Prior testing and industry practice have shown composite metal floor systems – floors systems constructed from concrete composite with metal decking – behave stiffer than the current state-of-the-practice simplified calculations and estimations predict. Specifically, the dovetail decking does not have the quantity of available research and universal design guidance compared to the more common trapezoidal composite decking; this lack of a more accurate design standard has made the calculation of the non-linear stiffness behavior of the dovetail composite deck floor systems under small to intermediate strains inaccurate, and therefore limits its use for long-span configurations where deflection limits (i.e., serviceability limits) control the design.The objective of this research is to create an analytical model of the flexural behavior of re-entrant dovetail composite decking floor systems for service (i.e., deflection) and strength (i.e., ultimate capacity) limit states and to understand the unique mechanical behavior of the slab system. By creating a more accurate analytical model of the flexural behavior of the dovetail composite deck system, a robust design guide table for engineering use is developed for a multitude of variables typically seen in construction, including but not limited to: various loads, deck gauges (thicknesses), concrete strength, concrete depths, etc. The flexural behavior of the composite metal deck is modeled based on its material properties and the following base assumptions: the composite slab is in pure bending; plane sections remain plane and are orthogonal to the neutral axis; the laws of static equilibrium apply; and loads are assumed to be static. Application of this composite theory to determine the moment-curvature relationship using a numerical strain-compatibility computer-based solver is compared against physical tests to validate and calibrate the theoretical assumptions that make up the basis for the calculations. The resulting flexural behavior derived from this numerical strain-compatibility method has a multitude of uses including but not limited to: the derivation of a robust design table for a number of decking gauges, common slab thickness values, concrete strength ranges, and so forth; and variable stiffness properties for use in simplified finite element plate models.
The real-world purpose for this new numerical strain-compatibility model is to provide robust design guidance and engineering resources for practicing structural engineers, without a time-consuming and expensive finite element model. With the numerical strain-compatibility analysis, an engineer can accurately analyze and specify composite concrete slabs in building projects without being limited by shorter spans or thicker slabs due to inaccuracies in deflection calculations.