Philosophy of Lateral Bracing
Philosophy of Lateral Bracing
(OP)
Hi guys, steel frame grasshopper here.
I am doing some design for a tower concept and I am wondering whether either of these bracing patterns is better or more conventional than the other. One has the bracing symmetric in the bays. The other has the bracing spiral.
I have the same types of questions when setting diagonal webs on trusses. I know there are famous "named" truss styles but what are the benefits of each? As long as the truss/frame is stable and has the desired redundancy/indeterminacy what difference should it make to the analysis?
Thanks in advance
I am doing some design for a tower concept and I am wondering whether either of these bracing patterns is better or more conventional than the other. One has the bracing symmetric in the bays. The other has the bracing spiral.
I have the same types of questions when setting diagonal webs on trusses. I know there are famous "named" truss styles but what are the benefits of each? As long as the truss/frame is stable and has the desired redundancy/indeterminacy what difference should it make to the analysis?
Thanks in advance






RE: Philosophy of Lateral Bracing
In regards to the truss styles. Again, from an analysis stand point some trusses are a little easier to design by hand than others. Where the benefit comes in is with the design of the web members and the material required resist the forces in the truss. A member will resist more load in tension than compression (due to buckling). Also, some trusses may be more acceptable than others architecturally.
Others may have more opinions and this is just my $0.02
RE: Philosophy of Lateral Bracing
BA
RE: Philosophy of Lateral Bracing
Quando Omni Flunkus Moritati
RE: Philosophy of Lateral Bracing
What if the braces were completely random? I suppose that could result in irregular load concentrations for a very tall slender structure, but that should still show up in the frame analysis and be accounted for in the member sizing and connection design I think. As BAR says...not efficient or simple...but still functional I believe.
RE: Philosophy of Lateral Bracing
Usually multiple member connections all at one point where they would geometrically conflict with each other causes problems with detailing, design and cost.
(also note that you are missing a brace between levels 3 and 4 on the Right Hand example.)
RE: Philosophy of Lateral Bracing
I also agree with BAretired, that economy usually control design.
Personally I would use a bracing layout that is symmetric, with the braces on opposite sides of walls oriented the same. While the elongation or shrinkage on opposite’s side would be the same for the same loads and member sizes, compression members would also experience some amount of buckling (hence the stricter requirement of slenderness ratio for compression members.) With an un-symmetric layout, where the brace on one wall is in tension and the other in compression, I assume there could be torsion induced into the building.
Eric McDonald, PE
McDonald Structural Engineering, PLLC
RE: Philosophy of Lateral Bracing
RE: Philosophy of Lateral Bracing
I think your spiral bracing scheme on a tall slender tower will lead to some unintended torsional problems, whereas those unsymmetrical conditions might be easier to deal with on a lower huskier structure. Look at the design of any existing type of tower, those aren’t designed and detailed that way to be clever. Time and experience has proven that to be a fairly efficient way to do it. So, you better have a reason for trying to reinvent the wheel.
RE: Philosophy of Lateral Bracing