Ultimate capacity assessment of reinforced concrete half-joints

Half-joints are elements widely used in bridge construction from the 1960s onwards. They are considered critical elements since they are particularly susceptible to deterioration, and their failure may cause the collapse of the entire bridge deck without guarantee any strength reserve. The aim of this paper is to analyse the different approaches to evaluate half-joint shear capacity, comparing both analytical predictions present in main design codes and the results obtained using refined non-linear finite element analyses. The accuracy of different codes’ formulations is evaluated on a dataset of experimental results collected in literature, while that of numerical models is evaluated on available experimental tests. Numerical models are capable to estimate with high accuracy the failure mode, the cracking pattern and the load-bearing capacity. Furthermore, a parametric analysis is carried out to evaluate the influence of geometrical parameters, material properties and amount and position of reinforcement on the overall capacity of the saddles. Results highlight how code formulations provide similar estimate of the capacity of the members, regardless of the failure mode involved, and are more conservative for slender half-joints. • High accuracy of NLFEA to predict half-joint ultimate capacity is achieved. • Existing code formulations underestimate half-joint capacity of 35 % in average. • Failure modes predicted by the codes do not always correspond to the effective ones. • The accuracy of code formulations depends highly on saddles geometry (deep or slender members).