Cold Formed Steel Structural Members
This Standard for the design of Cold Formed Steel Structural Members is the second edition of CSA Standard $136. The first edition appeared in 1963 and was entitled The Design of Light Gauge Steel Structural Members. The change in title does not reflect a change in scope but merely a change in usage that has occurred in the past decade.
The American Iron and Steel Institute first published their Specification Design of Light Gauge Cold-Formed Steel Structural Members in 1946 and have revised it several times. The latest edition is dated 1968. The data used in compiling this Standard remains chiefly the results of large testing programs directed by Professor George Winter of Cornell University. In addition, the Standard is based on theoretical and experimental work carried out in Canadian, British and German institutions.
The present Standard differs significantly from the first edition in many respects. It is the first Canadian structural standard to provide a limit states design option, in conjunction with design loads and load factors specified in the 1975 National Building Code of Canada. It is also the first Canadian structural standard which has undergone soft conversion to calculation using modernized metric (SI) units as an option. These changes have affected a reorganization of the material Into one clause applicable only in established working stress design (see Clause S), one clause applicable only in limit states design (see Clause 12), and the balance of the Standard common to both design methods.
In addition to these changes, the Standard contains new formulations of buckling analyses, effective width formulas and formulas for effective width of stiffened elements, equivalent thickness of multiple-stiffened elements, utilization of cold work of forming, and stiffener adequacy, to mention-a few. These changes are either dictated by new theoretical analysis or experimental evidence, or advanced in order to simplify the design procedures that are often complex. A commentary is under preparation by CSA which will explain these changes in detail. A book of design aids similar in scope to the AISI Cold—Formed Steel Design Manual is also in preparation.
The Committee wishes to acknowledge its indebtedness to the many individuals and organizations who assisted in the preparation of this edition. We wish to thank the former members of the Committee for their effective cooperation in preparing the many drafts of the Standard. We especially wish to thank also the following individuals for their generous cooperation in the preparation of this Standard:
D. E. ALLEN ........ National Research Council of Canada, Ottawa
E. B. GIBSON ........ The Steel Company of Canada Limited, Hamilton
A. L. JOHNSON ...... American Iron and Steel Institute, Washington, D.C.
G. MILLAR .......... The Steel Company of Canada, Limited, Hamilton
S. R. PARIMI ........ Fluor Pioneer Corporation, Chicago
M. K. RAVINDRA ..... Sargent and Lundy Engineers, Chicago
D. K. SHROFF ....... Peter Shameld & Associates, Toronto
W. SIU ............. Taskmaster Computing Systems, Edmonton
C. TURKSTRA ........ McGill University, Montreal
G. WINTER .......... Cornell University, Ithaca, N.Y.
K. VENKATARAMAIAH ..Mangalore, Mysore, India
This Standard was prepared by the Committee on Design of Light Gauge Steel Structural Members under the jurisdiction of the Sectional Committee on Structures and was formally approved by these Committees.
This Standard applies to the design of structural members fabricated by cold forming carbon or low alloy sheet, strip or plate, and applies also to the design of any structural member fabricated by welding, riveting, and other methods, in which the width : thickness ratio of any component exceeds that normally allowed in other CSA Standards for the design of steel structural members used for load carrying purposes in buildings. It is intended to supplement and not to conflict with such Standards, if used in conjunction with same.
This Standard may also be used as a guide for members in structures other than buildings provided appropriate allowances are made for dynamic effects.
The provisions in this Standard are based on experimental evidence generally obtained on specimens with material thickness up to one inch.
Two alternative design procedures, each based on the elastic theory, are presented, namely:
(a) Working Stress Design (WSD), referring to allowable stress under specified loads using Clause 5; and
(b) Limit States Design (LSD), referring to a capacity under factored loads, using Clause 12.
No attempt is made to specify load requirements for the several categories into which structures and structural members may be divided. Loads shall be those stipulated in the Standards under which the structure is to be designed, or as specified by the authority having jurisdiction.
Wherever empirical or semi-empirical formulas or dimensional limitations are provided in this Standard as a design convenience, a rational design based on theory, test, analysis and engineering practice together with a margin of safety acceptable to the authority having jurisdiction may be used instead.