A nut and bolt fastens two perforated flat plates by threading fully into a nut on the opposing side of the plates. A threaded post, emanating from a flat, threaded into a complementarily threaded post hole cannot be equipped with strengthening features such as chamfers, fillets, or ribs because these devices block the strengthened threaded post from being fully threaded through perforated plates into a threaded posthole. The negative rib is a concavity spanning the orthogonal join between the post and the flat from which it emanates, and provides the same benefits that a regular rib provides, including discontinuity of join between post and flat, a variable distribution of forces amongst a more complex boundary area between post and flat, and the ability to increase the number, width, and depth of negative rib to achieve design objectives. The negative rib can also be decorated with fillets further strengthening the post against dehiscion from the flat to which it is attached.