Experimental Research On Arch Bridge Static Behavior Monitoring Based On Distributed Optical Fiber Sensor

As the main component of the arch bridge,the arch rib is of great significance to its monitoring for linear control and structural performance evaluation after construction.However,because the height difference between the monitoring points on the arch rib varies greatly,the traditional monitoring method can only perform point-type measurement,so the health detection accuracy of the arch rib is difficult to meet the needs of actual projects.Distributed optical fiber sensor based on Optical Frequency Domain Reflectance Technology(OFDR)can realize real-time distributed measurement of structural strain.Using the unique advantages of this sensor,it is studied to apply this technology to the field of health monitoring of arch bridges and provide new solutions for bridge health monitoring.With the goal of exploring the strain distribution of arch ribs,this paper conducts the following research work on distributed optical fiber sensing technology based on OFDR and its application in the monitoring of static behavior of arch bridges:(1)Based on the high-precision strain temperature analyzer,the basic principle of optical frequency domain reflection technology is analyzed;the principle of surface-adhesive optical fiber strain transmission is analyzed,and the calibration experiment of optical fiber strain sensor is carried out.It is found that the strain monitoring results of the surface-mounted optical fiber are stable,and the correlation coefficient results are good.Therefore,it is proposed to apply this sensor to the distributed strain monitoring of the steel arch bridge model.(2)The finite element modeling of the arch bridge was carried out by ANSYS Workbench,and the strain distribution of the arch rib under different static load conditions was analyzed.Using the life and death function of the element,the internal force and strain changes of the arch ribs after different suspenders are restrained,and the changes in the stress of other suspenders are analyzed.(3)The distributed strain monitoring test of the steel arch bridge model was carried out.The finite element arch rib strain simulation results were compared with the measured values of sensors,the accuracy of the monitoring results and the causes of errors were analyzed,and the reliability of the finite element model was verified.(4)The suspender breakage monitoring test was carried out,and the real-time change law of strain distribution was summarized.The breakage is identified through the change of the strain distribution of the arch rib,and the monitoring result is located in real time and compared with the actual breaking position,and the accuracy and error rate of the damage location are analyzed.(5)A multi-channel suspender strain monitoring test was carried out,and the real-time strain of the suspender was obtained by step loading.The tensile force value calculated by the conversion was compared with the theoretical value.The result showed that the error of the tensile force value monitoring result was about 5%.