Application of Deflection Amplification Factor per ASCE 7-16 §11.2.1

SYMBOLS

C_d = Deflection amplification factor
R = Response modification coefficient
I_e = Importance factor
δ_xe = Deflection

Deflection Amplification Factor, C_d, is defined in Table 12.2-1.

The application of the factor R/I_e to the design response spectrum reduces not only design forces but also displacements. To compensate for this, ASCE 7 requires that the deflections at level x at the center of mass, δ_x, be determined in accordance with where C_d is from Table 12.2-1, I_e and δ_xe. Using a value C_d equal to R would result in the displacement δ_x being equal to δ_xe, which would be consistent with the equal displacement rule.

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

Next Topic

https://idecad.atlassian.net/wiki/spaces/IKP/pages/1185448191

Related Topics