| Lightweight steel framing (LSF), assembled from thin gauge cold formed steel members, is increasingly popular in commercial and residential construction in North America because of its non-combustibility, dimensional stability, ease of installation and other advantageous features. In many instances, LSF wall and floor assemblies are required to serve as fire compartment boundaries and provide adequate fire resistance, with the purpose of preventing (or delaying) the spread of fire and ensuring that building integrity is maintained while occupants evacuate and fire fighters perform suppression and rescue operations. Existing codes require the fire resistance ratings of structural assemblies to be determined on the basis of standard fire resistance tests, which are quite expensive and time consuming. As a result, in Canada, the number of LSF assemblies tested for fire resistance is extremely limited compared to the variety of designs that LSF technology can offer. The experimental part of this research thesis adds to the existing database on the fire resistance of loadbearing LSF walls protected with two layers of fire resistant gypsum board by presenting detailed results of three new tests. These tests were designed to complement earlier experiments and investigate the effect of stud spacing, cavity insulation and resilient channels on the fire resistance of loadbearing LSF walls, Test results indicate that, contrary to generally held beliefs, cavity insulation and resilient channels reduce the fire resistance of loadbearing LSF walls while increased stud spacing does not.; In addition to standard instrumentation used in fire resistance tests, more than 50 thermocouples and ten deflection gauges were used in each test to generate temperature and deformation data suitable for analytical studies. The analytical part of this research thesis is devoted to the development and calibration of numerical modelling techniques in retrospective simulations of six wall tests and five floor tests. This task included the development of computer program TRACE for thermal simulations and computer programs STUD and JOIST for structural simulations. Theoretical structural models, presented in this thesis, form the basis of the latter two programs. Both thermal and structural simulations showed a reasonable agreement with experimental data. |
