhombic truss structure member and the stability of the roof structure.4. The thesis will sum up its research and use effective data to prove that it is necessary to take measures of anticorrosion and timely reinforcement after the corroded degree had been determined, and put forward some feasible suggestions in this part.