Table Colombia 1
Structural Systems Permitted and Values of R and Cd

Structural System

Lateral Load- 
Resisting System

Note

Material
Design
Requirements
(Chapters)

Seismic Risk Zone

Low

Intermediate

High

R

Cd

R

Cd

R

Cd

Frame

Reinforced concrete unbraced frames
— High ductility
— Moderate ductility
— Low ductility

 

(1)
(2)
(3)

C.21
C.20
C.1 to C.19

 6.0
4.0
2.0		 5.0
3.5
2.0		 6.0
4.0
N.P.		 5.0
3.5
N.P.		 6.0
N.P.
N.P.		 5.0
N.P.
N.P.

Structural steel frames

 (4) Title F 4.5 4.0 4.5 4.0 4.5 4.0

Structural Walls

Reinforced concrete walls
— High ductility
— Low ductility

  

(1)
(3)

C.21
C.1 to C.19

 5.0
4.0		 4.5
3.5		 5.0
4.0		 4.5
3.5		 5.0
N.P.		 4.5
N.P.

Reinforced concrete braced frames
— High ductility
— Moderate ductility
— Low ductility

  

(1)
(2)
(3)

 C.21
C.20
C.1 to C.19		 4.5
3.5
2.0		 4.0
3.0
2.0		 4.5
3.5
N.P.		 4.0
3.0
N.P.		 4.5
3.0
N.P.		 4.0
N.P.
N.P.

Unreinforced masonry

 (5) D.4 1.0 1.0 N.P. N.P. N.P. N.P.

Partially reinforced masonry

 (6) D.5 2.0 2.0 2.0 2.0 N.P. N.P.

Reinforced masonry

 (6) D.6 3.5 3.0 3.5 3.0 3.5 3.0

Confined masonry
— With internal reinforcement
— Without internal reinforcement

  

(7)

(7)

 D.7

D.7		 2.5

1.5		 2.5

1.5		 2.5

1.5		 2.5

1.5		 2.5

1.5		 2.5

1.5

Dual System

Reinforced concrete wall
— High ductility
— Low ductility
(1)
(3)
C.21
C.1 to C.19		 7.0
5.0		 6.0
4.5		 7.0
5.0		 6.0
4.5		 7.0
N.P.		 6.0
N.P.

Reinforced concrete braced frames
— High ductility
— Moderate ductility
— Low ductility

  

(1)
(2)
(3)

  

C.21
C.20
C.1 to C.19

  

5.0
4.0
2.0

  

4.5
3.5
2.0

  

5.0
4.0
N.P.

  

4.5
3.5
N.P.

  

5.0
N.P.
N.P.

  

4.5
N.P.
N.P.

Partially reinforced masonry walls

 (6) D.5 3.0 3.0 N.P. N.P. N.P. N.P.

Reinforced masonry walls

 (6) D.6 4.5 4.0 4.5 4.0 5.5 5.0

 

Notes:
NP. = Not Permitted
(1) Chapter C. 21 is based on Appendix A of ACI 318-83 and is equivalent to Chapter 21 of ACI 318-89. These structures must also comply with the reinforced concrete requirements of Chapters C.1 to C.19.
(2) Chapter C.20 is based on Section A.9 of Appendix A of ACI 318-83 and is equivalent to Section 21.9 of ACI 318-89. These structures must also comply with the reinforced concrete requirements of Chapters C.1 to C.19.
(3) Chapter C.1 to C.19 is based on Chapters 1 to 19 of ACI 318-83.
(4) Title F of the Code is based on the AISC Specifications.
(5) Unreinforced masonry is permitted only in those parts of zones of Low seismic risk where Aa and Av are both less than 0.05.
(6) Chapters D.5 and D.6 cover reinforced masonry made out of hollow concrete block and hollow clay brick, in which the reinforcement is grouted within the vertical cells. The only difference between Chapter D.5 and Chapter D.6 is that the latter requires higher reinforcement ratios.
(7) Confined Mason consists of a masonry wall that carries the vertical loads and is surrounded by a light reinforced concrete frame that confines the masonry and gives strength for lateral loads. ‘The light concrete Frame is cast alter he wall is built. The concrete frame elements have longitudinal and transverse reinforcement. The masonry wall can be built with or without internal reinforcement.