Flange Local Buckling 2.3 2002/07/29 2003/07/25 10:04:34 GMT-5 Michael Terk terk@rice.edu Joanna Gonzalez joannag@owlnet.rice.edu Michael Terk terk@rice.edu Jeffrey Silverman jsilv@rice.edu beam buckling flange limit state local (Blank Abstract)

Introduction to Flange Local Buckling The fourth limit state for beams is Flange Local Buckling, or FLB for short. It is exactly the same as Web Local Buckling, except the width-thickness ratio is in terms of the flange and not the web. This type of buckling occurs when the width-thickness ratio is not large enough to withstand the moment on the beam. The way to prevent this type of buckling is to limit the with-thickness ratio. The limits can be computed for flange local buckling. The width-thickness ratio is compared to λ p and λ r . Then the maximum moment can be calculated.

Equations to determine FLB

The graph illustrates the options for FLB

When, b t λ p there is no FLB and the cross section is compact because, M n M p M p F y Z 1.5 M y from the yielding state. When, λ p b t λ r the graph is linear, and therefore a linear interpolation between M p and M y is used for the maximum moment. And finally, when b t λ r the graph is non-linear, the flange is non-slender, and there is an equation to find the maximum moment in Appendix F of the Specification section of the Manual (page 16.1-96).