An overview of different design and verification techniques of half-joints: application to a case study

Existing concrete bridges with half-joints, also called Gerber saddles, represent a large part of the bridges still in service today, very often affected by pronounced degradation, due to the lack of an adequate maintenance. Therefore, in order to correctly predict their vertical load capacity, it is necessary to know the methods adopted in the past for their design and assessment. This paper aims to study several methods related to the half-joints. At first, an overview of different methods available in the literature is conducted. Moreover, to improve knowledge of these structural elements, an investigation on their differences and similarities, in relation to typical geometric proportions and reinforcement layouts, is conducted. Then, results from the application of these methods to a selected existing half-joint, belonging to an existing reinforced concrete bridge, are shown and commented, in order to simulate different assessments of half-joints and to perform comparisons.