SEISMIC FRAGILITY ASSESSMENT OF RC BUILDINGS AT LARGE SCALE
Creators: name: Del Gaudio, Carlo
Publisher: name: Università degli Studi di Napoli Federico II
Year: 2015

description: In this study, a simplified method for seismic vulnerability assessment of infilled RC building is presented. The methodology is essentially based on a simulated design procedure to evaluate the geometrical and structural model of the building based on few data such as number of storeys, global dimensions and type of design (Verderame et al. 2010). Building non-linear static response is evaluated trough a closed-form procedure starting from non-linear behavior of structural (RC columns) and non-structural components (infill panels), considering acting in parallel, thanks to the simplified assumption of a Shear Type behavior.
The assessment of the seismic capacity is based on the mechanical interpretation of the damage states described by the European Macroseismic Scale (EMS-98) (Grünthal, 1998) through the simplified IDA curves derived from (Vamvatsikos and Cornell, 2006). Hence the methodology allow to take into account the influence of infill panel both in the definition of the non-linear static response of building and seismic capacity, relating displacement thresholds on the non-linear behavior of infill sub-assemblages, selected on mechanical basis and experimentally validated, to the description of damage reported in EMS98.
A simulation technique is introduced to take into account uncertainties, and a probabilistic seismic capacity assessment is carried out, leading to the construction of fragility curves and, finally, to the evaluation of the failure probability in given time windows for the assumed damage states.
Hence, the procedure is applied, considering data with different level of detail as input parameters, namely from data provided by the field survey carried out within the framework of the SIMURAI Research Project (2010), and data derived from post-earthquake inspection form collected after 2009 L'Aquila earthquake (Dolce et al, 2015a; Dolce et al, 2015b).
Therefore, the influence of the detail level of input data on seismic vulnerability assessment at urban scale is investigated within a multilevel approach. To this aim, data from field survey are assumed as a reference, and when using census or Remote Sensing data, due to the lack of information affecting such data sources, some of the input parameters to the seismic vulnerability assessment procedure are assumed as random variables. 
Finally, a comparison between predicted and observed damage scenario, the latter derived from the damage grades reported for vertical structures and infill panels in the inspection form, is shown. The comparison between the results is used to test the reliability of numerical results and to allow validation and calibration of the analytical methodology. To this aim, proper analytical displacement thresholds corresponding to the damage to structural and non-structural elements described by EMS-98, based on the mechanical interpretation of the reported description of damage, have been set.
Afterwards, in order to investigate the influence of infill panels on global and local behaviour of the frame preliminary results of an experimental campaign on non-seismically designed infilled frames are presented. Experimental results show the importance in considering the local interaction between infill panel and surrounding RC frame. Hence, the post-elastic behavior of specimens was controlled by brittle failure mechanisms. In particular, failure of infilled specimen was due to shear failure at the top of the columns due to local interaction with infill panel.