Fragility curves for retaining walls in infrastructure road networks

Retaining walls are crucial elements in infrastructure road and railway networks, as they provide essential support for earth structures, such as embankments and bridge abutments. A proper evaluation of their seismic performance is therefore a fundamental step for assessing the functionality of a transportation network after the occurrence of an earthquake. This study investigates the seismic performance of retaining walls supporting roads in a probabilistic framework. Hundreds of nonlinear dynamic analyses were executed by considering recordings from different soil classes, as well as different wall layouts and critical accelerations. The results were interpreted to develop fragility curves, based on damage scales available in literature. The latter were then exploited to derive new functionality loss functions referring to different road types. The proposed fragility and loss of serviceability curves provide an effective tool for evaluating the probability of failure for different types of retaining walls. Therefore, these curves can be used in risk assessment and related decision-making when the unsatisfactory seismic performance of geotechnical systems may result in a compromised functionality of the overall road network.