Ultimate Bearing Capacity Research On The Improved Rigid-frame Concrete Arch Bridge

The rigid-frame concrete arch bridge which is a light structure includes the characteristics of the traditional arch bridge as well as the modern characteristics of the current bridges. However, there is grate difference between current codes and the standard design which regulated by the Research Institute of Highway and the Highway Survey and Design Research Institute of Hunan Province in 1983, and the original standard design doesn't meet the demands of the new codes. So, the study on the based improved type becomes urgent.Based on the Yanzhou SiRiver Bridge in Jining City, Shandong Province, this article studies the improvement measures and the ultimate bearing capacity. Because of the typical and general diseases of existing rigid-frame arch bridge, the research of optimization of design parameters is carried out. On one hand, the following parameters proceeded: the main bearing figure, the arch axis, the rib distance, the span, the rise-span ratio. Therefore, the conclusions are listed as follows: increasing the main bearing figure can improve the mechanics feature of structures; decreasing the rib distance can strengthen the lateral connection of the whole bridge; it's more suitable to use the parabola; with the increasing of the span, the axial force and moment are both increased; when the rise-span ratio changes from 1/6 to 1/12, the axial force is decreased. On the other hand, on the basis of the spatial stabilization theory, nonlinear theory, single material's constitutional relationship under the unified theory of the finite element method. The finite element model about the improved design of the engineering and the standard design are established. And then, the first stability theory problem of the improved design and the standard design according to the whole bridge and one arch rib of single span are analyzed. The ultimate bearing capacity can be carried out by using double nonlinear method in the case of regarding the eigen-value about the first stability problem as the maximum. A useful conclusion is drawn that the ultimate bearing capacity of the same kind of bridge can obviously promote by the improved design.This study can offer a technical guide for the improved design of rigid-frame concrete arch bridge in future, and also can provide a favorable reference to the evaluation of ultimate bearing capacity and safety for the rigid-frame arch bridge.