Investigation of the mechanical behavior of trapezoidal roofing sheets using genetic algorithms

The steel profiled sheets are an economical alternative for roofing and siding in industrial stores, hangars and other kinds of pavilions, since these structural components are able to close large openings without too much increasing of the load over the cladding system structures. Trapezoidal sheets are specifically a good alternative to close this kind of structures. The opening span that this kind of sheet is able to cover can be determined through the serviceability displacement limit state. Since the steel sheet cross-sectional elements have little thickness, the local buckling collapse modes must be considered in this calculus. With this study, we attempt to evaluate the best alternatives for trapezoidal-shaped cross-sections of steel sheets to be used in roof cladding, subjected to bending moments. The sheets analysis has been carried out by using three-dimensional shell finite element models combined with optimization routines based on genetic algorithms procedures. The first profile to be obtained has been the one that has showed the lowest displacement and the highest critical elastic buckling load, at the same time maximizing the roof covering area. Finally, as a result of a sensitivity analysis, it has been possible to state some useful criteria for the trapezoidal steel roofing sheets design by modifying the weights of the proposed optimization objectives.