Fire performance of LSF walls with web stiffened channel sections using finite element analysis

Light-gauge steel framed (LSF) walls with plasterboard lining are increasingly used in modern building construction due to their numerous advantages. Their fire performance has been investigated using both numerical and experimental studies in the past for lipped channel section (LCS) and welded hollow flange section (HFC) studs. A new riveted HFC stud was also considered. However, no attempt was made to use a structurally and economically optimum stud section in the wall configurations. This paper investigates the fire performance of a new stiffened channel section (SCS) as LSF wall studs. The proposed section succeeds in delaying both local and distortional buckling modes. At ambient temperature, the member compression capacity of each stud section, normalized to its squash capacity, was used to compare the performance of the three sections. It was found that the performance of SCS is equivalent to the LSB and superior to the LCS. The fire performance of LSF wall studs made of LCS, LSB, and the proposed section has also been assessed for three common wall configurations using finite element (FE) analyses. The walls were exposed to the standard ISO 834-1 fire curve on one side. Stud time-temperature profiles were developed for the three wall configurations using finite element thermal analyses and validated using available full-scale fire test data. Fire Resistance Levels (FRL) of load bearing and non-load bearing walls were determined and validated using previous experimental and numerical results. For the same load ratio, the three stud sections perform similarly, giving close FRL values for each of the configurations considered. Due to the elimination of the necessity for welding or riveting, it is proposed that SCS is used to develop structurally and economically optimum LSF walls compared to those made using LCS and welded or riveted HFC sections. FRL versus Load Ratio curves were developed for the full range of load ratio using both steady and transient state FE analyses. Using them, the susceptibility of cavity insulated, non-load bearing LSF walls to failure due to structural inadequacy was also identified