BEHAVIOR AND DESIGN OF PRESTRESSED CONCRETE BEAMS WITH LARGE WEB OPENINGS.

Results of tests on 18 full-size prestressed, pretensioned concrete tee beams representing one-half of a structural double tee section are reported. The variables investigated were opening size, location of opening along the span, type and amount of web shear reinforcement, and amount of primary flexural reinforcement. Behavior of beams with openings was found to be similar to that of a Vierendeel truss. For the sizes of openings studied, distribution of shear force above and below an opening was dependent on the relative flexural stiffnesses of the struts. Based on these findings, a method of analysis was established. Criteria for strength design are presented and a fully worked numerical example is included to illustrate the application of the proposed design method.