Reliable Design of Thin Axisymmetric Shells Using Partial Factor Calibration

Abstract

The mechanical behavior of thin axisymmetric shells subjected to buckling largely depends on variability (loading, material properties, geometrical imperfections,...). The design of this kind of structure is traditionally based on deterministic analytical calculations and on the use of the well-known empirical safety factors listed in the British Standard BS5500 [1]. This empirical standard could be improved by a probabilistic design rule based on the use of the λ a knock-down factor, which only takes into account geometrical imperfections, and on the use of n partial safety factors noted γ i which consider all the structural variability except geometrical imperfections. The Arbocz method used to calculate the λ a -factor has been efficiently applied [2] to an industrial axisymmetric shell requiring a tool which links two types of software: INCA-STANLAX for the numerical finite element mechanical modeling and RYFES for the calculation of the reliability level. This present paper focuses on the γ i -factors. The calibration of partial factors is treated, with the aim of proposing values to bring to the design rule for thin shel1 structures subjected to buckling.