Estudo experimental de ligações aparafusadas autoperfurantes de chapas finas a temperaturas elevadas

Cold-formed steel structural members have been used widely in steel construction, mainly due to its high structural efficiency and constructions times. Because these elements are usually thin sheet profiles the structural connections by self-tapping screws and self-drilling screws are the most used. For the self-drilling screwed connections, considering that the steel sheets range between 0.5 and 3 [mm], the joint is made without the need of opening a hole. These connections behave differently than the conventional bolted connections. In the case of self-drilling screwed connections of thin steel sheets, the joint collapse load is usually determined by the bearing resistance of the plates, and only in thicker plates by the screw shear resistance. This distinction is even more noticeable in the case of structures under fire conditions. This work presents a numerical study of the behaviour of cold-formed thin steel sheeting screwed connections at room temperature and high temperatures. The study comprises a parametric analysis, considering: (i) different high temperature values; (ii) cold-formed steel grades; (iii) board effect of the screw position; (iv) and different steel sheet thicknesses. The structural model used in the numerical simulations, by the finite elements method, consider both implicit and explicit dynamics simulations of the connection behaviour. The simulations are performed in the Ansys® software considering geometric and material non-linear analysis and an Augmented Lagrange Formulation to model the frictional contact between surfaces. The numerical results are compared with the simplified calculation method presented in the European standards.