Concrete beam crack detection using tapered polymer optical fiber sensors

•We present a TPFS to evaluate its performance for CB crack detection.•A simple sensing principle based on V-number theory is provided.•CB crack detection is investigated for sensors with different installation methods.•A low cost multiplexing system for multi-points detection is designed.

In this paper, a tapered polymer fiber sensor (TPFS) is employed to detect the crack of Concrete Beam (CB). The sensing principle for crack detection is simply described based on V-number theory. The experiments are carried out by cement mixture mixed with high reactive powder to form the CB, in which the TPFSs are embedded and surface glued. Thermocouples and strain gauges are also embedded to calibrate and determine the ambient temperature and applied strain, meanwhile, the Linear Variable Differential Transformer (LVDT) sensors are used to measure the deflection of the CBs. Four points loading test is applied for several samples to evaluate the sensors’ ability for monitoring the beam deflection and crack. Experimental results also indicate that the TPFSs can be used for post-crack detection.