Dapped-end beams retrofitted with Fabric-Reinforced Cementitious Mortars: experimental and preliminary analytical study

Reinforced Concrete (RC) dapped-end beams are structural elements characterized by a relevant reduc-tion of the beam cross section (about 50%). Despite the simplifications in terms of design and construc-tion, when used as suspended spans in reinforced concrete bridges, dapped-end beams may represent a vulnerable component of the infrastructure. The degradation effects and the environmental actions (e.g. carbonation and chloride ingress) can significantly affect the structural robustness of the bridge when dapped-end beams (also referred to as RC half-joints) are not properly designed, built or maintained. In this context, the need of analysing the structural performance of this type of elements has arisen in the last years, drawing the attention to the implementation of innovative retrofitting solutions (cementi-tious composites) that might contribute to extend the service life of bridges characterized by this con-struction solution. The paper presents an experimental investigation on RC precast dapped-end beams retrofitted with FRCM composites. The structural performance of the cementitious composite is eval-uated in terms of its contribution to the load bearing capacity of the joint, highlighting also the beneficial effects on the crack distribution at SLS and ULS. A preliminary analytical approach for the simulation of the mechanical behaviour of dapped-end beams is proposed and validated with respect to the exper-imental results.