Research On Mechanical Properties Of Steel-Concrete Joint Of Ultra-Wide Hybrid Beam Cable-Stayed Bridge

Based on the engineering background of Zhangjiakou Wei’er Bridge,an ultra-wide hybrid girder cable-stayed bridge that has already been built,this paper firstly analyzes the stress conditions of the whole bridge model in the bridge state and the operating state,and determines the joint section of the hybrid girder.The internal force and stress distribution are applied to the local refined finite element model,and the steel-concrete joint section is analyzed in detail to study the stress distribution of each member in the joint section and the internal force of the member under the most unfavorable load.The force transfer ratio problem.Finally,the parameters of the bearing plate and the PBL shear member are analyzed,and the influence of the construction deviation of the stay cable on the force of the joint section is analyzed.The main research contents and results are as follows:(1)The concept and development history of the hybrid girder cable-stayed bridge are introduced,the research status of the hybrid girder cable-stayed bridge is summarized,the structural classification and characteristics of the steel-concrete joint section are expounded,and the main work of this paper is explained.(2)The spatial rod system model of the full bridge was established by Midas Civil finite element software.In the bridge state and operation state,the stress situation of Zhangjiakou Wei’er Bridge was analyzed,and the internal force and the steel-concrete joint section were extracted.Stress distribution,which provides force and displacement boundary conditions for subsequent detailed analysis.At the same time,by changing the span ratio of the concrete beam and the steel box beam,the reasonable position of the steel-concrete joint section is studied and analyzed.(3)The local refined finite element model of the steel-concrete joint is established by ANSYS software,and the boundary conditions obtained in the previous stage are equivalently applied to the local model.The stress distribution of each member of the steel-concrete joint section under the most unfavorable load is studied.(4)The slip differential equation of the steel-concrete joint section under load is deduced,and the internal force borne by each component is calculated by means of integration and accumulation,and then the proportion of the internal force borne by the component and the force transmission of the shear connection are studied.analyze.Then,by changing the parameters of the bearing plate and the PBL shear key,the parameters of the steel-concrete joint section are analyzed.The internal force of the steel beam can be effectively transmitted to the concrete beam through the steel-concrete joint.Among them,the effect of the PBL shear connector in transmitting the axial force is better than that of the shear nail.shape distribution,and changing the parameters properly can effectively exert the force transmission performance of the steel-concrete joint section.(5)By changing the initial tension of the stay cable and the inclination angle of the back cable,the mechanical properties of the steel-concrete joint section considering the construction error of the stay cable are studied,and the factors that affect the initial tension are obtained through sensitivity analysis,and then Continue to study and analyze the influence of the initial tension of the stay cable on the members of the steel-concrete joint.The change of the initial tension of the stay cable will no change the overall distribution of the stress of the steel-concrete joint.In the operating state,the stress of the steel-concrete joint is more sensitive to the increase of the initial tensile force of the stay cable.The stress is more sensitive to the decrease of the initial tension of the stay cable.