Electronic Thesis and Dissertation Repository


Master of Engineering Science


Civil and Environmental Engineering


Prof. F. M. Bartlett


Reinforced concrete highway bridge girders are regularly repaired by replacing deteriorated concrete with new concrete, temporarily exposing the flexural reinforcement. The absence of bond between the concrete and steel at this stage makes it difficult to compute the flexural capacity and the current code criteria provide no guidance to assist practitioners.

The research reported in this thesis rectifies this knowledge gap. A thorough examination is presented of experimental and analytical investigations by others to determine the typical behaviour, including probable failure modes, of reinforced concrete specimens with exposed flexural reinforcement. Based on these findings, two analytical approaches are developed to predict the longest length of flexural reinforcement that could be exposed that ensures a girder will still exhibit a ductile failure with no reduction in yield capacity. The Strain Compatibility Analysis derived by Harris was enhanced to involve realistic concrete stress-strain relationships and was validated experimentally using five 4-metre T-section specimens subjected to simultaneous point and uniformly distributed loading. A Strut-and Tie Analysis was also derived for this generic loading condition that could only be indirectly validated experimentally. The ratios of the test failure load to the failure load predicted using the Strain Compatibility Analysis had a mean value of 1.00 and a standard deviation of 0.068.