Probabilistic resilience assessment of structures considering the functional uncertainty: A case study for external prestressed subframe in strengthening

Seismic resilience is a critical index in the earthquake engineering. In recent years, it has received extensive attention and has been broadly used in post-earthquake assessments, especially for the structures after strengthening. At this stage, the seismic resilience is commonly analyzed using deterministic approaches, while the corresponding probabilistic resilience assessment still needs further research. In this paper, a probabilistic resilience assessment framework of structures considering the functional uncertainty is proposed, and a case study for external prestressed subframe in seismic strengthening is performed. The probabilistic resilience assessment framework consists of the probabilistic analyses of fragility, expected loss, residual functionality, recovery time and resilience index, and the resilience developments along with the intensity level or recovery time are detailedly discussed in the procedure. Subsequently, an implementary example of the existing frame strengthened by an external prestressed subframe is given, and the proposed probabilistic resilience assessment framework is performed for comprehensive analyses. In general, the functionality varying with recovery time presents significant uncertainty for each scenario and intensity level, which proves the necessity of resilience analyses in a probabilistic way. With the increase of prestress level, the obtained mean resilience index increases, and the resilience exceeding probability curves move upward for all the conditions, which signifies the superiority of a higher prestress level to increase the seismic resilience and to improve the risk-resistant capacity in external strengthening. In a sense, the probabilistic resilience assessment framework evaluates the resilience development from an uncertain perspective, which provides a significant reference for the subsequent probabilistic risk analyses in engineering structures.