Shear behavior of Reinforced Concrete (RC) beams with circular web openings without additional shear reinforcement

Abstract

The introduction of an opening into a Reinforced Concrete (RC) beam leads to a reduction to both the beam's stiffness and its overall structural capacity due to stress concentrations and local cracking around the opening. This paper uses both the experimental and finite element (FE) method to analyze the shear behavior of RC beams with opening. The shear span-to-depth ratios (av/d), opening size, and opening location were considered as the main parameters. The beams were divided into three series according to the shear span-to-depth ratios. Three reinforced concrete beams without openings and one beam with openings were tested experimentally under two-point loading. These beams were considered as control beams so as to validate the FE model using ANSYS14.5 software. A total of 31 specimens were analyzed using ANSYS14.5 while considering the above mentioned parameters. Results showed that the openings located in a high shear region (the line connecting the load and support points) led to the early collapse of the beam. In addition, by comparing the experimental results with those of the non-linear FE analysis, it was concluded that both results were in accordance. An analytical equation for predicting the shear strength of RC beams with circular openings was then proposed, and the obtained results later compared with those from FE model. Furthermore, the developed FE models can serve as a numerical platform for performance predictions of RC beams with different web opening geometries.