Acceleration for FBE and DBE

[wuhaoshrek]

Hi, I have been confused with the acceleration results using force based (FBE) beam column elements. I used a simple 2D one story one bay frame model for validation. Both the column and beam elements are elastic. For the beam element I used the following options: 1. elatsic beam column element, 2. FBE with elatsic section, 3. FBE with fiber section assgining each fiber with elastic material, 4. DBE with elatsic section and 5. DBE with fiber section assgining each fiber with elastic material.

For the acceleration results, the resuls of DBE and elatsic element are identical. However the results from FBE are different than the others. It seems to me that the axial stiffness of FBE is different than the others. Anybody knows what's the problem behind this? thanks a lot.

[selimgunay]

Could you tell the periods of your five models?