Csa masonry s304.1-04

S304.1-04
Design of masonry structures
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S304.1-04
CSA Standards Update Service
S304.1-04
December 2004
Title: Design of masonry structures
Pagination: 139 pages (xiii preliminary and 126 text), each dated December 2004
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S304.1-04
CSA Standard

ISBN 1-55397-402-6
Technical Editor: Mark Braiter
© Canadian Standards Association — 2004
All rights reserved. No part of this publication may be reproduced in any form whatsoever
without the prior permission of the publisher.

December 2004 iii
Contents
© Canadian Standards Association Design of masonry structures
Technical Committee on Masonry Design x
Preface xii
1 Scope 1
2 Reference publications, definitions and standard notation, and units 2
2.1 Reference publications 2
2.2 Definitions and standard notation 4
2.2.1 Definitions 4
2.2.2 Standard notation 8
2.3 Units 14
3 General requirements 14
3.1 Design methods 14
3.2 Other design methods 14
3.3 Drawings and related documents 14
3.4 Materials 15
4 Design requirements 15
4.1 Specified loads and effects 15
4.1.1 Loads and effects 15
4.1.2 Dynamic effects 15
4.1.3 Importance factor 16
4.1.4 Loads not listed 16
4.2 Limit states design 16
4.2.1 Terminology 16
4.2.2 Strength and stability 16
4.3 Factored resistance 17
4.3.1 General 17
4.3.2 Resistance factors 18
4.3.3 Masonry connectors 18
4.3.4 Effective stiffness 18
4.4 Structural integrity 18
4.5 Limits on use of unreinforced masonry 18
4.5.1 Seismic limitation for unreinforced masonry 18
4.5.2 Locally reinforced masonry 18
4.5.3 Unreinforced shear walls 19
4.6 Seismic design 19
4.6.1 General 19
4.6.2 Veneer secured by ties 19
4.6.3 Seismic limitation for masonry of conventional construction 19
4.6.4 Limited ductility shear walls 19
4.6.5 Moderately ductile shear walls 19
4.6.6 Moderately ductile squat shear walls 19
4.7 Fire resistance 20
4.8 Support of masonry 20
4.8.1 Rigidity requirements 20
4.8.2 Vertical support of masonry 20
4.8.3 Lateral support of masonry 21
4.9 Connectors 21

S304.1-04 © Canadian Standards Association
iv December 2004
4.10 Serviceability 21
4.10.1 Effects of differential movements and dimensional changes 21
4.10.2 Displacements 22
4.10.3 Crack control 22
4.11 Durability 22
4.11.1 General 22
4.11.2 Reclaimed masonry units 22
4.11.3 Corrosion protection of metal components 22
4.12 Fibre-reinforced polymers 24
5 Specified strengths used in design 24
5.1 Masonry compressive strength 24
5.1.1 Design strength 24
5.1.2 Compressive strength based on masonry prism tests 24
5.1.3 Compressive strength based on unit, mortar, and grout tests 25
5.2 Masonry tensile strength 26
5.2.1 Specified flexural tensile strength 26
5.2.2 Test for masonry flexural tensile bond strength 26
5.2.3 Specified axial tensile strength 26
5.3 Masonry shear strength 27
5.3.1 Walls and columns 27
5.3.2 Beams 27
5.4 Masonry bearing strength 27
5.5 Reinforcing steel yield strength 27
5.6 Prestressing steel strength 27
5.7 Connector strength 27
6 Analysis of the structure 27
6.1 Safety and serviceability 27
6.2 Methods of analysis 27
6.3 Alternative methods of analysis 27
6.4 Secondary effects 27
6.5 Modulus of elasticity 27
6.6 Composite members 28
6.7 Cavity walls 28
6.7.1 Lateral loads 28
6.7.2 Axial load and bending 28
7 Design of unreinforced walls and columns 28
7.1 General 28
7.1.1 Factored resistance 28
7.1.2 Masonry columns 28
7.1.3 Limitations 28
7.1.4 Toothed joints 29
7.2 Design requirements for axial load and bending 29
7.3 Effective cross-sectional area 29
7.4 Maximum factored axial load resistance 29
7.5 Effective height 29
7.6 Shear wall flanges 30
7.6.1 Shear wall flange width 30
7.6.2 Flange intersections 30
7.6.3 Chases and openings 30
7.7 Axial load and minor axis bending in walls 30
7.7.1 Cavity walls 30

December 2004 v
7.7.2 Composite and other multi-wythe solid walls 30
7.7.3 Minimum primary moment 31
7.7.4 Section total moment effects 31
7.7.5 Slenderness limits 31
7.7.6 Design methods 32
7.8 Axial load and biaxial bending in walls 33
7.8.1 Design of compression zone 33
7.8.2 Design of tension zone 33
7.9 Columns 33
7.9.1 General 33
7.9.2 Axial load and single axis bending in columns 33
7.9.3 Axial load and biaxial bending in columns 33
7.10 Shear in walls and columns 34
7.10.1 Factored in-plane shear resistance for walls 34
7.10.2 Factored out-of-plane shear resistance for walls and columns 35
7.10.3 Stack pattern factored shear resistance 35
7.10.4 Factored sliding shear resistance 35
7.11 Intersections 36
7.12 Flexural wall panels 37
7.12.1 General 37
7.12.2 Flexural wall panel dimension limits 37
7.12.3 Calculation of factored moments in panels 37
7.12.4 Calculation of resisting moment in panel 37
7.13 Infill shear walls 38
7.13.1 General 38
7.13.2 Analytical models 38
7.13.3 Design of infill shear walls 39
7.14 Bearing resistance for concentrated load 40
7.14.1 Stress distribution under beams 40
7.14.2 Dispersion of concentrated load 40
7.14.3 Walls of fully grouted masonry or solid brick masonry 40
7.14.4 Walls of hollow block or brick units not fully grouted 41
7.14.5 Partially grouted hollow masonry 42
7.14.6 Other masonry 42
8 Glass block masonry 42
8.1 General 42
8.2 Design requirements 42
8.2.1 Serviceability 42
8.2.2 Material strength 43
8.2.3 Analysis 43
8.2.4 Safety 43
9 Veneer 43
9.1 Unit masonry veneer 43
9.1.1 Flexural bond strength 43
9.1.2 Unit material and dimension limitations 43
9.1.3 Ties and joint reinforcement 44
9.1.4 Structural backing 44
9.2 Dimension cut stone and manufactured stone veneer 44
10 Design of reinforced walls and columns 45
10.1 General 45

vi December 2004
10.1.2 Grouting of reinforced columns 45
10.1.3 Toothed joints 45
10.2 Design requirements for axial load and bending 45
10.2.1 Plane sections assumption 45
10.2.2 Maximum usable masonry strain 45
10.2.3 Reinforcement stress-strain relationships 45
10.2.4 Tensile strength of masonry 45
10.2.5 Masonry stress-strain relationship 45
10.2.6 Equivalent rectangular masonry stress block 46
10.2.7 Compression reinforcement 46
10.2.8 Low-aspect-ratios (squat) shear walls 46
10.3 Effective cross-sectional area 46
10.4 Maximum factored axial load resistance 46
10.5 Effective height 47
10.6 Effective compression zone width 47
10.6.1 General 47
10.6.2 Shear wall flange width 47
10.6.3 Flange intersections 47
10.6.4 Chases and openings 47
10.7 Axial load and minor axis bending in walls 47
10.7.1 Composite and other multi-wythe solid walls 48
10.7.2 Minimum primary moment 48
10.7.3 Section total moment effects 49
10.7.4 Design methods 49
10.8 Axial load and biaxial bending in walls 52
10.9 Columns 52
10.9.1 General 52
10.9.2 Axial load and single axis bending in columns 52
10.9.3 Axial load and biaxial bending in columns 52
10.10 Shear in walls and columns 52
10.10.1 Factored in-plane shear resistance of walls 52
10.10.2 Factored out-of-plane shear resistance of walls and columns 54
10.10.3 Stack pattern factored shear resistance 54
10.10.4 Factored sliding shear resistance 54
10.11 Intersections 55
10.12 Infill shear walls 55
10.12.1 General 55
10.12.2 Minimum reinforcement requirements for infill shear walls 55
10.12.3 Length of the diagonal strut for slenderness effects 55
10.12.4 In-plane shear 55
10.13 Bearing resistance for concentrated load 55
10.14 Service load deflections 56
10.14.1 General 56
10.14.2 Mid-height deflection 56
10.14.3 Allowable deflection 56
10.15 Minimum and maximum reinforcement in walls and columns 57
10.15.1 Minimum requirements for reinforced walls 57
10.15.2 Minimum seismic reinforcement for walls 57
10.15.3 Maximum reinforcement for walls 58
10.15.4 Horizontal joint reinforcement in walls 58
10.15.5 Limits on reinforcement for columns 58
10.16 Seismic design of ductile shear walls 58
10.16.1 Applicability 58
10.16.2 Terminology 59

