Deflection of Reinforced Concrete Beams with Longitudinal Circular Hole

Abstract

The main aim of this investigation was to study the behavior of simply supported rectangular RC beams with longitudinal circular hole subjected to gradually increased and symmetrically applied two-point loads. Each hollow beam had a 25-, 4-, or 5-mm diameter hole, and the position of center of hole also varied from 45 to 18 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 M2 grade of concrete was adopted for all of the beams. Theoretical equations were developed or existing equations were modified by taking into account the area and position of holes to determine the maximum deflection at precracking and postcracking stages of the RC hollow beams. To examine the validity of the developed theoretical equations, a total of 76 RC hollow beams and 1 RC solid beams were cast and tested up to failure. Also, the behavior of these hollow beams was compared with RC solid beams having the same outer dimensions and reinforcements. The behavior of all of these beams was studied by measuring deflections and observing crack patterns. The comparison shows that the developed theoretical model satisfactorily predicts the maximum deflection at pre- and postcracking stages of RC hollow beams.