289,580. Tann, Ltd., J., and Tann, J. L. Feb. 15, 1927. Reinforced-concrete walls, floors, and roofs.- The concrete walls, floors, and roofs of safes and strong rooms are reinforced with sheets of mesh metal bent into deep S-shaped corrugations a or into U-shapes alternately inverted and overlapping. all closely arranged and approximately as deep as the thickness of the wall. The sheets are connected by hook bolts b.