Evaluation of MMFX Steel for Concrete Bridge Decks
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Date
2006-05-19
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Abstract
Commercially available Micro-Composite, Multi-Structural, Formable (MMFX) steel reinforcing bars are a proprietary product claiming to provide both high tensile strength and excellent corrosion-resistance when compared to conventional Grade 60 steel. Use of MMFX steel reinforcement could potentially lead to significant cost savings due to these unique characteristics. Recently, many state transportation departments, including the North Carolina Department of Transportation (NCDOT), have begun to use MMFX steel as a direct replacement for conventional steel in reinforced concrete bridge decks. However, the behavior of bridge decks reinforced with MMFX steel bars was previously undocumented. In light of this fact, a research program was commissioned by the NCDOT in which three concrete bridge decks, each having a span-to-depth ratio of 12.5, were constructed and tested to failure under simulated truck wheel loads. Two of the decks were constructed with identical reinforcement ratios, one utilizing conventional Grade 60 steel and the other MMFX steel. The third bridge deck was also reinforced with MMFX steel, but was reinforced with 33 percent less steel in an attempt to utilize the higher tensile strength offered by MMFX.
The results of the experimental program demonstrate that taking advantage of lowered reinforcement ratios by utilizing the higher strength of MMFX steel is a definite possibility in reinforced concrete bridge decks. The bridge deck reinforced with 33 percent less MMFX steel developed the same load-carrying capacity as the deck reinforced with conventional Grade 60 steel. In addition, the same deck showed the same deflections at service load as the deck reinforced with Grade 60 steel.
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Keywords
Corrosion, High-Strength Steel, Concrete Bridge Decks, MMFX, Punching Shear
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Degree
MS
Discipline
Civil Engineering
