Individual Component Buckling

In this option, the effective length of an element or a chain of compressive Beam elements in a structure can be estimated. Elements specified should not be Bars or Struts. This is useful for estimating the degree of restraint offered by the whole structure under a particular load condition. This is particularly relevant to nonlinear structures where the degree of restraint offered by ties and cables varies with load case.

The program analyses the structure with 100% imposed loads. This is called the first step analysis. If this converges, the structure is well conditioned; the number of cycles required for convergence under applied loads is stored as a measure of the stability of the structure. The program stores the equilibrium element forces and adds a small moment to the member under investigation. (Buckling will not occur without a small disturbance to the member)

The next step is to reanalyse with the resultant element forces and imposed loads from the initial analysis but with a factored axial force in the member under consideration. This is repeated until the member in question buckles.

Buckling is deemed to occur when the analysis fails to converge within 5 times the number of cycles that achieved the convergence in the first step analysis. If snap through occurs in the analysis, the buckling load will not be given directly by the analysis, but the buckling load can be found out by plotting load–deflection curve using the data given in the report view. If a load deflection curve is not output, check the results carefully.