December 2004 vii
10.16.3 General requirements 59
10.16.4 Limited ductility shear walls (Rd = 1.5) 59
10.16.5 Moderately ductile shear walls (Rd = 2.0) 60
10.16.6 Moderately ductile squat shear walls (Rd = 2.0) 61
11 Design of reinforced beams 62
11.1 General 62
11.1.2 Factored bearing resistance 62
11.1.3 Applicability 62
11.2 Bending in beams 62
11.2.1 Design assumptions 62
11.2.2 Maximum reinforcement in flexural members 63
11.2.3 Minimum reinforcement of flexural members 63
11.2.4 Effective cross-sectional area 63
11.2.5 Distance between lateral supports of beams 64
11.2.6 Distribution of flexural reinforcement in beams 64
11.2.7 Deep beams 65
11.3 Shear in beams 65
11.3.1 General principles and requirements: Design methods and design considerations 65
11.3.2 Shear reinforcement details 65
11.3.3 Low and normal density concrete masonry units 66
11.3.4 Shear design 66
11.3.5 Special provisions for deep shear spans 68
11.4 Service load deflection of beams 68
11.4.1 General 68
11.4.2 Immediate deflection 69
11.4.3 Effective moment of inertia for deflection calculations at service loads 69
11.4.4 Long-term deflection 69
11.4.5 Allowable deflection 70
12 Reinforcement: Details, development, and splices 72
12.1 General 72
12.2 Lateral ties of reinforcement in compression 72
12.3 Hooks and bends 73
12.4 Development of reinforcement 73
12.4.1 General 73
12.4.2 Development of smooth and deformed bars and wire in tension 73
12.4.3 Development of smooth and deformed bars in compression 75
12.4.4 Development of bundled bars 75
12.4.5 Development of standard hooks in tension 75
12.4.6 Hooks for development of bars in compression 76
12.4.7 Mechanical anchorage 76
12.4.8 Development of flexural reinforcement — General 76
12.4.9 Development of positive moment reinforcement 77
12.4.10 Development of negative moment reinforcement 78
12.4.11 Anchorage of shear reinforcement 78
12.5 Splicing of reinforcement 79
12.5.1 Limitations on use 79
12.5.2 Lap splices 79
12.5.3 Welded splices and mechanical connections 79
12.5.4 Splices of smooth and deformed bars and wire in tension 79
12.5.5 Splices of deformed bars in compression 80

viii December 2004
13 Design of prestressed masonry 81
13.1 General 81
13.1.1 Scope 81
13.1.2 Design 81
13.1.3 Plane sections assumption 81
13.1.4 Maximum usable masonry strain 81
13.1.5 Reinforcement stress-strain relationships 81
13.1.6 Factored force in the prestressed reinforcement 81
13.1.7 Tensile strength of masonry 82
13.1.8 Slenderness effects 82
13.2 Serviceability 82
13.2.1 General 82
13.2.2 Maximum compressive stresses 82
13.2.3 Permissible stress in steel prestressing tendons 82
13.2.4 Loss of prestress 83
13.3 Ultimate strength 83
13.3.1 General 83
13.3.2 Stress in tendon at ultimate strength of member 83
13.3.3 Partial prestressing 84
13.4 Minimum bending strength 84
13.5 Shear resistance 84
13.5.1 Shear resistance of walls and columns 84
13.5.2 Shear resistance of beams 84
13.6 Tendon anchorage zones 85
14 Design of prefabricated masonry 85
14.1 General 85
14.2 Additional details on drawings 85
14.3 Lifting devices 85
14.4 Additional loads 85
14.5 Joints and bearings 86
14.6 Tolerances at joints and connections 86
15 Field control tests during construction 86
15.1 Masonry unit tests 86
15.1.1 Test frequency 86
15.1.2 Design strength based on masonry unit and mortar tests 86
15.1.3 Design strength based on masonry prism tests 86
15.2 Mortar tests 86
15.2.1 General 86
15.2.2 Tests 87
15.2.4 Acceptance 88
15.3 Grout tests 88
15.3.1 General 88
15.3.2 Tests 88
15.3.4 Acceptance 89
15.4 Masonry assembly tests — Flexural tensile bond strength 89
Annexes
A (normative) — Dimension cut stone and manufactured stone veneer 97
B (normative) — Effective length factors 102
C (normative) — Determination of specified strength 103

December 2004 ix
D (normative) — Method of test for compressive strength and modulus of elasticity of masonry
prisms 105
E (normative) — Method of test for flexural tensile bond strength 112
F (normative) — Empirical design for unreinforced masonry 116
Tables
1 — Masonry dimensional properties 90
2 — Coefficient of friction for serviceability 91
3 — Specified compressive strength normal to the bed joint, f’m, for solid brick masonry, MPa 92
4 — Specified compressive strength normal to the bed joint, f’m, for concrete block masonry, MPa 93
5 — Specified flexural tensile strength, ft 94
6 — Flexural wall panels — Bending moment coefficients in simply supported laterally loaded wall
panels 95
Figures
1 — Reinforced grouted hollow masonry 70
2 — Reinforced grouted brick masonry of solid units 71
3 — Reinforced brick masonry of solid units 71

x December 2004
Technical Committee on Masonry
Design
D.A. Laird Halsall Associates Limited,
Toronto, Ontario
Chair
R.G. Drysdale McMaster University,
Hamilton, Ontario
Vice-Chair
D.L. Anderson University of British Columbia,
Vancouver, British Columbia
J.W. Cowie J.W. Cowie Engineering Limited,
Halifax, Nova Scotia
L. Crepeau Le Groupe Teknika,
Montréal, Québec
J.L. Dawe University of New Brunswick,
Fredericton, New Brunswick
A. Elwi University of Alberta,
Edmonton, Alberta
Associate
S. Fasullo Davroc Testing Laboratories Inc.,
Brampton, Ontario
Associate
M. Hatzinikolas Fero Corp.,
Edmonton, Alberta
J. Hendricks Yolles Partnership Inc.,
Toronto, Ontario
Associate
K. Ibrahim KIB Consultants Inc.,
Kanata, Ontario
P. Kelly Hanson Brick Ltd.,
Mississauga, Ontario
G. LeBlanc GA Masonry Ltd.,
Breslau, Ontario
Associate
S. Lissel University of Calgary,
Calgary, Alberta
Associate
A.H.P. Maurenbrecher National Research Council Canada,
Ottawa, Ontario
W.C. McEwen Masonry Institute of British Columbia,
Vancouver, British Columbia
R.J. McGrath Cement Association of Canada,
Ottawa, Ontario

December 2004 xi
R. McKeown City of Toronto,
Toronto, Ontario
P. Meades Meades Engineering Ltd.,
Barrie, Ontario
K. Mutti Arriscraft International Inc.,
Cambridge, Ontario
R. Pacholok Building Science Engineering Ltd.,
St. Albert, Alberta
M. Petrescu-Comnene Adjeleian Allen Rubeli Limited,
Ottawa, Ontario
M. Picco Picco Engineering,
Concord, Ontario
R. Rosati J.N.E. Consulting Ltd.,
Burlington, Ontario
Associate
N. Shrive University of Calgary,
Calgary, Alberta
A. Steen Ontario Ministry of Municipal Affairs and
Housing,
Toronto, Ontario
D. Stubbs Canada Masonry Design Centre,
G.R. Sturgeon Canada Masonry Design Centre,
Calgary, Alberta
G.T. Suter Carleton University,
Ottawa, Ontario
G. Sykora City of Calgary,
Calgary, Alberta
C.R. Taraschuk National Research Council Canada,
Ottawa, Ontario
Associate
M. Braiter CSA,
Project Manager

xii December 2004
Preface
This is the second edition of CSA S304.1, Design of masonry structures. It supersedes the previous edition,
published in 1994 under the title Masonry Design for Buildings (Limit States Design).
This is a limit states design standard. The working stress design version, CSA S304-M84, has been
withdrawn. An earlier version of CSA S304 had been issued in 1977 (imperial version) and 1978 (metric
version).
Major changes have been made in this edition. The empirical design requirements are now contained in
an annex. Other major changes include
(a) new and revised test methods;
(b) the incorporation of a revised version of CSA A369.1 into an annex;
(c) new and revised seismic provisions;
(d) revised reinforcement provisions;
(e) revised load factors and load combination equations in accordance with changes in the National
Building Code of Canada;
(f) an increased resistance factor for masonry;
(g) new concentrated bearing resistance provisions;
(h) revised serviceability requirements for walls and columns;
(i) new design provisions for two-way action of unreinforced masonry wall panels subject to lateral
loading (flexural walls);
(j) new design provisions for composite walls;
(k) new design provisions for masonry infill walls acting as shear walls;
(l) revised sliding shear capacity of walls;
(m) revised shear capacity of beams;
(n) revised tying and deflection requirements for masonry veneer;
(o) new empirical design requirements for anchorage and for shear walls;
(p) prestressed masonry provisions for beams, walls, and columns;
(q) new provisions for fibre-reinforced polymer used as reinforcement; and
(r) new provisions for dimension cut stone and manufactured stone veneer.
Masonry Canada and the Canadian Masonry Contractors’ Association provided funding for the
development of this Standard.
This Standard was prepared by the Technical Committee on Masonry Design, under the jurisdiction of
the Strategic Steering Committee on Structures (Design), and has been formally approved by the
Technical Committee.
December 2004
Notes:
(1) Use of the singular does not exclude the plural (and vice versa) when the sense allows.
(2) Although the intended primary application of this Standard is stated in its Scope, it is important to note that it remains
the responsibility of the users of the Standard to judge its suitability for their particular purpose.
(3) This publication was developed by consensus, which is defined by CSA Policy governing standardization — Code of
good practice for standardization as “substantial agreement. Consensus implies much more than a simple majority,
but not necessarily unanimity”. It is consistent with this definition that a member may be included in the Technical
Committee list and yet not be in full agreement with all clauses of this publication.
(4) CSA Standards are subject to periodic review, and suggestions for their improvement will be referred to the appropriate
committee.
(5) All enquiries regarding this Standard, including requests for interpretation, should be addressed to Canadian Standards
Association, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6.
Requests for interpretation should
(a) define the problem, making reference to the specific clause, and, where appropriate, include an illustrative sketch;
(b) provide an explanation of circumstances surrounding the actual field condition; and
(c) be phrased where possible to permit a specific “yes” or “no” answer.

