Structural design of a GFRP sandwich panel for canopy roofs

The use of composite and sandwich materials in civil engineering applications can be an efficient and sustainable alternative to the traditional ones. A composite sandwich panel, composed by glass fiber reinforced polymer (GFRP) skins and a PET foam core, is the object of study to potentially substitute conventional panels/roofs of canopy structures in train stations. The main advantages are a high strength-to-weight ratio, durability, lightness, limited interference on railway traffic thanks to reduced installation times, factory production which reduces dangerous activities carried out on construction sites and the sustainability provided by the possibility of using recycled materials. However, in spite of the profound knowledge of these materials gained in the last decades in automotive, aerospace, and aeronautic fields, their use in the construction industry is not straightforward due to different and various design requirements, ranging from adequate load bearing capacity at the ultimate limit state, to limited deformations in the serviceability limit state, and to a standard durability of 50 years. Moreover, National and European design Standards are not yet available, leading to extensive research in literature in order to adequately design the panel. Also, due to the lack of Standards, extensive experimental tests were carried out to characterize material's mechanical and physical properties. Finally, two numerical models were developed, first a simplified one considering the sandwich panel as a simply supported beam structure and, afterwards, a FE model using ANSYS software. From the model’s results, it emerges that the geometrical characteristics, i.e. the thickness of the panel, are mainly defined by the fulfilment of the limitations imposed for the operational conditions (SLS) while the ultimate limit strength (ULS) requirements are easily fulfilled. Both models were validated with real scale laboratory tests.dwich di grandi dimensioni per applicazioni strutturali civili