Deflections of reinforced concrete beams with transverse openings of different geometries

The present study pertains to the in-plane bending deflections of reinforced concrete beams with multiple regular transverse openings along the beam length. The total deflections in the beam were obtained from bending deflections and the additional deflections from the Vierendeel panel action. The accuracy of the deflection estimates from the proposed formula were observed to depend on the opening geometry. Among different geometries, the presence of rectangular and parallelogram web openings resulted in the experimental deflections to deviate more considerably from the analytical values due to the stress concentrations around the corners of the openings. Consequently, a multiplier was incorporated into the deflection formula to account for the opening geometry. The new revised formula was found to generate analytical load-deflection curves in close agreement with the experimental ones and service-load deflections close to the FEA values of beams with varying amount of tension reinforcement. The diagonal reinforcement around the openings and the short stirrups in the posts and chords increased the accuracy of the analytical deflection estimates by reducing the undesired additional deformations in the beam due to the poorer integrity of the posts and chords around the openings.