Strange forces in bolts simulation question

Hi everybody

I created the attached screw joint to better understand the way SW computes connector forces.

I put an upward 10000N force applied to the upper face of the upper plate.

The lower plate has fixed geometry fixtures applied to 2 vertical faces.

There is a no penetration contact between the 2 plates.

Every bolt has 5000N axial preload.

After the simulation I expected 5000 + 10000/4  = 7500N force in every bolt but I got disappointed.

Can anybody clarify this problem to me?

Thanks

Maurizio

SolidworksSimulation