This specification covers high-yield, quenched, and tempered alloy steel plates for use in welded bridges and other structures. Plates shall be subjected to heat treatment to conform to the tensile and hardness requirements for thickness, tensile strength, yield strength, elongation, reduction of area, and Brinell hardness. Heat and product analysis shall conform to the chemical requirements for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, vanadium, titanium, zirconium, copper, boron, and columbium. Conformance to required mechanical properties shall be determined by tension and hardness tests.