A Slim-Floor is a flooring system that combines steel beams and slabs integrated into the structure, resulting in a significant reduction in the overall floor height. It allows for a more efficient design, eliminating the need for mechanical connectors between steel and concrete, making construction easier and saving space. Despite these advantages, the use of mechanical shear connectors (stud bolts, Perforbond, Crestbond, and others) in the steel profile is not feasible, as the concrete layer above the steel is not thick enough for these connectors to work properly. Thus, over the last few years, several studies have been carried out to develop composite mechanisms capable of "activating" the composite behavior between steel and concrete in Slim-Floor systems. In the present study, the bending behavior of Slim-Floor beams was analyzed using finite element models developed in the ABAQUS software. The validity of these models was demonstrated by comparing the numerical results obtained with the results presented by Lawson et al. (1997), Leskelä and Hopia (2000), Paes (2003), and Braun et al. (2014). Through parametric evaluations, considering the influence of geometric parameters, parameters associated with connection mechanisms and mechanical parameters, the following findings were verified: (i) in all analyzed cases, the connection mechanisms adopted (concrete pins, reinforcing steel bars, and adhesion) were able to activate the composite behavior between steel and concrete; (ii) the spacing between the openings, the number of openings, and the diameter of the reinforcing steel bars determine the behavior of the connection; (iii) adherence contributes little to the strength of the connection, and therefore, its contribution can be neglected; (iv) unlike the connection mechanisms studied by Lawson et al. (1997) and Leskelä and Hopia (2000), the connection mechanisms adopted in this study can promote the ductile behavior of the Slim-Floor beams.