December 2004 xiii
Committee interpretations are processed in accordance with the CSA Directives and guidelines governing
standardization and are published in CSA’s periodical Info Update, which is available on the CSA Web site at
www.csa.ca.

December 2004 1
S304.1-04
1 Scope
1.1
This Standard provides requirements for the structural design of unreinforced, reinforced, and
prefabricated masonry structures and components in accordance with the limit states design method of
the National Building Code of Canada. This Standard also provides requirements for the structural design of
prestressed masonry beams, walls, and columns in accordance with the limit states design method of the
National Building Code of Canada. In addition, this Standard provides requirements for the empirical design
of unreinforced masonry in Annex F.
Note: This Standard assumes that review of the structural work designed under this Standard and review of the inspection
and test results required by this Standard will be carried out during construction by the designer or another suitably qualified
person to determine general conformance with the design.
1.2
Requirements for mortar and grout for unit masonry, masonry connectors, and masonry construction are
specified in CSA A179, A370, and A371, respectively. These Standards include requirements that affect the
design and are required for use with this Standard.
1.3
This Standard does not apply to the structural design of vehicular bridges.
1.4
This Standard applies to the structural design of partitions subject to unusual loads such as wind loads,
significant internal air pressure differences, or large eccentric loads mounted to the wall. Where it can be
shown that the masonry partitions are not subjected to these unusual loads, the masonry partitions may
be designed using Annex F.
1.5
This Standard does not apply to the structural design of thin veneers individually secured by mortar
adhesion to a structural support or to the structural design of rough stone veneer. See CSA A371 for
prescriptive requirements and limitations.
1.6
This Standard does not apply to the structural design of rubble stone masonry, except as covered in
Annex F. See CSA A371 for prescriptive requirements.
1.7
In CSA Standards, “shall” is used to express a requirement, i.e., a provision that the user is obliged to
satisfy in order to comply with the standard; “should” is used to express a recommendation or that which
is advised but not required; “may” is used to express an option or that which is permissible within the
limits of the standard; and “can” is used to express possibility or capability. Notes accompanying clauses
do not include requirements or alternative requirements; the purpose of a note accompanying a clause is
to separate from the text explanatory or informative material. Notes to tables and figures are considered
part of the table or figure and may be written as requirements. Annexes are designated normative
(mandatory) or informative (non-mandatory) to define their application.

2 December 2004
2 Reference publications, definitions and standard notation,
and units
2.1 Reference publications
This Standard refers to the following publications, and where such reference is made, it shall be to the
edition listed below, including all amendments published thereto.
CSA (Canadian Standards Association)
A23.1-04/A23.2-04
Concrete materials and methods of concrete construction/Methods of test and standard practices for concrete
CAN/CSA-A82.1-M87 (R2003)
Burned Clay Brick (Solid Masonry Units Made from Clay or Shale)
CAN3-A82.2-M78 (R2003)
Methods of Sampling and Testing Brick
CAN3-A82.8-M78 (R2003)
Hollow Clay Brick
A165 Series-04
CSA Standards on concrete masonry units
A179-04
Mortar and grout for unit masonry
A370-04
Connectors for masonry
A371-04
Masonry construction for buildings
G30.14-M1983 (withdrawn)
Deformed Steel Wire for Concrete Reinforcement
G30.15-M1983 (withdrawn)
Welded Deformed Steel Wire Fabric for Concrete Reinforcement
CAN/CSA-G30.18-M92 (R2002)
Billet-Steel Bars for Concrete Reinforcement
CAN/CSA-S16-01
Limit States Design of Steel Structures
S478-95 (R2001)
Guideline on Durability in Buildings
CAN/CSA-S806-02
Design and Construction of Building Components with Fibre-Reinforced Polymers
W186-M1990 (R2002)
Welding of Reinforcing Bars in Reinforced Concrete Construction

December 2004 3
ASTM International (American Society for Testing and Materials)
A 416/A 416M-02
Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete
A 421/A 421M-02
Standard Specification for Uncoated Stress-Relieved Steel Wire for Prestressed Concrete
A 722/A 722M-98 (2003)
Standard Specification for Uncoated High-Strength Steel Bar for Prestressing Concrete
C 73-99a
Standard Specification for Calcium Silicate Brick (Sand-Lime Brick)
C 97-02
Standard Test Methods for Absorption and Bulk Specific Gravity of Dimension Stone
C 99-87 (2000)
Standard Test Method for Modulus of Rupture of Dimension Stone
C 140-03
Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units
C 170-90 (1999)
Standard Test Method for Compressive Strength of Dimension Stone
C 503-03
Standard Specification for Marble Dimension Stone (Exterior)
C 568-03
Standard Specification for Limestone Dimension Stone
C 615-03
Standard Specification for Granite Dimension Stone
C 616-03
Standard Specification for Quartz-Based Dimension Stone
C 629-03
Standard Specification for Slate Dimension Stone
C 880-98
Standard Test Method for Flexural Strength of Dimension Stone
C 1072-00a
Standard Test Method for Measurement of Masonry Flexural Bond Strength
C 1201-91(2003)
Standard Test Method for Structural Performance of Exterior Dimension Stone Cladding Systems by Uniform
Static Air Pressure Difference
C 1242-04
Standard Guide for Selection, Design, and Installation of Dimension Stone Anchoring Systems
C 1314-03b
Standard Test Method for Compressive Strength of Masonry Prisms

4 December 2004
C 1354-96 (2004)
Standard Test Method for Strength of Individual Stone Anchorages in Dimension Stone
C 1357-04
Standard Test Methods for Evaluating Masonry Bond Strength
E 4-03
Standard Practices for Force Verification of Testing Machines
E 72-04
Standard Test Methods of Conducting Strength Tests of Panels for Building Construction
NRCC (National Research Council Canada)
National Building Code of Canada, 2005
User’s Guide — NBC 2005 Structural Commentaries (Part 4)
SAA (Standards Association of Australia)
AS 3700-2001/Amdt-2002
Masonry Structures
ULC (Underwriters’ Laboratories of Canada)
S706-02
Standard for Wood Fibre Thermal Insulation for Buildings
Other Publications
Drysdale, R.G., and C. Baker. “Failure Line Design of Unreinforced Masonry Walls Subject to Out-of-Plane
Loading.” Centre for Effective Design of Structures Report, McMaster University, Hamilton, Ontario, 2003.
Fintel, M., and G. Annamalai. “Philosophy of structural integrity of multi-storey loadbearing concrete
masonry structures.” Concrete International (May 1979), Vol. 1, No. 5, pp. 27–35.
Lissel, L., N. Shrive, and A. Page. “Shear in plane, bed joint reinforced and post tensioned masonry.”
Canadian Journal of Civil Engineering (October 2000), pp. 1021–1030.
2.2 Definitions and standard notation
2.2.1 Definitions
The following definitions apply in this Standard:
Anchor — a device used to connect masonry walls at their intersections or to attach them to their
supports or to other structural members or systems. The term also includes any device that is used to
connect stone to its structural backing or to interconnect stone and is engaged directly in the stone or in
the mortar joint (see CSA A370).
Beam — a horizontal masonry member supporting vertical loads. The flexural forces are applied
horizontally against the mortar in the head joints between the masonry units and against any grout in the
spaces in and between the units.
Bond — one of the following:
(a) the overlapping arrangement of masonry units between successive courses having a regular pattern
and intended to increase the strength or enhance the appearance of a construction;
(b) the overlap of units across the collar joint of a multi-wythe masonry wall system so as to increase its
strength; or
(c) the adhesion between units and mortar or grout.

