Structural performance of concrete bridge decks reinforced with epoxy-coated steel under fatigue loading.

摘要

Thirty-four slab specimens of two types of cross section with splices and transverse steel were tested in the laboratory to evaluate the structural performance of concrete bridge decks reinforced with epoxy-coated steel subjected to fatigue loading. Thirty specimens were tested under fatigue loading, and four were tested monotonically. Evaluations were made by comparing the performance of uncoated specimens with epoxy-coated specimens under service and ultimate load conditions. In addition, a field evaluation of six bridges was conducted to assess the in-service condition of concrete bridge decks reinforced with epoxy-coated steel in Indiana.;The test variables includes concrete compressive strength, bar deformation pattern, coating thickness, splice length, peak stress, stress range, and mean stress.;Fewer but wider cracks were found for specimens with epoxy-coated specimens. No significant differences in the first cracking load were found between uncoated specimens and epoxy-coated specimens. The splitting crack load and failure load were lower for epoxy-coated specimens. Deflections of epoxy-coated specimens were larger. The differences in crack width and deflection were reduced with repeated loading. The average bond ratios were 0.78 and 0.75 for repeated loading test.;Higher concrete compressive strength resulted in lower bond ratio. Higher stress range resulted in lower splitting load. The influence of stress range on bond ratio was not clear. Higher peak stress resulted in larger splitting and failure deflection. Higher mean stress caused larger splitting and failure load for uncoated specimens. The influence of deformation pattern on crack width and deflection was unclear. The influence of extra-thickness of coating on bond ratio was not significant. Specimens with extra thickness of coating had larger deflection. The influence of extra thickness of coating on crack width was inconclusive. The post splitting load for epoxy coated specimens was smaller than that of uncoated specimens. A single modification factor of 1.35 for members with epoxy-coated steel was recommended for revision of ACI 318-89 Building Codes.;No sign of corrosion was found for the steel extracted from coring samples from the six bridges evaluated. Evaluation of the field data and samples revealed that the combination of adequate concrete cover and epoxy coating provided a good corrosion protection.