Research On Failure Mechanism Of Steel Arch Bridge With Box Ribs And Its Design Method

Instability and earthquake damage are two typical failure modes of steel arch bridge with box ribs, in structural static and dynamic failure mechanisms areas. So far, many scholars researching static and dynamic failure mechanism of steel arch bridge mainly use truss structure models. Bending-curvature model or elastic-plastic large deformation fiber model is used to calculate the result of structural damage form, which ignores the steel plate of local buckling. However, the cross-section of the box-shaped steel arch ribs by a thin steel plate, local buckling of the steel plate is the main reason for the failure caused the steel bridge truss structure theory can not consider the impact of the steel plate local instability, therefore, decided that this method does not precisely simulation of structural failure process.At present, the common model domestic and foreign scholars used to study the steel arch bridge is fiber and beam element model, which can not consider the deformation and buckling of local steel plate. On the other hand, research result about3D shell model of steel box arch bridge is obtained relatively less. Design codes and methods of the steel arch bridge have not been completely established in many countries. In order to study on the failure mechanism of steel arch bridge in more depth and to put forward the design proposal of useful, for this purpose, this paper mainly studies the following:(1) The failure mechanism of a through arch bridge with two asymmetric steel-box-ribs, in application of the finite element program (ABAQUS) to analyze the static characteristics and nonlinear failure mechanism of this bridge. By changing the load arrangement, the thickness of the arch rib steel plate, the difference between the shell model and fiber model are compared, and the proposed stability safety factor is given.(2) To establish the finite element model of steel box section, failure mode of steel box structure is analyzed under different axial force and horizontal load. And the average strain of damage area at limit state is obtained. Using section model is relatively simple to design a steel arch bridge with box ribs, and it will make useful suggestion in the design process.(3)The nonlinear seismic failure mechanisms of a large-span steel box bridge is researched, with the application of finite element program (ABAQUS) analysis on a fine3D full-bridge shell model. With different seismic wave input, the difference between the shell model and fiber model are compared. And then method of the average ultimate compressive strain to evaluate seismic damage is proposed. But the accuracy need to be improved.