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Concrete Girders with Exposed Flexural Reinforcement

2013; Taylor & Francis; Volume: 23; Issue: 4 Linguagem: Inglês

10.2749/101686613x13627351081597

1683-0350

Trevor Scott, Michael F. Bartlett,

Infrastructure Maintenance and Monitoring

Deteriorated reinforced concrete highway bridge girders are regularly repaired by replacing existing concrete with new concrete, temporarily exposing the flexural reinforcement. The absence of bond between the concrete and the steel reinforcement makes it difficult to compute the flexural capacity of the girder and current code criteria provide no guidance to assist practitioners. In Canada, it is common for the reinforcement to be exposed for periods of days or even weeks while unrestricted traffic continues in the lane supported by the girder being repaired. Two analytical approaches are developed to predict the longest length of exposed flexural reinforcement that ensures a girder will still exhibit a ductile failure with no reduction in yield capacity. A new experimental investigation is reported comprising five 4 m concrete T-section specimens with reinforcement ratios of 0,37%, and exposed flexural reinforcement, loaded with a simulated uniformly distributed load and a concurrent single-point load to realistically simulate the loading applied to a typical bridge girder. All specimens yielded, exhibited ductile behavior with no strain hardening, and failed by the crushing of the concrete compression region at applied moments of 75 to 81% of the predicted moment of the original specimen without exposed reinforcement. The results validated a strain-compatibility-based analysis with an average test-to-predicted ratio of 1,00 and a standard deviation of 0,068. A strut-and-tie-based analysis could only be indirectly validated. These approaches will assist practicing engineers in designing rehabilitations.