Effect of Load Position and Concrete Compressive Strength on Reinforced Concrete Deep Cantilever Beams

Abstract

This study focuses on the effects of load position and concrete compressive strength on the structural response of reinforced concrete deep cantilever beams. Three groups of specimens with compressive strengths of 26, 33, and 41 MPa were analyzed. To evaluate the effect of load position, the load was applied at five locations along the cantilever portion of the deep beam, namely 100%, 80%, 60%, 40%, and 20% of the cantilever length. The study used the Finite Element Method (FEM) in ETABS, with numerical results compared to theoretical calculations based on the STM method, as required by ACI 318-25. The results showed that moving the load position from the farthest point in the cantilever part to 20% of its length increases the beam load capacity and reduces the maximum deflection by about 34-55% and 83-95%, respectively. It was also found that increasing concrete compressive strength increases load capacity and reduces deflection under different loading cases. The STM method also proved to be conservative when compared with the FEM results by about 30-67%, depending on the loading case. The novelty of this study lies in evaluating the combined influence of load position and concrete compressive strength on reinforced concrete deep cantilever beams through a comparative STM–FEM framework