Structural modelling and probabilistic seismic assessment of existing long-span precast industrial buildings

Precast concrete frame structures constitute a major construction technology of the industrial built heritage within the Italian territory. Most of these buildings were conceived according to obsolete seismic design criteria with lower hazard than currently recognised standards, whilst the most industrialised areas spread over the Italian territory were declared seismically active since less than 20 years. This paper focuses on seismic performance assessment of long-span flat-roof industrial buildings, representative of modern design technologies. Buildings located in areas with increasing seismic hazard over the Italian territory were designed following an archetype existing building based on standards in force after 1996. Seismic performance is investigated by 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 are addressed by exploring progressively advanced modelling strategies up to a detailed assembly comprising roof members, peripheral panels, and all related connections. Mechanical non-linearities regarding column elements, dowel beam-to-column and slab-to-beam connections, strap tie-back and bracket bearing panel-to-frame connections are modelled with lumped plasticity employing experimentally calibrated constitutive laws. Seismic risk is assessed by estimating via multi-stripe analysis failure rates encompassing performance levels from usability preventing damage to global collapse. The results are site-dependent, 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.