Effect of an Opening on Reinforced Concrete Hollow Beam Web Under Torsional, Flexural, and Cyclic Loadings

Abstract Hollow sections have been increasingly applied in the construction of buildings, bridges, offshore structures, and towers for passing electrical and mechanical pipes or other utilities. Torsion caused by external force is a weakness of hollow sections that is rarely investigated. In particular, the behavior of hollow sections with high-strength concrete (HSC) and ultra-high performance concrete (UHPC) remains poorly studied. This study aims to examine the behavior of a reinforced concrete hollow beam with opening and compare it with a hollow beam without opening. The hollow beam with an opening is modeled using the finite element method and analyzed under torsional, flexural, and cyclic loading with HSC and UHPC materials. The effect of the opening section size on the behavior of hollow beam is also evaluated. The openings created in the web of hollow beams led to a decrease in beam capacity although the hollow beam with small opening can carry almost the same load as that of hollow beam without an opening. The result also shows that the capacity of UHPC beams for twisting is twice that of HSC beams