Structural Design Study on a Light - Gauge Steel Portal Frame with Cold-formed Sigma Sections

Design study is conducted on a thin-gauge cold-formed steel portal frame with compound double (back-to-back) sigma sections in columns and rafters. Experimental study on the sem-irigid rafter-to-column connection behaviour is first carried out for two special bolted connection types based upon specific thin connection plates between the double sections. First connection plate studied was a compact corner plate bolted between double sigma sections of rafter and column end parts. Other connection plate type studied was composed of four together layered thin plates with the edges of two outer plates outwardly lipped at the free side of the corner plate. Connection behaviour in the ridge joint of the portal frame also constructed with using a connection plate between double sigma sections of rafter ends was experimentally studied in a similar way as the rafter-to-column connection behaviour. Analytical models are developed for the semi-rigid connection behaviour in the corners and in the ridge of the portal frame and these models are then used in design calculations for the whole portal frame. One design case study for a 12 m span portal frame is completed by using the newest version of Eurocode 3