The Ontario Building Code | General Requirements
188.8.131.52. General Requirements
(3) The structure shall have a clearly defined Seismic Force Resisting System(s) (SFRS), as defined in Article 184.108.40.206.
(4) The SFRS shall be designed to resist 100% of the earthquake loads and their effects.
(5) All structural framing elements not considered to be part of the SFRS must be investigated and shown to behave elastically or to have sufficient non-linear capacity to support their gravity loads while undergoing earthquake-induced deformations calculated from the deflections determined in Article 220.127.116.11.
(a) separated from all structural elements of the building such that no interaction takes place as the building undergoes deflections due to earthquake effects as calculated in this Subsection, or
(b) made part of the SFRS and satisfy the requirements of this Subsection.
(7) Stiffness imparted to the structure from elements not part of the SFRS, other than those described in Sentence (6), shall not be used to resist earthquake deflections but shall be accounted for,
(a) in calculating the period of the structure for determining forces if the added stiffness decreases the fundamental lateral period by more than 15%,
(b) in determining the irregularity of the structure, except the additional stiffness shall not be used to make an irregular SFRS regular or to reduce the effects of torsion, and
(c) in designing the SFRS if inclusion of the elements not part of the SFRS in the analysis has an adverse effect on the SFRS.
(8) Structural modelling shall be representative of the magnitude and spatial distribution of the mass of the building and of the stiffness of all elements of the SFRS, including stiff elements that are not separated in accordance with Sentence 18.104.22.168.(6), and shall account for,
(a) the effect of cracked sections in reinforced concrete and reinforced masonry elements,
(b) the effect of the finite size of members and joints,
(c) sway effects arising from the interaction of gravity loads with the displaced configuration of the structure, and
(d) other effects that influence the lateral stiffness of the building.