OBC 2006 › Division B

4.1.8.6.

Version 1 — in force 1 January 2010

In force · amended

Verified · covered Verified against the 2010-01-01–2010-03-31 consolidation, whose range covers the query date. How to read this

In force · amended

Verified · covered Verified against the 2010-01-01–2010-03-31 consolidation, whose range covers the query date. How to read this

Provenance

New in this edition — no OBC 1997 predecessor

Base · O. Reg. 350/06 · ext v0 →

O. Reg. 503/09, cl. 59 · ext ← current

In force 2010-01-01

OBC 2012 · continues as 4.1.8.6. — Pro

4.1.8.6. — Structural Configuration

(1) Structures having any of the features listed in Table 4.1.8.6. shall be designated irregular.

(2) Structures not classified as irregular according to Sentence 4.1.8.6.(1) may be considered regular.

(3) Except as required by Article 4.1.8.10., in cases where I_EF_aS_a(0.2) is equal to or greater than 0.35, structures designated as irregular must satisfy the provisions referenced in Table 4.1.8.6.

Text · e-Laws consolidated snapshot

Table 4.1.8.6. Structural Irregularities(1) Forming Part of Sentence 4.1.8.6.(1)

Column 1	Column 2	Column 3
Type	Irregularity Type and Definition	Notes
	Vertical Stiffness Irregularity
1	Vertical stiffness irregularity shall be considered to exist when the lateral stiffness of the SFRS in a storey is less than 70% of the stiffness of any adjacent storey, or less than 80% of the average stiffness of the three storeys above or below.	(2)(3)
	Weight (mass) Irregularity	(2)
2	Weight irregularity shall be considered to exist where the weight, W_i, of any storey is more than 150% of the weight of an adjacent storey. A roof that is lighter than the floor below need not be considered.
	Vertical Geometric Irregularity	(2)(3)(4)
3	Vertical geometric irregularity shall be considered to exist where the horizontal dimension of the SFRS in any storey is more than 130% of that in an adjacent storey.
	In-Plane Discontinuity in Vertical Lateral-Force-Resisting Element
4	An in-plane offset of a lateral-force-resisting element of the SFRS or a reduction in lateral stiffness of the resisting element in the storey below.	(2)(3)(4)
	Out-of-Plane Offsets
5	Discontinuities in a lateral force path, such as out-of-plane offsets of the vertical elements of the SFRS.	(2)(3)(4)
	Discontinuity in Capacity – Weak Storey
6	A weak storey is one in which the storey shear strength is less than that in the storey above. The storey shear strength is the total strength of all seismic-resisting elements of the SFRS sharing the storey shear fo the direction under consideration.	(3)
	Torsional Sensitivity (to be considered when diaphragms are not flexible)
7	Torsional sensitivity shall be considered to exist when the ratio B calculated according to Sentence 4.1.8.11.(9) exceeds 1.7.	(2)(3)(5)
	Non-orthogonal Systems
8	A non-orthogonal system irregularity shall be considered to exist when the SFRS is not oriented along a set of orthogonal axes.	(6)

Notes to Table 4.1.8.6.:

⁽¹⁾One-storey penthouses with a weight of less than 10% of the level below need not be considered in the application of this Table.

(2)See Article 4.1.8.7.

(3)See Article 4.1.8.10.

(4)See Article 4.1.8.15.

(5)See Sentences 4.1.8.11.(9), (10) and 4.1.8.12.(4).

(6)See Article 4.1.8.8.