Removing X-Bracing for New Doorway

[Genie0501]

Hello!

I'm looking for some conceptual ideas about removing existing steel cross bracing in a steel-framed 2-story space. The bracing was buried in an existing wall that the architect wants to put a new door through (of course - the door absolutely has to go in that location). Obviously, we'll run numbers on whatever approach we decide to take but we're looking for some conceptual ideas on how to handle this condition. Relocating the brace to the adjacent bay is not ideal because significant asbestos remediation is required to remove the masonry - although I acknowledge this may be the best/most cost effective option. Does anyone else have experience with this and can offer some ideas on how to move the lateral support?

Thanks in advance!

 

[DaveAtkins]

First, I would check if the building is stable without the bracing. Perhaps there is enough bracing in other parts of the building to pick up the additional lateral load.

If this doesn't work, consider using knee braces to create a moment frame where the cross bracing is removed.

DaveAtkins

 

[MotorCity]

Create a shearwall or partial shearwall + drag strut within the bay?

 

[EngineerEIT]

Assuming you aren't in a seismic area. Look at replacing the braces with a chevron brace and put door in the middle of the bay. Or try a single brace if the door needs to go towards the end of the bay.

 

[msquared48]

Or position the door to one side of the bay and reattach one end of the X brace to a location near the door jamb.

Mike McCann, PE, SE (WA)

 

[msquared48]

Is this building a PEMB with mainframes and rod bracing in the side or endwalls, or metal building with larger angle, pipe or tube cross bracing, possibly special in design?

If it is the latter, push back and say no. Move the door.

Mike McCann, PE, SE (WA)

 

[hokie66]

Sometimes, it makes sense to replace cross bracing with a moment frame. This can replace the lost strength, but is usually less stiff.

 

[oldestguy]

Will the masonry in the wall do the job? Many times things like new walls which were not there originally, but later, provide resistance needed.

 

[structSU10]

Yeah, be careful with replacing it with something less stiff. To keep it as simple as possible, I have always replaced it with something of the same stiffness if possible, so the other braces within the building will see the same load. Most of the time, a moment frame would not attract nearly the load that was originally there if the other building bracing is braced frames, and you could overload them.