| Compared with the steel-concrete composite beam with traditional mechanical connectors,the adhesive steel reinforced concrete composite beam has the advantages of avoiding stress concentration,continuous interface force transmission,no welding,suitable for prefabricated assembly construction and reducing the risk of longitudinal cracking of concrete slabs,but the bond-slip effect of the interface cannot be ignored.Therefore,on the basis of considering the bond-slip effect,this thesis studies the bending performance of bonded steel-concrete composite beams.The research method used in this thesis is the combination of mechanical test and numerical calculation.First of all,the basic properties of the material are obtained by material performance test.Then,the push-out test was carried out to obtain the shear performance,failure mode and phenomenon of different adhesives,and the results were compared with existing results.The bond-slip relationship of adhesive shear connectors was obtained.The load-strain curve and load-slip curve were analyzed.Theoretical distribution of stress in pushout test is obtained by numerical calculation.Subsequently,the composite beam test was carried out to compare and analyze the influence of parameters such as the thickness and type of adhesive layer,the thickness of concrete slab.The failure mode and phenomenon were obtained and compared with the stud composite beam.The plastic limit load was calculated,and the load-strain relationship,the strain distribution of the mid-span section,the mid-span deflection and the slip distribution along the beam length were analyzed.Finally,two numerical models for bonded steel-concrete composite beams are established.According to whether the interface bond-slip is considered or not,they are divided into perfect bond model and relative slip model.Finally,the finite element software is used to study the numerical simulation method suitable for adhesive composite beams,and the calculation results are compared with the measured results to verify the accuracy of the prediction.The results show that,(1)The average shear strength of the epoxy resin connector on the natural flat surface is 4.068 MPa,at a good level.It is a rigid connector with good stability.Under the condition of good connection,it can be regarded as an ideal perfect connection,which can ensure the uniform and continuous transmission of shear force.(2)Appropriately increasing the thickness of the adhesive layer is conducive to the bearing capacity of the structure.When the adhesive layer is 6mm,the composite beam with good connection will not be debonding,the bearing capacity is higher than that of the stud composite beam,the stiffness is large,the deformation is small,and the failure mode is close to the ideal plastic limit state.On the premise of similar bearing capacity,adhesive shear connectors can reduce the thickness of concrete slabs,reduce weight and increase span.(3)The finite element simulation results can well predict the measured results,and when the adhesive layer thickness is greater than 4mm,the stress state of the structure is close to the ideal state of the finite element simulation,and the bearing capacity is not less than the calculated value.The results of numerical analysis method can better predict the measured results,in which the partial bond model considering the bond-slip effect is more in line with the actual situation of the adhesive composite beam,and the degree of agreement is high.Both numerical models and finite element models can provide reference for the same type of research. |
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