DESIGN OF PRESTRESSED CONCRETE BEAMS WITH OPENINGS

Web openings in beams occur quite often in practice to provide conveni ent passage of environmental services. As a result, story heights in b uildings can be reduced resulting in major cost savings. In this paper the nonlinear analysis and design of simply supported posttensioned p restressed concrete beams with rectangular openings are presented. Sev eral design parameters are varied such as: opening width and depth, ho rizontal and vertical locations of the opening, and type of cross sect ion. The results from a nonlinear finite-element analysis are substant iated by test results from 13 unbonded posttensioned prestressed concr ete beams, six of which are rectangular in section, five are T-section , and the remaining two are I-section. Good agreement is shown between the theoretical and the experimental results. The effect of the openi ngs on the behavior of such beams at different stages of loading is pr esented. A simple design method for estimating the ultimate failure lo ad for each type of failure mode is proposed. An illustrative design e xample is presented.