Lateral Torsional-Buckling of Class 4 Steel Plate Beams at Elevated Temperature: Experimental and Numerical Comparison

Abstract

This paper presents ongoing research in behaviour of laterally unrestrained beams (I or H section) of Class 4 cross-sections at elevated temperatures, which is based on the RFCS project FIDESC4 - Fire Design of Steel Members with Welded or Hot-rolled Class 4 Cross-sections. Despite the current EC3 contains a number of simple rules for design of slender Class 4 cross-sections at elevated temperature, based on recent numerical simulations they were found to be over-conservative. Therefore, new well representing design models, which simulate the actual behaviour of the structures exposed to fire, are crucial. These design rules should be based on extensive numerical simulation validated on experimental data. Within this task, several tests were carried out to study lateral torsional buckling of Class 4 beams in fire. The design of the test set-up and description of the experiment is given, as well as verification of numerical model.

Fire buckling curves for torsionally sensitive steel members subjected to axial compression

“…In the last decades, researchers investigated different instability phenomena in steel elements in fire situation, such as lateral-torsional buckling (Bailey et al , 1996; Vila Real and Franssen, 2000; Vila Real et al , 2004b) and its interaction with local instabilities (Vila Real et al , 2004a; Couto et al , 2014; Prachar et al , 2015; Couto et al , 2016; Couto et al , 2018; Franssen et al , 2016). Nevertheless, there is a lack of studies about the torsional and flexural-torsional buckling of angles and built-up steel members in compression at elevated temperature made of hot-rolled profiles, whereas such buckling phenomena have been studied for cold-formed steel profiles at both ambient and elevated temperatures (Schafer, 2008; Popovic et al , 2001; Ranawaka and Mahendran, 2010; Silvestre et al , 2013; Laím and Rodrigues, 2018; Craveiro et al , 2018; Arrais et al , 2021).…”

Methodology for the elaboration of the design table of GFRP structures subjected to fire

“…At higher temperatures (fire situations), Class 4 steel sections are usually oversized in most buildings Couto et al (2016); Knobloch et al (2012); Couto et al (2018); Maia et al (2016), due to the fact that, in practice, they are limited to the critical temperature of 350ºC CEN (2005), when, in reality, they could continue to work at higher temperatures Franssen, Zhao, and Gernay (2016); Jandera, Prachař, and Wald (2020); Prachar et al (2015).…”

Compressive resistance of high-strength and normal-strength steel CHS members at elevated temperatures

“…The existing column buckling design rules of EN 1993-1-2 [21] are based upon numerical simulations [24,25] and physical experiments [26] that have been primarily focused on normal-strength steel I-section members. As part of the FIDESC4 [27] project supported by the European Commission Research Fund for Coal and Steel (RFCS), [28][29][30][31][32][33][34][35][36] have comprehensively investigated the behaviour of structural steel members with Class 4 sections in fire, which resulted in major developments in understanding the response of structural steel elements at elevated temperatures and the revisions of a number of design provisions of EN 1993-1-2 [21] which will be implemented in the upcoming version of the standard. However, in this project [27], the behaviour and design of only normal-strength Iand H-section steel members were investigated, signifying that further studies focusing on the structural response and design of high-strength steel elements in fire are necessary.…”