On 20 and 29 May 2012, two earthquakes of MW5.9 and MW5.8 occurred in the Emilia region of northern Italy, one of the most developed industrial centers in the country. A complete photographic report collected in the epicentral zone shows the seismic vulnerability of precast structures, the damage to which is mainly caused by connection systems. Indeed, the main recorded damage is either the loss of support of structural horizontal elements, due to the failure of friction beam-to-column and roof-to-beam connections, or the collapse of the cladding panels, due to the failure of the panel-to-structure connections. The damage can be explained by the intensity of the recorded seismic event and by the exclusion of the epicentral region from the seismic areas recognized by the Italian building code up to 2003. Simple considerations related to the recorded acceleration spectra allow motivating the extensive damage due to the loss of support.

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The paper assesses the adequacy of existing numerical models in predicting the seismic response of freestanding nonstructural components that exhibit rocking-dominated behavior. Based on a previous experimental test program on hospital building contents carried out by the authors, the study focuses on two different modelling techniques: (a) finite element method (FEM) and (b) rigid block model. The ability to predict the response of two hospital cabinets tested in the laboratory is verified by comparing the numerical response with the experimental one. The applicability and limitations of each modelling technique are also discussed. The outcomes of the present study show that both the adopted modeling techniques can provide a reliable prediction of the occurrence of rocking mechanism in hospital cabinets. Rigid block model can also predict the occurrence of the overturning, whereas FEM model can provide a prediction of the acceleration distribution at different locations of the cabinets, e.g. at different shelf levels. The efficiency of different intensity measures in predicting the damage states in rigid block is estimated. Comprehensive incremental dynamic analyses on different rigid blocks highlight that dimensionless intensity measure PGA/(gtgα) is the most efficient intensity measure to predict rocking and overturning in small rigid blocks, whereas pPGV/(gtgα) is the most effective for large rigid blocks. Such intensity measures also allow generalizing the results to different rigid blocks, through the definition of a fragility approach

The damage of nonstructural components represents the largest contribution to the economic loss caused by an earthquake. Since nonstructural components are not amenable to traditional structural analysis, full-scale experimental testing is crucial to understand their behaviour under earthquake. For this reason, shaking table tests are performed to investigate the seismic behaviour of plasterboard partitions. A steel test frame is properly designed in order to simulate the seismic effects at a generic building storey. The tests are performed shaking the table simultaneously in both horizontal directions. To investigate a wide range of interstorey drift demand and seismic damage, the shakes are performed scaling the accelerograms at eleven different intensity levels.The tested plasterboard partitions from Siniat exhibit a good seismic behaviour, both in their own plane and out of plane, showing limited damage up to 1.1% interstorey drift ratio. The correlation between the dynamic characteristics of the test setup and the recorded damage is evidenced. Finally, an interesting comparison between the experimental results and the analytical model is also performed.