PART 4 — STRUCTURAL DESIGNUpdated for the 2024 Ontario Building Code
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4.1.8.23.Additional Performance Requirements for Post-disaster Buildings, High
Importance Category Buildings, and a Subset of Normal Importance
Category Buildings
(1) Buildings designed in accordance with Articles 4.1.8.19. to 4.1.8.22. need not comply with this Article.
(2) The design of post-disaster buildings in Seismic Category SC2, SC3 or SC4 shall be verified using 5%-damped
spectral acceleration values based on a 5% probability of exceedance in 50 years and shall satisfy the following
requirements:
(a) the building shall be shown to behave elastically for a specified lateral earthquake force, V, determined in
accordance with Sentence 4.1.8.11.(2) using IE = 1.0 and RdRo = 1.3,
(b) the largest interstorey deflection at any level of the building, as determined in accordance with Sentence 4.1.8.13.(2)
using IE = 1.0 and RdRo = 1.0, shall not exceed 0.005hs, and
(c) the connections of elements and components of the building described in Table 4.1.8.18. with Rp > 1.5 shall be
shown to behave elastically for a specified lateral earthquake force, V p, determined in accordance with Sentence
4.1.8.18.(1) using Rp = 1.5.
(3) The design of High Importance Category buildings in Seismic Category SC3 or SC4 shall be verified using 5%-
damped spectral acceleration values based on a 10% probability of exceedance in 50 years and shall satisfy the following
requirements:
(a) the building shall be shown to behave elastically for a specified lateral earthquake force, V, determined in
accordance with Sentence 4.1.8.11.(2) using IE = 1.0 and RdRo = 1.3,
(b) the largest interstorey deflection at any level of the building, as determined in accordance with Sentence 4.1.8.13.(2)
using IE = 1.0 and RdRo = 1.0, shall not exceed 0.005hs, and
(c) the connections of elements and components of the building described in Table 4.1.8.18. with Rp > 1.3 shall be
shown to behave elastically for a specified lateral earthquake force, V p, determined in accordance with Sentence
4.1.8.18.(1) using Rp = 1.3.
(4) For Normal Importance Category buildings in Seismic Category SC4 with a height above grade of more than 30 m,
the structural framing elements not considered to be part of the SFRS shall be designed to behave elastically for a
specified lateral earthquake force, V, determined in accordance with Sentence 4.1.8.11.(2) using spectral acceleration
values based on a 10% probability of exceedance in 50 years and RdRo = 1.3.
(5) For the purposes of applying Sentences (2) to (4), torsional moments due to accidental eccentricities need not be
considered if B, as determined in accordance with Sentence 4.1.8.11.(10), does not exceed 1.7.
(6) For the purposes of applying Sentences (2) to (4), elements of the SFRS and structural framing elements not
considered to be part of the SFRS, when included in the analysis, shall be modeled in accordance with Sentence
4.1.8.3.(8) using elastic properties.
(7) All other requirements of Articles 4.1.8.2. to 4.1.8.18. shall be satisfied in meeting the additional requirements of
this Article.
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.