PSI - Issue 70

Saravanakumar P. et al. / Procedia Structural Integrity 70 (2025) 533–539

534

E-mail address: psaravana2000@gmail.com

In certain cases, beams may not have enough resistance to shear forces, especially in instances where the loading is concentrated or the depth of the beam is limited. Shear failure in beams is typically sudden and brittle, making it one of the most undesirable forms of structural failure. Thus, enhancing the shear strength and ductility of RCC beams through optimized reinforcement strategies is a crucial area of investigation. Traditional design codes such as IS 456:2000, ACI 318, and Eurocode 2 provide general guidelines for shear reinforcement, but emerging studies suggest that alternate configurations can offer improved performance in terms of load-carrying capacity, crack control, and energy dissipation. Several researchers have explored the effects of various shear reinforcement layouts. For instance, Sharma and Sharma (2017) investigated the use of inclined stirrups and concluded that they offer better resistance against diagonal shear cracking compared to vertical stirrups. Similarly, Al-Shaarbaf et al. (2019) demonstrated that hybrid stirrup systems can delay crack propagation and improve post-cracking behavior under cyclic loading. Li et al. (2021) conducted experimental investigations on different integrated shear reinforcements, providing quantitative data on load-carrying capacity and crack control. More and Mohite (2023) explored the use of wire mesh as shear reinforcement, offering a novel approach that improved crack distribution. Meanwhile, Hassan et al. (2012) focused on the behavior of high-strength steel reinforcement in beams, indicating improved bond characteristics and shear strength. Studies by Mofidi and Chaallal (2011) and El Gamal et al. (2019) investigated the use of externally bonded CFRP, suggesting potential for enhanced ductility and stiffness. These findings collectively highlight the importance of optimizing reinforcement layouts to improve both shear and flexural behavior in RCC structures. Saravanakumar et.al. (2016) in his earlier study found that the combined pattern will be more effective than vertical stirrup pattern. These studies underscore the need for further investigation into how different configurations affect both shear and flexural responses, especially under varying load conditions. This study was conducted to analyse the shear effect on beams and enhance the shear performance by altering the orientation of shear stirrups different from the conventional type and simultaneously checking upon the deflection of the beam also. 2. Experimental Program Reinforced concrete beams were cast by varying the stirrup patterns as shown in figure 2 and tested. The material specification, test procedures and results carried are presented in the following sections. 3. Material Specifications The mix proportion used for the beams to cast was 1:1.52:3.1. Ordinary Portland cement of grade 43 was used and M-sand falls intoZone II as fine aggregate and 20 mm coarse aggregate were used for casting the beams. The concrete cubes were cast and the test results were tabulated in Table 1. It was found that the 28 days average compressive strength of the design mix was 23.5 MPa. The water-cement ratio was set at 0.45 for beam casting. Grade Fe415 steel bar were used as reinforcement, with 10mm ∅ bars employed in the place of main reinforcement and 8mm ∅ bars for shear reinforcement. The reinforcement details were presented in Table 2. Table 1. Compressive strength of Cube specimens Concrete Mix Ratio Specimen 1 Specimen 2 Specimen 3 Average strength MPa MPa MPa MPa

1:1.52:3.1

24.43

23.36

22. 71

23.50

4. Test Specimens For the study four series of beams were cast with different patterns of stirrups. All the RC beams were cast for the designed mix proportion of M20 grade concrete with cross sectional dimension of 150mm width and 200 mm depth and length of 1.2 m. In each type 3 Nos. of beams were cast and tested for this study. Concrete cubes of 150 X 150 X