Fire safety verifications of a prestressed concrete structure: natural fire vs ISO 834 curve

During years, the codes that regulate verifications against fire change a lot. They allow the use of engineering methods to approach problems by using Fire Safety Engineering. This thesis keeps in consideration the most recent fire prevention code (DM 16/10/2018) and highlights the difference between a compliant and an alternative solution for fire verification with a performance level III of a prestressed concrete warehouse with an ESFR shutdown system. To do it, has been done a comparison between the ISO 845 curve and a natural fire curve. For the natural fire case has been considered all the factors that influence the propagation or mitigation of the fire scenario (e.g. materials, fire load, ESFR system, type of activity and so on). Once do that, two FDS® simulations has been performed. The first one detects the ESFR time activation and the second has the aim to know time-temperature curves on load bearing elements through the implementation of the assumed final natural fire curve. Then, the behavior of the precast and prestressed concrete structure has been investigated, both with the ISO curve and the natural fire curve. In order to apply time-temperature curves in cross sections, some SAFIR® simulations has been done on the principal structural elements with both the fire curves. On the thinner cross section has been done also some hand-made verifications (from EC 1992-1-2). Then 2D and 3D mechanical analysis has been performed with SAFIR® considering the previous thermal mappings. The case analyzed with the ISO curve present wide displacements and the collapse of secondary beams, instead the case analyzed with the natural fire curve meets the requirements.