Research On Damage Monitoring Of Prestressed Concrete Beams With CFRP Tendons Based On FBG-CFRP Testing Technology

With the development of age and technology,the building volume and number are increasing,which makes problems of structural damage or destruction needed to be cope with more obvious.So Structural Health Monitoring appeared,among which Intelligent Structural Health Monitoring is the most conspicuous.Carbon Fiber Reinforced Polymer(CFRP)has excellent characteristics of light weight,high strength,fatigue resistance,self sensing,etc.Meanwhile,Fiber Bragg Grating(FBG)has high measurement accuracy,anti-interference,good electrical insulation,corrosion resistance,etc.Hence the research and application of CFRP and FBG in Intelligent Structural Health Monitoring has become a hot topic.This paper mainly introduces compound sensor combining above two kinds of smart materials and the monitoring result of common reinforced and prestressed concrete structure.The main contents are as follows:FBG-CFRP sensor was designed and produced,then the tensile test of the sensor was carried out.The strain,resistance and wavelength of the FBG sensor were measured,after which the curves of resistance change rate-strain,wavelength-strain were analyzed.Results showed that in the small strain stage,the change of resistance and strain of the sensing element is approximately linear,and the linear fitting is above 0.95.The sensing performance of the FBG sensor in the sensor element is almost constant,and the strain sensitivity is maintained at 1.2pm/??,linear correlation coefficient is above 0.9998.The FBG-CFRP sensor was embedded into three groups of ordinary reinforced concrete beam.Then Three Point Loading Test of the concrete beam was carried out to obtain the resistance and strain of the sensor,during which the cracking and failure process of concrete beam were observed.Then the curve of resistance change-load,Strain-load of sensor were analyzed.Considering the strain mutation and the cracking of the concrete beam,conclusion that the FBG-CFRP sensor can be used to monitor the load,strain,damage of ordinary reinforced concrete beam was drawn.The FBG-CFRP sensor was embedded into Post Tensioning prestressed concrete beams with CFRP tendons.Then Three Point Lading Test on the prestressed beam was carried out,during which resistance and strain of the sensor were measured,and the cracking and failure process of the prestressed beam was observed,the curves of resistance change-load,strainload of sensor were drawn.Similarly,analyzing the strain mutation and the cracking of the prestressed beam,the results showed that the test results of the FBG-CFRP sensing elements were consistent with the actual damage and failure process of the prestressed beams.