Top and Bot Moment happened at same location under same load case (DL)

[wpllamto]

Dear all

A simple model has been built up which is:
1) 15m(Length) x 5m (width) with 2m thk slab
2) two point (pinned) supports assigned.(see attached)
3) one point load with only DL=10000kN.(See attached)
4) two inclined tie beams (as line element) assigned.

After running the R.C. design, both top and bot moment happened in one of the Y-Y strip.

I wonder where do the bot moment come from??

Thanks!!

WPLLAM