December 2004 5
Bond beam — a course or courses of a masonry wall grouted and reinforced in the horizontal direction
with reinforcing bars. A bond beam may serve as a horizontal wall tie, as a bearing surface for structural
members, or as a beam.
Cavity wall — a construction of masonry units laid up with a cavity or unfilled collar joint between the
wythes. The wythes are connected together with ties or bonding units and are assumed to act together in
resisting lateral loads, but not to act compositely.
Note: For resistance to rain penetration, see the requirements for drainage and minimum air space in CSA A371.
Clay masonry unit — a masonry unit made of fired clay as specified in CAN/CSA-A82.1.
Collar joint — the space separating one wythe from another wythe. The space is filled with mortar or
grout. If unfilled with mortar or grout, it is considered to be a cavity.
Note: Where the space separating two wythes exceeds 20 mm, the space should be grouted in accordance with CSA A371.
Column — a vertical masonry member that has a height greater than (5 × (t + 10)) and a length less than
(3 × (t + 10)) and that supports vertical and horizontal loads.
Note: For walls with openings, where the part of the wall between openings satisfies the above conditions, that part of the
wall may be considered to be a column or to be a wall in accordance with Clause 10.15.5.3.
Composite wall — a multi-wythe wall in which wythes of dissimilar materials are connected together by
ties and filled collar joints, bonding units, or other mechanical means, or by a combination thereof,
sufficient to ensure shear transfer between wythes and effective composite action.
Note: See Clauses 7.7.2 and 10.7.1.
Concrete masonry unit — a masonry block or brick unit made from cementitious materials, water, and
aggregates, with or without other materials, with dimensions and properties in accordance with the
requirements of the CSA A165 Series.
Connector — a general term for ties, anchors, and fasteners as specified in CSA A370.
Control joint — a term no longer used; see Movement joint.
Cross-sectional area — the area of masonry on a plane parallel to the bearing surface of a masonry unit.
Effective cross-sectional area — the area of masonry based on the area that includes the mortar
bedded area and the area of voids filled with grout.
Note: See Clauses 7.3, 10.3, and 11.2.4.
Gross cross-sectional area — the area of masonry on a plane parallel to the bearing surface of a
masonry unit, calculated by multiplying the actual length by the actual thickness.
Net cross-sectional area — the solid area of masonry in a plane parallel to the bearing surface of a
masonry unit.
Designer — the person responsible for the structural design.
Face shell bedding — the application of mortar to vertical and horizontal surfaces of face shells of
semi-solid concrete block units and hollow masonry units.
Factored load — the product of a specified load and its load factor.
Factored resistance — the product of the calculated resistance and the appropriate resistance factor or
factors.
Grout — as specified in CSA A179, a high-slump mixture of cementitious material, aggregate, and water
of a consistency suitable for pouring or pumping without segregation of the constituents.

6 December 2004
Hollow unit — a unit that has a net cross-sectional area in any plane parallel to the bearing surface that
is less than 75% of the gross cross-sectional area measured in the same plane as specified in
CSA CAN3-A82.8 and the CSA A165 Series.
Importance factor — a factor in Clause 4.1.3 applied to the factored loads other than dead load to take
into account the consequences of collapse as related to the use and occupancy of the building.
Infill shear wall — masonry built within a structural frame to share in the axial and lateral load resistance
of the structure.
Lateral support — a structural member or system of structural members resisting the horizontal
out-of-plane component of loads applied to masonry.
Loadbearing — a term which indicates the presence of loads on a building component other than its
own dead load and any out-of-plane wind and earthquake loads. These components include beams,
columns, shear walls, and walls supporting floors and roofs.
Load factor — a factor in Clause 4.2, applied to a specified load, that for the limit states under
consideration takes into account the variability of the loads and load patterns and analysis of their effects.
Masonry — a construction of masonry units
(a) laid up with mortar, and possibly containing grout and reinforcement; or
(b) individually secured by metal anchors to a structural support.
Masonry prism — see Prism.
Masonry unit — a unit made of clay (shale), concrete, calcium silicate (sand-lime), glass, and/or natural
stone materials, usually shaped to a rectangular prism, and usually of such size and mass that it can be
hand-placed into position.
Mortar — as specified in CSA A179, a mixture of cementitious material or materials, aggregate, and
water used for bedding, jointing, and bonding of masonry or other structural units.
Mortar bedded area — the horizontal area of mortar in a bed joint that is in full contact with both the
masonry unit above and the masonry unit below.
Movement joint — a continuous joint in the structure, used to minimize the development of stresses
due to differential movement.
Note: Temperature- and moisture-related movement and structural displacement are examples of differential movements to
be accommodated.
Nonloadbearing — a term that indicates that no loads are present on a building component other than
its own dead load and any out-of-plane wind and earthquake loads. These components include partitions
and exterior walls, other than shear walls, that do not support floors and roofs.
Partition — an interior nonloadbearing wall of one storey or part of one storey in height.
Plain masonry — a term no longer used; see Unreinforced masonry.
Prism — a small assemblage of masonry units, mortar, and possibly grout used as a test specimen for
determining the strength of masonry. See Annexes D and E.
Racking — the laying of the lead or the end of a wall with a series of battered steps so that when work is
resumed the bond can be continued easily.
Reinforced masonry — masonry containing reinforcing steel that acts together compositely with the
other masonry components in resisting forces.

December 2004 7
Resistance — the maximum load that a member, connection, or structure can sustain at a limit state,
calculated in accordance with this Standard from the geometry, the material properties, and actual
dimensions.
Resistance factor — a factor, applied to a specified material property or to the resistance of a member,
connection, or structure, that for the limit state under consideration takes into account the variability of
dimensions and material properties, quality of work, type of failure, and uncertainty in the prediction of
resistance.
Running bond — the placement of masonry units such that head joints in successive courses are
horizontally offset at least 25% of the unit length.
Note: Patterns that do not satisfy the requirements of running bond can be treated as stack pattern for design purposes.
Fifty percent running bond — the placement of masonry units such that the head joints are
centred on the units below in successive courses.
Note: For shear strength of beams and flexural tensile strength parallel to the bed joints, performance of the masonry
has been based upon fifty percent running bond.
Shear wall — a loadbearing wall providing resistance to lateral loads applied in the plane of the wall.
Solid brick unit — a brick unit that has a net cross-sectional area in all planes parallel to the bearing
surface of at least 75% of the gross cross-sectional area measured in the same plane as specified in
CAN/CSA-A82.1 and CSA A165.2.
Solid concrete block unit — a semi-solid concrete block unit or a full solid concrete block unit as
specified in CSA A165.1.
Full solid concrete block unit — a unit that has a net cross-sectional area in all planes parallel to
the bearing surface of 100% of the gross cross-sectional area measured in the same plane.
Semi-solid concrete block unit — a unit that has a net cross-sectional area in all planes parallel to
the bearing surface of at least 75%, but less than 100%, of the gross cross-sectional area measured in
the same plane.
Solid masonry — multi-wythe masonry of solid, semi-solid, or hollow units, with wythes of similar
materials and with filled collar joints, that are connected together by ties, bonding units, or other
mechanical means, or by a combination thereof, sufficient to ensure shear transfer between wythes and
effective composite action; hollow and semi-solid units need not be filled.
Splitter block — a unit designed to be split into two separate half blocks. The splitter block has a narrow
void within the centre web of the block that cannot normally be filled with grout.
Note: See Clause 11.2.1.6.
Stack pattern — the arrangement of masonry units in which the head joints form continuous vertical
lines. (Also incorrectly called “stack bond”, although there is no bond due to overlapping units because
the units do not overlap.)
Strength — the ultimate material stress or connector force at failure measured in accordance with
appropriate test standards.
Structural backing — the masonry or system of structural members to which masonry veneer is tied.
The backing is designed to resist the applied lateral loads.
Tie — a device for connecting two or more wythes or for connecting a masonry veneer to its structural
backing as specified in CSA A370.

8 December 2004
Toothing back — a means of creating a temporary end to a masonry wall so that the end stretchers of
every alternate course project for bonding to future work. (This method of construction is not permitted
by CSA A371 unless approved by the designer.)
Transformed section — a derived section of one material similar to and having the same elastic
properties as a section composed of two materials having different elastic properties.
Unit masonry — masonry construction using clay (shale) masonry units, calcium silicate (sand-lime)
masonry units, or concrete masonry units; the individual units are limited in height to not more than
200 mm, limited in length to not more than 400 mm, and limited in thickness to not less than 75 mm.
Unit masonry veneer — a veneer that consists of not less than one wythe of unit masonry laid up with
mortar that meets CSA A179 and that is tied to a structural backing with ties that meet CSA A370 and are
placed in the mortar joints of the veneer.
Unreinforced masonry — masonry constructed without the use of steel reinforcement other than that
required for tying or for material dimensional change control.
Veneer — a nonloadbearing masonry facing attached to and laterally supported by a structural backing.
Virtual eccentricity — the eccentricity of the axial load at a section calculated by dividing the total
moment at the section by the axial load at the section.
Wall — a vertical masonry member, other than a column, supporting vertical loads or resisting horizontal
loads, or both. A wall may span either vertically or horizontally, or in both directions.
Web — that portion of a shear wall or beam which resists the shear, except in Clause 10.10.2 where webs
are the cross-walls connecting the face shells of a hollow or semi-solid concrete masonry unit, or a hollow
clay brick.
Wythe — a continuous vertical section of a masonry wall, one unit in thickness.
2.2.2 Standard notation
2.2.2.1
Throughout this Standard when used as the first letter in subscripts, the subscript “f ” (f) denotes a factored
load, and the subscript “r” (r) denotes a factored resistance.
2.2.2.2
The following notations apply in this Standard. Deviations and additions are noted where they occur in the
text of the Standard.
a = depth of the equivalent rectangular stress block, mm
ah = the loaded length of the wall, immediately beneath the solid brick or grout-filled concrete block
masonry or the masonry spreader beam, allowing for dispersion of a concentrated load at a slope
of 2.5:1 (vertical:horizontal), mm
a1 = the distance from the end of the wall or pier to the nearest edge of the bearing plate, mm
a2 = the distance of the load from the end of the wall, mm
A = effective tension area of masonry surrounding the main flexural tension reinforcement and
extending from the extreme tension fibre to the centroid of the flexural tension reinforcement
and an equal distance past that centroid, divided by the number of bars, mm2
. When the flexural
reinforcement consists of bars of different sizes, the number of bars used to compute A is taken as
the total area of reinforcement divided by the area of the largest bar used, mm2
.
Ab = area of reinforcement bar, mm2

