Influence of a Longitudinal Circular Hole on Flexural Strength of Reinforced Concrete Beams: Fid-Bau Portal

Influence of a Longitudinal Circular Hole on Flexural Strength of Reinforced Concrete Beams

Murugesan, Arun

AbstractThe main aim of this investigation was to study the flexural strength of simply supported rectangular RC hollow beams (with a longitudinal circular hole) subjected to gradually increased and symmetrically applied two-point loads. Each hollow beam had a 25-, 40-, or 50-mm-diameter hole, and the position of the center of the hole also varied from 45 to 180 mm from the top. The cross section of the beam, the amount of longitudinal steel, and the transverse steel of the beam were kept constant. The same M20 grade of concrete was adopted for all of the beams. The shear span-to-effective depth ratio (av/d) of 2.69 was kept constant. Theoretical equations are developed, or existing equations are modified, to determine the first cracking load and the ultimate load of the beams. The influence of the hole on the strength of the beams is studied by taking into account the area and position of the hole. To examine the validity of the developed theoretical equation, 12 hollow RC beams and one solid RC beam were cast and tested to failure. The behavior and flexural strength of these hollow beams were compared with that of a solid RC beam that had the same outer dimensions and steel reinforcements. The flexural mode of failure was observed in all hollow RC beams tested. A comparison of experimental results shows that the developed theoretical model satisfactorily predicts the first cracking load and the ultimate flexural strength of hollow RC beams.