Numerous recent investigations have concentrated on improving the structural efficiency and reliability of concrete structural elements. This experimental study investigates the structural behavior of reinforced high‐strength concrete (HSC) columns incorporating hybrid steel‐polypropylene (PP) fibers under eccentric axial loading. Thirteen column specimens were tested to evaluate the effects of longitudinal and transverse reinforcement ratios, slenderness ratio, fiber type, and load eccentricity. The applied eccentricities corresponded to eccentricity‐to‐thickness (e/t) ratios of 0, 0.16, 0.34, 0.5, and ∞. Parameters such as vertical and lateral deformations, ultimate load capacities, failure modes, and ductility were measured and analyzed. Experimental results indicate that the hybrid fiber system enhanced both load capacity and deformation capacity compared to single‐fiber systems. Steel fibers (SF) contributed more significantly to the load‐bearing capacity, whereas PP fibers had a limited structural effect, primarily enhancing crack resistance and post‐peak ductility. Moreover, columns with hybrid fibers exhibited higher load capacity than those with only polypropylene fibers by up to 13.65%, while SF provided the primary contribution to load resistance. Increasing the longitudinal reinforcement ratio enhanced load capacity by up to 47%, whereas increasing the slenderness ratio reduced it by up to 26.9%. Increasing load eccentricity had the most pronounced effect, reducing axial capacity by up to ~83%. A load–moment (P–M) interaction diagram was developed based on the experimental results and showed reasonable agreement with code‐based predictions.
AMRELSAID et al. (Thu,) studied this question.