Structural Behavior of Reinforced Concrete Stepped Beams: Experimental and Numerical Study.

Stepped beams are non-prismatic structural elements designed to distribute stress at the stepped joints. To prevent sudden failure, these joints must be adequately detailed. This study includes an experimental analysis of the structural performance of reinforced concrete stepped beams. The experimental program comprised seven reinforced concrete beams, each beam was tested under a four-point loading setup. The study examined three key parameters: step height, configuration, and location, with each variable systematically investigated. Using step heights less than, equal to, or greater than the beam depth resulted in reductions in failure load of 34%, 35%, and 40%, respectively. Incorporating haunching along the tension face at the step location significantly improves the structural performance of the beam, whereas haunching within the compression zone exhibits negligible influence on overall behavior. It is strongly recommended to position steps within shear critical zones, as this strategy consistently enhances the overall structural performance of the beam. A nonlinear finite element model was developed using ANSYS to simulate the behavior of reinforced concrete stepped beams. Seven models, identical to those tested experimentally, were constructed. Crack patterns and failure modes were illustrated, and load–deflection plots were generated. The analytical results demonstrated strong correlation with the experimental findings, confirming the validity of the proposed model.