Structural performance of cold-formed steel trusses used in electric power substations

This paper presents a detailed investigation of the lateral characteristics of cold-formed steel truss structures used in electric power substations. Five full-scale specimens were tested, and their responses were recorded under monotonic and cyclic loading regimes. Of particular interest were the specimens' maximum lateral load capacities and deformation behaviours. A rational estimation of the seismic response modification factor, R, of the truss structures is also provided. In addition, different types of stiffened sections were employed in order to examine the impact of the presence of stiffeners and lips on seismic behaviour, as well as on the lateral resistance of the structure. Detailed comparisons between relevant code methods, finite element modelling and an experimental study were then conducted to suggest an appropriate value for the R factor. A financial evaluation was also performed, to highlight the advantages of employing cold-formed steel trusses in the electric power substation industry. The results show that the cold-formed steel structural system is a reasonable alternative to the currently used hot-rolled steel structures, and that its use decreases the cost of the structures by almost 50%.