Dear Biswa

I don't think a 1.5 m depth is sufficient for a 75 m truss

As for your question, I don't see any problem, and since both the truss and the girder are simply supported, the pier will only be subjected to axial load. However, I think you need to pay a special attention to the joint between the truss and the girder due to thermal displacement considerations

Option 1: step the pier headstock - but you will need to make it look ok so talk to an architect

Option 2: create a higher position for the bearing by the use of a sort of stepped diaphragm - tricky, expensive, and still have problems making it look good.