Study on the Design of Main Girder of Wide Steel Box Girder Cable-Stayed Bridge with Single-Column Pylon

With the increasingly strict requirements of railway safety, the span of municipal engineering bridge over the railway is gradually increasing. In order to solve the construction problems of crossing high-speed railway and large-scale railway marshalling station, a long-span single column central cable-stayed bridge was taken as the research object, and the main beam design was studied in detail. The cross railway channel is generally a scarce channel resource, with many traffic functions and wide bridge deck. If the concrete section is used, its transverse stress is difficult to effectively control and the construction quality is difficult to guarantee. The process of steel-concrete composite beam is complex and needs to be pointed out to the Railway Administration for a long construction time. Considering that it is convenient to cross the railway and minimize the impact on the railway, and at the same time reduce the weight of swivel as far as possible, steel box girder was recommended as the main beam structure form of railway crossing bridge. According to the layout of stay cables and the types of integral and split steel box girder, three kinds of transverse arrangement of steel girder were compared and selected. Due to the low height of pylon and pylon of single column bridge, the stay cables arranged on both sides of steel box girder would incline into the traffic lane clearance. Meanwhile, there is still the risk of vehicles or foreign matters falling into the railway under the bridge in the separation of steel box girder central guardrail area. The whole steel box girder structure with central cable plane was recommended form. On the basis of determining that the main beam structure of cable-stayed bridge was the whole steel box girder, the height of steel box girder was further optimized. Taking the stress state of cable-stayed bridge structure and steel consumption as the optimization objectives, three kinds of steel box girder beam height schemes were preliminarily selected, with the section height of 3.0, 3.3, 3.5 m respectively.
Considering the stress state of the structure and the engineering economy, the 3.3 m beam height scheme was the best configuration for the stress of main beam and pylon and the saving of engineering materials. In order to study the mechanical performance of wide steel box girder, the design and research of wide steel box girder cable-stayed bridge with single column pylon was carried out. Based on the limit state method, the static load calculation and fatigue analysis of steel box girder were carried out. The static load analysis included the determination of loading mode, stiffness condition of steel box girder bridge deck and other indicators. Based on ANSYS, the spatial local stress analysis of standard steel box girder and steel box girder in ballast area was carried out. The fatigue calculation was carried out by selecting a reasonable fatigue load model and considering different loading positions of fatigue load comprehensively. The results of static load calculation and fatigue check showed that the static load deformation of steel box girder of bridge and the stress met the requirements of the code, the fatigue stress amplitude of each component and connection was less than the standard limit value, and there was appropriate safety margin, and the fatigue performance was good. In this paper, a hybrid finite element model was established by using the mixed finite element method of member system and plate shell. The shear lag effects of the mid span section, the intersection area of pylon and beam and the auxiliary pier area of side span in the control area of single column wide steel box girder cable-stayed bridge were analyzed, and the parameter indexes were extracted, which played an important guiding role in the design. The main girder of single column pylon wide steel box cable-stayed bridge has good economy and aesthetics, which could provide reference for long-span and wide bridge deck structure.