Study On Mechanical Behavior Of PCSS Shear Connectors Under Complicated Stress Condition

PCSS shear connector,as a new type of shear connection,adopts prefabricated construction to avoid the use of cast-in-place concrete,which can improve construction quality and construction efficiency.Relying on the Chongqing Natural Science Foundation "Research on the Mechanical Behavior of Fully Assembled Composite Beams Considering the Influence of the Complex and Multidimensional Forces of PCSS Shear Connector "(cstc2020jcyj-msxm1602),this paper reveals the influence of complex forces on the shear performance of PCSS shear connector.A refined finite element modeling method for PCSS shear connector was proposed,and the correctness of the modeling method was verified by the comparison with the experimental results.Based on the finite element model,the influence of the prestressing effect and the lateral bending effect of the wheel load on the shear performance of PCSS was studied,and the calculation method of the shear resistance of the PCSS under the complex force state was proposed.The main work and conclusions are as follows:(1)Based on the characteristics of production method of PCSS shear connector,a FEA modeling method considering the PCSS’s interface mechanical characteristics was proposed by ABAQUS: the cohesive zone model was used to simulate the bond-slip contact between the vertical side steel plate and the concrete,the tie constraint was used to simulate the contact between the stud and the concrete stud slot,the surface-to-surface contact with friction coefficient 0.6 and hard contact was used to simulate the contact between the bottom of the concrete rib and the top surface of the steel beam,and the effectiveness of the finite element modeling method was verified by experiments.(2)A experiment was carried out on the influence of whether there is adhesion bond between the vertical steel plate and the concrete slab on the shear resistance performance of PCSS.The results showed that the shear resistance of the F specimen with adhesion bonding characteristics is 11% higher than that of the N specimen without adhesion bonding characteristics,and the shear stiffness of single stud of the F specimen is 12%higher than that of the N specimen.It was verified that the existence of the adhesion bonding between the vertical steel plate and the concrete interface can significantly improve the shear stiffness and shear capacity of the PCSS shear connector,and the adhesion bonding must be considered in the finite element simulation.(3)The solid finite element model of PCSS shear connector was established.The influence of the arrangement height,arrangement number,tensile stress value of the prestressed tendons on the load-slip curve,shear capacity,shear stiffness,stud stress and concrete stress of the PCSS shear connector were analyzed in the solid finite element model of PCSS.It was revealed that the three prestress parameters have significant effects on the mechanical performance of the PCSS shear connector,but the transverse bending load caused by the vehicle has a limited effect on the mechanical performance of the PCSS shear connector,and the influence of the transverse bending effect can be ignored.(4)Under the prestressed state,the effects of concrete strength,stud strength,and stud diamete on the shear load slip curve and shear capacity of PCSS were carried out.The shear capacity of the PCSS shear connector is divided into two parts: stud shear contribution and steel-concrete interface shear contribution.And a formula for calculating the shear capacity of PCSS shear connector,which is composed of the contribution of studs and the contribution of the steel-concrete interface taking into account the influence of prestressing factors,was proposed.