Monitoring Degradation of Reinforced Concrete Members Subject to Shear Loading

Background: In comparison with the prediction of bending failure, the existing design models for the calculation of the shear resistance are still rather vague. Therefore, currently strong efforts are being undertaken to improve and update current design models. In order to better understand the mechanism of shear failure and finally to identify the degree of shear degradation in existing structures in use, refined measuring techniques have to be applied for monitoring the short-term and long-term loadbearing behavior. Objective: A Monitoring system has to provide reliable information on the shear degradation development. The evaluation and optimisation of standard monitoring systems regarding shear failure based on shear testing are presented in this paper. Method: Different conventional structural health monitoring methods were used to monitor the external and internal deformations caused by shear loading, in order to evaluate the sensitivity and correlation of the different measurements. Based on adapted material models, as well as a nonlinear numerical finite element simulation together with a sophisticated monitoring layout, the internal flow of forces and the crack formation process can be recorded and visualized. The comparison of the experimentally required data with the provided numerical solutions allows an optimization of the monitoring system. Results and Conclusion: The sensitivity studies performed so far show that different measurement devices exhibit a characteristic sensitivity to the behavior of the structure at each testing stage. Evaluating the data of sensors which are sensitive enough regarding shear failure enables the approximation of the shear failure initiation point at an early stage.