Structural response in thin-walled steel structures subjected to dynamic loading

Abstract

As Swedish cities become increasingly dense, the distance between transportation routes and adjacent buildings decreases, heightening concerns about the potential effects of exceptional events on nearby structures, such as explosions originating from transport corridors. Structural members designed for static loads may not be suitable for dynamic loads from explosions. An example of such a structural member is corrugated sheet metal (CSM), commonly used in roofing applications. CSM falls into the category of thin-walled elements, meaning that it has a limited load capacity due to buckling. This also limits the capacity to resist dynamic loads from explosions, posing a risk to the overall structural integrity of the building. Current calculation methods may be overly conservative due to simplified and/or limited understanding of the post-buckling behaviour of CSM. This thesis aims to investigate the structural response of thin-walled steel structures subjected to static and dynamic loading. Simplified models, consisting of steel plates classified into various cross-section categories and subjected to axial loading under both static and dynamic conditions, were employed to explore the fundamentals of dynamic buckling. Once the fundamentals of dynamic buckling had been investigated, a more complex geometry was analysed, involving a simplified CSM section. The methodology is based on numerical analyses conducted using the finite element software Abaqus CAE. The results were validated through comparison with analytical expressions derived from the Eurocode. Findings from numerical analyses reveal that the structural response of both the steel plates and the CSM strip is primarily governed by buckling. At higher loading rates, the material exhibits a rate-dependent strengthening effect evident as an increased critical buckling load in the steel plates and reduced deflection in the CSM strip. Inertia effects, manifested as dynamic oscillations, become more pronounced at elevated strain rates, with their onset occurring earlier for slender structures. Increased slenderness and/or initial imperfections lead to a reduction in load-bearing capacity. Additionally, larger initial imperfections contribute to reducing the amplitude of dynamic oscillations.