Existing shear-cracked structures need to be reliably verified in order to avoid redundant interventions. Code provisions often raise shear safety and/or fatigue life concerns of the reinforcement subjected to stress concentrations due to cyclic dowel action. This paper presents an experimental investigation on dowel action under cyclic/monotonic loading based on advanced measurement techniques: Digital Image Correlation and Optical Fibres. The aim is to develop a mechanical model which allows calculating the steel stress variations on the basis of the measured crack openings and to assess existing structures which are theoretically shear-critical. The test results show a significant dependence on bar diameter, crack kinematics and crack-bar angle. Based on the test measurements, the internal forces, the deformed bar shape and the local pressure on concrete embedment are derived.