Numerical Fragility of Typical Italian Industrial Precast RC Frames: Effect of Geometry and Non-Structural Components

Abstract eng:
Two mainshocks and a series of smaller earthquakes struck the Emilia region, in Northern Italy, in May 2012. The earthquake sequence has highlighted the vulnerability of prefabricated industrial RC buildings, which were quite numerous in a region that is one of the most productive in Italy. Remarkable damage was observed during the field surveys that followed the mainshocks. According to some estimates, almost 70% of reinforced concrete precast buildings in the affected areas collapsed or were severely damaged by the earthquake. The main reason of the poor seismic behavior observed is arguably the lack of seismic provisions at the time of design and construction. In fact, the area affected by the events was not considered a “seismic region” until recently. Scope of this study is to assess the structural fragility of this building typology and it is a first step in a more comprehensive study that aims to understand the seismic behavior of these industrial precast structures, taking into account various failure modes and the interaction between structural and non-structural components. In fact, in spite of their apparent simplicity, there is still a critical lack of information on their seismic performance. On the other hand, these buildings present many commonalities, suggesting that useful information about the vulnerability of the building stock could be obtained by analyzing a number of prototype structures, whose geometrical and mechanical characteristics are representative of those found in the area of interest. In fact, when a vulnerability assessment is required at a regional scale, analyzing single buildings would become extremely onerous and thus impracticable due to both time and economic constraints. In this contribution, the seismic vulnerability and expected performance of this typology of industrial buildings is assessed through seismic fragility curves. Different geometries as well as a range of possible material properties are considered in order to assess their influence on the overall seismic behavior. Moreover, the interaction with non-structural infills is investigated. Following such an approach, valuable information about the seismic behavior of single-storey precast RC frame structures built without specific seismic provisions can be obtained. Hence, indications about the most critical structural configurations can be provided, helping to identify and prioritize the required repairing and/or retrofitting interventions either in the postearthquake emergency and reconstruction phase as well as a part of a risk-reduction national plan of preventive retrofit interventions.

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