Study On The Distributed Monitoring For The Steel Bar Corrosion In Concrete Using BOTDR

Steel bar corrosion is a major cause of damage to the concrete structures, in order to control the development of steel bar corrosion, correctly assess the durable life and maintain the safety of the buildings, the monitoring of the corrosion procedure in concrete structures is very essential. Brillouin Optical Time Domain Reflectometer (BOTDR) is a distributed sensing technology based on spontaneous Brillouin backscattering, beyond the traditional point-type sensing technology, BOTDR characterizes the intrinsic continuous monitoring of the strain. By using the BOTDR, a number of laboratory and theory researches on the distributed monitoring for the steel bar corrosion in concrete are conducted in this dissertation and the achieved results are as follows:1. Based on the BOTDR, the reinforcing steel corrosion induced concrete expansion of two cylinders was studied comparatively. The experimental data indicated that the BOTDR can monitor the outer concrete expansion procedure caused by the steel bar corrosion effectively, the variation pattern of concrete deformation in different regions of the cylinder is greatly reported by the BOTDR which demonstrate the superiority of the reinforcing steel corrosion monitoring by use of the distributed monitoring method.2. With different temperatures, the temperature effective of steel bar corrosion in concrete was studied. According to the experiment results, as the temperature increases from0℃to40℃, the corrosion rate of the rebar doubled at least, and BOTDR can both reflect the variation of reinforcement steel corrosion before or after the concrete split in different temperature environments.3. Based on linear elasticity theory, the theoretical formula of the expansion force caused by steel bar corrosion in concrete was deduced, and the impacts of every factor in the formula and the origin of the calculation errors were analyzed. Due to the experiment results, the thesis tried to evaluate the corrosion rate of the steel bar.4. As an application research, the feasibility and the promotional value of the distributed monitoring for the steel bar corrosion in concrete by using BOTDR were discussed, and the possible problems it may encountered at the promotion procedure were analyzed.