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, S_{a} is determined automatically according to Section 12.9.1.2.
According to the structural system type, using the R, C_{d} and Ω_{o} coefficients obtained from Table 12.2-1, R/I_{e }and the reduced design spectral acceleration are calculated automatically.
Symbols
C_{d} = Deflection amplification factor
I_{e}= Seismic importance factor
R = Response modification coefficient
The reduced design spectral acceleration S_{a}, 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 S_{a} 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 I_{e}.
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 S_{a} 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 T_{0 }.
_{ }
It’s equal S_{DS } from T_{0 }to T_{s }._{ }
It’s determined with the equation 11.4-6 from T_{s} to T_{L }._{ }
It’s determined with the equation 11.4-7 for periods greater than T_{L}._{ }
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, Ω_{o} | Deflection Amplification Factor, C_{d} | Structural System Limitations Including Structural Height, h_{n} (ft) Limits | ||||
---|---|---|---|---|---|---|---|---|
Seismic Design Category | ||||||||
B | C | D | E | F | ||||
A. Bearing Wall Systems | ||||||||
A1 - Special reinforced concrete shear walls | 5 | 2^{1/2} | 5 | NL | NL | 160 | 160 | 100 |
A2 - Ordinary reinforced concrete shear walls | 4 | 2^{1/2} | 4 | NL | NL | NP | NP | NP |
A3 - Detailed plain concrete shear walls | 2 | 2^{1/2} | 2 | NL | NP | NP | NP | NP |
A4 - Ordinary plain concrete shear walls | 1^{1/2} | 2^{1/2} | 1^{1/2} | 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 | 3^{1/4} | 2 | 3^{1/4} | NL | NL | 35 | 35 | NP |
B4 - Special reinforced concrete shear walls | 6 | 2^{1/2} | 5 | NL | NL | 160 | 160 | 100 |
B5 - Ordinary reinforced concrete shear walls | 5 | 2^{1/2} | 4^{1/2} | NL | NL | NP | NP | NP |
B6 - Detailed plain concrete shear walls | 2 | 2^{1/2} | 2 | NL | NP | NP | NP | NP |
B7 - Ordinary plain concrete shear walls | 1^{1/2} | 2^{1/2} | 1^{1/2} | NL | NP | NP | NP | NP |
C. Moment-Resisting Frame Systems | ||||||||
C1 - Steel special moment frames | 8 | 3 | 5^{1/2} | NL | NL | NL | NL | NL |
C2 - Steel special truss moment frames | 7 | 3 | 5^{1/2} | NL | NL | 160 | 100 | NP |
C3 - Steel intermediate moment frames | 4^{1/2} | 3 | 4 | NL | NL | 35 | NP | NP |
C4 - Steel ordinary moment frames | 3^{1/2} | 3 | 3 | NL | NL | NP | NP | NP |
C5 - Special reinforced concrete moment frames | 8 | 3 | 5^{1/2} | NL | NL | NL | NL | NL |
C6 - Intermediate reinforced concrete moment frames | 5 | 3 | 4^{1/2} | NL | NL | NP | NP | NP |
C7 - Ordinary reinforced concrete moment frames | 3 | 3 | 2^{1/2} | 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 | 2^{1/2} | 4 | NL | NL | NL | NL | NL |
D2 - Steel special concentrically braced frames | 7 | 2^{1/2} | 5^{1/2} | NL | NL | NL | NL | NL |
D3 - Special reinforced concrete shear walls | 7 | 2^{1/2} | 5^{1/2} | NL | NL | NL | NL | NL |
D4 - Ordinary reinforced concrete shear walls | 6 | 2^{1/2} | 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 | 2^{1/2} | 5 | NL | NL | 35 | NP | NP |
E2 - Special reinforced concrete shear walls | 6^{1/2} | 2^{1/2} | 5 | NL | NL | 160 | 100 | 100 |
E8 - Ordinary reinforced concrete shear walls | 5^{1/2} | 2^{1/2} | 4^{1/2} | 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 | 4^{1/2} | 2^{1/2} | 4 | NL | NP | NP | NP | NP |
G. Cantilevered Column Systems Detailed to Conform to the Requirement for | ||||||||
G1 - Steel special cantilever column systems | 2^{1/2} | 1^{1/4} | 2^{1/2} | 35 | 35 | 35 | 35 | 35 |
G2 - Steel ordinary cantilever column systems | 1^{1/4} | 1^{1/4} | 1^{1/4} | 35 | 35 | NP | NP | NP |
G3 - Special reinforced concrete moment frames | 2^{1/2} | 1^{1/4} | 2^{1/2} | 35 | 35 | 35 | 35 | 35 |
G4 - Intermediate reinforced concrete moment frames | 1^{1/2} | 1^{1/4} | 1^{1/2} | 35 | 35 | NP | NP | NP |
G5 - Ordinary reinforced concrete moment frames | 1 | 1^{1/4} | 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 |