Investigations on non-linear behavior of castellated steel beams with circular, hexagonal and diamond-shaped openings using CFRP stiffeners

Castellated beams (CSB) are widely used for long-span structural applications due to their high strength-weight ratio. The perforations in CSB causes stress-concentrations at edges and web-post buckling. The provision of stiffeners in the web of CSB contribute in preventing such failures. In recent years, Fiber Reinforced Polymer (FRP) is preferred material over mild steel for stiffeners. Studies have indicated that FRP stiffeners improves performance of CSB under linear behaviour. However, linear behaviour of CSBs may underestimate actual behaviour leading to inaccurate design decisions. Hence, for accurate representation of CSBs behaviour, its non-linear analysis becomes ‘essential’. In this paper, non-linear behaviour of CSBs consisting ‘circular’, ‘hexagonal’ and ‘diamond’ openings is analyzed under two-point loading (till failure) using ABAQUS and results are validated experimentally. Analysis is done considering without and with provision of Carbon Fiber Reinforced Polymer (CFRP) stiffeners for determining ultimate load-carrying capacity (ULCC) and deflection. Results indicate that, ‘ULCC’ of CSBs consisting ‘diamond’ openings without considering provision of ‘CFRP-stiffeners’ increased by an average value of 14.18% while deflection reduced by an average value of 3.76% when compared over CSBs with circular and hexagonal openings. Additionally, ULCC of CSBs consisting diamond openings with CFRP stiffeners increased by an average value of 17.09% while ‘deflection’ reduced by an average value of 3.25% when compared over CSBs with other openings. Study concludes that CSBs with diamond openings outperforms over CSBs consisting circular and hexagonal openings in respect of ULCC and deflection without and with CFRP stiffeners when subjected to loading till failure.