Experimental Research On Anti-seismic Properties Of Steel Fiber Reinforced High-Strength Concrete Interior Joints With Different Steel Fiber Ratios

Steel fiber reinforced concrete is a newly emerging construction materials. Besides the advantages of solidity and high impermeability, it is, meanwhile, able to overcome the shortcoming of poor ductility due to the incorporation of steel fiber. Therefore, steel fiber reinforced concrete has been frequently used in major construction projects. Through the low reversed cyclic loading tests with one interior joint of high-strength concrete and three interior joints of steel fiber reinforced concretes, this thesis aims to explore the influence of ratio of steel fiber at beam ends in joint areas on stiffness, energy dissipation capacity and ductility and seismic performance of the joints.The main content of this thesis is as follows:(1) By the contrastive analysis of crack developments, bearing capacity changes and destruction shapes between the beam ends and the core areas of the specimens, it draws the following conclusion:the ratio increasement of steel fiber at beam ends has made their stiffness and anti-crack capacity strenghthened, however, this increasement has also made the crack developments at core areas of the joints speeded up and has made the stiffness and anti-shear capacity of the core areas decreased.(2) By the research on the deformation patterns of the beam ends and the core areas, it draws the c following onclusion:the ratio increasement of steel fiber at the beam ends has made the deformation capacity and plastic hinge rotation of beam ends reduced, which forces the plastic hinge penetrating to the core areas, and has made the shear deformation of the core areas increased.(3) By the analysis of the longitudinal reinforcements and stirrups strains of the specimens, it draws the following onclusion:the ratio increasement of steel fiber at the beam ends has made the longitudinal reinforcement of beam ends near the core area and the stirrups strains of core areas increased and has made the outer beam ends longitudinal reinforcement reduced.(4) By the contrasive analysis of hysteresis curves, skeleton curves, curve ductility, bearing capacity and stiffness degradation as well as the restoring force characteristics, such as energy absorption capacity and dissipation capacity of the joints of each specimen, it draws the following conclusion:the ratio increasement of steel fiber at the beam ends has made the ultimate bearing capacity and initial stiffness of the joints increased, but it has also made the ductility and energy dissipation capacity of the joints reduced, which has made the hysteresis curve tend to "pinch", and has made the bearing capacity and stiffness degradation of the joints accelerated as well as the overall seismic performance of the joints reduced.