Structural Behavior of Concrete Deep Beams Reinforced with Steel Ducts

Abstract

The aim of the research is to investigate the structural behavior of deep beams with a longitudinal opening reinforced by steel pipes. The experimental program included a test of (10) specimens with dimensions of (1500mm) length, (500mm) overall height and (250mm) width. One of these specimens was casted with solid section (without longitudinal opening) to keep it as a reference specimen for comparison purposes. The variables considered in this research were, the shape of the openings (circular, square, and rectangular) was adopted, opening size (three variable sizes of circular openings 4in,3in, and 2in) were used, in addition to the void’s ratio. The Load-deflection curves and crack patterns for the tested beams were discussed. The experimental results showed that the structural behavior of specimens with circular openings was approximately equal to the reference beam, where it gave efficiency about (103%) with respect to the reference beam. The specimens with square and rectangular openings gave an average load carrying capacity about (81%-35%) respectively with respect to the reference beam. Also, its noticed that the specimens containing rectangular openings were inefficient and caused early collapse. Using of steel pipes to reinforce the longitudinal opening was observed to be efficient for improving the load carrying capacity and stiffness of deep beams, the results showed that the ultimate load was increased by 22.6% compared to the beam with unreinforced opening.