A review on behaviour of castellated beam with different shaped openings using FRP stiffeners

In recent years, use of castellated steel beams (CSB) is gaining more popularity due to their various benefits viz. increased section depth without any additional weight, higher strength to weight ratio, lower maintenance cost, good aesthetic appearance, etc. A CSB is a beam that is fabricated by cutting a steel I-beam longitudinally along its web in a specified pattern, and then re-joining the two cut parts by welding so as to get a beam of increased depth. This increased depth of CSB is generally 50% more than the parent steel I beam and contributes in enhancing its performance. However, the presence of web openings reduces the strength, causes stress concentration around the openings and also results into web-post buckling failure when subjected to loading. In order to prevent such failures, the CSB needs to be strengthened using stiffeners. The use of mild steel stiffeners is commonly done for strengthening the CSB. However, in recent years the use of fiber reinforced polymers (FRP) has been widely done for repair and rehabilitation works because of the excellent tensile strength and light weight property of FRP. This paper provides a rigorous literature review on the behavior of CSB provided with stiffeners of different materials. From the study, it is concluded that CSB are the efficient structural elements and perform better when provided with FRP stiffeners, but their behavior needs to be studied when they are provided with different shaped web openings and considering stiffeners of different FRP under two-point loading.