unexpected weak axis moment and deformation

Question:

Hello,


I am getting some unexpected weak axis moment/deformations from my model attached from pretty much every single loadcase. Could you please help me do a quick diagnosis on what might be the causes of these? 


Model is attached for reference.


Thanks,





Answer:

Hello,

The main reason for the obtained weak axis moment is the transverse connectivity of girders.  The substructure stiffness also affects the rotations in girders and thus these deformations.  Kindly have a look at the image below.
When the substructure is removed and only transverse members are kept, then this behaviour is noted only near the edge of the structure.  For the girder with doesn't have any transverse connectivity, this deformation and moment is not obtained.  As such, the structural modelling is proper and the moments would be obtained, unless construction stages are introduced.  With construction stages, these deformations and moments would be obtained only after the transverse elements are activated.
Kindly let us know if further assistance would be required.

Regards,
Nandeep
Technical Manager, MIDAS
Creation date: 10/17/2018 9:44 PM (dklee@midasit.com)      Updated: 10/18/2018 7:15 AM (dklee@midasit.com)
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spread footing V8 3.05 spacing single pier.mcb