How to mesh this concrete slab with embedded loop

This is a concrete slab with embedded loop. I don't want to use the free tetrahedral to mesh this model since the result is not as accurate as quad element do if the order of the shape function is the same according to the finite element method. So I am writing this email to ask whether there is a reasonable solution to this model?

Thanks for your help!

Sincerely,

Jiaxing