Research On Bilateral Shear Strength Of Rectangular Frame Columns Under Seismic Action

Experimental results about shear strength of reinforced concrete rectangular frame columns under oblique horizontal seismic action had been published by domestic and overseas researchers in decades. It is indicated that the correlation of shear strength between X and Y axis of rectangular frame column with same or different stirrup area on two principal axes can be approximately described as a correlation equation of ellipse by analyzing these results. The bilateral shear strength of rectangular frame column can be calculated according to the correlation relationship of bilateral shear strength. Based on test results of oblique shear strength of rectangular frame columns and correlation of bilateral shear strength, some conservative calculation methods for bilateral shear strength of rectangular frame columns were put forward by the domestic researchers. For that reason, searching for the methods more suited to calculate the bilateral shear strength of rectangular frame columns with different stirrup area on two principal axes was necessary.To investigate the correlation relationship of bilateral shear strength of rectangular frame column without stirrup and with different stirrup area on two principal axes, the regression analysis based on the experiment results of 5 rectangular frame columns without stirrup and 7 rectangular frame columns with different stirrup area on two principal axes was made. By analyzing the experimental data of the columns, it is showed that the correlation relationship of shear strength of rectangular frame columns without stirrup and with different stirrup area on two principal axes can be approximately described as ellipse.Combined with experimental data of frame columns, three major design methods of shear strength were compared. It is shown that these methods can safely calculate bilateral shear strength of rectangular frame column by comparing the results between calculation and experiment. Moreover, according to the formula of bilateral shear strength of frame column offered by Design Code of Concrete Structure, the calculation results of bilateral shear strength of rectangular frame column with different stirrup area on two principal axes were safe.Considering the effect of the axial compression term and stirrup term on shear strength, a reduced coefficient of bilateral shear strength of rectangular frame column without stirrup was introduced to calculate bilateral shear strength of rectangular frame columns with different stirrup area on two principal axes under low-cyclic reversed horizontal load by based on the above conclusion. The comparison between the calculation and test results was made, which showed that the formula is feasible and safe. Compared with the calculation of the proposed formula and CODE formula, it is shown that the calculation of the former was closer to the test results. Considering seismic action combination, recommend formulas and section restrictive condition for calculations of bilateral shear strength of rectangular frame column with different stirrup area on two principal axes were put forward by means of applying simplified calculation methods of bilateral shear strength of frame column.