Reinforcement Requirements for Girder Web Openings

A method for determining the amount of, and the necessity for, reinforcement around large rectangular openings in the webs of wide-flange beams subjected to varying combinations of bending moment and shear is presented. The proposed method is based on the theory that a member having such openings located on the neutral axis acts as a Vierendeel truss in the vicinity of such openings and therefore has points of contraflexure above and below each opening at the center-line of the opening. Based on this theory, a number of sample beams of various geometric properties having various sizes of reinforced openings were fabricated and tested. The analytical investigations of laboratory data verified the analogy and suggested satisfactory configurations for the reinforcement of beams subject to varying combinations of bending moment and shear.