Non-linear structural models and the partial safety factor concept

Most modern structural design codes are based on the partial safety factor concept. The partial safety factors are calibrated on linear limit states. Structural design codes such as the Eurocode provide simplified rules on the application of partial safety factors to non-linear limit states. This paper investigates these rules and their effect on the structural reliability for various non-linear limit states. Moreover, we motivate adaptations of the current design rules. We focus on non-linear structural response functions, i.e., the non-linear relation between actions and their effects. In order to characterize the non-linearity of a structural response function, we introduce a new measure of non-linearity. We conduct a detailed parametric study and investigate two example structures. Our results show that for the case of a single dominant action, current design rules lead to sufficiently safe or only marginally unsafe structures. However, they can lead to a strong over-design.