Are there any elements or connections to describe the connection as a welded connection to perform non-linear analysis or i just have to give it as a bonded connection.
You got that right! A bonded contact is the closest option you can use on our platform. Taking into account hardening effects or effects on hardened steel let alone the welding techniques cannot be simulated (yet). Feel free to add your feature request here: SimScale - Feature Request Section. You can find some projects in the project library that deal with welding processes or heating welded areas.
Let me know if that helped and if you have any further questions!