Critical Temperature of Load Bearing LSF Walls Under Fire

Abstract

Light Steel Frame (LSF) walls are widely used in building structures, used as partition walls and load bearing walls. The LSF is usually protected by layers of homogeneous plates or composite plates, with or without insulation materials in the cavity. This investigation presents the experimental and the simulation results of composite LSF walls in reduced scale and full scale, based on variable load levels (20 to 80%). The numerical model is validated with experimental results, at reduced and full scale, both at room temperature and under fire conditions. This modelling technique can follow the thermal and mechanical degradation of the protection layers of the LSF wall and determine the fire rating for load (R) and insulation (I). The fire resistance (R) decreases with the increase of the load level, being the critical temperature of the steel structure presented by the maximum temperature of the Hot Flange (HF). A new proposal is presented for the critical temperature of the LSF, based on the maximum temperature of the LSF during the fire. The insulation ability is also predicted for different protection materials. Relevant conclusions are presented to increase the insulation ability of LSF walls.

Light timber framed wall under fire: Effect of the load and cladding

“…For the validation of the full-scale model, and because this load-bearing model considers the wall submitted to fire from both sides, the standard fire ISO834 has been applied for the bulk temperature of the furnace side, while a different fire scenario (lower bulk temperature) has been applied on the other side (due to the limitation of the experimental testing facilities). Two numerical techniques have been used, based on our previous experience to validate 3D numerical models [19,20]. For the reduced-scale model, an extra boundary condition for convection and radiation is considered inside the cavity, based on the bulk cavity temperature measured during the experimental tests developed in the LTFW with a single and a double cladding system.…”