Numerical analysis on shear behaviour of cold formed steel concrete composite beam with inverted U-shaped internal shear connector

The utilization of cold-formed steel (CFS) in residential, low-rise commercial, and light industrial constructions has gained popularity owing to its lightweight and installation ease. This research investigates the shear behaviour of cold-formed U-shaped steel–concrete composite (CFSCC) beams incorporating internal shear connectors, comparing their performance to traditional reinforced concrete (RC) beams. Finite element models developed in ABAQUS were validated against experimental data for both CFSCC and RC beams, demonstrating satisfactory agreement. Subsequently, 30 finite element simulations were conducted to evaluate the impact of critical parameters such as width-to-height ratio (B/D), reinforcement ratio (RR), CFS thickness (Tcfs), and length-to-area ratio (Lsc/Asc) of shear connectors on structural performance. Results indicate shear capacity significantly correlates with the reinforcement ratio and CFS thickness. Specifically, shear capacity increased by 2.93% when the B/D ratio decreased from 0.75 to 0.6 and by an additional 8.16% when B/D reduced from 0.6 to 0.5. Increasing the shear reinforcement ratio from 0.4 to 0.5 enhanced shear capacity by 5.1%, while increasing CFS thickness from 1.5 mm to 2 mm improved shear capacity by 8.53%. Slip values for shear connectors varied significantly, with the lowest slip (6.2 mm) recorded for specimen RCS11 and the highest (16 mm) for RCS13. Furthermore, increasing CFS thickness from 1.5 mm to 2 mm reduced shear connector slip by 10.5%. Adequate shear connector distribution enabled the CFS sheet to effectively function as tension reinforcement, enhancing flexural performance, while reduced B/D ratios increased shear connector slip, and higher shear reinforcement ratios improved post-cracking beam behaviour.