摘要: |
The objective of the subject program is to develop a new "improved" steel composition with weathering characteristics significantly superior to any of the steels listed in ASTM 709, "Standard Specification for Structural Steel for Bridges", such that its life cycle will be at least two times longer than any ASTM 709 steel in a highway bridge subjected to extensive use of salt as a deicing agent. The "improved" steel shall (1) be readily producible by American steel companies on existing facilities, (2) meet the design specifications of the American Association of State Highway and Transportation Officials (AASHTO)and have mechanical properites similar to "today's steel grades", (3) have a high level of weldability when joined by processess such as SAW, SMAW, FCAW, and GMAW, and (4) have a cost similar to the corresponding A709 steels unless the steel has a "higher strength that reduces the steel required for a given application" and provides "improved corrosion resistance in mild chloride environments and life cycle cost"; and thereby justifies a "first cost premium". |