Dear Bikip,
1. the 1D bars only have axial stiffness and there is no way to represent lateral expansion = only expansion in axial direction can be considered.
2. Please see the ATENA Engineering 2D User's Manual, 4.6.8 Temperature. The document is included in ATENA installation and also available for separate download from our web (Products - ATENA - Documentation).
3. If you seek advice on modelling a particular setup, you can follow ATENA Troubleshooting, 2.1.1 to send us more information such that we can recommend a way.
Regards.