Mechanics of Materials - Statically indeterminate axially loaded members thermal expansion example 2

Mechanics of Materials
Strength of Materials
Statically indeterminate axially loaded members with a temperature change
thermal expansion Like and subscribe! And get the notes here:

[legendj.a]

To know if the bolts/cylinder is on Tension or Compression: draw a FBD of the object alone it self after cutting it.

[alperenkurt]

how can't we consider that bolts are pushing (compressing) the plate from the top to bottom? how can be sure that they are in tension?