CAN3-A23.3-M84

Preface

CSA Standard CAN3-A23.3, Design of Concrete Structures for Buildings, is intended for use in the design of concrete structures for buildings in conjunction with CSA Standards CAN3-A23.1-M and CAN3-A23.4-M. It supersedes the previous edition published in 1977 and the imperial edition published in 1973. With the publication of this edition, the commentary on the 1973 edition (A23.3.1) is withdrawn.

Explanatory material on this Standard is included in Appendices B, C, D, F and G and in the revised edition of the Canadian Portland Cement Association Concrete Design Handbook. This Standard is generally based on ACI Standard 318-83, Building Code Requirements for Reinforced Concrete, published by the American Concrete Institute. There are however, many differences from the ACI Code.

CSA Standard CAN3-A23.3-M84 differs from the previous edition as follows:

(a) the clause numbering has been changed to correspond to ACI Standard 318, whenever possible;

(b) clauses dealing with the design of beam-column joints in CAN3-A23.3-M77 (Clauses 5.12 and 9.14.1) have been collected together in Clause 7.7;

(c) the load factors in Clause 9.2 are based on those in the National Building Code of Canada, 1985. This has required the introduction of new resistance factors in Clause 9.3. These have been presented in a material understrength format with o factors applied to concrete strength and steel strength rather than a structural action format in which factors are applied to flexure, shear, etc. The application of Clauses 9.2 and 9.3 is explained more fully in Appendix B;

(d) the introduction of the new resistance factors has resulted in a number of changes throughout the Standard. The most significant of these occur in Clauses 10.2.4, 10.3.3, 11.3.4, 11.3.5, 11.7.4.3, and 11.10.2;

(e) limitations in Clauses 8.4, 10.3.3, and 18.8 which were expressed in terms of the balanced steel ratio in CAN3-A23.3-M77, are rewritten in terms of the neutral axis depth ratio c/d or c/h. This simplifies the presentation and the calculations while providing essentially the same limits on steel ratios, etc;

(f) Clauses 10.10 and 10.11 have been rewritten to more clearly separate the effects on stability of lateral deflections of frames and deflections between the ends of columns. Appendix C provides a brief explanation of the changes;

(g) Clause 11 on Shear and Torsion contains two alternative design procedures for beams. The simplified method in Clause 11.3 is an abbreviated version of the provisions in CAN3-A23.3-M77. The general method in Clause 11.4 is based on the compression field theory and is briefly explained in Appendix D;

(h) in addition to the two design methods for two-way slabs given in Clause 13, Appendix E contains moment coefficients for use in the design of slabs supported by walls or stiff beams;

(i) Clause 13.4.9 requires that a portion of the bottom reinforcement in slabs be lap spliced over columns or supports to improve the structural integrity of slabs;

(j) requirements that precast members be produced in certified plants have been revised. (See Clause 16.2.2.) The administrative requirements of Clause 16, specifically in respect to design responsibility, have been completely revised. The revised Clause offers the designer suggested divisions of design responsibility that conform to current industry practice. (See the Note following Clause 16.1.2);

(k) partial prestressing is permitted in Clauses 9 and 18. Appendix G provides a brief explanation of the changes in Clause 18;

(l) Clause 21 is completely revised, based on Appendix A of ACI Standard 318. The sections on walls and joints in Clause 21 differ from those in ACI Standard 318, Appendix A. The requirements for buildings qualifying for a K value of 1.3 in the lateral seismic force equation of the National Building Code of Canada have been completely revised;

(m) portions of ACI Standard 318.1-83, Building Code Requirements for Structural Plain Concrete, are included in Clause 22; and

(n) a number of Appendices are included. Appendix H presents guidance on the design of anchorage devices embedded in concrete.

This Standard was prepared by the CSA Technical Committee on Reinforced Concrete Design under the jurisdiction of the Standards Steering Committee on Structures (Design), and was formally approved by these Committees. It has been approved as a National Standard of Canada by the Standards Council of Canada.

Scope

1.1.1 General

This Standard provides requirements for the design and strength evaluation of building structures of reinforced concrete in accordance with the National Building Code of Canada.

Notes:

(1) In addition to the requirements of this Standard it is necessary that the design of building structures of reinforced concrete be carried out in accordance with the provisions of the National Building Code of Canada governing fire resistance.

(2) The use of design methods, materials, and structural components not in accordance with this Standard is covered in Part 2 of the National Building Code of Canada.

(3) The National Building Code of Canada requires that certain reviews be carried out by the designer or another suitably qualified person to determine conformance with the design.

1.1.2

Requirements for the design of certain unreinforced concrete building elements are also included in this Standard.

1.1.3 Special Structures

For special structures such as arches, tanks, reservoirs, bins and silos, towers, water towers, blast-resistant structures and chimneys, and for plain concrete, the provisions of this Standard shall govern insofar as they are applicable.

Note: Extensive structural deterioration has occurred in parking structures in areas where de-icing salts have been used. Designers should note that the durability of a parking structure, whether a separate structure or part of a structure, is a function of adequate cover, concrete quality, drainage, protection from environmental effects, such as freeze-thaw, chloride and water penetration, and allowance for structural effects, such as cracking and deflection due to temperature changes, creep, shrinkage, and restraint.

Concrete materials, strengths, cover, finishing methods, and curing methods should conform to the requirements of CSA Standard CAN3-A23.1 for corrosive environments. The use of protective systems such as waterproofing membranes or epoxy coated reinforcement should be considered. For further guidance see Parking Structures. In: Concrete International, Vol. 2, No.3, March 1980 and Canadian Building Digests 224 and 225, Division of Building Research, National Research Council of Canada, 1983.