Improved fire resistant performance of load bearing cold-formed steel interior and exterior wall systems

In order to improve the fire performance of load-bearing CFS wall systems for applications in mid-rise buildings, different panels and external insulation were examined in this paper. Experiments on six full-scale CFS wall specimens were performed in which the insulation material of aluminum silicate wool was located outside the CFS frame and sandwiched between two layers of boards on the fire side instead of being placed in the cavity. Five types of panels were involved in the experiments, including gypsum plasterboard, bolivian magnesium board, oriented standard boards (OSB), autoclaved lightweight concrete (ALC) boards and rock wool boards. The results showed a noticeable reduction of heat transfer to the surface of steel stud and a considerable improvement of fire performance of CFS walls by using aluminum silicate wool as external insulation. For CFS walls with aluminum silicate wool as external insulation on fire side, gypsum plasterboard as face layer and bolivian magnesium board as base layer on both sides, different load ratios may result in different failure modes, and the fire resistant time can be more than 150 min when the load ratio was less than 0.65. It was also demonstrated that the fire performance of CFS wall systems lined with bolivian magnesium board or ALC boards were superior to those lined with gypsum plasterboard and OSB. Therefore, bolivian magnesium board may be recommended to replace gypsum plasterboards as the base layer and ALC board may be used to replace OSB as exterior wall panels of CFS wall systems for applications in mid-rise buildings.