This study examines the behavior of composite steel-concrete beams, focusing on the role of shear connectors, particularly demountable types. Finite element simulations using ATENA software [1] were conducted to compare the performance of different connectors in push-out tests. The finite element model takes into account the contact between elements, the elastic-plastic behaviour of steel and damage in concrete part. Various configurations of connectors are compared to obtain the best performances regarding the stiffness, the resistance and the deformation capacity. The results indicate that connectors with integrated nuts embedded in concrete provide superior strength and stiffness compared to traditional welded studs. Although widening the diameter of the external nut or holding the connector with a nut on the external part of the steel profile did not lead to significant changes. In fact, increasing the contact surface with the concrete can be considered as a key factor. These findings support the development of a demountable connector for steel-concrete composite beams. These connectors can be used in new construction as well as in existing structures with the aim of increasing the stiffness and the resistance of existing elements to be rehabilitated.