Analysis On Incremental Launching Construction Process And Bridge Operation Of PC Box Girder Bridge With Corrugated Steel Webs

As a new type of composite structures, prestressed concrete box girder bridge with corrugated steel webs has the increasing number of applications in the domestic.Its construction methods are multiple, but there is little precedent for incremental launching method, the correlative calculation and analysis is relatively less. This paper, which is relying on Longhai Road fast-track project Changzhuang Reservoir viaduct in Zhengzhou City, researches on the incremental launching of PC box girder bridge with corrugated steel webs, the main work and conclusions are as follows.1. To introduce the main material and parameters, the structure of the girder, the setting of the corrugated steel webs, the technique standards for design and the construction method of Changzhuang Reservoir Bridge. The finite element model of the whole bridge is established by using special software for bridge Midas/Civil, the section properties, calculation assumptions and simplification of the model, boundary conditions and load cases in the course of modeling are explained in detail. Moreover,clearing the specific incremental launching construction stage of the bridge to provide a good theoretical basis for the next finite element analysis.2. To simulate analysis on the incremental launching construction process of the bridge model is carded out. Firstly the overall calculation of the construction process is made. The results show that the stress of the main girder section meets the requirements of the specification and the internal force value of the girder section is reasonable. The vertical displacement of the launching nose is also within the controllable range, so the structure construction can be carried out smoothly. Then the construction process’ s analysis of the key stages is carried. It is pointed out that the three cases which include maximum launching nose cantilever, maximum launching nose and girder cantilever, lapping the front pier of launching nose should pay special attention to. The research on the maximum bending moment value of the girder shows that with the push of construction, the mechanical behaviors of the structure will tend to be stable. The checking result of the shearing stress shows that the corrugated steel webs can bear all the shear forces if the concrete roof and bottomplate are not subjected to the shear force of the main beam in the process of construction.3. To study on the mechanical properties of the bridge in operation stage. Aimed at the separate action of the load condition of the bridge in operation stage, the results of analysis shows that the temperature stress generated by the gradient temperature reaches more than half of the live load and it’s necessary to pay attention to its influence on the internal force and the stress of the structure. The load combination of the integral checking of the bridge is compiled into a table. Then the stress and deformation of ultimate limit state and serviceability limit state are checked and the results satisfy the demand of the code. The shear stress value of the key nodes is given according to the load combinations of corrugated steel webs under design load and ultimate load. Its value is less than the allowable shear stress of steel, meeting the design requirements of structural shear design.