AISC-ASD89 and sap 2000 out put

[sukocek]

i have a queestion about output of sap2000,
the nominal compression strenght is the minumum value obtained from flexural buckling,torsional buckling and fleaksual-torsional buckling.

my question is:where can I see valuse of flexural buckling,torsional buckling or flexual-torsional buckling . (how can i understand if i have a problem about flexural buckling,torsional buckling or flexual-torsional-buckling)

i use AISC-ASD89 and some times i get some alert
for example :fa>fe or kl/r>200 etc... can you expain all of those meaning.

i think answers of these question will be useful either forme and other sap 2000 users.

i will wait your answers.

have a good work

 

[CivilTanju]

Excerpted from AISC-ASD

Torsional buckling of symmetric shapes and flexural-torsional buckling of unsymmetric shapes are failure modes usually not considered in the design of hotrolled
columns. They generally do not govern or the critical load differs very little from the weak axis planar buckling load. Such buckling loads may, however, control the capacity of symmetric columns made from relatively thin
plate elements and of unsymmetric columns.

So, Even in AISC-ASD it refers to the LRFD E2-1 or E2-2 equations, where it leads you to slenderness ratio with which you can specify the critical load for flexural-torsional buckling check.

When it comes to the KI/r issue, it's been specified as limiting the slenderness ratio in ASD (B7) it preferably shouldn't exceed the 200. In the case that this limitation is violated, then calculated axial load (fa) shouldn't exceed the critical Euler buckling(Fe).

Hope that helps.

Civil-Eng