Hello,
I am running my steel design and seismic provisions in the Frame Module and I am getting an odd output for the beam design. I have BRB frames in a K-Brace configuration. When I click view/update I get the following output:
Beam Parameters
Story: Level 2 Frame No: 2 Member No: 36
Fy (ksi): 50.00 Size: W21X93
Frame Type: Buckling Restrained Braced Frame
F4.3 Non-V and Non-Inverted V-Braced Frame Unbalanced Forces
Beam must be designed for unbalanced brace axial horizontal force component on beam ends.
F4.5a Basic Requirements (D1.1 Highly Ductile) --- OK
Flange b/tf = 4.53 Limit = 7.22 OK
Web h/tw = 32.31 Limit = 35.88 OK
Note: Beam axial load from F4.3 Analysis not determined; Web h/tw limit assumed to be 1.49 sqrt(E/Fy).”
Verify brace properties with the brace manufacturer prior to finalizing structural design.
Is there a reason that RAM does not calculate the unbalanced brace axial horizontal force component on the beam? If so, is there a way to turn it on to design the beam for the axial load?