Design Guidelines for Concrete Beams Reinforced with Mmfx Microcomposite Reinforcing Bars

Corrosion of steel reinforcement in concrete structures and bridges is a major problem facing the departments of transportation worldwide. In the United States, maintenance and replacement costs are measured in billions of dollars. Salt environment in hot climate and the use of deicing salts in cold regions have resulted in steady deterioration of bridge decks due to corrosion. These concerns have initiated continual development of protective measures including the use of corrosion-resistant MMFX Microcomposite reinforcing bars. This paper provides design guidelines for the use of MMFX steel as flexural reinforcement for concrete beams and slabs. The behavior of concrete beams reinforced with MMFX reinforcing bars is evaluated and characterized using cracked section analysis. Principles used for the design of MMFX-reinforced concrete beams are discussed. The behavior of concrete beams reinforced with MMFX is compared to the behavior of the beams reinforced with conventional Grade 60 steel. Using the principles of equilibrium and compatibility, the effect of reinforcement ratio on the strength of concrete beams reinforced with MMFX is examined. The ductility of concrete sections reinforced with MMFX steel throughout the entire loading range is evaluated and design limits for tension and compression controlled failure modes are proposed. In addition to the concrete bridges constructed recently using MMFX steel, this paper discusses the construction procedures of a new bridge at North Carolina where the concrete deck is totally reinforced with MMFX steel.