Abstract
Test results of 13 rectangular plain high-strength concrete beams subjected to pure torsion are presented. The variable was the concrete strength, with the nominal concrete strength ranging from 40 to 90 MPa (5800 to 13,000 psi). Coarse aggregate with high crushing strength and sand having a high fineness modulus were used along with a Type I portland cement. The plain high-strength concrete beams under torsion failed suddenly and violently along a smooth surface. The skew-bending theory is found suitable for predicting the torsional capacity of plain high-strength concrete beams, provided that the splitting tensile strength is taken to represent the concrete tensile strength.