ON THE IMPACTS OF STRUCTURE-TO-STRUCTURE DAMAGE CORRELATION FOR REGIONAL SEISMIC RISK ASSESSMENT

One of the main challenges of implementing the performance-based earthquake engineering framework and computing risk and associated consequences on a regional scale is incorporating structure-to-structure damage correlation in the analysis. This correlation relates to the expected damage between different structures in a region, considering they were likely built with similar characteristics, resulting in similar strengths or deficiencies. While this type of correlation is often neglected, it can be estimated analytically from nonlinear time history analyses (NLTH) when models of all buildings in the region are available, requiring a computationally demanding and time-consuming method. Some strategies, however, can be implemented to simplify the procedure, such as analysing equivalent single degree of freedom (SDOF) oscillators instead of full 3D models of the buildings, an approach commonly found in the literature for similar applications. To examine the impact of considering such correlation in a regional seismic risk assessment a case study was conducted, involving the assessment of mid-rise concrete frame buildings in the Province of Caserta, southern Italy. The correlation was estimated from the results of Incremental Dynamic Analysis (IDA) performed on equivalent SDOF oscillators. Even though it was found that the incorporation of the correlation in the analysis does not significantly alter the estimates of the mean and median number of damaged buildings from a given earthquake scenario, it affects the probability distribution of the data, increasing the estimated risk of large-scale damage. Incorporating this aspect into the analysis leads then to more accurate damage and loss estimates, enabling improved strategies for risk preparedness and mitigation.