- Author
- Gerlich, J. T.
- Title
- Design of Loadbearing Light Steel Frame Walls for Fire Resistance. Fire Engineering Research Report.
- Coporate
- University of Canterbury, Christchurch, New Zealand
- Report
- Fire Engineering Research Report 95/3, August 1995, 126 p.
- Keywords
- walls | laod bearing elements | fire resistance rating | structural design | temperature effects | large scale fires
- Identifiers
- Light Steel Frame (LSF) building system; New Zealand; loadbearing LSF drywall systems; cold-formed steel members; thermal model
- Abstract
- Light steel frame (LSF) building systems are becoming more prevalent in commercial, industrial and residential construction in New Zealand. Tested fire resistance ratings are generally available for non-loading LSF drywall systems lined with gypsum plasterboard. No test information exists for loadbearing systems. Current solutions are based on limiting steel temperature. This study investigates the parameters which affect the performance of loadbearing LSF drywall systems exposed to fire. Structural design codes for cold-formed steel members are compared. Methods are presented for calculating the reduction of steel strength and stiffness at elevated temperatures, and for predicting the deformations resulting from temperature gradients and P-delta effects. Heat transfer modelling by computer is used to predict steel framing temperatures for systems exposed to the standard ISO 834 time-temperature curve and real fires. Three full-scale furnace tests were carried out to evaluate analytical predictions. A model is proposed for predicting the performance of loadbearing LSF systems exposed to fire. Results are within 80-90% of test results. The current practice of designing to a limiting steel temperature results in unduly conservative predictions, particularly for systems with low applied axial loads. It was also found that fire tests may give non-conservative results for systems with low stud loads due to fractional restraints.