Geometric imperfections in CFS structural members, Part II: Data-driven modeling and probabilistic validation. (April 2023)

• Record Type: Journal Article
• Authors: Farzanian, S.; Louhghalam, A.; Schafer, B.W.; Tootkaboni, M.
• Is Part Of: Thin-walled structures. Volume 185(2023)
• Publication Date: 2023-04
• Subjects: Geometric imperfections -- CFS structural members -- Data-driven stochastic fields -- Monte Carlo simulation -- Shell FE collapse analysis -- Probabilistic validation metrics; Thin-walled structures -- Periodicals; 690.1
• DOI: 10.1016/j.tws.2023.110620
• Languages: English
• ISSNs: 0263-8231

Abstract

Abstract: This paper is the second part in a two-part series that examines the role of geometric imperfections in load–displacement response and collapse behavior of cold-formed steel (CFS) structural members. In part I (Farzanian et al., 2023) a review of the basics and a summary of efforts geared towards modeling geometric imperfections was provided. This included the ingredients needed for systematic identification of elastic buckling mode shapes, due to their frequent use in approximating geometric imperfections, and the development of high fidelity shell finite element (FE) nonlinear collapse analysis of CFS members seeded with different geometric imperfection models. Part II is the companion to the analysis in part I that revealed a noticeable variability in the collapse behavior and load carrying capacity of CFS members as a result of adopting different imperfection modeling strategies. In this part we provide the necessary steps to build a probabilistic framework that rests on machine learning, polynomial approximation, and parametric and non-parametric statistical inference and uses imperfection data to build a consistent stochastic field model of geometric imperfections. This data-driven model is then used to generate the much needed realizations of geometric imperfections that are faithful to the underlying statistics of measured data and therefore can be seeded, directly, in nonlinear collapse analysis of CFS members. Nonlinear shell FE analysis, within a stochastic simulation framework, is finally used to (statistically) quantify the impact of geometric imperfections and to enable probabilistic validation of geometric imperfection models. Highlights: The impact of random geometric imperfections on nonlinear response of CFS members is studied. A data-driven framework for building stochastic field models over measured imperfection data is presented. Realizations of geometric imperfections, faithful to the underlying statistics of measured data, are generated. Statistically consistent realizations of imperfections are used in stochastic nonlinear analysis of CFS members. The statistics of nonlinear response are used for the validation of geometric imperfection models.