WATER TANK TOP SLAB BEHAVIOUR

Hi ,

Please help me to sort out this issue.

Actually, I am modeling an underground rectangular water tank of 13m x 10m with top slab on it .

Top slab is supported on side walls and intermediate beams in between the slab.

After assigning all the loads, analysis done. Top slab is behaving as a  whole without considering the intermediate beams.(i.e. slab is spanning for whole length )

Hence the slab thickness arrived was very huge.

Please help me to sort out this issue.

regards

Varunkumar P