Experimental Evaluation of ACI and AASHTO-LRFD Design Provisions for Combined Shear and Torsion

摘要

The experimental results from four large nonprestressed specimens loaded in combined shear and torsion are used to evaluate the torsion design procedures of ACI 318-02 and AASHTO-LRFD. Both sets of procedures calculate the required amounts of hoop reinforcement for torsion based on a space truss model with compression diagonals inclined at an angle of 9 to the longitudinal axis. It is shown that the ACI provisions give very conservative results if the recommended value of 45 degrees is used for θ. If the lower limit of 30 degrees is used, however, some unconservative results are possible. The AASHTO-LRFD provisions predicted values of θ of approximately 36 degrees for these specimens and gave accurate estimates of the strengths.