| When the hybrid cable-stayed bridge is subject to construction conditions and other restrictions,the asymmetric cantilever construction method must be used.The unbalanced load on the main girders on both sides will produce a large additional moment at the tower girder consolidation point.It may endanger the safety of the structure,so the effectiveness and safety of the temporary consolidation of the tower and girder are worth studying.At the same time,the steel-concrete joint section is an important force transmission member of the hybrid cable-stayed bridge.When the construction technology of pouring steel fiber reinforced concrete first and then hoisting the steel-concrete joint section is adopted,the structural safety is also worthy of argumentation and analysis.Based on the engineering background of the Yinzhou Lake long-span cable-stayed bridge of Zhongkai expressway,this paper focuses on the temporary consolidation of the asymmetric cantilever construction of the hybrid cable-stayed bridge and the safety of the steel-concrete joint section.The specific work and main results are as follows:(1)Midas/Civil and FBR CAL SUO bridge calculation software are used to establish the finite element frame model of the whole process.The calculation results of the two are basically the same,which verifies the accuracy of the calculation model in this paper.The working condition of the maximum unbalanced moment when the tower girder is consolidated is obtained.(2)The finite element model of tower girder consolidation space was established by ABAQUS,and the influence of different reinforcement parameters on the calculation results of the model was analyzed.The calculation results showed that:the calculation results of the model considering the reinforcement meet the specification requirements;the inside of the main girder and the inclined floor are not considered.And the result of the manhole stress in the solid section exceeds the allowable stress of the material.Similar analysis should consider the influence of steel bars,otherwise the requirements may not be met.(3)Analyze the effect of different consolidation prestress losses on the simulation results.The results show that the loss of consolidation prestress has a greater impact on the longitudinal barrier and the standard section of the thin plate.When the loss of consolidation prestress reaches 30%,the longitudinal barrier stress reaches the ultimate tensile strength of the material;the transition between the main beam and the solid section is less affected During the construction,the loss of consolidation prestress should not exceed 30%.(4)Based on the previous research results,the elastoplastic damage constitutive of steel fiber reinforced concrete was constructed.In view of the uncertainty of the Zhang Jing formula method value corresponding to different materials,through the comparison of the tilt beam test results and the finite element analysis results,the study obtained a value suitable for 2%steel fiber volume ratio CF55 steel fiber concrete.(5)Using ABAQUS to simulate the lifting problem of the steel-concrete joint section of the poured concrete,the results show that:according to the original structure,the steel fiber reinforced concrete will be destroyed.To analyze the reason,it is proposed to strengthen under the lattice steel plate under the lifting ear to increase the structural rigidity under the lifting ear.After optimization,the stress near the nail hole of the steel fiber reinforced concrete is reduced from 4.16MPa to less than 0.5MPa,and the effect is significant.(6)The difference between the optimization effect of different stiffener height and thickness on the steel-concrete joint section during hoisting is analyzed,and the rules between the stiffener height and thickness and the stress of each structure is obtained.The combination of the rules gives a reasonable stiffener size. |
