## 5 Conclusions  
The objective of this study was to resolve the problems of initial slip and relatively low shear resistance strength in the embedded nut-style bolted shear connectors that are mainly used today. We developed a demountable stud bolt shear connector that has an expanded section in which the embedded nut is integrated into the stud bolt as well as a Y-shaped tapering surface and conducted push-out tests by fabricating shear specimens to verify the strength performance. The specimens were fabricated using not only the regular welded headed studs that are listed in the design standards, but also embedded nut-style bolted shear connectors, and a comparison was performed. In addition, FE analysis was conducted on each specimen model, and the results were compared with the experimental results. The results that were derived from this study can be summarized as follows:  
1. Welded headed studs (model S1) are superior to conventional bolted shear connectors in terms of ductile deformation and shear strength. 2. In the conventional bolted shear connectors, fracturing occurred in both the nut that was embedded in the concrete slab and the stud bolt threads, which are located at the upper flange interface, and the fracture load was very low, at 47.8% of the fracture load of model S1. In addition, the failure slip deformation was 50.8% of the failure slip deformation of model S1 at 6.03 mm. 3. Looking at the Y-shaped embedded nut shear connectors (model S3), the failure load of the model with a Y-shape angle of 20\({}^{\circ}\) was larger than that of model S2, but the slip deformation during failure was very small at 4.27 mm. On the other hand, the failure load of the model with a 45\({}^{\circ}\) angle was lower than that of the welded stud and higher than that of the embedded nut model (model S2). 4. The ultimate load of the Y-shaped integrated demountable stud bolt (model S4) was 196% (20\({}^{\circ}\))-219% (45\({}^{\circ}\)) of the ultimate load of the conventional bolted shear connector (model S2), and it was higher than that of the welded stud (model S1) at 93.9% (20\({}^{\circ}\))-104.6% (45\({}^{\circ}\)). The amount of slip deformation during failure was 6.91 mm (20\({}^{\circ}\)) and 7.76 mm (45\({}^{\circ}\)), exceeding the design standard of 6 mm and showing ductile behavior. However, the stud bolt experienced fracturing at the threads of the nut fastening part, and it is thought that additional research on this aspect is needed. 5. The South Korean bridge design standard for shear connector ductile deformation, which is 6 mm, was satisfied by all models except for model S3-20. 6. The FE analysis results obtained using the concrete CDP models matched the experimental load-slip behaviors well overall. In particular, it was possible to confirm the failure mode of the shear connectors adequately in an analytical manner. 7. Model S4, which was ultimately proposed in this paper, could prevent initial slip and increases in the initial stiffness and failure strength by not using an embedded nut and by introducing a bolt load to remove the tolerance caused by the wedging effect. Therefore, the use of Y-shaped demountable stud bolt shear connectors can resolve the problems of increased initial slip, decreased stiffness, and reduced ultimate failure