小半径曲线钢箱梁步履式顶推局部受力及稳定性研究OA

Aiming at the complex internal force distribution problem in the incremental launching construction with walking joints of small-radius curve steel box girder bridges,this study focuses on the local stress and stability of steel box girders and proposes corresponding control methods based on the incremental launching of a 70 m radius ramp bridge.An overall analysis model was established by Midas/Civil software to simulate the whole incremental launching construction process.And the typical unfavorable working conditions were determined by the control indicators of the reaction force of temporary piers and the internal force of steel box girders;A local analysis model was established by shell elements to analyze the local stress and stability of the girder segments.The influence law of changes in main parameters on them was discussed.The results show that stress concentration occurs at the bottom of plate support and the root of the guide girder,while both the local stress and stability of the girder segments meet the requirements of relevant specifications;That increasing the thickness of the connecting structure plate of the guide girder can reduce the stress of the connecting web and significantly improve its local stability;The safe thresholds of the support height difference between the inner and outer fulcrums of the D3 temporary pier are 5 mm and 10 mm respectively.The fulcrum elevation should be strictly controlled during the construction;The structural safety still meets the requirements after reducing the stiffness of the base plate.The flexible materials for the upper base plate can improve the stress concentration at the bottom of plate;That adding corner stiffeners between the bottom plate and the web can greatly reduce the stress of each main force-bearing plate.