A State-of-the-Art-Review on Performance RC Beams with Openings

The inclusion of web openings in reinforced concrete (RC) beams has become increasingly necessary to accommodate utility services like electrical wiring, plumbing, HVAC systems, and network cables. However, these openings significantly influence both the serviceability and strength of RC beams. In the service stage, they reduce stiffness, leading to increased deflection. At the ultimate stage, they cause stress concentrations due to the disruption of stress flow around the opening area. This geometric discontinuity can lead to premature failures if not properly addressed. Researchers have proposed various methods to counteract the reduction in strength and stiffness caused by openings. This paper reviews recent developments in the behavior and strengthening of RC beams with web openings. Openings are classified based on size, shape, position, orientation, and the stage at which they are introduced. Typical failure modes, such as flexural and shear failures, are also discussed. Among different shapes, circular openings perform better due to smoother stress distribution. Beams with openings in the flexural region generally show improved behavior compared to those in shear zones. Strengthening techniques using ferrocement and strain-hardening cementitious composites (SHCC) have proven effective. The study highlights the importance of considering web openings during the design phase to enhance structural performance and avoid unexpected failures. Key Words: Reinforced concrete beams, web openings, structural performance, serviceability, stress concentration, strengthening techniques.