Application of distributed optical technique in sensing interface disengaging and cracks of steel tube-confined concrete

Detecting of crack and Disengaging is very important to prevent major accident in civil engineering, but it is still problematic in implement. Detecting of crack by burying distributed optical fiber into civil engineering can solve this problem effectively. With the ability of continuous information gathering in large scale, optical fiber can perform its function of crack and Disengaging detecting well. Based on Optical Time Domain Reflectometry, distributed optical fiber sensing technique of health monitoring for steel tube-confined concrete (STCC) is investigated in the paper. The principle of such sensing means has been discussed in detail, and also, the layout of optical fiber sensing net has been brought forward. In its application in one Tube-Confined Concrete structure, the disengagement in a large scale at the interfaces of STCC have been detected successfully, and its corresponding disengagement value (2 ~ 3mm), position and range are determined. Moreover, monitoring of the occurrence and development of disengaging for long term is realized. This is of far reaching importance to improve nondestructive detection level for Tube-Confined Concrete structure.