Upvote:0
If you don't have a plan to go out of the airport in Sri Lanka, then you don't have to apply any visa.
Upvote:1
Since you have an US visa, you don't need a transit visa in frankfurt. Srilanka doesn't need transit visa anyways.
You can make this trip without any transit visa, provided it is same ticket and you do not plan to get out of the airport.