December 2004 9
Abp = area of the bearing plate, mm2
Ae = effective cross-sectional area of masonry (see definitions in Clauses 7.3, 10.3, and 11.2.4), mm2
AFR = the area of the lower base of the largest frustum of a right pyramid having the bearing plate of
area, Abp, as the upper area and slopes of 2.5:1 (vertical: horizontal), wholly contained in the solid
masonry, complying with Clause 7.14.4.2, mm2
Ag = gross cross-sectional area of masonry, mm2
Ah = the effective area of dispersion of the concentrated load at mid-height of the wall, having the area
of the bearing plate, Abp, as the source of dispersion, and complying with Clause 7.14.2, mm2
Amh = the effective cross-sectional area of hollow masonry immediately below the solid brick or
grout-filled concrete block masonry or the masonry spreader beam, allowing for dispersion of a
concentrated load at a slope of 2.5:1 (vertical:horizontal), mm2
Amv = minimum area of masonry resisting shear; the minimum width of member times the distance
from the extreme compression fibre to the centroid of prestressing reinforcement, mm2
Ap = area of prestressed reinforcement, mm2
As = area of nonprestressed tension reinforcement, mm2
= area of nonprestressed compression reinforcement, mm2
Ast = the total area of longitudinal reinforcement, mm2
Atr = the total cross-sectional area of transverse reinforcement that is within the spacings and which
crosses the potential plane of bond splitting through the reinforcing being developed, mm2
Auc = uncracked area of the cross-section, mm2
Av = cross-sectional area of shear reinforcement, mm2
b = effective width of rectangular member, or flange for T and I sections or webs as defined for each
case, mm
bw = overall web width, mm
Note: γg accounts for sections that are not 100% solid.
= bearing plate dimension in direction of eccentricity, mm
Br = local factored bearing resistance, N (see Clause 7.14)
c = distance from extreme compression fibre to the neutral axis, mm
C = compressive force in the masonry acting normal to the sliding plane, usually taken as Pd plus the
factored tensile resistance at yield of the vertical reinforcing, N
Ch = compressive force in the masonry acting normal to the head joint, normally taken as the factored
tensile resistance at yield of the horizontal reinforcement that crosses the vertical section and has
been detailed to develop the yield strength on both sides of the masonry joint at the intersection,
N
Cm = factor relating actual moment diagram to an equivalent uniform moment diagram
Ct = coefficient of thermal expansion of the masonry
d = distance from extreme compression fibre to centroid of tension reinforcement, mm
db = nominal diameter of reinforcing bar, wire, or prestressing strand, mm
dc = thickness of masonry cover measured from extreme tension fibre to the centre of the longitudinal
bar located closest thereto, mm
dcs = the smaller of
(a) the distance from the closest masonry surface to the centre of the bar being developed, mm;
or
(b) two-thirds the centre-to-centre spacing of the bars being developed, mm
dp = distance from extreme compression fibre to centroid of prestressing tendon, mm
dv = effective depth for shear calculations, which need not be taken as less than 0.8 w for walls, mm
e = virtual eccentricity (see definition in Clause 2.2.1), mm
′As
′b

10 December 2004
= the eccentricity of the load on the bearing plate, mm
ek = the Kern eccentricity value for the effective cross-sectional area (Ae), mm
ep = Eccentricity of prestress tendons about the centroid of the uncracked section, mm
e1 = the smaller virtual eccentricity occurring at the top or bottom of a vertical member at lateral
supports, mm
e2 = the larger virtual eccentricity occurring at the top or bottom of a vertical member at lateral
supports, mm
Ef = modulus of elasticity of the frame material in infill shear wall calculations, MPa (see
Clause 7.13.3.2)
Em = modulus of elasticity of masonry, MPa (see Clause 6.5)
Ep = modulus of elasticity of prestressing tendon obtained from the manufacturer, MPa
Es = modulus of elasticity of steel, MPa (see Clause 6.5)
(EI)eff = effective stiffness of walls and columns, N•mm2
fcp = effective compression on section, MPa (see Clause 13.5.1.1)
fcs = axial compressive stress due to unfactored axial loads, including prestressing force, MPa
fgm = modulus of rupture of glass block masonry, MPa
= in-situ compressive strength of grout or mortar, MPa
= compressive strength of masonry normal to the bed joint at 28 d, MPa
= the compressive strength of the masonry at the time of transfer, MPa
fp = stress in prestressing tendon at ultimate limit state, MPa
fpe = effective prestress in prestressing tendons after losses, MPa
fpu = ultimate strength of prestressing tendon, MPa
fpy = yield strength of prestressing tendons, MPa
fs = stress in reinforcement at the specified load in crack control calculations for beams, MPa
(see Clause 11.2.6.2)
ft = flexural tensile strength of masonry (also called the modulus of rupture or the flexural bond
strength), MPa (see Table 5)
ftn = flexural tensile strength normal to the bed joint, MPa
ftp = flexural tensile strength parallel to the bed joint, MPa
fy = yield strength of reinforcement, MPa
fyt = yield strength of transverse reinforcement, MPa
h = unsupported height of a wall or column, mm
hb = overall height of a beam, mm
hw = total wall height, mm
I = the moment of inertia of wall section for out-of-plane bending, mm4
Ib = moment of inertia of the beam of the frame for infill shear wall calculations, mm4
Ic = moment of inertia of the column of the frame for infill shear wall calculations, mm4
Icr = the moment of inertia of the compression zone and the transformed area of the tension
steel about the centroidal axis of the cracked section when subjected to a moment larger
than Mcr, ignoring the effects of axial load except when calculating service load deflections.
The transformed area of the reinforcement in the compression zone is included when the
reinforcement is tied in accordance with Clause 12.2, mm4
IEFaSa(0.2) = seismic hazard index, where IE, Fa, and Sa (0.2) are defined in the National Building Code of
Canada
Ieff = effective moment of inertia of beams, mm4
Ieffc = effective moment of inertia at continuous end of a beam, mm4
′e
′fgr
′fm
′fmt

December 2004 11
Ieffm = effective moment of inertia at the midspan of a beam, mm4
Ieff1 = effective moment of inertia at end one of a continuous beam, mm4
Ieff2 = effective moment of inertia at end two of a continuous beam, mm4
Io = moment of inertia of the effective cross-sectional area (Ae) about its centroidal axis, mm4
k = effective length factor for compression member (see Annex B)
k1 = location modification factor used in calculating the development length of reinforcement
k2 = coating modification factor used in calculating the development length of reinforcement
k3 = size modification factor used in calculating the development length of reinforcement (see
Clause 12.4.2.5)
kp = factor for type of prestressing (see Clause 13.3.2.2)
Ktr = transverse reinforcement index (see Clause 12.4.2.3)
= length of flexural wall panel or length of masonry infill shear wall, mm
2 = the length of the wall between ends and/or movement joints in bearing calculations, mm
a = embedment length beyond the centre of the support, mm
d = development length of reinforcement bar or wire, mm
db = basic development length of bars in compression, mm
dh = development length of reinforcement bar terminating in a standard hook, mm
hb = basic development length of hooked bar, mm
o = length of prestressing tendon between anchorages, mm
p = length of plastic hinge region, mm
u = length of brick unit in direction of movement under consideration, mm
w = wall length, mm
M1 = the smaller factored end moment in a compression member associated with the same
loading case as M2, positive if member is bent in single curvature, negative if bent in double
curvature, N•mm
M2 = the larger factored end moment in a compression member, always positive, N•mm
Ma = maximum moment due to specified loads, N•mm
Mcr = cracking moment, N•mm
Mf = factored moment, N•mm
Mfn = factored moment for bending in the vertical direction, N•mm
Mfp = factored primary moment at the section due to the end factored moments and lateral loads,
N•mm
Mfpa = factored moment for bending in the horizontal direction, N•mm
Mftot = total factored moment, including secondary moments, N•mm
Mfx = total factored moment about the x-axis, including the effects of slenderness, N•mm
Mfy = total factored moment about the y-axis, including the effects of slenderness, N•mm
Mr = factored moment resistance, N•mm
Mrn = design moment of resistance for bending in the vertical direction, N•mm
Mrpa = design moment of resistance for bending in the horizontal direction, N•mm
Mrx = factored moment resistance about the x-axis, N•mm
Mry = factored moment resistance about the y-axis, N•mm
Ms = service moment at mid-height of wall or column, including secondary moments, N•mm

