Pretension

Hi all,

I’m trying to make a small model to show how pretension is working. For this I made a bolt and fixed it on both sides with DOF1-6 and added one pretension in the middle of the bolt. But it shows me deflection by 10^5. I expected a positive and a negative defection since the nodes at the spoint are copied an overlapped. Where is my error I reasoning?

Thanks!

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