I believe what you're looking for is "chemical anchor". It's a type of epoxy that's made for putting steel rods into concrete, forever.

Depending on your brackets and how much space there is inside the shelves, best would be to use chemical anchor to stick threaded rod into the holes, wait for it to cure, and then screw on the shelf brackets with nuts onto the threaded rod.

Edit: Forgot to add - the longer you can make your anchor the better. 6 inches if you can :)