Most gravity dams have been designed and built during the past century with methods of analysis that are now considered inadequate. In recent decades, knowledge of seismology, structural dynamics and earthquake engineering has greatly evolved, leading to the evaluation of existing dams to ensure public safety. This study proposes a methodology for the proper modelling and characterisation of the uncertainties to assess the seismic vulnerability of a dam-type structure. This study also includes all the required analyses and verifications of the numerical model prior to performing a seismic fragility analysis and generating the corresponding fragility curves. The procedure presented herein also makes it possible to account for the uncertainties associated with the modelling parameters as well as the randomness in the seismic solicitation. The methodology was applied to a case study dam in Eastern Canada, whose vulnerability was assessed against seismic events with characteristics established by the current safety guidelines.

This study aims to understand the conditions and the mechanisms that led to aboveground storage tank (AST) failures during Hurricane Harvey. First, a detailed survey of the damage suffered by ASTs is performed using aerial imagery and governmental incident databases. Analysis of incidents identifies to two main failure modes: flotation due to flooding and floating roof failures due to rainfall. Next, fragility models are developed to assess the structural vulnerability of ASTs. An existing fragility model for the flotation of ASTs is improved to include hydrodynamic effects, while a new model based on buoyancy and drainage calculations is proposed for the failure of floating roofs. Finally, the fragility models are coupled with empirical data to ascertain the conditions that could have led to the observed failures during Harvey. Results indicate that in preparation for a storm, ASTs should be filled with product to prevent flotation and improve floating roof drainage. Results also highlight the importance of adequate terrain drainage to avoid water accumulation around ASTs that can lead to AST flotation or to inefficient roof drains.

This paper explores the buckling behavior of a typical aboveground storage tank (AST) under wave impacts. A finite element model is first developed and validated against experimental results to determine the hydrodynamic pressure time histories on the AST from hurricane-induced waves; the characteristics of a severe wave impact are derived from numerical simulations of hurricanes in the Houston Ship Channel. The pressure time histories are then applied on a separate finite element model of the AST and its internal liquid, considering geometric and material nonlinearities. Dynamic buckling analyses are performed using the Budiansky-Roth criterion and compared with simpler buckling analysis procedures. This comparison is performed for two different internal liquids, gasoline and crude oil, and three internal liquid heights. Results indicate that the dynamic effects from wave impacts are not significant and could be reasonably omitted to estimate the critical load. Simpler static pressure models and computationally cheaper static buckling analysis methods provide, for practical purposes, an adequate estimate of the buckling strength of the AST. However, dynamic buckling analysis may still be required if the objective is to assess the post-buckling behavior and deformation of an AST under wave impacts, rather than only to estimate the critical load.