Modelling beam - solid element connection for lateral loading analysis

[MekGreek]

Hi OpenSees Community.

I've built a model which rapresent a wind turbine tower with beneath a shallow conical foundation. The tower is modelled with Timoshenko beams (about 15 elements for 5meters lenght) and the foundation with SSPbrick elements. The software has properly written the equal dof condition between the end node of the beam element in contact with the foundation and the node of the solid element of the latter.
Applying a vertical load the analysis works and converges but in the interval after applying a lateral load at the top of the tower the analysis does not converge, does not crash but the test does not go under tollerance and gives really high delta.

What is the problem according to you? Should I have to introduce some other conditions for a lateral loading analysis?

I'd be really grateful for your help!