AMPLIFIED SEISMIC LOAD 4

[JPH.SE]

Hi to all, i'm looking for the correct interpretation of AISC 341-10 about the use of "amplified seismic load" in a SCBF system.

1. Make a model using the load combinations without Omega.
2. Once selected the required brace with the loads in item 1, make another model replacing the seismic load by the both cases indicated in AISC 341-10 F2.3 (i) and (ii) section, separately.
3. With this new cases, check the beam and column for the braced frame.

Then, the load cases with omega serve to determine the upper limit for the required resistance of the beam and column? or in which case do i have to use de load combinations with omega regarding to check of beam and columns in the braced frame?

Thanks in advance.

 

[sandman21]

AISC Video on the design of SCBF I recommend you watch the whole thing but the SCBF example starts at 45 mins

You have three cases to check. Capacity based, OmegaFp, and Post-buckling. The checks of F2.3 are localized not to the system. If I recall correctly case 1 controls for vertical loading on the connection, case 2 controls for load to the frame, and case 3 controls for the horizontal load. If you are designing the column you compare the results of the model with the requirements of F2.3. Do a free body diagram of the brace frame with the max tension force/max compression force, then max tension force/post-buckled compression force. Take the higher of the results

 

[OUe]

sandman21 is right. Capacity design should be used for the 1.1RyFyAg load to the column. Typically this will control over the Omega load - especially if adding multiple brace levels to a lower column.

 

[JPH.SE]

Omegafication, inertial and capacity forces are the 3 cases that we have to check into the frame that contain the braces. This also serve to design beams, columns and connectios.

Excellent!!!