Study of cold-formed steel structural members made of thick sheets and plates

This report consists of two parts: I - Local Buckling of Cold-Formed Steel Structural Members Having Compression Elements which Exhibit Initial Out-of-Flatness; and II - Effects of Cold Work on Mechanical Properties of Thick, Cold-Formed Steel Members and Bolted Connections. The first part of the study involved an analysis of the literature related to the topic. Both qualitative and quantitative trends were sought for this relationship, and the suitability of using the present AISI requirements for local buckling and post-buckling strength of thick sheets and plates are examined in detail. The question of correlating the results presented here to actual initial deviations from flatness found in standard cold-forming practices, and the observation that initial deviation from flatness may have more bearing on design requirements for unstiffened plates than for stiffened plates are discussed in relation to design criteria. The second part of the study was designed to investigate the structural behavior of cold-formed steel structural members, and to develop design recommendations for the increase of yield point at corners due to cold work and allowable stresses for bolted connections. The mechanical properties of steel sheets and plates before cold-forming into structural shapes was studied, and analytical and experimental investigations were carried out on the mechanical properties of corners. The applicability of AISI formulas for corners was verified. The study of bolted connections made of thick cold-formed steel members involved a comparison and evaluation of various design specifications for both thick and thin cold-formed steel members and thick, hot-rolled steel shapes shapes.