Feasibility of using cold formed steel sections for medium span portal frames in Sri Lanka

Abstract

Cold formed and thin walled steel (CFS) sectional members are used in building industry in many fields around the world. CFS sectional members are combined and used as a primary load bearing members on medium span structures. However use of combined CFS members on medium span portal frames in Sri Lanka is limited due to lack of knowledge. This research is to design and analyze the feasibility of using back to back CFS lipped channels on industrial portal framed building. There were 16 nos. models selected with varying spans of 6m, 9m, 12m and 15m, heights 4m and 6m and bay distance 4m and 6m. The models were first analyzed with computer analysis software called PROKON and optimum sections of back to back combined CFS lipped channels were selected so that it’s serviceability conditions were satisfied. Further the selected section sizes were revised until it’s combined moment and compression overall buckling criteria ( ) ( ) is satisfied. The major feasibility was carried through cost analysis with compared to hot rolled sectional portal frames are being constructed in Sri Lanka’s western region. Therefore the wind speed kept as constant of 140 km/hr (Maximum wind speed in western region). Out of 16 nos. models 14 nos. models shows cost effective ad saving on cost varied from 14% to 21.5% and an average of 12.5%. 4m bay distance is economical than 6m bay distance. 12m span is found to be the most economical span in these models.