Flexural Behaviour of Hollow Reinforced Concrete T-Beams

Abstract Hollow reinforced concrete Tee beam (HRCTB) is a beam that has longitudinal cavities that can be made usually by placing recycled plastic pipes in the web of beam within the tension zone. These cavities are used to pass electrical and mechanical equipment as well as the economic and sustainable benefits coming from subtraction some amount of concrete from these beams. This study tries to investigate experimentally the effect of circular cavities depth and its geometrical shape on the flexural behaviour of hollow reinforced concrete Tee beams. The experimental program comprises constructing and testing seven reinforced concrete Tee beams that have total height of 300 mm, flange width of 250 mm, flange depth of 75 mm as well as web width of 150 mm with beam length of 2000 mm. The first specimen is solid specimen while the others are divided into two groups, the first group consists of three specimens that have different longitudinal cavities depth which are 105 mm, 170 mm and 235 mm measured from top fibre of beam, and the second group includes three specimens that have different geometrical shape which are sharp parabolic (diameters are 35 mm by 65 mm), normal parabolic (diameters are 40 mm by 60 mm) and circular cavity of 50 mm diameter respectively. The results showed that increasing cavities depth from 105 to 170 and 235 mm from the top fibre of beam reduced the relevant first crack load by 3.57 %, 7.14 % and 17.86 % respectively and reduced ultimate strength by 0.39 %, 1.03 %, and 2.31 % respectively. In addition, the results revealed that the first crack load decreased by 3.57 %, 7.14 % and 7.14 % and ultimate load strength decreased by 0.26 %, 0.39 % and 1.03 % respectively for sharp parabolic, normal parabolic and circular specimen respectively.