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 C_d 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
h_n = 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, C_d, 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, h_n.

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, 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