Local buckling behaviour of high strength steel and hybrid I-sections under axial compression : numerical modelling and design

Abstract

This paper presents a numerical investigation on the local buckling behaviour of high strength steel (HSS) and hybrid I-sections under axial compression, which has not been comprehensively discussed in previous literature. Three sectional steel combinations, featuring different web strength grades (Q690, Q460, and Q355) and using HSS Q690 flange plates, were studied. Through the validated numerical method, parametric studies on the effect of web strength grade, boundary condition and plate slenderness were carried out. The design specifications in European, Australian, and American codes were evaluated using the results of 243 numerical models and collated test data. In addition, the continuous strength method (CSM), direct strength method (DSM), and Kato’s method, which can account for element interaction were extended to design for the local buckling behaviour of HSS and hybrid I-sections subjected to axial compression. Assessment results showed that ANSI/AISC 360-16 provides more accurate results than Eurocode 3 and AS 4100. Statistical and reliability results demonstrated the satisfactory reliability level of the proposed design expressions for CSM, DSM, and Kato’s design methods. This paper provides insight into the local buckling behaviour and mechanism behind plate interaction of hybrid I-sections.