# Study of Innovative Connector for Steel-Concrete Composite Structures
## 1 Introduction
The solution of a composite beam made of the reinforced concrete slab connected to an I-beam with a properly cut web is known from bridge structures, as presented in [17; 18]. Therefore, they can also be used on heavily loaded industrial or warehouse ceilings [2]. As presented in [19], the main advantage of the \"composite dowel\" compared to head studs is a higher load capacity and adequate resistance to deformation even in high-strength concrete, thanks to which, according to EN 1994-1-1 [20], they can be classified as ductile shear connectors. The test results of an innovative connector in the form of a steel sheet with an embossed steel plate are presented in [21]. The fasteners are welded to the steel beam. The proposed connector is very durable due to the strength of bonding with concrete. The stiffness of this connector turned out to be greater than that of the headed studs. At the same time, the results of the experiment showed that the slip ability of the sheet metal fastener was also greater than that of the stud. In addition, the sheet metal connection turned out to be less prone to cracking as the embossing pattern used is very durable and resistant to dynamic loads. For mechanical connection, a popular design solution is the use of trapezoidal sheet metal with embossing [22; 23]. Most of them, in the upper part of the fold of the sheet, have concave ribbing so that the concrete can connect with the sheet [8]. There are also solutions in which the upper part of the fold uses convex embossing, so that the sheet can be embedded in the concrete. An innovative alternative to trapezoidal sheets was presented in [24], where the sheet with a sinusoidal cross-section was used. Experimental tests, as well as numerical simulations, confirm the possibility of using such a sheet shape. However, the sinusoidal cross-section prevents the welding of the studs. Therefore, the authors of [24] designed a dedicated connector, which is much heavier than a headed stud. In the steel-concrete composite structures, the friction joint is created using specially shaped sheet folds. As presented in the works [22; 25], such a shape of the cross-section improves the stability of the sheet and also acts as hooks connecting to the concrete, preventing the global buckling of the slab. Among the advantages of slabs on all types of corrugated sheets, there is no need to make formwork, because the sheet performs this function. This article proposes a novel connector for manufacturing the steel-concrete composite beam. The connector consists of shot nails and corrugated sheet in the shape of the dovetail. Nails are driven through the bottom fold of the sheet into the I-beam flange. The sheet provides stay-in-place formwork for a monolithic reinforced concrete slab, and its shape affects the connection of the reinforced concrete slab with the steel I-beam. The experimental tests of the shear load capacity of the fasteners were carried out. Three types of fasteners, differentiated in sheet thicknesses and the number of nails driven into the sheet fold, were analyzed. The research aims to verify the thesis of whether it is possible to provide the steel-concrete connection without the use of additional connecting components. In the proposed solution, the most popular type of connector, i.e., head studs, were eliminated. The connection was achieved only using a properly formed corrugated sheet. At the same time, these are the first tests of this type of connector. In the future, it is planned that a numerical model of this type of connection as well as parametric analysis and the optimization of the solution will be developed.