1. Idealized Model of Column Buckling in Frame Column Buckling in Frame
Rotational Spring stiffness K= 4EIb/Lb
Pcr
Pcr
Pcr
Idealized Model of Column Buckling in Frame
Column buckling
Column Buckling in Frame

2. Moment Resisting Frame
Braced Frame
Bracing Member
Unstable Frame
Moment Resisting Frame
Moment connection

3. 0< K  1.0 K = 1.0 0< K < 1.0 1  K <  2.0  K
Pcr
Pcr
Pcr
Pcr
Columns in Braced Frames have
0< K  1.0
Buckling of columns in braced frames with pin connections at ends
Buckling of columns in braced frames with moment connections at ends
K = 1.0
0< K < 1.0
Pcr
Pcr
Pcr
Pcr
Columns in Sway Frames have
1  K < 
Buckling of columns in moment resisting frames with pin connections at one end
Buckling of columns in moment resisting frames with moment connections at both ends
2.0  K
1.0  K  2.0

4. Buckling of Unbraced or Sway Frames Buckling of Braced Frames
Pcr
Substructure
Substructure

6. 10 ft.
12 ft.
15 ft.
20 ft.
18 ft.
W14 x 68 B A
W12 x 79
Ky = 1.0

7. 12 ft.
15 ft.
W14 x 74 B A
W12 x 79
20 ft.
18 ft.
Kx = 2.0
Best Case Scenario
from Pg