Experimental Study On Bending Performance Of Prestressed Reinforced Concrete Composite Beam

Prestressed reinforced concrete composite beam,combined with the characteristics of unbonded prestressed concrete structure,is constructed by prefabrication first,and then by post pouring concrete.The construction organization is more efficient,which can reduce the construction cost and enhance the industrialization degree of concrete beam.At present,the relevant research of prestressed reinforced concrete composite beam and the formulation of relevant specifications are relatively few.Based on this,the research and analysis of the flexural performance of prestressed reinforced concrete composite beams can promote the related research of composite beams and the formulation of relevant specifications.Based on the test results of six prestressed reinforced concrete composite beams and one reinforced concrete composite beam,the test data are processed and analyzed,and the calculation methods of crack resistance performance,crack width,short-term stiffness deformation and normal section bending capacity of prestressed reinforced concrete composite beams are proposed.The main work is as follows.(1)In this experiment,6 prestressed reinforced concrete composite beams and 1reinforced concrete composite beam are designed,and the prestressed reinforced concrete composite beam is studied under different parameters,such as the size of prestress,the form of prestressed reinforcement(linear type,parabolic type),the sequence of prestress application(the prestress is applied before and after the cast-in-place part of concrete pouring,that is,the prestress is applied to the precast beam and the whole beam respectively),the failure mode,crack resistance,crack generation and development law,bending stiffness and calculation method of bending bearing capacity of prestressed reinforced concrete composite beams are compared and analyzed.(2)Combined with the actual construction process of prestressed reinforced concrete composite beam,the stress and strain of the member section in the production stage,construction stage and use stage are analyzed,and the crack resistance checking calculation method in each stage is put forward.(3)The crack distribution and development of prestressed reinforced concrete composite beams with different design parameters are discussed.The improvement of prestress can effectively limit the crack development.The linear prestressed reinforced concrete composite beam has better effect than the parabolic prestressed reinforced concrete composite beam in limiting the crack development.The influence of prestress application sequence on the crack development is very small.Combined with the existing calculation methods,the calculation of equivalent stress of tensile reinforcement is deduced,and the calculation method of crack width of prestressed reinforced concrete composite beam is proposed.(4)According to the section characteristics of prestressed reinforced concrete composite beam,the section is divided into two parts,namely,peripheral concrete(including prestressed reinforcement,which is regarded as prestressed concrete)and section steel.(5)Based on the basic assumption and the calculation method of reinforced concrete beam,the calculation method of flexural capacity of prestressed reinforced concrete composite beam is derived.