Experimental Studies On Flexural Behavior And Compressive Behavior Of Concrete Members Strengthened By UHPC

Construction Engineering has entered into the key period of reinforcement and transformation,conventional methods of reinforcement for RC concrete structure may have some drawbacks in some time.The excellent mechanical properties and durability of ultra-high performance concrete provide the possibility for its application in reinforcement.Two series of experiments studying the flexural behavior of RC beams strengthened by UHPC and the behavior of stub concrete columns strengthened by UHPC under axial compression were carried out to investigate the effect of UHPC used in reinforcement.Twenty specimens were included in experiments to study the flexural behavior of concrete beams strengthened with UHPC.The main parameters of experiments were different methods of reinforcement?thickness of reinforcement layer?strength of concrete and steel reinforcement ratio in tensile region of beam.The results showed that the reinforcement layer split from the concrete when the interface was not treated.The ultimate strength of specimens strengthened by UHPC exclusively did not improve comparing with the specimens unreinforced.With the thickness of UHPC-CFRP reinforcement layer increasing,the stiffness and ultimate strength of specimens increased obviously.Nineteen specimens were included in experiments to study the behavior of stub concrete columns with strengthened UHPC under axial compression.The main parameters of experiments included thickness of reinforcement layer?strength of concrete?steel reinforcement ratio and origin pressure on specimens.The results showed that with the thickness of reinforcement layer increasing,the stiffness and ultimate strength of specimens increased obviously,while the ductility of specimens decreased.Different strength of concrete and steel reinforcement ratio had little effect on strength of specimens strengthened by UHPC.Different origin pressure on specimens had little effect on ultimate strength of specimens in this experiments.The theoretical analysis of the test members was carried out considering the test material properties and existing analytical methods.The results of theoretical analysis were compared with the results of experiments to verify the accuracy of the theoretical analysis.Simplified formula was proposed for its application in practical projects.Finite element simulation analysis of specimens was carried out too.The results of finite element analysis were compared with the results of experiments to verify the accuracy of the finite element model,laying the foundation for the future analysis.