Investigation of the failure modes of ultra high strength steel bolted connections at elevated temperatures

Abstract

Recent investigations have highlighted the critical influence of both temperature and geometric parameters on the failure modes of bolted connections in structural systems. The present study investigates the performance of ultra high strength steel bolted connections under ambient and elevated temperatures. A finite element model was developed to capture nonlinear material response and stress redistribution within the joint and was validated against experimental results. Parametric studies were then conducted, to assess the influence of key variables such as edge distances. The model was employed to analyse joint's performance, offering detailed insights into stress development, strain localization, and ultimate failure. Systematic variation of these parameters enables identification of thresholds governing failure‐mode transitions. A methodology for determining the bearing resistance is confirmed and proposed. The findings provide an improved understanding of the mechanisms governing ultra high strength steel joints under fire conditions. They also offer a basis for refining design approaches and developing more robust strategies for enhancing the fire resilience of steel structures.