CSA Group Strength design in aluminum / Commentary on CSA S157-17, Strength design in aluminum S157-17/S157.1-17

Preface This is the fifth edition of CSA S157, Strength design in aluminum. It supersedes the previous editions published in 2005, 1983, 1969, and 1962. This Standard is for building applications but it is written in a form that may be used for all types of aluminum load-bearing components or assemblies. Expressions for the strength of structural components are based on the concept of limit states design. Requirements to satisfy the ultimate limit state form the core of the Standard. As a document referenced by the National Building Code of Canada, the load factors and resistance factors specified by that Code are given. However, because the design expressions predict the nominal resistance of components and connections, this Standard is useful in any field of engineering in which known applied loads are to be supported. Serviceability limit states depend on the desired behaviour under service loads for each particular application and are not specified in this Standard. For components used in buildings, reference is made to Commentary A of the National Building Code of Canada. CSA S157.1, Commentary on CSA S157-17, Strength design in aluminum (hereinafter referred to as the Commentary), is provided which, while not a mandatory part of the Standard, is essential to the implementation of this Standard%u2019s requirements. In this Standard, cross-references to the Commentary are identified by the prefix "C" before the clause, table, or figure number. This edition of CSA S157 contains significant changes from the previous edition and follows, wherever possible, the same order of presentation as CSA S16, in order to facilitate the use of these two Standards: a) A more comprehensive list of symbols is provided in Clause 3. b) Clause 4 contains a new set of requirements on structural documents. c) A significantly longer list of wrought aluminum products conforming to the ASTM specifications is presented in Table 1. Time-temperature limits are provided for T5 and T6 tempers and nominal strengths of aluminum filler metals are given in a new table. d) In Clause 8, elastic analyses of structures now include second order effects and the effects of geometric imperfections. This has significant implications on the design of members subject to flexure and axial forces (Clause 14). e) The design of built-up compression members is moved to a mandatory Annex. f) Clause 11 presents generalized design equations for members subject to lateral-torsional buckling. g) The extent of the heat-affected-zone (HAZ) in welded connections is redefined in Clause 15. It is now similar to the provisions of Eurocode 9 and Section 17 of CSA S6. h) A new set of recommendations for the design of screws is included in Clause 16.7. i) Clauses 18, 20, 21, and 22 on fabrication, erection, inspection and testing, respectively, are new clauses. They are adapted from CSA S16. j) The specifications on the fatigue of aluminum presented in Clause 23 have been revised by incorporating the detail category and S-N curve definitions from Section 17 of CSA S6. The detail category definitions are similar to the steel definitions in Section 10 of CSA S6. The S-N curve definitions are consistent with the Aluminum Design Manual. k) Clause 24 presents a new set of provisions for the design of composite beams (concrete slab on aluminum girders). This is an adaptation of the provisions of CSA S16 to aluminum. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of the Aluminum Association of Canada, Alubec, and the Centre québécois de recherche et de développement de l%u2019aluminium.