Fin Buckling - Australian Code AS1288

[maramos]

Anyone know how to interpret table C1 in appendix C of AS1288 "COEFFICIENTS FOR SLENDERNESS FACTOR"

More specifically how to choose the right moment parameter (beta)on the attached table.

Need to choose the appropriate g1 factor but don't know if the moment parameter (beta) should be 1,0.5,0,-0.5 or -1.

I'm designing a single span glass fin with an intermediate buckling restraint.

 

[hokie66]

Beta is just the ratio of bending moments at the two locations which are restrained against buckling. For a simple span restrained in the middle, the moment at one end would be zero and maximum at midspan, so Beta is 0.0.

 

[maramos]

hokie66
so in same scenario as above but with two buckling restraints equally spaced the beta value would be 1.0? same would apply if 3,4,5 equally spaced restraints where present as restraints near max moment would govern. Correct?

Lastly when due the negative beta values come into play?
In negative loading?

Thanks for your quick reply

 

[hokie66]

maramos,
The code is not specific for conditions where the moment curve is not linear. So for two restraints and point loads at those locations, Beta in the central section would be 1.0. If uniformly loaded, Beta would perhaps be a bit greater than 1.0, but since the table doesn't go any higher, you are probably justified in using 1.0. Same logic for additional restraints.

Negative values would apply when a member is in double curvature between restraints, e.g. with fixed ends. The signs of the moment would be different, so the ratio is negative. But again, when the sign changes and changes back before the next restraint, you are left to interpret.

Take this with a grain of salt, as I am not an expert in glass design. Just trying to help interpret this provision.