A23.3-94 (R2000)

Preface

This is the fourth edition of CSA Standard A23.3, Design of Concrete Structures. It is intended for use in the design of concrete structures for buildings in conjunction with CSA Standards A23.1-94 and A23.4-94. It supersedes previous editions published in 1984, 1977, and 1973.

CSA Standard A23.3-94 differs from the previous edition as follows:

(a) New provisions have been added to take account of some of the features of high-strength concrete up to a compressive strength of 80 MPa. These include new expressions for the modulus of elasticity (Clause 8), revised stress block factors and a new expression for the minimum amount of flexural reinforcement (Clause 10), a new expression for the minimum amount of shear reinforcement (Clause 11), and an upper limit on the value of the concrete compressive strength to be used in determining the development and splice length requirements of reinforcement (Clause 12).

(b) Clauses 8 and 9 have been rearranged.

(c) The load factors in Clauses 8.2 and 8.3 are based on those in the National Building Code of Canada, 1995.

(d) Clause 10 on Flexure and Axial Loads contains new expressions for determining stress block factors. The provisions for the design of slender columns have been changed and the transmission of column load through floors has been changed.

(e) Clause 11 on Shear and Torsion contains a new design procedure for beams which is based on the modified compression field theory.

(f) Clause 12 on Development and Splices of Reinforcement has new development length expressions which take into account the influence of concrete cover, spacing and transverse reinforcement, and epoxy coating on the reinforcement.

(g) Clause 13 on Two-Way Slab Systems has been revised to permit the use of elastic plate theory, plasticity, elastic frame analysis, or the direct design method for analysing two-way

slab systems. Provisions for the shear design of two-way slab systems have been moved from Clause 11 to Clause 13. Provisions for the minimum thickness of two-way slabs have been modified and moved from Clause 9 to Clause 13.

(h) Clause 16 on Precast Concrete includes new provisions for structural integrity.

(i) Clause 18 on Prestressed Concrete has a new expression for the stress in prestressing tendons at factored resistance. Provisions for the shear design of prestressed two-way slab systems have been moved from Clause 11 to Clause 18.

(j) Clause 21 on Special Provision for Seismic Design now distinguishes between ductile coupled walls and other ductile wall systems to conform to new categories in the National Building Code of Canada, 1995. Provisions for structures with nominal ductility have been expanded.

(k) Clause 22 on Structural Plain Concrete has been rearranged and simplified.

(l) Clause 23 on Tilt-Up Wall Panels is a new clause for the analysis and design of tilt-up construction.

Scope

1.1 General Requirements

1.1.1 General

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

Note: In addition to the requirements of this Standard, it is necessary that the design be carried out in accordance with the provisions of applicable Building Codes governing fire resistance.

1.1.2 Plain Concrete Building Elements

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

1.1.3 Structural Equivalents

Designs using procedures not covered by this Standard, which are carried out by a person qualified in the specific methods applied, and which provide a level of safety and performance equivalent to design conforming to this Standard, are acceptable if carried out by one of the following methods:

(a) analysis based on generally established theory;

(b) evaluation of a full-scale structure or a prototype by a loading test; or

(c) studies of model analogues.

1.1.4 Special Structures

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

Note: Special requirements for parking structures are specified in CSA Standard S413.

1.2 Drawings and Related Documents

In addition to the information required by the applicable Building Codes, the drawings and related documents for structures designed in accordance with this Standard shall include:

(a) size and location of all structural elements, reinforcement, and prestressing tendons;

(b) provision for dimensional changes resulting from prestress, creep, shrinkage, and temperature;

(c) locations and details of expansion or contraction joints and permissible locations and details for construction joints;

(d) magnitude and location of prestressing forces;

(e) specified strength of concrete in various parts of the

structure at stated ages or stages of construction and nominal maximum size and type of aggregate;

(f) required cover;

(g) reinforcing steel standard and specified type and grade of reinforcement;

(h) anchorage length and the location and length of lap splices;

(i) type and location of welded splices and mechanical connections of reinforcement;

(j) type and grade of prestressing steel; and

(k) protective coatings for reinforcement, prestressing tendons, and hardware.