Shear Transfer along Interfaces in Repaired/Strengthened RC Elements subjected to Cyclic Actions

Efficient repair or strengthening of existing RC structures strongly depends on the behaviour of interfaces between old and new added concrete, crossed by reinforcing bars. The mobilization of the two main shear transfer mechanisms, namely friction and dowel action, depends on the imposed cyclic displacement along the interface, as well as on the number of cycles. In this paper, part of the experimental results of a systematic program are presented and commented upon. Artificially roughened interfaces between old and new concrete crossed by reinforcing bars are subjected to cyclic imposed shear slips of varying amplitude (±0,1 mm to ±2,0 mm). The opening of the crack, the mobilized shear resistance, the axial stresses of the steel bars, as well as the force-response degradation due to cycling are measured.