System-Level Seismic Risk Assessment Methodology: Application to Reinforced Masonry Buildings with Boundary Elements

The development of system-level seismic fragility curves, which describe the probability of building systems reaching different damage states under a given ground motion intensity level, is an essential step in preearthquake and postearthquake risk assessment and resilience quantification. Nonetheless, current methodologies for generating fragility curves do not provide clear directions regarding how to integrate the fragility of different building components within the overall building seismic risk assessment. However, several recent studies demonstrate that neglecting some of these components’ contributions may lead to an erroneous seismic risk prediction of the overall building system. Recent research has also emphasized the need to develop alternative techniques to evaluate the system-level fragility to be adopted in the next generation of seismic risk assessment and resilience quantification standards. To address these issues, this study presents a new methodology that adopts two approaches, based on either component-level seismic losses or component strengths, to evaluate the overall system-level fragility. To demonstrate its practical application, the methodology is used to generate fragility curves for a reinforced masonry shear wall building with boundary elements. In this respect, OpenSees is used to develop a three-dimensional model of the building and subsequently conduct incremental dynamic analyses (IDA) by using a suite of 44 ground motion records. On the basis of the IDA results, component-level damage states are identified and used to generate component-level and, subsequently, system-level fragility curves. The analysis results show that the two proposed approaches yield consistent results, for the studied building configuration, that fall between a lower- and an upper-bound fragility estimate of the individual building components.