Performance of Reinforced Concrete Gable Beam with Quadrilateral Openings of Different Side Inclinations

Civil Engineering Department, University of Baghdad, Baghdad, Iraq

^a* Corresponding author mohammed.mohammed2001d@coeng.uobaghdad.edu.iq
^b amer.f@coeng.uobaghdad.edu.iq

Abstract

The existence of openings in a gable beam would have numerous advantages, the most important of which would be a reduction in the overall weight. These advantages include geometric flexibility, ease of handling when erected, and more. This study aims to investigate the flexural behavior of reinforced concrete gable beams with quadrilateral openings of different side inclinations; this goal has been specified with beam stiffness, the maximum load-carrying capacity, and strains of the beams. Beams are identical in their dimensions and reinforcement. The experimental program involved casting and testing four simply supported beams: a solid beam (reference beam) and others with quadrilateral openings. They were 3000mm long, 100mm wide, and 400 mm deep in the middle, tapering to 250 mm on both ends, concentrically loaded. The results demonstrate the load-carrying capacity is reduced by 6.1–12.9%, and the mid-span deflection is increased by 13–52% when openings exist compared to the solid gable beam. Enhancement represented by increases in strength and decreases in deflection was observed when the inclination of the quadrilateral side opening decreased from 90 to 60 and then 45o, respectively. In contrast, the total opening area was maintained. The creation of openings in concrete gable beams can reduce their weight by about 12.5%.