A composite slab consisting of in-situ casted reinforced concrete on profiled sheeting, which is connected to steel beams by shear connectors, is a common structural flooring system in office and multi-storey car park buildings. The headed welded studs, which are most widely used shear connectors, are inexpensive and easy to install because they can be welded to the steel beam through the profiled sheeting. A permanent link is created between the composite slab and steel beams leading to a time-consuming and expensive deconstruction process. Various types of bolted shear connections, recently investigated by various researchers in Europe, Australia, and the USA, provide a demountable alternative for the flooring system. A part of this thesis describes the experimental study using a bolted shear connector consisting of an embedded bolt/coupler and external bolt, originally developed for a prefabricated solid concrete deck. A full-scale composite beam was tested in two life cycles under total working loads up to $200kN$ in a 4-point bending set-up. In addition to bolted shear connectors, a timber joist was embedded in the composite slab over the web of the steel beam. After the first life cycle, the timber joist provides the cut edge of the slab. The experiment is used to model behavior of the composite beam in the first life cycle. The slab is then cut, demounted, re-assembled and tested again in the second life cycle. The load was applied up to $200kN$ and finally to failure. Multiple arrangements of shear connectors were investigated in second life cycle to analyze the performance of a prefabricated composite beam Experience gained by the experiments on the composite beam in the first and the second life cycles is accompanied by FE analysis. Recommendations for practical use of the demountable composite floor system are proposed based on the experimental and numerical findings. In addition, an investigation in the field of BIM (Building Information Modeling) functionality in the context of demountable structures was conducted. In order to identify the potential benefits of the BIM a case study of an in-situ casted car park was conducted. A number of software packages were used to conduct structural analysis, modeling and visualization of the construction sequence. As a result of this case study, valuable experience was gained on an application of BIM technologies for a design of demountable and reusable structures.