I am modeling a steel building with braced frame (OBF). I want the braces to carry lateral loads only and not the gravity loads. How can I do that?
This can be achieved by making the bracing members inactive for the gravity load cases and re-activating them for the lateral load cases. The INACTIVE specification for beam members is available within General > Spec page. You can find more details on inactive specification within section 5.18 of the technical reference manual. There is also an example 4, demonstrating how to use the INACTIVE specification, which can be found within Help > Contents > Application Examples. The corresponding .std file is provided with the software and can be found within the folder X:\SProV8i\STAAD\Examp\US where X represents the drive in which STAAD is installed.