Abstract
Precast concrete frame structures constitute the major a relevant construction technology of the industrial built heritage within the Italian territory. Most of these buildings were designed neglecting seismic actions or according to obsolete seismic design criteria associated with much lower hazard than currently recognised standards. Indeed, the most industrialised areas spread over the Italian territory were declared seismically active since less than 20 years. Thus, governmental bodies, academies, and technical communities are currently engaged in evaluating the seismic risk associated with existing precast structures designed with older code provisions. This paper focuses on the assessment of the seismic performance of industrial buildings, with specific attention on a long-span flat-roof typology representative of modern technologies. Buildings located in areas representative of moderate, average, and high seismic hazard over the Italian territory were designed following an archetype existing building by applying the design criteria of the standards in force after 1996. The seismic performance of the buildings is investigated by several structural analysis techniques such as modal response analysis, non-linear static pushover analysis, and non-linear time-history analysis with a multi-stripe approach. The flexibility of the horizontal diaphragm and the interaction of the resisting frame with the cladding system, including a series of panel-support uncoupled columns, are addressed by exploring progressively advanced modelling strategies up to a detailed assembly comprising explicit modelling of roof members, peripheral panels, and all the related connections. In addition to the non-linear modelling of the column elements, the non-linear behaviour of dowel beam-to-column and slab-to-beam connections, as well as strap tie-back and bracket bearing panel-to-frame connections, is modelled with lumped plasticity approach employing non-linear constitutive laws calibrated on the basis of experimental evidence. Based on the result population from multi-stripe analysis, failure rates are assessed for the three reference sites and for different engineering demand parameters encompassing performance levels from usability preventing damage to global collapse. The results are site-dependant, and the need for retrofit of these typical precast systems is deemed to be urgent for both buildings designed in areas of average and high seismicity.