Why do SCI P292 and Amplified Moments Method Frame Stability Checks fail?
18
Tekla Portal Frame Designer
Environment
British Standard
For certain frame configurations these checks can be shown as Fail on the Design Summary because the elastic critical load factor is shown as 0.000.
This will occur when there is the unusual situation where a member is changing from being in tension to compression along its length. The program traps this situation out because the calculation would otherwise have to assume the member in one state or the other along its entire length, which would mean the answer could be either too conservative or too unconservative.
To check if this is the problem simply examine the axial force diagram for the combination in question.
This could be particularly relevant to portal frames in which there is a tie.
This will occur when there is the unusual situation where a member is changing from being in tension to compression along its length. The program traps this situation out because the calculation would otherwise have to assume the member in one state or the other along its entire length, which would mean the answer could be either too conservative or too unconservative.
To check if this is the problem simply examine the axial force diagram for the combination in question.
This could be particularly relevant to portal frames in which there is a tie.