The Ontario Building Code | Design Provisions
18.104.22.168. design Provisions
(1) Except as provided in Sentences (2) and (3), diaphragms, collectors, chords, struts and connections shall be designed so as not to yield, and the design shall account for the shape of the diaphragm, including openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings, and for the forces generated in the diaphragm due to the following cases, whichever one governs:
(a) forces due to loads determined in Article 22.214.171.124. or 126.96.36.199. applied to the diaphragm are increased to reflect the lateral load capacity of the SFRS, plus forces in the diaphragm due to the transfer of forces between elements of the SFRS associated with the lateral load capacity of such elements and accounting for discontinuities and changes in stiffness in these elements, or
(b) a minimum force corresponding to the design-based shear divided by N for the diaphragm at level x.
(2) Steel deck roof diaphragms in buildings of less than 4 storeys or wood diaphragms that are designed and detailed according to the applicable referenced design standards to exhibit ductile behaviour shall meet the requirements of Sentence (1), except that they may yield and the forces shall be,
(b) for wood diaphragms acting in combination with other SFRS, not less than the force corresponding to RdRo= 2.0, and
(c) for steel deck roof diaphragms, not less than the force corresponding to RdRo = 2.0.
(3) Where diaphragms are designed in accordance with Sentence (2), the struts shall be designed in accordance with Clause (1)(a) and the collectors, chords and connections between the diaphragms and the vertical elements of the SFRS shall be designed for forces corresponding to the capacity of the diaphragms in accordance with the applicable CSA standards.
(4) In cases where IEFaSa(0.2) is equal to or greater than 0.35, the elements supporting any discontinuous wall, column or braced frame shall be designed for the lateral load capacity of the components of the SFRS they support.
(5) Where structures have vertical variations of RdRo satisfying Sentence 188.8.131.52.(4), the elements of the SFRS below the level where the change in RdRo occurs shall be designed for the forces associated with the lateral load capacity of the SFRS above that level.
(6) Where earthquake effects can produce forces in a column or wall due to lateral loading along both orthogonal axes, account shall be taken of the effects of potential concurrent yielding of other elements framing into the column or wall from all directions at the level under consideration and as appropriate at other levels.
(7) Except as provided in Sentence (8), the design forces associated with the lateral capacity of the SFRS need not exceed the forces determined in accordance with Sentence 184.108.40.206.(1) with RdRo taken as 1.0, unless otherwise provided by the applicable referenced design standards for elements, in which case the design forces associated with the lateral capacity of the SFRS need not exceed the forces determined in accordance with Sentence 220.127.116.11.(1) with RdRotaken as 1.3.
(8) If foundation rocking is accounted for, the design forces for the SFRS need not exceed the maximum values associated with foundation rocking, provided that Rd and Rofor the type of SFRS used conform to Table 18.104.22.168. and that the foundation is designed in accordance with Sentence 22.214.171.124.(1).