This paper presents a validated finite element approach to investigate the behaviour of demountable shear connections in innovative composite floor systems developed within the LWT-FLOOR project at the Faculty of Civil Engineering in Zagreb. Addressing critical sustainability and usability challenges in the construction industry, the research project focuses on enhancing the life cycle of structural elements through the system dismantling process. The LWT-FLOOR system, featuring cold-formed steel (CFS) sections and concrete slabs, was thoroughly analysed using finite element models validated against experimental data. This study observed two configurations of CFS-concrete composite specimens: one comprised of BB series models featuring back-to-back CFS sections, and the other consisting of BCWB series models that incorporate a corrugated web between the C-profiles. The mechanical behaviour, in particular of the bolted shear connections, was evaluated by 18 push-out tests in which the shear resistance, ductility, failure modes and initial stiffness were investigated. These validated models were then employed in a comprehensive parametric analysis to investigate the influence of key parameters on the performance of the bolted shear connection. The key parameters such as CFS profile thickness, bolt diameter, bolt height, and concrete strength were systematically varied. This approach revealed the complex behaviour of shear connections, highlighting the interaction between multiple failure modes that impacts the ultimate resistance of the shear connection.