Category

Description of Lat. Force Res. Systems

Value of R

A
1a
1b
2
3
4a
4b
5
6

Reinforced Concrete
Moment resistant frames without stiff masonry infill
Moment resistant frames with stiff masonry infill
Bearing shear walls
Central core
Mixed moment resistant frames/ shear walls with interaction
Frames braced by shear walls
Vertical cantilever with distributed masses
Inverted pendulum

5
3.5
3.5
3.5
5
4
2
2

B
7
8
9a
9b
10a
10b
11

Steel
Ductile moment resistant flames
Ordinary moment resistant flames
Structure braced by X triangulated elements
Structure braced by V triangulated elements
Mixed moment resisting frames/ X triangulated frames
Mixed moment resisting frames/ V triangulated frames
Vertical cantilever frames

6
4
4
3
5
4
2

C
12

Masonry
Bearing tied Masonry

2.5

D
13
14
15
16

17

Other Systems
Steel structure braced by diaphragm
Steel structure braced by reinforced concrete core
Steel structure braced by reinforced concrete shear walls
Steel structure with mixed bracing including a reinforced concrete core and steel braces or frames in façade
Systems including transparencies (soft stories)

2
3
3.5
4

2