Development of Cold-Formed Steel Portal Frames with PRY Sections

Abstract

A series of column, beam, and connection tests for portal frames which consisted of closed cold-formed steel PRY sections as columns and rafters were carried out. Firstly the compressive and the flexural strengths of the PRY sections were investigated, and secondly the structural behavior of the connections including the moment-rotation relation, the yield and the ultimate moment capacities of the connections were studied. The connection test specimens consisted of column-base, column-to-rafter, and rafter-to-rafter connections. The main testing parameters of the connection tests were the thickness and the shape of mild steel connectors, which were important for the proposed attachment system of wall panels. The connection test results were compared with those achieved by using advanced analysis procedures. The semi-rigid connection concept was considered appropriate for the analyses of the portal frames using the secant stiffness of the connections, which were estimated from the measured moment-rotation curves of the connections tested. Simple formulae for the shear resistances of the screwed connections were also proposed after calibrated with test results. The performance of the portal frame with PRY sections was investigated through the full scale tests.