Brace Loads

[L17Aurora]

Could I roughly calc a brace compression load by splitting the beam in two & treating the brace end as an end support & resolving for the angled load. Or do you steelwork guys use another formulae for finding brace loads?
As a seperate question, what is the effective length of beam under the loads. I would guess if the brace is strong enough then L is the distance between the end support & the point where the brace hits the beam?
Cheers

 

[csd72]

These braces are installed for lateral loads not vertical. Also if this is in a seismic zone then the brace configuration needs to be designed for ductility, energy dissipation and have sufficient buckling restraint in order to achieve plastic hinge capacity.

This seismic stuff is mostly above my head and I would say way above your level of structural knowledge.

Effective length is complicated on this and could be longer than the actual length depending on how restrained the beam is.

 

[ishvaaag]

It will be better and almost as maybe even quicker to make a model in a program. Include P-Delta and then assume K=1 between nodes.

P-Delta analysis brings the structure to a stable deformed state as if nodes are prevented of further lateral movement, i.e., a non-sway braced state, so K=1 is safe.

All this assuming forces standing in the section do not require axial and bending stiffess degradation to properly account for material nonlinearities, in which case such degradation should be considered with properly corrected input data.

 

[csd72]

ishvaaag,

Only problem is the effect of out of plane buckling if it is analysed as a plane frame. Just remember that the OP is an ME not an SE.

 

[L17Aurora]

hey, hey, hey. Remember I'm a mechanical boy not a steelwork guru. I only wanted simple answers. AH! just spotted the OP is an ME - EXCELLENT
cds72, your original answer satisfies me.
Thanks