12 December 2004
n = number of bars or wires being spliced or developed along the potential plane of bond splitting
np = number of plastic hinges required to develop a failure mechanism (see Clause 13.3.2.3)
Nf = factored axial load in a beam with a positive value for axial tension, N
Nr = factored axial tension resistance of a beam, N (see Clause 11.3.4.3)
P1 = compressive force in the unreinforced masonry acting normal to the sliding plane, normally taken
as Pd plus 90% of the factored vertical component of the compressive forces resulting from the
diagonal strut action found in infill shear walls, N
P2 = compressive force in the reinforced masonry acting normal to the sliding plane, normally taken as
Pd plus the factored tensile resistance at yield of the vertical reinforcement and 90% of the
factored vertical component of the compressive forces resulting from the diagonal strut action
found in infill walls, N
Pcr = critical axial compressive load, N (see Clauses 7.7.6.3 and 10.7.4.3)
Pd = axial compressive load on the section under consideration, based on 0.9 times dead load plus any
factored axial load arising from bending in coupling beams where applicable, N
Pdl = axial dead load used in shear resistance calculations for prestressed masonry, N (see
Clause 13.5.1.1)
Pe = effective prestress force after losses, Apfpe, N
Pf = factored axial load, N
Pft = factored load from tributary roof or floor area, N
Pfw = factored weight of wall tributary to and above design section, N
Pr = factored axial load resistance, N
P•δ = secondary moments due to axial loads and member displacements caused by primary and
secondary moments, N•mm
Q = first moment of area of the masonry wythe adjacent to the plane under consideration about the
centroid of the section, mm3
R = nominal resistance of a member, connection, or structure based on the dimensions and on the
specific properties of structural materials (see Clause 4.2)
Rd = ductility related force modification factor that reflects the capability of a structure to dissipate
energy through inelastic behaviour
Rm = control value of ratio of mass of sand to cementitious material for the mortar being tested,
determined in accordance with CSA A179
Rt = factor to account for the axial tension on the shear capacity of beams (see Clause 11.3.4.3)
s = spacing of shear reinforcement measured parallel to the longitudinal axis of the member, mm
sh = horizontal spacing of the ties, mm
sv = vertical spacing of the ties, mm
S1 = time-dependent factor (see Clause 11.4.4)
Se = section modulus of effective cross-sectional area (Ae), mm3
Sn = section modulus for bending in the vertical direction, mm3
Sp = section modulus for bending in the horizontal direction, mm3
t = thickness of a wall or column, taking into account any reduction in thickness due to raked joints,
chases, or recesses, mm
te = sum of the thickness of the two face shells for hollow or semi-solid block units not fully grouted
and the thickness of the wall for solid or fully grouted hollow or semi-solid block units, mm
Tcm = mean temperature of masonry at time of construction, °C
Tm = maximum mean temperature of masonry in service, °C
vbond = the shear bond strength between mortar or grout in the collar joint and the adjacent masonry
wythe (see Clauses 7.7.2 and 10.7.1.2)

December 2004 13
vm = shear strength of masonry, MPa
Vf = shear under factored loads, N
Vm = factored shear resistance of masonry members provided by the masonry, N
Vr = factored shear resistance, N
Vs = factored shear resistance provided by shear reinforcement, N
w = diagonal strut width, mm
wf = factored uniform lateral wind or seismic load on the wall, N/mm
wj = width of joint in direction of movement under consideration, mm
yt = distance from neutral axis to the extreme tension fibre of the uncracked section, mm
z = quantity limiting distribution of flexural reinforcement in beams, kN/mm (see Clause 11.2.6.2)
αh = vertical contact length between the frame and diagonal strut, mm
αL = horizontal contact length between the frame and diagonal strut, mm
βb = ratio of area of cut-off reinforcement to total area of tension reinforcement at a section
βd = ratio of factored dead load moment to total factored moment
βf = moment coefficient (see Clause 7.12.3.2)
β1 = ratio of depth of rectangular compression block to depth to the neutral axis
γ = mean compressive strength of the units intended for use in the construction divided by the mean
compressive strength of the units used in the masonry prisms tested to determine f ′m , but not
greater than 1 (see Clause 5.1.2.2)
γg = factor to account for partially grouted walls or columns or ungrouted walls and columns when
calculating the shear resistance
δ = lateral displacement of walls or columns due to end moments, lateral loads, and secondary
moments, mm
δf = lateral deflection of walls or columns at critical section under factored lateral and axial loads,
including effect of secondary moments, mm
∆f = lateral deflection of walls or columns at mid-height under factored lateral and axial loads,
including effect of secondary moments, mm
∆s = lateral deflection of walls or columns at mid-height under service lateral and axial loads, including
effect of secondary moments, mm
εblc = specific creep strain for concrete block masonry, /MPa
εblm = moisture strain in concrete block masonry, mm/mm
εbrc = specific creep strain for clay brick masonry, /MPa
εbrm = moisture strain in clay brick masonry, mm/mm
εmu = total unrestrained permanent moisture movement of the clay brick unit, mm/mm
εs = strain in reinforcing steel
εt = average unrestrained thermal strain of masonry
λ = factor to account for the density of concrete masonry units when calculating shear capacity of
beams (see Clause 11.3.3)
θ = angle of diagonal strut measured from the horizontal (see Clause 7.13.3.2)
µ = coefficient of friction
µm = orthogonal strength ratio
ρ = ratio of the area of nonprestressed tensile reinforcement, As , to effective masonry area between
the extreme compression fibre and the centroid of the tensile reinforcement
= ratio of the area of nonprestressed compression reinforcement, , to effective masonry area
located between the extreme compression fibre and the centroid of the tensile reinforcement
ρg = ratio of cross-sectional area of reinforcement, As , to the gross cross-sectional area of the masonry, Ag
′ρ ′As

14 December 2004
ρh = reinforcement ratio in the horizontal direction
ρv = reinforcement ratio in the vertical direction
φco = resistance factor for the failure mode of the connectors (see Clauses 4.3.3 and 10.7.1.3)
φe = resistance factor for member stiffness used in the determination of slenderness effects on the
capacity of the unreinforced masonry (see Clause 4.3.4)
φer = resistance factor for member stiffness used in the determination of slenderness effects on the
capacity of reinforced masonry (see Clause 4.3.4)
φm = resistance factor for masonry (see Clause 4.3.2.1)
φp = resistance factor for prestressing tendons (see Clause 4.3.2.2)
φs = resistance factor for reinforcing bars (see Clause 4.3.2.2)
χ = factor used to account for direction of compressive stress in a masonry member relative to the
direction used for the determination of (see Clauses 10.2.6 and 11.2.1.6)
2.3 Units
Equations appearing in this Standard are compatible with the following units:
(a) force: N (newtons);
(b) dimension: mm (millimetres);
(c) moment: N•mm; and
(d) stress: MPa (megapascals).
3 General requirements
3.1 Design methods
Engineered masonry design under this Standard shall be carried out in conformance with Clauses 1 to 15
and Annexes A to E. Unreinforced masonry may be designed using the empirical method in Annex F
where permitted.
3.2 Other design methods
A rational design based on engineering practice and theory or tests or analysis and acceptable to the
regulatory authority may be used in lieu of the formulae and rules provided in this Standard. In such cases
the design shall provide for nominal levels of safety and serviceability at least equal to those implied by the
provisions of this Standard.
3.3 Drawings and related documents
In addition to the information required by the National Building Code of Canada, the drawings and related
documents for structures designed in accordance with this Standard shall include, where appropriate, the
(a) materials to be used in masonry;
(b) specified compressive strength of masonry ( );
(c) specified flexural tensile strength of masonry (ft);
(d) specified compressive strength of masonry units;
(e) specified strength or grade of reinforcement;
(f) specified mortar type (Type N or S);
(g) specified grout type (fine or coarse);
(h) locations and dimensions of loadbearing masonry;
(i) types of mortar joints (see CSA A371);
(j) location, size, spacing, splicing, anchorage, and details of reinforcement;
(k) details of bonding units in a wythe (fifty percent running bond, running bond, or stack pattern);
(l) details of tying or bonding wythes together or tying veneer to structural backing;
(m) details of anchorage of masonry to its supports;
(n) type of corrosion protection of metal components;
′fm
′fm

December 2004 15
(o) details and locations of movement joints;
(p) details and location of chases and recesses;
(q) position, location, type, spacing, and size of ties, anchors, lifting devices, and other supports for
prefabricated masonry and dimension cut stone or manufactured stone masonry; and
(r) governing set of forces required for the preparation of shop or detail drawings for prefabricated
masonry; alternatively, such information may be provided by supplementary material to the drawings
and specifications.
3.4 Materials
3.4.1
Materials used in masonry construction shall conform to the requirements of CSA A371.
3.4.2
Masonry constructed with materials other than those defined in Clause 3.4.1 shall satisfy the requirements
for serviceability and safety provided in this Standard. The performance of the unit, mortar, or grout and of
the masonry constructed with these materials shall be verified by comprehensive testing and methods of
analysis which conform to recognized engineering principles.
Note: Construction methods, durability, flexural tensile bond, compressive strength, water penetration, and uniform quality
are among the aspects of performance to be investigated.
4 Design requirements
4.1 Specified loads and effects
4.1.1 Loads and effects
The following categories of loads, specified loads, and effects shall be considered in the design of a
building and its structural members and connections:
D: dead load — a permanent load due to the weight of building components;
E: earthquake load and effects — a rare load due to earthquake;
H: a permanent load due to lateral earth pressure, including groundwater;
L: live load — a variable load due to intended use and occupancy (including loads due to cranes and
pressure of liquids in containers);
P: permanent effects caused by prestress;
S: variable load due to snow, including ice and associated rain, or due to rain;
T: effects due to contraction, expansion, or deflection caused by temperature changes, shrinkage,
moisture changes, creep, temperature, ground settlement, or combination thereof; and
W: wind load — a variable load due to wind.
In these descriptions of loads
(a) “load” means the forces, pressures, and imposed deformations applied to the building structure;
(b) “permanent load” is a load that changes very little once it has been applied to the structure, except
during repair;
(c) “variable load” is a load that frequently changes in magnitude, direction, or location;
(d) “rare load” is a load that occurs infrequently and for a short time only; and
(e) “imposed deformation” is a deflection, displacement, or motion applied to the structure that induces
deformations and forces in the structures.
4.1.2 Dynamic effects
Minimum specified values of these loads shall be increased to account for dynamic effects where
applicable.

