Study On The Performance Of Steel Reinforced High-Strength Concrete Columns Under Low Cyclic Reversed Loading

Steel reinforced high-strength concrete is a combination of steel and high-strength concrete. It is a new way for development of steel structures and concrete structures. This paper mainly studies the seismic performance, shear strength and bond-slip property of steel reinforced high strength concrete columns by experiments and theoretical analysis.Failure patterns, hysteretic curves, skeleton curves, ductile coefficients, energy dissipation and strength degeneration of steel reinforced high strength concrete columns are obtained by tests of 23 specimens with concrete strength from 65.4MPa to 84.9MPa under low cyclic reversed loading. The influences of shear span ratio, axial compression ratio, stirrup ratio and concrete strength on the seismic performance of steel reinforced high strength concrete columns are analyzed.The limit value of axial compression ratio of steel reinforced concrete columns with concrete strength grades from C65 to C80 is determined based on the equilibrium condition of force under balanced failure and test results, which satisfies certain requirement of ductility.The influences of shear span ratio, axial compression ratio, stirrup ratio and concrete strength on shear strength are discussed and the mechanism of shear-resistant of specimens is inquired. The formula of shear strength for different failure patterns of steel reinforced high strength concrete columns is put forward, and the practical formula is also presented.The measure method for bond stress between steel shape and concrete is found according to the load state of specimens. On the base of test results, the distribution law of bond stress along column is obtained and the formula of bond stress degeneration in the condition of reversed loading is put forward.Interior slip between steel shape and concrete along column is directly measuredand the hysteretic and skeleton curves of load-slip of steel reinforced high strength concrete columns is obtained in the utilize of a new type of slip transfer named "Embedded Electronic Steel-Concrete Slip Transfer" invented by task group. The distribution law of slip along column is also achieved.According to the distribution laws of bond stress and slip along columns, the constitutive relation as well as the resilience mode of bond-slip in low cyclic reversed loading is established.