ASTM A615 Grade 60 is the standard reinforcing steel for structural concrete in North America. Available sizes: #3 (3/8 dia) through #18 (2.257 dia), with #4-#11 most common. Properties: yield strength 60 ksi, tensile 90 ksi minimum. Bar markings identify producing mill, bar size, steel type (S for carbon), and grade (4 for Grade 60). Splice lengths per ACI 318 Table 10.7.1.2 — typically 48-60 bar diameters for tension splices. Cover requirements: 3 inches for concrete exposed to earth, 1.5 inches for beams/columns not exposed, 0.75 inches for slabs. Epoxy-coated (ASTM A775) required in corrosive environments and bridge decks. Stainless steel (ASTM A955) for extreme durability. Welding requires A706 weldable grade, not A615.