Combining tension-only and ten-comp bracing

[Andrewstructure]

Is there any rule about combining tension-only and ten-comp bracing?

I would normally ignore the tension only bracing if it were rods, but now I have L5x4x5/16 angles.

(please include a reference if possible)

 

[amecENG]

Do you mean:

Analyzing an existing tension only bracing system as a tension/compression system?

OR

Analyzing a structure that has both tension only bracing and tension/compression bracing?

In either case, there are no code restrictions about combining lateral load resisting systems only that your assumption would effect your overstrength and ductility factors (Ro & Rd in NBCC2005) for seismic design and would have a large effect on capacity design.

 

[Andrewstructure]

I mean:

Analyzing a structure that has both tension only bracing and
tension/compression bracing.

More specifically, adding t/c bracing to an existing structure that only has tension only bracing.

 

[rb1957]

if you're not changing the loads (ie upgrading the structure) then what's the problem ? ... it sounds like you're replacing some rods (tension only) with angles (which have some compression capability but this was not considered in the original analysis). wouldn't the additional compression capability "merely" provide more loadpaths than the original structure, which should make it "better".