Shape an object using another one

Hi helpers,

I'm trying to create the letter D in the following design:

I would like to curve one of my blue bars so it follows an arc or circle that I would use as a guide. Is this possible? I think it is in Adobe Illustrator. The envelope tool is difficult to use for this and I can't find an easy way to do it.

The blue bars are really just rectangles with filleted corners and thick outlines. When I'm done, I will make the top of the arc overlap the straight bar of the D letter, and the bottom will lay underneath, to replicate the effect in the letter A.