Study On Shear Resistance Mechanism And Shear Capacity Of Steel Reinforced Concrete Columns With Unsymmetrical Steel Section

This paper mainly studies the seismic performance, shear resistance mechanism and shear strength of steel reinforced concrete columns with unsymmetrical steel section by experiments and theoretical analysis.To study seismic behavior of unsymmetrical steel reinforced concrete column, cyclic loading tests were carried out on12columns with T-shaped section steel and12columns with L-shaped section steel. The test parameters included shear span ratio, axial compression ratio, stirrup ratio and presence of cross tie. Mechanical process, failure mode, hysteretic characteristics, skeleton curves, ductility and energy dissipation ability were taken into comparison. The failure mode contained bending failure, shear-bond failure, shear compression failure. The span ratio has great influence on failure mode and the specimen with high span ratio possesses good ductility. With increase of axial compression ratio, the ductility is decreasing, which is obvious in L-shaped steel section column. The ductility and bearing capacity of the T-shaped steel section columns improved greatly with increase of stirrup ratio, but not obvious for T-shaped steel section column with smaller span ratio. Cross tie can improve ultimate bearing capacity, limit strength attenuation and stiffness degradation and enhance deformation capacity of L-shape steel section columns clearly.According to the experimental research of seismic performance, the shear resistance mechanism and main influencing factors were analyzed. The load-strain curves of steel web and stirrup are acquired through the analysis of the failure mechanism. Based on the analysis of failure mechanism, the shear strength of T-shaped section was established. The results indicate that the typical failure patterns of the SRC columns with unsymmetrical steel section contains shear-bond failure and shear compression failure. According to the analysis of test data, the formula for calculation of the shear capacity of the reinforced concrete was proposed. Based on the strength superposition methods, the calculation formula of shear capacity was put forward under the modes of shear compression failure and shear-bond failure. The formulas agree well with test data, which provide references for practical engineering design.