Post-fire behaviour of cold-formed high strength steel tubular T- and X-joints

Pandey, Madhup; Young, Ben

Abstract

An experimental programme to investigate the post-fire residual strengths of cold-formed high strength steel (CFHSS) tubular T- and X-joints subjected to ISO-834 standard fire [1] exposure has been presented in this study. A total of 32 joints, including 16 T-joints and 16 X-joints, was tested. The tubular members of T- and X-joints were made of S900 and S960 steel grades. The test specimens were divided into 3 sets, and subsequently, these sets were then heated up to 300 °C, 550 °C and 750 °C by generally following the ISO-834 standard fire [1] curve, respectively. Once the fire exposed tubular T- and X-joints cool down to ambient temperature, tests were then conducted. The brace members of tubular T- and X-joints were made of square, rectangular and circular hollow sections (SHS, RHS and CHS), while SHS and RHS were used as the chord members. In this study, two configurations of tubular T- and X-joints were tested, first, where SHS and RHS were used as the brace and chord members (i.e. RHS-RHS), and second, where braces were made of CHS and chords were made of SHS and RHS (i.e. CHS-RHS). The T-joints were tested by applying axial compression load through the brace members and the chord ends were supported on rollers. The X-joints were tested by applying axial compression load through the brace members without chord preload. The welding was performed using automatic gas metal arc welding process. For T- and X-joints, the nominal values of brace-to-chord width ratio (β) ranged from 0.42 to 1, brace-to-chord thickness ratio (τ) ranged from 0.75 to 1, chord width-to-thickness ratio (2γ) ranged from 25 to 35 and chord side wall slenderness ratio (h0/t0) ranged from 15 to 35. Currently, there are no specific design rules to predict the post-fire residual strengths of tubular joints. Thus, the post-fire residual joint strengths obtained in this investigation were compared with the nominal strengths calculated from the CIDECT [2] and Eurocode 3 (EC3) [3] using the measured post-fire residual mechanical properties. It is shown that the current design rules of T- and X-joints given in the CIDECT [2] and EC3 [3] could not accurately predict the post-fire residual strengths of cold-formed S900 and S960 steel grades tubular T- and X-joints.

Citation

Pandey, M., & Young, B. (2021). Post-fire behaviour of cold-formed high strength steel tubular T- and X-joints. Journal of Constructional Steel Research, 186, Article 106859. https://doi.org/10.1016/j.jcsr.2021.106859

• Journal Article Type: Article
• Acceptance Date: Jul 10, 2021
• Online Publication Date: Sep 2, 2021
• Publication Date: 2021-11
• Deposit Date: Apr 2, 2023
• Journal: Journal of Constructional Steel Research
• Print ISSN: 0143-974X
• Publisher: Elsevier BV
• Peer Reviewed: Peer Reviewed
• Volume: 186
• Article Number: 106859
• DOI: https://doi.org/10.1016/j.jcsr.2021.106859
• Keywords: Metals and Alloys; Mechanics of Materials; Building and Construction; Civil and Structural Engineering
• Public URL: https://nottingham-repository.worktribe.com/output/15940600
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0143974X21003412?via%3Dihub