In this paper the behaviour of stud shear connectors in composite structures is analysed. The composite section is formed by steel profiles connected to solid concrete slabs. Some effective numerical models using the finite element method to simulate the push-out test are proposed. The results obtained from the numerical analysis were verified against experimental results. The material nonlinearities were considered in the models. A bilinear model for steel was considered, and a model of plastic damage (Concrete Damaged Plasticity) in concrete was also adopted. The shear connection capacity obtained from the finite element analysis is compared with the connection strength calculated using the American Specification and the European Code for headed stud shear connector in solid slab composite section. Modifications to existing expressions in these codes are proposed. New factors that improve the prediction of the shear connection capacity are considered.