Design of reinforced concrete beams with small openings under combined loading

A method is presented for strength design of reinforced concrete beams that contain a small opening and are subjected to combined torsion, bending, and shear. The proposed method recognizes two different types of failure, labeled as beam-type and frame-type failures. The design for the beam-type failure is accomplished on the basis of the familiar skew-bending theory for torsion in concrete beams. Using the Australian approach, the problem of combined loading is reduced to the usual flexural and shear design procedures. For frame-type failure, recommendations are given on the basis of available information to achieve a satisfactory design. The method is illustrated by a numerical example.