CSA O86:24

Preface 

This is the twelfth edition of CSA O86, Engineering design in wood . It is presented in limit states design (LSD) format and supersedes the previous editions published in 2019, 2014, 2009, 2001, 1994, 1989, 1984, 1980, 1976, 1970, and 1959, including their Supplements. Editions of CSA O86 published in 1959, 1970, 1976, 1980, and 1984 were all developed using working stress design (WSD) theory. The last WSD version, CSA CAN3-O86-M84, Engineering design in wood (working stress design), existed concurrently with the first (1984) and second (1989) LSD versions, Engineering design in wood (limit states design). The WSD version was withdrawn upon publication of the 1994 LSD edition. Three LSD editions were published in 1984, 1989, and 1994 with the CSA designation O86.1. Supplements to each of these editions were published in 1987, 1993, and 1998, respectively. Although the 2001 edition was also based on the LSD method, the O86 designation was reinstated. Primary changes in this edition include the following: • revisions to Clause 5.4.2 to include creep in the deflection calculation, and the deletion of Clause 5.4.3; • revisions to the lateral stability provisions for built-up beams in Clause 6.5.3.2.4 and for glulam in Clauses 7.5.6.3 to 7.5.6.6; • addition of a new Clause 8.2 on mechanically laminated timber (MLT), including prefabricated dowel- laminated timber (DLT) and nail-laminated timber (NLT); • revisions to Clause 11.9 for the design of cross-laminated timber (CLT) shearwalls and diaphragms for platform-type construction; • addition of a new Clause 12.12 and the associated Clause 17.6 on self-tapping screws; • addition of a new Clause 13 and the associated Clauses 17.7, A.13, and B.11 on timber-concrete- composite (TCC) floors; and • as a result of the addition of TCC floors, the relocation of Clauses 13 to 16 in CSA O86:19 to Clauses 14 to 17 in CSA O86:24. Other significant changes include the following: • addition of a new definition for "specified modulus of elasticity" (Clause 3.1); • clarification of the calculation of the KD factor for non-uniform and multi-directional loads (Clause 5.3.2.3); • addition of a design provision for built-up compression members with piece-to-piece nailing (Clause 6.5.5.4.3); • revisions to Clause 7.5.6.6.1 for the application of the KL and KZbg factors for glulam bending moment resistance; • revisions to shear-load coefficient, Cv, for glulam shear resistance (Clause 7.5.7.6); • modification of Table 9.3 to add specified capacities for W24 rated oriented strand board (OSB); • editorial changes to all clauses, especially the terminology and figures in Clause 12; • revisions to the measurement of shear depth at connections (Clause 12.2.1.6); • revisions to the spacing perpendicular to grain, SQ, for bolt and dowel connections (Table 12.16); • addition of the requirements for fabricators of metal plate connected wood trusses to be certified in accordance with CSA S349 (Clause 12.8); • revisions to Figure 12.16 for inclined wood members with nail connections; • correction to the unit of the lateral slip resistance, ys, for lag screw lateral deformation (Clause A.12.6.5.4); • revisions to Annex B for the charring rates of CLT; and • revisions to Clause B.8 for the fire-resistance of large cross-section wood elements protected by gypsum board. This Standard was prepared by the Technical Committee on Engineering Design in Wood, under the jurisdiction of the Strategic Steering Committee on Construction and Civil Infrastructure, and has been formally approved by the Technical Committee. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. 

Scope 

1.1 General 

This Standard provides criteria in accordance with the National Building Code of Canada, for the structural design and evaluation of structures or structural elements made from wood or wood products, including: a) graded lumber; b) glued-laminated timber; c) cross-laminated timber (CLT); d) mechanically laminated timber (MLT); e) unsanded plywood; f) oriented strand board (OSB); g) composite building components; h) shearwalls and diaphragms; i) timber-concrete-composite (TCC); j) timber piling; k) pole-type construction; l) prefabricated wood I-joists; m) structural composite lumber; n) permanent wood foundations; o) plank decking; p) nail-laminated decking; and q) structural connections. 

1.2 Exclusions 

This Standard does not include design of timber bridges. 

1.3 Design method 

This Standard employs the limit states design method. 

1.4 Terminology 

In this Standard, "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. 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. 

1.5 Units of measurement 

If a value for measurement as given in this Standard is followed by an equivalent value in other units, the first stated value is to be regarded as the specification.