Structural assessment of existing R.C. half-joint bridges according to the new Italian guidelines

In 2020, the Italian Guidelines for the classification, assessment and management of bridges were published, introducing a novel multilevel approach to assess the degree of risk of existing bridges at the national scale. Even if these guidelines give, for the first time in Italy, a comprehensive approach to the assessment and management of bridges, in some cases, detailed procedures are missing. One of these cases is represented by the R.C. half-joint, a kind of deck/girder connection that was commonly used in the past. This joint deserves particular attention in the assessment since in many cases it is subjected to deterioration and the relevant reinforcement is not properly designed for the lack of specific provisions in the old Italian technical standards. In this scenario, this article aims to propose a specific methodology for the assessment of half-joints that is consistent with both the above-mentioned Italian Guidelines and the current Italian Technical Standard. However, this methodology can be used as a reference also in other countries since most of the relevant provisions are general whilst the detailed rules are Eurocode based. In this article, first the type of investigations to be performed to reach a proper knowledge level is defined, describing possible destructive and non-destructive tests. Then, a procedure for numerical verification of the joint is described. This procedure, based on the adoption of three different Strut-and-Tie Models is introduced and deeply analysed, highlighting the limits and the benefits of each model. Finally, the application of this procedure to a case study is shown.