Design Formulas for Cracking Torque and Twist in Hollow Reinforced Concrete Members

Abstract

Hollow concrete members are in wide use and are becoming increasingly important in terms of energy savings and carbon reduction. To date, the prediction of cracking torque in hollow reinforced concrete (RC) members still relies on simplistic empirical formulas, and the accuracy of the existing formulas is rarely examined. In this study, four existing formulas are used to calculate the cracking torques Tcr and twists qcr of 44 hollow RC beam specimens currently available in the literature. An existing empirical formula for Tcr is modified to fit the test values. Based on the latest rational formula for solid members, a new formula for the Tcr and qcr of hollow RC members is developed to form a unified formula for solid and hollow sections. The predicting accuracies of these formulas are compared and evaluated. It is shown that the proposed formulas produce significantly more accurate and reliable predictions than the existing formulas.