Effects of Cross-Section Type and Degree of Utilization on Failure Time and Temperature of Cold-Formed Steel Column under ISO Fire

Fadhluhartini Muftah,Mohd Syahrul Hisyam Mohd Sani,Shahrin Mohammad

doi:10.3390/met9090964

Fadhluhartini Muftah, Mohd Syahrul Hisyam Mohd Sani + Show 1 more

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https://doi.org/10.3390/met9090964

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Abstract

An investigation into fire resistance subjected to the ISO fire standard was conducted on a cold-formed steel (CFS) column. The variables involved were the CFS sections with various cross-section types and service loadings known as the degree of utilization. Three types of cross-section, known as channel, back-to-back (BTB), and box-up (BU) sections, were studied. All supports for the column are in constant condition. To simulate the real fire situation, the column was preloaded at 30%, 50%, and 70% of its ultimate strength. After the load was static, the column was exposed to the ISO fire standard. The column was loaded at the centroid of the section. The temperature at the column surface and the time was recorded until the column became unstable. The results show that the shape did not have any significant effects on the critical temperature of the CFS columns. The higher the applied load—or as used in this study, the higher the degree of utilization of the CFS columns—the greater the negative linear effect on their critical temperature. It is concluded that the minimum limiting temperature is 400 °C and the minimum limiting time is four minutes for the CFS column.

Highlights

Failure time and temperature of the column is important information in estimating the resistance capacity of a column in a fire situation
The results show that the shape did not have any significant effects on the critical temperature of the Cold-formed steel (CFS) columns
It is concluded that the minimum limiting temperature is 400 ◦ C and the minimum limiting time is four minutes for the CFS column

Summary

Introduction

Failure time and temperature of the column is important information in estimating the resistance capacity of a column in a fire situation. Most investigations conducted on individual columns evaluate the failure time and temperature. Cold-formed steel (CFS) is a very sensitive material due to its thinner width, which is perceived to have low resistance when on fire. The thermal conductivity of material and the section factor of CFS contribute to low fire resistance [1]. The estimation of CFS capacity in EN 1993-1-2:2005 is based on hot-rolled steel with a Class 4 cross-section. The prediction includes the variety of buckling mode, i.e., local, global, and distortional buckling, and their interactions [2]. The degradation of material strength of CFS under fire conditions was found to be the dominant factor influencing fire resistance [3]

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