Fragility Curves for a Small Zoned Earth Dam

Abstract

The paper presents a suite of fragility curves to evaluate the seismic vulnerability of a small earth dam. The goal is to provide a user-friendly tool to estimate the expected damage of this type of barrages that, since classified as small, are typically subjected to less restricting controls than large dams with the consequent increase of their vulnerability. In this study, the incremental dynamic analysis method (IDA) was applied to a prototype of small zoned earth dam. To perform nonlinear dynamic analyses through the finite element software Plaxis2D, an advanced soil constitutive model combined to a three-phase formulation was adopted. To develop the fragility curves for each damage type relevant for the seismic performance of the dam, ten representative accelerometric signals were selected. Four damage measures (DMs) were considered, namely the settlement ratio at the dam crest, the lateral displacements of the dam crest, the freeboard reduction and the maximum plastic shear strain of the watertightness element. These damage indicators were later related to three intensity measures (IMs), i.e. PGA, PGV and the Arias Intensity. As outcome of the study, the fragility curves for different limit states of the identified DMs were obtained.