Study On Flexural Behavior In Normal Section Of Reinforced Concrete/HPFRCC Composite Beams

High Performance Fiber Reinforced Cement Composite(HPFRCC)is a kind of engineering material with high strength,high ductility and high durability.The ultra high tensile strain capacity and excellent crack control ability,can effectively overcome the shortcoming of low tensile strength,easy cracking and the crack width is difficult to control in reinforced concrete.The material has important meanings to increasing the bearing capacity,durability and earthquake-proof of structure.The article uses HPFRCC to replace parts of concrete in the tension zone of the ordinary reinforced concrete beam to make reinforced concrete/ HPFRCC composite beam.Based on four-point banding test of composite beams,a series of studies on flexural performance of the beams were made.The main research contents are as follows:(1)The bending process,the development rule of cracks and failure mechanism of reinforced concrete/ HPFRCC composite beams and reinforced HPFRCC beam are described.(2)The influence of PVA fiber content by volume,longitudinal reinforcement ratio,thickness of HPFRCC layer and strength of HPFRCC/concrete on load-deflection curves,load-Longitudinal reinforcement strain curves,the cracking load,yielding load and ultimate load and deformation capacity on reinforced concrete/ HPFRCC composite beams are studied.The effect of HPFRCC in tension region is considered,the theoretical formula is proposed,and the experimental value have good agreement with theoretical value.(3)Based on the calculation formula of average crack distance of ordinary concrete beam,and combined with the mechanic features and crack development feature of reinforced concrete/ HPFRCC composite beam,the calculation models for the average crack spacing of the same level of steel bar and the upper concrete of reinforced concrete/ HPFRCC composite beam are set up.The various influencing factors was analyzed.