# Structural Systems in Different Directions per ASCE 7-16 with ideCAD

How ideCAD defines structural systems for two earthquake directions according to ASCE 7-16?

• The ductility levels of the structural systems in perpendicular directions cannot be chosen differently. They must be the same. It is controlled automatically.

• Different responce modification coeffricients, R can be used in perpendicular directions.

• The values for R, Ω0, and Cd at structural systems in Table 12.2-1 are chosen for structural steel and reinforced concrete systems by the user.

SYMBOLS
R = Response modification coefficient
hn = Structural height

#### 12.2.2 Combinations of Framing Systems in Different Directions

It is allowed to use different seismic-force resisting systems to resist seismic forces along the two orthogonal axes of the structure. Where different systems are used, the R, Cd, and Ω0 coefficients apply to each system, including the structural system limitations contained in Table 12.2-1.

Depending on the structural systems selected, one of the two systems may limit the extent of the overall system with regard to structural system limitations or structural height, hn.

With the ASCE 7-16 Wizard, the ductility levels of the structural systems in perpendicular directions are selected the same. Different seismic force-resisting systems can be used along each of the two orthogonal axes of the structure. As can be seen in the picture below, there are structural system options with special frame systems in Table 12.2-1 on the R coefficient selection screen of a structure with special frame systems.

Structural System Type

Response Modification Coefficient, R

Overstrengh Factor, Ωo

Deflection Amplification Factor, Cd

Structural System Limitations Including Structural Height, hn (ft) Limits

Seismic Design Category

B

C

D

E

F

A. Bearing Wall Systems

A1 - Special reinforced concrete shear walls

5

21/2

5

NL

NL

160

160

100

A2 - Ordinary reinforced concrete shear walls

4

21/2

4

NL

NL

NP

NP

NP

A3 - Detailed plain concrete shear walls

2

21/2

2

NL

NP

NP

NP

NP

A4 - Ordinary plain concrete shear walls

11/2

21/2

11/2

NL

NP

NP

NP

NP

B. Building Frame Systems

B1 - Steel eccentrically braced frames

8

2

4

NL

NL

160

160

100

B2 - Steel special concentrically braced frames

6

2

5

NL

NL

160

160

100

B3 - Steel ordinary concentrically braced frames

31/4

2

31/4

NL

NL

35

35

NP

B4 - Special reinforced concrete shear walls

6

21/2

5

NL

NL

160

160

100

B5 - Ordinary reinforced concrete shear walls

5

21/2

41/2

NL

NL

NP

NP

NP

B6 - Detailed plain concrete shear walls

2

21/2

2

NL

NP

NP

NP

NP

B7 - Ordinary plain concrete shear walls

11/2

21/2

11/2

NL

NP

NP

NP

NP

C. Moment-Resisting Frame Systems

C1 - Steel special moment frames

8

3

51/2

NL

NL

NL

NL

NL

C2 - Steel special truss moment frames

7

3

51/2

NL

NL

160

100

NP

C3 - Steel intermediate moment frames

41/2

3

4

NL

NL

35

NP

NP

C4 - Steel ordinary moment frames

31/2

3

3

NL

NL

NP

NP

NP

C5 - Special reinforced concrete moment frames

8

3

51/2

NL

NL

NL

NL

NL

C6 - Intermediate reinforced concrete moment frames

5

3

41/2

NL

NL

NP

NP

NP

C7 - Ordinary reinforced concrete moment frames

3

3

21/2

NL

NP

NP

NP

NP

D. Dual Systems with Special Moment Frames Capable of Resisting at Least 25% of Prescribed Seismic Foces

D1 - Steel eccentrically braced frames

8

21/2

4

NL

NL

NL

NL

NL

D2 - Steel special concentrically braced frames

7

21/2

51/2

NL

NL

NL

NL

NL

D3 - Special reinforced concrete shear walls

7

21/2

51/2

NL

NL

NL

NL

NL

D4 - Ordinary reinforced concrete shear walls

6

21/2

5

NL

NL

NP

NP

NP

E. Dual Systems with Intermediate Moment Frames Capable of Resisting at Least 25% of Prescribed Seismic Foces

E1 - Steel special concentrically braced frames

6

21/2

5

NL

NL

35

NP

NP

E2 - Special reinforced concrete shear walls

61/2

21/2

5

NL

NL

160

100

100

E8 - Ordinary reinforced concrete shear walls

51/2

21/2

41/2

NL

NL

NP

NP

NP

F. Shear Wall-Frame Interactive System with Ordinary Reinforced Concrete Moment Frames And Ordinary Reinforced Concrete Shear Walls

F1 - Shear wall-frame interactive system

41/2

21/2

4

NL

NP

NP

NP

NP

G. Cantilevered Column Systems Detailed to Conform to the Requirement for

G1 - Steel special cantilever column systems

21/2

11/4

21/2

35

35

35

35

35

G2 - Steel ordinary cantilever column systems

11/4

11/4

11/4

35

35

NP

NP

NP

G3 - Special reinforced concrete moment frames

21/2

11/4

21/2

35

35

35

35

35

G4 - Intermediate reinforced concrete moment frames

11/2

11/4

11/2

35

35

NP

NP

NP

G5 - Ordinary reinforced concrete moment frames

1

11/4

1

35

NP

NP

NP

NP

H. Steel Systems not Specifically Detailed for Seismic Resistance, Excluding Cantilever Column Systems

H - Steel Systems not Specifically Detailed for Seismic Resistance

3

3

3

NL

NL

NP

NP

NP

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