huangyhg

analysis model
i have an analysis model composed of bracings,beams and columns.
when i have verical loads only applied to my structure, i find the axial forces in bracing (in some of them) greater than the columns connected to it.
what could be the reason?
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could be one of several reasons. if you have an animation feature in your software, animate the model and see if it reacts as you expect.
next look at nodal restraints. you might have some restraint conditions that are not correct.
what type of software are you using?
is this a chevron braced frame? if so, then the natural load path will go through the braced frames rather than through beam flexure. that's why the seismic codes tell you to analyze / design the beams as if the braced frames were not present.
if this isn't a chevron, then is it possible that the axial stiffness of the brace (ae/l) is greater than the axial stiffness of the column?
no axial stiffness of the brace is not greater than axial stiffness of the column.both have same area but the brace is longer than the column.

atee01,
we need more info, a sketch maybe?
it sounds like you have a full building model, or at least a model with multiple frames and columns.
pull out one braced frame with only its nodal loads. you should be able to manually compute the brace and column loads or at least estimate them. also, at least you'll have an easier model to let you zero in on the problem.
this kind of exercise should be one of the *first* steps when the program seems to have done something weird.
i know that when i use ram structural system, we design the gravity framing first, using gravity loads only. then enable the ram frame module. what i'm trying to say is that by the time i'm on my lateral analysis, the gravity design is pretty close to complete, save for any iteration coming from ram frame. but generally if you are just analyzing vertical loads, i'd not include braces for the intial sizing of your
hi--here is a picture--can anyone advise now?
check sshield's response, it make sense to me - take out the diagonals for gravity load analysis, and make sure your model is stable under such load.
again, yank out one of the braced frames into a model by itself and see what happens.
i removed the bracings and checked that the frame remains stable.
the compressive force in the column (the column which has less axial force in the presence of bracing) without bracing was 7.89 kn
when, i put all the bracings the compressive force in that columns was 3.5 kn and in the brace was 8.5 kn?
any thoughts?

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