Ashwin
You should clarify whether girder is located e.g. in a Building or Bridge or any other structure e.g. industrial building to support equipment load. If you have a drawing/ skech which shows ocation of girder then that will be help.
For a building, assuming concrete floor, you should take dead loads of floor slab, floor screed, plaster, ceiling, services e.g fire fighting etc. & self weight of girder together with any other load e.g from secondary beams. In addition to above you need to take wall loads, if any. Live loads should be in accordance with the recommendations of the Code of Practice you are using.
For a Bridge, assuming concrete deck, you should take dead loads of Deck slab, Asphalt concrete or similar surfacing, services, parapets / guard rails, pedestrian walkways, self weight of girder together with any other load e.g from secondary beams. Live loads should be in accordance with the recommendations of the Code of Practice you are using.
In case girder is used for industrial building to support an equipment then the live loads from equipment have to be taken as per Equipment Supplier's recommendations.
Regards
Shashank N Pendharkar