STRUCTURAL BEHAVIOR OF STEEL STORAGE RACKS UNDER DIFFERENT FIRE SCENARIOS

Steel solutions commonly used in logistic to store goods and products (i.e. racks) are assembled by thin-walled cold-formed components and their competitiveness on the market depends essentially on the total weight of the framed system. Despite great efforts have been done on seismic and static design, very limited attention was given to the problem of the fire design and to the robustness of such structures. Due to the limited thickness of the structural elements, it is well-known that their resistance to the fire load is quite limited. No specific design rules or design procedures have been developed till now. Nowadays, the only way to protect these frames against fire is the use of sprinkler or more complex solutions, like isolated chambers. However, fire hazard cannot be always eliminated and when these strategies were not effective, global structural collapse of the racks, during a fire, have been observed. In this paper a parametric analysis is proposed to deeply understand the behavior of racks against fire. In particular, starting from an existing rack configuration, different fire scenarios were modeled by changing the fire position along the fame and the fire design curve. Moreover, the progressive collapse of the rack is discussed proposing also two reinforcing strategies. Final results discuss about the best way to design these slender structures against fire, trying to prevent the global failure or, at least, to guarantee a safe collapse mode.