A half-joint is a particular type of RC structure that has been historically used in bridge decks as a means of simplifying the design and construction procedures. However, when assessing the integrity of existing reinforced concrete half-joints, engineers can be confronted with internal steel reinforcement lay-outs that do not comply with current design practice. The locations, percentage and spacing of the steel reinforcing bars may be non compliant, bars may be missing and/or there may be differences between the as-designed and as-built situations. In addition, half-joints are vulnerable to local reinforcement corrosion especially in the inner nib. An experimental test program was undertaken to provide a better understanding of the contribution of the different reinforcing bars found in typical half joint details. Four different scenarios were tested using full-scale half-joint beams to identify the impact due to the absence of specific bars. Results indicate that the overall load bearing capacity of a half-joint can be reduced by approximately 40% of that of a properly designed detail if certain bars are missing.