COLD-FORMED STEEL RESEARCH AT THE UNIVERSITY OF WATERLOO
R. M. Schuster
Department of Civil Engineering, University of Waterloo, Canada
Active cold-formed steel research started in the early 70s at the University of Waterloo with Profs.
N. C. Lind, A. N. Sherbourne, J. Roorda, and R. M. Schuster, and their respective graduate students. More recently, Prof. L. Xu and his graduate students have also contributed in this area of research. Numerous publications have been documented in National and International sources over the past 35 years. Presented in this paper are the many noteworthy contributions that have been made as a result of the cold-formed steel research activities at the University of Waterloo. What is of particular interest is the number of design recommendations that have been adopted by National and International cold- formed steel design Standards and Specifications. With the recently formed Canadian Cold-Formed Steel Research Group, cold-formed steel research is very much alive at the University of Waterloo.
The use of cold-formed steel as a structural building material dates back to the 1850s in the USA and the UK. Initially, the acceptance of cold-formed steel in the building construction industry faced difficulties because no published Specification for the design of cold-formed steel structures existed at that time. For such a Specification to be published, research had to be carried out. In 1939, the American Iron and Steel Institute (AISI) sponsored a research project at Cornell University under the direction of Professor George Winter with the objective of developing the necessary technical information that would lead to the development of the first cold-formed steel design Specification, which was published by AISI in 1946. This design Specification has been revised subsequently by AISI a number of times to reflect the technical developments resulting from the continuing research in the field of cold-formed steel. The Canadian Standards Association (CSA), following a number of subsequent editions, published the first cold-formed steel design Standard, S136, in Canada in 1963.
In comparison to hot-rolled structural steel members, cold-formed steel is uniquely different in that structural panel/deck sections and individual profile members are made of rather thin-coated steel plate material. This allows for the production of a great variety of geometric shapes, as can be seen in Figure 1. Most of the cold-formed steel shapes are produced economically by using roll-forming operations. Cold-formed steel structural members have one of the highest strength to mass ratios of any structural building material. The use of cold-formed steel in the construction industry in North America is steadily growing and gaining momentum, including cladding, roofing, composite decking, lightweight steel framing, corrugated steel pipe, storage racks, transmission towers and numerous other applications. Due to the thinness of the steel plate material, cold-formed steel products are subject to local buckling, resulting in more detailed and complicated calculations for the structural designer. Ongoing research in this field is extremely important in order to update and improve the governing cold-formed steel structural design Specifications and Standards.