Kinematics-Based Model for Shear-Dominated Wall-Type Bridge Piers Strengthened with UHPFRC

Wall-type bridge piers in existing concrete infrastructure can be strengthened in shear by casting UHPFRC jackets around the pier. The effectiveness of this solution has been demonstrated recently in an experimental program conducted at the University of Liege, where large scale specimens were tested to failure under vertical and lateral load. However, while this solution is effective, there is a need for rational mechanical models that can predict the effect of the UHPFRC jackets, in particular in piers with small aspect ratios where direct strut action can develop. This paper presents such a model based on kinematics. The model allows to evaluate the shear carried by the steel fibres across the cracks, as well as the increased resistance of the compression zones. Kinematic conditions and constitutive relationships are combined with equilibrium conditions to form a complete rational model for wall-type bridge piers with UHPFRC jackets. The model is validated with data from large-scale tests, showing adequate results.