Stress Analysis And Force Transfer Mechanism Of Steel-concrete Joint Section Of Hybrid Cable-stayed Bridge

The hybrid beam is more and more favored by engineering because it can give full play to the characteristics of concrete and steel and set the span ratio flexibly.The steel box girder of the main girder shall be connected with the prestressed concrete box girder in the steel-concrete joint section to achieve a smooth transition of stiffness and a smooth transfer of internal force,however,the structure of the steel-concrete joint section is relatively complex,and the force transfer path of the main beam in the steel-concrete joint section is not clear.If not handled properly,it will easily cause engineering safety risks.Therefore,it is very important to study the force transfer and performance of the mixed beam steel,which is one of the key technical problems to be further studied.This paper takes the construction of zhangjiakou jingkai district WEIER bridge as the engineering background,and on the basis of previous studies,it mainly does the following work:(1)MIDAS/CIVIL software was used to establish the whole bridge model of WEIER bridge.Boundary conditions,material characteristics,load selection and modeling process of the model were analyzed.Meanwhile,the stress and internal force distribution of the calculation results of the whole bridge was studied to verify the rationality of the whole bridge engineering design.The internal force of the steel box girder end section and the local model selection of the steel box girder end section are obtained through the software for the subsequent calculation of the model.(2)MIDAS/FEA finite element software was used to conduct finite element analysis on the steel-concrete joint,determining that the force in the steel-concrete joint was transferred from the steel box girder to the concrete,and calculating the stress distribution of each member in the steel-concrete joint under the most adverse load.(3)According to the established model of steel-concrete joint section,the section stress of each component of the steel-concrete joint section under the axial force is selected,and the force distribution of the section and the force transmission of the different sections of the steel-hybrid joint section are obtained by stress integration and the force transmission ratio changes,and then the force transfer mechanism of the steel box beam stiffening transition section and the steel-concrete joint section is determined,and the force transmission path of the roof bottom plate,the bearing plate and the PBL shear plate is clarified.(4)A local model of steel lattice at the bottom of the steel-concrete joint section was established.Based on the analysis of the ratio of force transfer,the influence of parameter changes on the ratio of force transfer was studied by setting three groups of parameter variables,namely,the thickness of bearing plate,the strength of concrete and the thickness of bridge deck.Based on the analysis of the force transfer ratio in the steel-concrete section,the most suitable parameter range for each member is determined.The reasonable thickness range of the bearing plate is 50mm-80 mm,the concrete strength is C40-C60,and the bridge deck is 25mm-40 mm.The above conclusions can provide a reference for the selection of the bearing plate thickness,concrete strength and bridge deck thickness parameters in the design of steel-concrete joint section of hybrid beam,and provide guidance for the construction of steel-concrete joint section by defining the force transmission path of steel composite section.