Notes to Table 4.1.8.6.:
4.1.8.9. SFRS Force Reduction Factors, System Overstrength Factors, and General Restrictions (1) The values of Rd and Ro and the corresponding system restrictions shall conform to Table 4.1.8.9. and the requirements of this Subsection. (2) When a particular va1ue of Rd is required by this Article, the corresponding Ro shall be used. (3) For combinations of different types of SFRS acting in the same direction in the same storey, RdRo shall be taken as the lowest value of RdRo corresponding to these systems. (4) For vertical variations of RdRo, excluding penthouses whose weight is less than 10% of the level below, the value of RdRo used in the design of any storey shall be less than or equal to the lowest value of RdRo used in the given direction for the storeys above, and the requirements of Sentence 4.1.8.15.(3) must be satisfied. (5) If it can be demonstrated through testing, research and analysis that the seismic performance of a structural system is at least equivalent to one of the types of SFRS mentioned in Table 4.1.8.9., then such a structural system will qualify for values of Rd and Ro corresponding to the equivalent type in that Table. Table 4.1.8.9.   SFRS Ductility-Related Force Modification Factors, Rd, Overstrength-Related Force Modification Factors, Ro, and General Restrictions (1) Forming Part of Sentence 4.1.8 9.(1)  Column 1

Column 2

Column 3

Column 4

Column 5

Column 6

Column 7

Column 8


 

 

 

Restrictions(2)


Type of SFRS

Rd

Ro

Cases Where IEFaSa(0.2)

Cases Where IEFvSa(1.0)


 

 

 

<0.2

≥0.2 to <0.35

≥0.35 to ≤0.75

>0.75

>0.3


Steel Structures Designed and Detailed According to CAN/CSA-S16


Ductile moment-resisting frames

5.0

1.5

NL

NL

NL

NL

NL


Moderately ductile moment-resisting frames

3.5

1.5

NL

NL

NL

NL

NL


Limited ductility moment-resisting frames

2.0

1.3

NL

NL

60

30

30


Moderately ductile concentrically braced frames

 

 

 

 

 

 

 


Non-chevron braces

3.0

1.3

NL

NL

40

40

40


Chevron braces

3.0

1.3

NL

NL

40

40

40


Tension only braces

3.0

1.3

NL

NL

20

20

20


Limited ductility concentrically braced frames

 

 

 

 

 

 

 


Non-chevron braces

2.0

1.3

NL

NL

60

60

60


Chevron braces

2.0

1.3

NL

NL

60

60

60


Tension only braces

2.0

1.3

NL

NL

40

40

40


Ductile eccentrically braced frames

4.0

1.5

NL

NL

NL

NL

NL


Ductile frame plate shear walls

5.0

1.6

NL

NL

NL

NL

NL


Moderately ductile plate shear walls

2

1.5

NL

NL

60

60

60


Conventional construction of moment frames, braced frames or shear walls

1.5

1.3

NL

NL

15

15

15


Other steel SFRS(s) not defined above

1.0

1.0

15

15

NP

NP

NP


Concrete Structures Designed and Detailed According to CSA A23.3


Ductile moment-resisting frames

4.0

1.7

NL

NL

NL

NL

NL


Moderately ductile moment-resisting frames

2.5

1.4

NL

NL

60

40

40


Ductile coupled walls

4.0

1.7

NL

NL

NL

NL

NL


Ductile partially coupled walls

3.5

1.7

NL

NL

NL

NL

NL


Ductile shear walls

3.5

1.6

NL

NL

NL

NL

NL


Moderately ductile shear walls

2.0

1.4

NL

NL

NL

60

60


Conventional construction Moment-resisting frames

1.5

1.3

NL

NL

15

NP

NP


Shear walls

1.5

1.3

NL

NL

40

30

30


Other concrete SFRS(s) not listed above

1.0

1.0

15

15

NP

NP

NP


Timber Structures Designed and Detailed According to CAN/CSA-O86


Shear walls

 

 

 

 

 

 

 


Nailed shear walls: wood-based panel

3.0

1.7

NL

NL

30

20

20


Shear walls: wood-based and gypsum panels in combination

2.0

1.7

NL

NL

20

20

20


Braced or moment-resisting frames with ductile connections

 

 

 

 

 

 

 


Moderately ductile

2.0

1.5

NL

NL

20

20

20


Limited ductility

1.5

1.5

NL

NL

15

15

15


Other wood-or gypsum-based SFRS(s) not listed above

1.0

1.0

15

15

NP

NP

NP


Masonry Structures Designed and Detailed According to CSA S304.1


Moderately ductile shear walls

2.0

1.5

NL

NL

60

40

40


Limited ductility shear walls

1.5

1.5

NL

NL

40

30

30


Conventional construction

 

 

 

 

 

 

 


Shear walls

1.5

1.5

NL

60

30

15

15


Moment-resisting frames

1.5

1.5

NL

30

NP

NP

NP


Unreinforced masonry

1.0

1.0

30

15

NP

NP

NP


Other masonry SFRS(s) not listed above

1.0

1.0

15

NP

NP

NP

NP