Finite element investigation of cold formed steel portal frames in fire
This paper presents the results of a full scale site fire test performed on a cold formed steel portal frame building with semi rigid joints. The purpose of the study is to establish a performance based approach for the design of such structures in fire boundary conditions. In the full scale site fire test, the building collapsed asymmetrically at a temperature of 714degC. A non linear elasto plastic finite element shell model is described and is validated against the results of the full scale test. A parametric study is presented that highlights the importance of in plane restraint from the side rails in preventing an outwards sway failure for both a single portal and full building geometry model. The study also demonstrates that the semi rigidity of the joints should be taken into account in the design. The single portal and full building geometry models display a close match to site test results with failure at 682degC and 704degC, respectively. A design case is described in accordance with Steel Constructio.