Structural Behavior of HS-SC Reinforced Concrete Beams with Longitudinal and Transverse Openings Strengthened with CFRP Laminates


Service runs had produced several shortcomings when congested in one place. So, using longitudinal and transverse opening in beams (BLTO) was creative solution for the purpose of serve those runs with other benefits, especially when utilized high strength self-compacting concrete (HS-SCC). To control cracks in web opening regions which lead to possible leakage, carbon fiber reinforced polymer (CFRP) laminates was significant strengthening system to realize that purpose. This study examined the behavior of thirteen reinforced concrete (RC) beams. These beams were involved into three groups. All beams were identical in dimensions, reinforcement, concrete type, and hole dimensions. The evaluation is used to elect the optimum hollow core section, position effect of web openings with fixed hollow core section, and effect of strengthened web openings. Due to recorded load capacity, a reduction was produced by hollow core position at mid and bottom section by about (2%-14%), respectively, with comparing by solid section. Therefore, the optimum hollow core section was when it locate in mid beam section which used to unify BLTO sections. BLTO types indicated different loading data according to web opening position. The decrement of opening provision was about (20.4%) by compared with hollow beam (without web-opening) and about (22%) by compared with solid beam. The optimum BLTO is when the web opening located in mid-shear zone, while the critical one recorded in web opening position in mid-span and near supports in same BLTO. Presence of CFRP system in same BLTO copy had enhanced beam resistance by about (29%) and prevents cracks to reach in web opening or with minimum hairline cracks without delaminating problem. The registered failure mode of all beams was contained two main type, suddenly flexural failure in compressive zone by concrete cover crushing and flexural-shear failure. Additionally, local failure occurred at central CFRP strips by ripping-off concrete cover through the edges of it.