Seismic performance of precast industrial facilities following major earthquakes in the Italian territory

Recent major earthquakes in the Italian territory have reaffirmed the seismic vulnerability of precast industrial buildings typical of past Italian building practices, highlighting structural deficiencies observed during previous events and primarily related to the transfer of horizontal forces between structural and nonstructural elements. An intrinsic lack of shear and ductility capacity has been observed in simply supported beam-to-joist and beam-to-column connections, primarily constituted by vertical steel dowels or solely relying on shear friction, with or without neoprene pads. These connections were designed neglecting seismic loads and their premature failure was observed during recent seismic events to cause a loss of support of beam elements, owing to the relative movements of elements, and the collapse of part of the buildings, primarily the roof. The seismic displacement demand of the industrial buildings under consideration is larger than traditional RC frame structures owing to their higher flexibility, according to both higher interstory height and to a cantilevered static scheme. Furthermore, this high flexibility may also result in displacement incompatibility between structural and nonstructural elements, such as precast cladding panels, causing their connection failure. On the basis of detailed field observations on a relevant number of buildings, collected just after the earthquakes, seven representative industrial facilities are examined to outline the primary vulnerabilities of one-story precast concrete structures not designed and detailed for seismic loads.