EFFECT OF EXISTING FLANGE OPENINGS AND COLD JOINTS ON STRENGTH OF RC T-BEAMS

Abstract

In the construction of modern buildings, a network of pipes and ducts is necessary to accommodate essential services like water supply, sewage, air-conditioning, electricity, telephone, and computer network. Passing these services vertically required creating openings in slab (Flanges of T-Beams) after or before construction.New researches show that the concrete flanges provide a certain level of shear resistance above a certain width. Therefore, due to existing of these openings or cold joints in slab (Flange) and abrupt changes in the sectional configuration, opening corners are subject to high stress concentration that may lead to reduction in stiffness of the T-Beam and produced cracking and excessive deflection.In the present research, shear behavior of reinforced concrete T-Beams which contains vertical opening (Flange openings) or cold joints at the flanges are studied as well as the effect of openings or cold joints locations. Eight beams were tested, one of which were constructed without any openings or cold joints (reference beam), while, the others were constructed with openings or cold joints in different locations.Experimental results show that the presence of flange openings reduce the shear capacity about (22% to 32%) for beams containing one opening and about (17%-39%) for beams containing two openings. For beams containing cold joints, the shear capacity decreased about (27%) in comparison with reference beam.