The building and construction sector play a key role in achieving a sustainable development. In European countries, buildings are responsible for 40-45% of energy consumption, leading to significant amounts of CO2 emissions. The implementation of reusable structures lead to less waste and harmful emissions to the environment. The main purpose of this thesis is to analyse and evaluate the use of a new type of demountable shear connectors, resin injected bolts, in steel-concrete composite structures through push-out tests. Steel-concrete composite structures are commonly used in flooring systems of offices, car parks and bridge decks throughout the world. The most widely used shear connectors are welded headed studs. Even though they are inexpensive and extended research has been conducted about their application, welded headed studs do not allow for the demountability and reusability of the structural components. An innovative type of shear connector consists of a coupler and a bolt which are embedded in the prefabricated concrete deck. The assembly of the concrete deck with the flange of the steel section which has oversized holes is achieved through resin injected bolts. Resin injected bolts are bolts in which the cavity formed by the clearance between the bolt and the hole is filled up with resin. Large hole clearances allow for fabrication tolerances and lead to a faster execution. Push-out tests were conducted in the laboratory in order to examine resin injected bolts in terms of shear capacity, stiffness and ductility. Two different test configurations were created, one with resin injected bolts and the other one with reinforced resin injected bolts. For each configuration three specimens were tested which were nominally identical, one was loaded until failure using displacement control and the other two were loaded initially in force-controlled load cycles and then until failure. The results obtained from the experiments are compared with the results from researches conducted on other types of demountable shear connectors. FEA models were developed with the same geometry, materials and loading as in experiments using the ABAQUS software and push-out test were performed in order to check the validity of the experimental work. In addition, a parametric study was conducted using FEA in order to evaluate the influence of certain parameters on shear resistance and stiffness. The parameters considered are: the concrete strength class, the bolt diameter, the bolt strength class, the embedded bolt height, the hole diameter of the steel section, the effect of the L-angle profile and the injection material.