Deflection of concrete members follows a bilinear curvature, and it can be affected by many different variables. Concrete members are often internally reinforced and/or tensioned, come in different shapes, and vary with regards to the ingredients and additives in the concrete. Despite these variations, engineers generalized concrete behavior and the ACI Code adopted these general procedures, though difficulties remain. Some research reported discrepancies between actual results and code predicted deflections. The Branson and Bischoff equations are currently in use for calculating Ie, but in reality, they also require calculations of y– and Icr, making the calculations of deflections lengthy and time consuming. In addition, the most recent ACI Code procedure is still dependent on curve fitting rather than a scientific basis.
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