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# Design Response Spectrum for Horizontal Earthquake Effects per ASCE 7-16 with ideCAD

How does ideCAD define design response spectrum, according to ASCE 7-16?

• By using the parameters determined in Table 12.2-1 and 11.5.1, the Reduced Design Spectral acceleration, Sa is determined automatically according to Section 12.9.1.2.

• According to the structural system type, using the R, Cd and Ωo coefficients obtained from Table 12.2-1, R/Ie and the reduced design spectral acceleration are calculated automatically.

Symbols

Cd = Deflection amplification factor
Ie= Seismic importance factor
R = Response modification coefficient

The reduced design spectral acceleration Sa, which is the ordinate of the reduced design acceleration spectrum for a given natural vibration period T, used to determine the reduced seismic loads in the horizontal direction, is that of Sa Design Response Spectrum., is obtained by dividing the R, Reduced Design Response Spectrum for Modal Analysis per ASCE 7-16 §12.9.1.2 and multiply with Ie.

On the Analysis ASCE 7-16 Wizard - Design Spectra tab, the spectral acceleration coefficients obtained from USGB based on the coordinates and the horizontal elastic design spectrum Sa is calculated according to the formula below. Design Response Spectrum. is represented by a total of 4 functions, different in each region, and shown in the function below.

• It’s determined with the equation 11.4-5 from T=0 to T0 .

• It’s equal SDS from T0 to Ts .

• It’s determined with the equation 11.4-6 from Ts to TL .

• It’s determined with the equation 11.4-7 for periods greater than TL.

In the Analysis Settings - Response Spectrum Function tab, the horizontal design spectrum is determined and shown using the design spectral response acceleration parameters.

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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