Applies To
	Product(s):	STAAD.Pro
	Version(s):	ALL
	Environment:	ALL
	Area:	Analysis Solutions
	Subarea:	Buckling Analysis
	Original Author:	Sye Chakraborty, Bentley Technical Support Group

 

Buckling analysis results that I get using basic solver and advanced solver are different. For example the advanced solver reports some higher buckling factors and the analysis results corresponding to the buckling load ( displacements, reactions, member forces etc. ) also do not match between the two solvers. Can you please explain why ?

 

The difference is due to the fact that each solver has it’s own way of handling buckling analysis. The basic solver calculates buckling factor for just one mode whereas the advanced solver solves for 4 modes and the higher modes obviously would have higher buckling factors. Moreover the basic solver actually analyzes the structure for the load multiplied by the buckling load factor to give you the results for the buckling load case whereas advanced solver does not do that. For an advanced solver, if you want to look at the results at or near the buckling loads, you have to create a REPEAT LOAD case with the load case multiplied by the load factor ( which may be just smaller than the buckling load factor). You can then analyze the structure using a first order or a second order analysis to get the results at near buckling load.