16 December 2004
4.1.3 Importance factor
Importance factors for determining specified loads S, W, or E shall be assigned based on an importance
category for the intended use and occupancy of the building in accordance with the National Building
Code of Canada.
4.1.4 Loads not listed
Where a building or structural member is expected to be subjected to the effects of loads, forces, or other
effects not listed in Clause 4.1.1, such effects shall be taken into account in the design based on the most
appropriate information available.
4.2 Limit states design
4.2.1 Terminology
The following terminology shall apply:
(a) “Limit states” means those conditions of a building structure in which the building ceases to fulfill the
function for which it was designed. (Those states concerning safety are called “ultimate limit states”
(ULS), and include exceeding the load carrying capacity, overturning, sliding, and fracture, while
those states which restrict the intended use and occupancy of the building are called “serviceability
limit states” (SLS), and include deflection, vibration, permanent deformation, and local structural
damage such as cracking. Those limit states that represent failure under repeated loading are called
“fatigue limit states”.)
(b) “Specified loads” (D, E, H, L, P, S, T, and W) mean those loads defined in Clause 4.1.1.
(c) “Principal load” is the specified variable load or rare load that dominates in a given load combination.
(d) “Companion load” is a specified variable load that accompanies the principal load in a given load
combination.
(e) “Service load” is a specified load used for the evaluation of a serviceability limit state.
(f) “Principal-load factor” is a factor applied to the principal load in the load combination to account for
the variability of the load and load pattern and analysis of its effects.
(g) “Companion-load factor” is a factor which, when applied to a companion load in the load
combination, gives the probable magnitude of a companion load acting simultaneously with the
factored principal load.
(h) “Importance factor”, I, is a factor applied to obtain the specified load to account for the
consequences of failure as related to the limit state and the use and occupancy of the building. See
National Building Code of Canada for values of I.
(i) “Factored load” means the product of a specified load and its principal-load factor or
companion-load factor.
(j) “Effects” are forces, moments, deformations, or vibrations that occur in the structure.
(k) “Nominal resistance”, R, of a member, connection, or structure is based on the dimensions and on
the specified properties of the structural materials.
(l) “Resistance factor”, φ, means a factor applied to a specified material property or to the resistance of a
member, connection, or structure, which for the limit state under consideration takes into account
the variability of dimensions and material properties, quality of work, type of failure, and uncertainty
in the prediction of resistance.
(m) “Factored resistance” means the product of nominal resistance and the applicable resistance factor.
4.2.2 Strength and stability
4.2.2.1
A building and its structural components shall be designed to have sufficient strength and stability so that
the factored resistance, φR, is greater than or equal to the effect of factored loads.

December 2004 17
4.2.2.2 Load combinations
The effect of factored loads for a building or structural component shall be determined in accordance with
the load combinations listed below and the requirements of Clause 4.2.2, the applicable combination
being that which results in the most critical effect.
4.2.2.3
Provision shall be made to ensure the adequate stability of a structure as a whole, and the adequate lateral,
torsional, and local stability of all structural parts.
4.2.2.4
Sway effects produced by vertical loads acting on the structure in its displaced configuration shall be taken
into account in the design of buildings and their structural members.
4.3 Factored resistance
4.3.1 General
The factored resistance of a member, its cross-sections, and its connections shall be taken as the resistance
calculated in accordance with the requirements and assumptions of this Standard, using the material
strengths specified in Clause 5 multiplied by resistance factors in accordance with Clause 4.3.2.
Case
Load combination
(1)
Principal loads Companion loads
1 1.4D —
2 (1.25D
(5)
or 0.9D
(2)
) + 1.5L
(3)
0.5S or 0.4W
3 (1.25D
(5)
or 0.9D
(2)
) + 1.5S 0.5L
(4)
or 0.4W
4 (1.25D(5)
or 0.9D(2)
) + 1.4W 0.5L(4)
or 0.5S
5 1.0D
(2)
+ 1.0E
(6)
0.5L
(4)
+ 0.25S
Notes:
(1) Where the effects due to lateral earth pressure, H, restraint effects from prestress, P,
and imposed deformation, T, affect the structural safety, they shall be taken into
account in the calculations, H with a load factor of 1.5, P with a load factor of 1.0,
and T with a load factor of 1.25.
(2) Except as provided in the National Building Code of Canada, the counteracting
factored dead load, 0.9D in load combinations (2), (3), and (4) and 1.0D in load
combination (5), shall be used when dead load acts to resist overturning, uplift,
sliding, or failure due to stress reversal and to determine anchorage requirements and
factored member resistances.
(3) The principal-load factor 1.5 for live load, L, may be reduced to 1.25 for liquids in
tanks.
(4) The companion-load factor 0.5 for live load, L, shall be increased to 1.0 for storage
occupancies.
(5) The load factor 1.25 for dead load, D, for soil, superimposed earth, plants, and trees
shall be increased to 1.5.
(6) Earthquake load, E, in load combination (5) includes horizontal earth pressure due to
earthquake.

18 December 2004
4.3.2 Resistance factors
4.3.2.1 Masonry
The resistance factor to be used in calculating the ultimate limit states for compression, tension, shear, and
bearing in masonry shall be taken as φm = 0.60.
4.3.2.2 Reinforcement
The resistance factors to be used in calculating the ultimate limit states for force in steel reinforcement shall
be taken as φs = 0.85 for reinforcing bars and wire and φp = 0.90 for prestressing steel.
4.3.3 Masonry connectors
The resistance factors to be used for masonry connectors shall be in accordance with CSA A370.
4.3.4 Effective stiffness
The effective stiffness, (EI)eff, used in determining slenderness effects on the capacity of a wall or column
by the P•δ and moment magnifier methods shall be reduced by a resistance factor taken as φe = 0.65 for
unreinforced masonry and φer = 0.75 for reinforced masonry.
4.4 Structural integrity
The general arrangement of the structural system and the interconnection of its members shall be
designed to provide resistance to widespread collapse due to local failure.
Note: The requirements of this Standard generally provide a satisfactory level of structural integrity for most masonry
buildings. Supplementary provisions can be required for masonry structures with precast floors or where accidental loads
such as vehicle impact or explosion are likely to occur. For further guidance, see the User’s Guide — NBC 2005 Structural
Commentaries (Part 4), Commentary B, “Structural Integrity” and particularly M. Fintel, and G. Annamalai, “Philosophy of
structural integrity of multi-storey loadbearing concrete masonry structures”, Concrete International (May 1979), Vol. 1,
No. 5, pp. 27–35.
4.5 Limits on use of unreinforced masonry
4.5.1 Seismic limitation for unreinforced masonry
Except as permitted in Clause 4.6.1(c) and Clause 4.6.2, unreinforced masonry shall be used only at sites
where the seismic hazard index, IEFaSa(0.2), is less than 0.35.
4.5.2 Locally reinforced masonry
Where masonry requires local reinforcement to resist applied loads, such as around openings, the design
shall consider the effects of flexural cracking in the reinforced section on adjacent unreinforced sections.
Notes:
(1) This requirement does not apply where local reinforcement is not relied upon for calculated flexural capacity or axial
tensile capacity.
(2) The purpose of this requirement is to accommodate deflection compatibility between a reinforced section of masonry
that is relying on tension in reinforcement to resist out-of-plane bending and an adjacent and integral unreinforced
section of masonry that is relying on flexural tensile bond strength to resist out-of-plane bending. The reinforced section
needs to crack in order for the reinforcement to be effective. Under load, this crack will propagate into the adjacent,
otherwise unreinforced sections, thereby reducing bond strength to zero across the crack, and reducing the flexural
tensile strength of the unreinforced masonry to zero normal to the crack.
(3) Means to address the effects of deflection compatibility between locally reinforced and adjacent unreinforced masonry
include
(a) limiting the affected area by creating masonry panels as follows:
(i) where the otherwise unreinforced masonry is intended to span in a direction parallel to the locally reinforced
strip of masonry, using an aligned movement joint with no keyway (which provides no shear transfer) to
structurally disconnect the locally reinforced masonry strip from the adjacent unreinforced masonry; or
(ii) determining the ability of the unreinforced masonry to span in the direction perpendicular to the direction of
span of the locally reinforced masonry, that is, its ability to span between the local reinforcement and a wall

