Hello Luay, do you use WB or APDL ?

You can use Static Structural or transient structural Analysis methods in ANSYS in which you can use thermal loads on the model

Hi,

Why do not you use COMSOL? it is much more user-friendly rather than ANSYS

For prestressed modal analysis, you need to use thermal (optional as per requirement) and static analysis output as input for modal analysis.

First prepare model with steady state thermal analysis with applying proper temparatures and then give output of this to static structural analysis in which you can use bolt pretension. After this give output of static structural analysis to modal analysis and solve.