Abstract
This paper presents the results of an experimental study of thirty-three simply supported reinforced concrete beams. The beams were monotonically loaded until failure, and the test variables in this study were the diameter of the openings, the distance between the openings, and the longitudinal reinforcement ratio. The percentages of the total opening area to the shear span area are 5.5%, 9.8%, and 15.3%, respectively, and the ratios of the diameter of the opening to the distance between the openings are 1, 2, and 3. Variations in the demand for shear forces are realized with three tensile reinforcement ratios of 0.7%, 1.0%, and 1.6%. The numerical method for obtaining the flexural capacity of reinforced concrete sections was carried out using the fiber element method. The test results show that the distance and size of openings in the shear span of the beam affect the crack pattern and failure mode significantly. It is shown that with an increase in the opening ratio and a decrease in the distance ratio, the shear capacity of the beam decreases. The fiber element method can predict the flexural response of the beams that failed in flexure with reasonable accuracy. Finally, based on the experimental data, a limitation for multiple openings with the function of area and distance between openings is proposed to ensure the safety of reinforced concrete structural elements.