Evaluating the interaction for embedded H-steel section in normal concrete under monotonic and repeated loads

This article presents an experimental investigation into alternative strategies for enhancing the interaction of H-shaped steel sections embedded in normal reinforced concrete. Utilizing 12 push-out specimens subjected to monotonic and repeated loading, the study examines the natural bond-effecting parameters and shear transfer mechanisms facilitated by studs. Key parameters under investigation include embedded length, confinement stirrups, concrete cover, and variations in stud welding configurations, specifically welding to the flange and both the flange and web. In summary, a mathematical model for bond slip was proposed. In enhancing steel‒concrete interaction, adding 10-mm-diameter studs to both flanges and the web of the steel section is more effective than increasing the embedded depth by 67%. The second most effective method is doubling the concrete cover, followed by increasing the stirrups ratio by 40%. However, adding studs just to flanges outperforms solely increasing the stirrups ratio under repeated loading but does not match the effectiveness of other enhancement parameters. Yet notable shift from brittle to ductile behavior by introducing shear studs attached to flanges. The study also explores the influence of loading type on natural bond, noting lower values (13–18%) in ultimate load and (8–18)% in residual load capacities under repeated loading compared to monotonic loading, this drop is effectively mitigated by shear stud connections, particularly on the flange.