Experimental Study of Trapezoidal-Shaped Steel Form Deck Composite Slab and Verifying the $m\text{-}k$ Constants

This paper investigates the flexural behavior of composite deck slabs using a two-point line load test. Six full-scale, one-way, single-span, simply supported composite slab specimens were tested using M20 grade concrete and two equal line loads applied symmetrically at six different shear span lengths. Additionally, two slabs containing polypropylene and steel fiber reinforcement were tested with loading at one-third span. The study analyzes various parameters such as load–deflection behavior, slip between the concrete and steel sheet, crack width, crack pattern, and ultimate load. The performance of fiber-reinforced slabs is compared with normal concrete mix slabs to assess the impact of fiber reinforcement on the flexural behavior. A standard methodology was employed to determine the slip modulus ($k$) and the slip-hardening coefficient ($m$) using the two-point test. The obtained $m$ and $k$ constants are compared with relevant data from the literature to validate the test’s accuracy. Furthermore, the ultimate load-carrying capacity of the composite slabs is calculated and analyzed. The findings confirm the relevance of the $m\text{-}k$ constants, highlighting their significance in characterizing the composite slab’s shear behavior and design considerations. Overall, the experimental investigation provides valuable insights into the flexural behavior of composite deck slabs, offering practical implications for construction practices and design guidelines. The comparison between normal and fiber-reinforced slabs sheds light on the benefits of using fiber reinforcement, while the validation of the $m$ and $k$ constants ensures their reliable application in assessing the shear performance of composite slabs.