Fibre-Optic Measurements for Monitoring Adhesively Bonded Composite Beams

Abstract

The technology of fibre-optic sensors (FOS) enables the continuous measurement of strains along the fibre axis. This offers the possibility of studying and monitoring the behaviour of the component to which the fibre is connected at any given point. In this paper, the FOS measurement technique is applied aiming to develop a monitoring tool for checking the integrity of the adhesively bonded joint between timber and concrete. Accordingly, tests with adhesively bonded timber-concrete composite beams, which have been loaded up to ultimate failure, are conducted. The measurement results are presented and checked for plausibility with the aid of an finite element model. Subsequently, a calculation model is presented with which the shear stresses in the adhesive joint can be derived directly from the strain measurements. As a result, it can be stated that it has been possible to monitor the integrity of the bonded joint and derive shear stresses directly from the measurement, however, more research is necessary to get an even better understanding of how to analyse and post-process the measurement data.