December 2004 19
panel end defined by a corner or tee intersection, or by a column designed to laterally brace the wall panel,
or by a locally reinforced movement joint which provides no shear transfer (in such cases, the wall panel ends
needs to be capable of resisting the loading laterally transferred from the unreinforced masonry); and
(b) providing reinforcement to the adjacent, otherwise unreinforced masonry sections to resist flexural stresses in
accordance with Clause 10, but not less than the minimum reinforcement required by this Standard.
4.5.3 Unreinforced shear walls
Unreinforced shear walls shall not be combined with reinforced shear walls in a lateral load-resisting
system where shear walls share the load as a function of wall rigidity.
4.6 Seismic design
4.6.1 General
At sites where the seismic hazard index, IEFaSa(0.2), is equal to or greater than 0.35, reinforcement
conforming to Clause 10.15.2 shall be provided for masonry construction in
(a) loadbearing and lateral load-resisting masonry;
(b) masonry enclosing elevator shafts and stairways, or used as exterior cladding except as permitted by
Clause 4.6.2; and
(c) masonry partitions, except for partitions that
(i) do not exceed 200 kg/m2
in mass;
(ii) do not exceed 3 m in height and are laterally supported at the top; and
(iii) are located at sites where the seismic hazard index, IEFaSa(0.2), is less than 0.75.
Note: Subject to the approval of the authority having jurisdiction, in Clause 4.6.1(c)(ii), unreinforced masonry partitions
that do not exceed 3 m in height, but are not laterally supported at the top, may be designed in accordance with Clause 7 to
span horizontally between vertical elements providing lateral support.
4.6.2 Veneer secured by ties
The minimum seismic reinforcement requirements of Clause 10.15.2 shall not apply to masonry veneer
secured by ties.
4.6.3 Seismic limitation for masonry of conventional construction
Except as permitted in Clauses 4.6.4 to 4.6.6, reinforced masonry designed for seismic loadings
corresponding to Rd = 1.5 and not exceeding the height restrictions for masonry shear walls of
conventional construction in accordance with Part 4 of the National Building Code of Canada shall be
designed in accordance with Clause 10.
4.6.4 Limited ductility shear walls
Except as permitted in Clause 4.6.5, masonry shear walls with a height-to-length ratio (hw/ w) equal to or
greater than one and exceeding the height restrictions for masonry shear walls of conventional
construction, capable of limited ductility and designed for seismic loadings corresponding to Rd = 1.5,
shall be designed in accordance with Clause 10.16.4 unless a more comprehensive analysis is performed.
4.6.5 Moderately ductile shear walls
Masonry shear walls with a height-to-length ratio (hw/ w) equal to or greater than one, capable of
moderate ductility and designed for seismic loadings corresponding to Rd = 2.0, shall be classified as
moderately ductile and shall be designed in accordance with Clause 10.16.5 unless a more comprehensive
analysis is performed.
4.6.6 Moderately ductile squat shear walls
Squat shear walls with a height-to-length ratio (hw/ w) less than one, capable of moderate ductility and
designed for seismic loadings corresponding to Rd = 2.0, shall be classified as moderately ductile squat
shear walls and shall be designed in accordance with Clause 10.16.6 unless a more comprehensive analysis
is performed.

20 December 2004
4.7 Fire resistance
Masonry structures, components, and assemblies shall satisfy the fire resistance requirements of the
National Building Code of Canada.
4.8 Support of masonry
4.8.1 Rigidity requirements
A structural element designed to support masonry shall have a rigidity compatible with the stiffness of the
masonry.
Notes:
(1) Roof diaphragms, beams supporting infill walls, lintels, girts providing lateral support, cross walls, and structural
frames are examples of supports to be designed to have rigidities compatible with the masonry they support.
(2) For the vertical support of masonry, the following items apply:
(a) Deflections to be considered should include that part of the total deflection of the supporting element under
specified loads occurring after and during construction of the masonry, including load due to the mass of the
masonry, the long-term deflection due to all sustained loads, and immediate deflection due to any additional live
load.
(b) Vertical deflection limits for elements supporting glass block masonry are contained in Clause 8.
(c) For assembly areas, the live load need not be taken greater than 2.4 kPa when calculating deflection.
(d) Recommended limits on vertical deflection include
(i) L/480 or less, but not more than 20 mm, for elements supporting masonry other than masonry veneer, and
other than reinforced masonry which satisfies the deflection requirements of Clause 11.4.5 by acting
compositely or non-compositely with the supporting element. For masonry partition walls and infill walls, this
deflection limit may be exceeded, provided that movement joints have sufficient width and are appropriately
placed in the wall to prevent cracking or to limit crack widths, and to prevent unintentional loading on other
masonry and non-masonry elements; and
(ii) L/480 or less for elements supporting unit masonry veneer, where limiting cracking and crack width is a
design consideration. This deflection limit may be exceeded, provided that movement joints have sufficient
width and are appropriately placed in the masonry veneer to prevent cracking or to limit crack widths, and to
prevent unintentional loading on other masonry and non-masonry elements.
(3) For the lateral support of masonry, the following items apply:
(a) Deflections to be considered should include immediate deflection normal to the masonry due to specified wind
loads.
(b) Lateral deflection limits for structural backing systems supporting masonry veneer are contained in Clauses 9.1
and 10.14.
(c) Lateral deflection limits for structural backing systems supporting glass block masonry are contained in Clause 8.
(d) Recommended limits on lateral deflection normal to the masonry include
(i) L/600 or less for unreinforced masonry where the flexural stress in the masonry is perpendicular to the bed
joint;
(ii) L/300 or less for unreinforced masonry where the flexural stress in the masonry is parallel to the bed joint;
and
(iii) L/240 or less for reinforced masonry.
4.8.2 Vertical support of masonry
4.8.2.1
The vertical support for any masonry shall
(a) have lateral stability;
(b) be noncombustible material, except for the support of minor masonry decorative features and except
as permitted by Clause 4.8.2.2; and
(c) meet the requirements of Clause 4.7.
4.8.2.2
For wood structures of four storeys or less, masonry veneer may be vertically supported by wood or by
shelf angles supported by wood, provided that the vertical support is designed in conformance with Part 4
of the National Building Code of Canada.

December 2004 21
Notes:
(1) Wood structures can undergo significant long-term shrinkage and creep (see Clause 4.10.1). The designer should take
such movement into account when considering movement joint widths and locations, tie movement capabilities, and
flashing details.
(2) The designer should take into account any expected rotation of the masonry support.
(3) Wood in contact with the masonry or in contact with the shelf angle supporting the masonry should be protected from
moisture or otherwise be resistant to the effects of moisture.
4.8.3 Lateral support of masonry
4.8.3.1 Anchorage at vertical support of masonry
Unless friction or bond are shown to provide adequate anchorage at bearing supports, the connection
shall be designed to have positive mechanical connection.
Note: Some flashing materials provide very low friction and bond.
4.8.3.2 Anchorage at lateral supports other than vertical supports
Masonry walls and partitions shall be anchored to their lateral supports by interlocking bond of masonry
units in accordance with CSA A371 or by anchors designed and placed in accordance with the
requirements of Clause 4.9.
Notes:
(1) Alternative design of anchorage systems, including reinforcement, may be used.
(2) At horizontal lateral supports, the spacing of the lateral support anchors may be large enough to require reinforcing
the wall to span between anchors.
4.9 Connectors
Connectors shall satisfy the requirements of CSA A370.
Note: Except as justified by engineering analysis, limits for maximum spacing for connectors are provided in CSA A370.
4.10 Serviceability
4.10.1 Effects of differential movements and dimensional changes
4.10.1.1 General
For all masonry members, cracking and the buildup of movement-related stresses shall be controlled
through the requirements of Clause 4.10.
4.10.1.2 Structural considerations
Consideration shall be given to the structural effects of differential movements within a masonry member,
between adjacent masonry elements, and between the masonry member and adjacent structural member
due to elastic deformation, creep, moisture changes, and temperature changes.
Notes:
(1) The provision of horizontal and vertical movement joints should be carefully considered by the designer.
(2) Further information may be obtained from the User’s Guide — NBC 2005 Structural Commentaries (Part 4),
Commentary E, “Effects of Deformations in Building Components”.
(3) In the absence of more specific information regarding the actual properties of materials used, the values for thermal
coefficients, moisture movement, creep movement, and coefficient of friction in Tables 1 and 2 may be used.
(4) Methods to approximate in-situ movement of unrestrained masonry elements due to temperature and moisture
changes and due to creep are provided in the Notes to Table 1.
4.10.1.3 Long-term effects within walls
Consideration shall be given to the effect of long-term differential movement in composite walls, veneer,
and cavity walls where the wythes or structural backing are of different materials or serve under different
exposures.
Note: See Notes to Clause 4.10.1.2.

Csa masonry s304.1-04

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