BIAXIAL BENDING AND TORSION OF CONCRETE BEAMS

As no earlier test results on concrete beams in torsion combined with biaxial bending moments were available, the proposed theory was used for the correlation of the calculated and measured ultimate torques of the 69 rectangular cross-section beams tested in different combinations of torsion, biaxial bending moments and axial compression. A unified approach for the ultimate strength of plain, reinforced and prestressed concrete beams was developed by combining the skew bending theory and the space truss theory extended for the case of biaxial bending moments and axial compression acting in combination with torsion. The ratio of measured and calculated ultimate torques was 1.14 with a mean deviation of 0.17. This showed that the proposed theory is reasonably conservative and may therefore be used as a design tool. (TRRL)