1. Introduction

This documentation presents the various numerical methodologies developed to simulate and analyze the seismic behavior of large metal reservoirs. The aim here is therefore to present the implementation and sequencing of various Code_Aster operators in order to successfully study this type of components, according to various modeling hypotheses that are mainly dictated by regulatory considerations. These reservoirs, which are thin metal structures, can present two preferred methods of ruin: breakage of the anchors or buckling of the shells.

The first methodology is based on a push-over regulatory method ([bib1], [bib2], [bib3], [bib4]). The reservoir is subjected to an imposed internal pressure that is spatially variable and increasing. The resolution is achieved in a semi-static manner and the fluid domain is not modelled directly: its influence on the wall is transcribed by a particular imposed pressure field. Nonlinearities are geometric and behavioral (plasticity). During the incremental calculation, this pressure is increased until the ultimate load is obtained, which corresponds to the buckling of the structure (you can use the keyword CRIT_STAB from STAT_NON_LINE for a non-linear stability analysis). In order to model anchors more finely, heave can be introduced at the level of anchors bolted with the ground [bib5]. It is also possible to increase the mechanical resistance to buckling by adding carbon fiber reinforcement to the shells. Its modeling is presented in this document.

The second approach is direct transient modeling with full consideration of the fluid domain through a coupled fluid-structure approach in large displacements [bib6]. This modeling, which is finer than the previous one, complements regulatory approaches, in particular by making it possible to better identify the limits of their field of validity, mainly with respect to large global nonlinearities such as large displacements. However, the practical use of these transitional approaches is limited by the numerical additional cost they induce (ratio of the order of 10). It is possible to combine the transitory approach with a non-linear stability analysis using the DYNA_NON_LINE CRIT_STAB keyword. Unlike quasistatic calculations, the particularities of the fluid-structure model require particular treatment in CRIT_STAB which will be detailed in this document.