STUDY ON THE TORSION PERFORMANCES OF CONCRETE SPECIALLY SHAPED COLUMNS UNDER THE ACTIONS OF COMPRESSION, BENDING, SHEAR AND TORSION

One L-shaped column, four T-shaped columns and one +-shaped column were tested under the combined actions of compression, bending, shear and torsion to investigate their torsion performances. The influence of axial load ratio, torsion-shear ratio and sectional shape on the torsion behavior of specially shaped columns was analyzed. The numerical model for the torsion performances of specially shaped columns under the combined actions was established by finite element software, and the corresponding model parameters were suggested. The results show that within the scope of test parameters, the torsion performances of T-shaped columns are increased with axial load ratios and with torsion-shear ratios. With the increase of axial load ratios from 0.114 to 0.314, the ultimate torque and the ultimate torsion angle of T-shaped column are increased by 203.8% and 41.7%. With the increase of torsion-shear ratios from 0.57 to 1.34, the ultimate torque and the ultimate torsion angle of T-shaped column are increased by 62.9% and 112.5%. The effect of sectional shape on the cracking torque and the ultimate torque of specially shaped columns is complicated. The cracking torque and the ultimate torque are well predicted by the proposed finite element model.