Application of Smart CFRP Embedding PPP-BOTDA Fiber Sensors on Fatigue Strengthening of Cracked Steel Structure

Detecting and slowing down cracks in damaged steel structures is crucial, and Carbon Fiber Reinforced Polymer (CFRP) reinforcement plays a significant role in achieving this. To monitor and slow down crack opening displacement (COD), a smart CFRP was created that incorporates distributed fiber optic sensors capable of measuring the strain singularity of externally bonded CFRP in the cracking zone. An experimental program was conducted to test the proposed COD model on a pre-cracked pure bending steel element. The distributed strain measurement on the CFRP was carried out using a commercial PPP-BOTDA sensor with high spatial resolution. The results obtained by comparing theoretical CODs with the measured ones using an electronic digital display micrometer (EDDM) confirmed the accuracy of the proposed model in COD estimation. This method, which utilizes smart CFRP embedded with distributed optical fibers, shows great promise for accurately and sensitively monitoring COD while also having the capability to detect and slow down cracks in damaged steel structures.