where element b31 and where b33

[nenia]

Hi,

I'm analysing a structure (a big truss) subjected to fire. An increase of temperature in the structure creates very large section forces, material looses its strength and so on. Additionally, large part of the structure is lateraly restrained to simulate interaction with remaining structure. Not sure if all this is relevant. The thing is that the program manages better with the problem when b33 elements are used instead of b31. My question is whether I can use the b33 elements and what difference it introduces to the solution.

Thanks,

nenia

 

[Drej]

If you RTFM:

B31 is a 2 node linear beam (single integration point per element)
B33 is a 2 node cubic beam (three integration points per element)

Hence, generally speaking for the same size mesh, B33 would give you more accurate stresses (the displacements between the two will be the same). B33 is also better suited to modelling "curved" structures because of its higher order integration scheme.


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