BILATERAL SHEAR STRENGTH OF RECTANGULAR FRAME COLUMNS UNDER LOW-CYCLIC REVERSED HORIZONTAL LOAD

摘要

To study bilateral shear strength of rectangular frame column (RFC) under low-cyclic reversed horizontal load,12 rectangular frame columns including 5 columns without stirrup and 7 columns with stirrup were tested.The loading angle of columns without stirrup is 0,30,45,60 and 90 degree respectively,and that with stirrup is 0,15,30,45,60,75 and 90 degree respectively.The analytical results indicated that the relationship of shear strength between two principal axes of RCF without stirrup could be approximately described as ellipse,and stirrups on two principal axes were independent. The oblique shear strength is less than the resultant force calculated by unilateral shear strength formula offered by Code for Design of Reinforced Concrete Structure. The reason for this is shear strength contributed by concrete is considered iteratively on two axes. Based on truss model and the above conclusion,a reduced coefficient is introduced to calculate the bilateral shear strength contributed by concrete and the axial force,and then a formula is proposed to calculate bilateral shear strength of RFC under low-cyclic reversed horizontal load. Comparison between the calculation and experimental results shows the formula is feasible and safe.