In modern construction the existence of openings in RC beams becomes a major engineering challenge especially when the construction system subjected to torsion. Accordingly, the main aim of this paper is to judge the possibility to use internal in-plane near opening strengthening technique (NOST) to improve the RC box beams’ torsion capacity. Seven beam specimens of dimensions (1800x300x300mm) were tested under the pure torsion; six were containing transverse web opening with dimensions of (100x100mm), while, the last beam specimen is poured without opening and considered as a reference. Variables investigated were including, the presence or absence of web opening, the position of web openings (at L/4 or L/2), the presence or absence of in-plane diaphragms and the number of in-plane diaphragms (one and two). The experimental results have shown the ultimate torque decreased by approximately (35% and 45%) for the tested specimens which contained web openings at a distance of respectively (L/4) and (L/2), compared to the reference beam. The ultimate torque was increased by approximately (5% and 82%) for the tested specimens which contain a web opening at (L/4) and strengthened by one and two inplane diaphragms respectively. The ultimate torque was increased by approximately (21% & 57%) for the tested specimens which contain a web opening at (L/2) and strengthened by one and two in-plane diaphragms respectively. It can be concluded that torsional capacity has been deteriorated due to the existence of web opening, and it has been enhanced due to the contribution of the adopted technique.
Volume 12 | Issue 4