Vulnerability of Pipelines Subjected to Permanent Deformation Due to Geotechnical Co-seismic Effects

Abstract

Pipelines are basilar structures for the development of civil and industrial activities. Their seismic behaviour could be analyzed by applying a multi-disciplinary approach. In particular, for underground pipelines, soil/structure interaction is considered determinant during the seismic event. Moreover, for specific site conditions, ground failure phenomena induced by earthquakes might occur. Since such phenomena are generally associated to permanent soil displacement, the related deformations could be not tolerated by the pipelines, causing structural breaks and/or the losses of fluid containment. On the basis of a large collection of damage occurred to pipelines during recent earthquakes, a class of fragility curves was built up for underground structures underground failure. These curves were given as the probability of the occurrence of certain damage in a pipeline segment as a function of a seismic parameter. Therefore, compared to the existing formulations based on the estimation of a repair rate, RR, this study gives fragility curves which are directly useable on HAZUS-like platform, similarly to punctual structures, as above ground tanks. These empirical formulations could be easily treated in order to obtain tools for the estimation of seismic vulnerability, implemented in numerical codes for QRA (Quantitative Risk Analyses) of industrial plants. For this purpose, in this paper, the probit parameters and the threshold values are also given.