I have attached a staad model that is a continuous beam with external moments placed at the nodes. The beam is on pinned supports. My issue is that the torsion created by the external moments does not seem to make sense. Can someone please help me? Thank you!
Catherine
This system isn't stable for rotation about the beam axis (global X), since there is no resitance to Rotation about X at any point in the system. You would need to provide some sort of support or spring to resist rotation somewhere in the model to get valid results.
Some realted wiki:
communities.bentley.com/.../3038.aspx
communities.bentley.com/.../2046.aspx
Answer Verified By: Catherine Stanley
You have applied moments at pinned supports. As the pinned supports are not capable to absorbing a moment, it renders the structure unstable.
If you look at the displacements and rotations for load case 2, you will find large values at the nodes. This is another manifestation of the instability.