Experimental Study On Shear Behavior Of Prestressed Reinforced Concrete Composite Beams

Prestressed Reinforced Concrete Composite Beam(PRCC),which is composed of precast and cast-in-place parts,combines the advantages of Prestressed Reinforced Concrete Beam and Concrete Composite Beam.It has the characteristics of small dead weight,high bearing capacity,large stiffness,good crack resistance,environmental protection and high construction efficiency.At present,there is a lack of relevant research on prestressed reinforced concrete composite beams,and no relevant norms or regulations have been formulated,which greatly restricts the application and popularization of PRCC beams.Therefore,this paper carries out experimental research and theoretical analysis on the shear performance of PRCC beams.Based on 8 prestressed reinforced concrete composite beams shear performance test,studied the different shear span ratio,prestressing degree,size,arrangement of prestressed reinforcement and prestressed reinforcement imposed order on PRCC beam shear bearing capacity and deformation parameters,such as the influence law of PRCC beam under concentrated load are analyzed under the different shear span ratio of failure process and form,the crack propagation law,load-deflection curve and the material load and strain curve.The test results show that the shear capacity of PRCC beams decreases with the increase of shear-span ratio.The prestress can improve the crack resistance and ultimate bearing capacity of PRCC beams,but it does not increase the ultimate bearing capacity much.The effect of the sequence of prestressing tendons on the stiffness and shear bearing capacity of PRCC beams is very small and can be ignored in practice.Arrangement of prestressed reinforcement of PRCC beam stiffness and shear bearing capacity and the influence of shear span ratio,shear span is small,linear horizontal prestressed reinforcement is greater than the effect of the parabolic vertical reinforcement,with the increase of shear span ratio,this effect gradually reduced,linear and parabolic combination of specimen showed good stiffness and ultimate bearing capacity;The PRCC beam has a good cooperative working ability.The precast part and the cast-inplace part can be reliably connected into a whole.In the test process,no obvious slip was observed on the contact surface between the steel and concrete as well as the old and new concrete,showing good overall working performance.Respectively using the current specification,the ACI 318-14 specifications and based on the superposition method and considering the deformation coordination of truss arch model method of PRCC beam shear bearing capacity calculation and comparison,the results show that the current specifications and the ACI 318-14 standard calculation results of an old-fashioned,based on the superposition method and considering the deformation coordination of truss arch model derivation of PRCC beam shear bearing capacity calculation formula of calculation result has good agreement with the test results.Therefore,the research results of this paper can provide theoretical reference for the engineering application and popularization of PRCC beams.