A novel distributed crack sensor for concrete structures

Concrete structures degrade through the formation and propagation of cracks. The severity of cracking in a concrete structure is therefore a good indicator of its 'health'. At the present, the assessment of cracking condition in concrete structures is carried out by manual inspection, which is inefficient, unreliable and costly. The objective of the present investigation is to develop a novel optical fiber sensor for the detection of cracks and the subsequent monitoring of their openings. Comparing with conventional approaches, the novel sensor possesses two major advantages: (i) no a-priori knowledge of crack location is required, (ii) a small number of fibers can be employed to detect and monitor a large nu_mber of cracks. In this paper, the sensing concept is described and preliminary experimental results are presented to demonstrate its feasibility. A theoretical model is also developed to provide guidelines for the optimization of sensor performance. Model predictions are in good qualitative agreement with experimental results.