Research On New Smart Cable Based On Strain Sensing Technology Of Polymer

As an important force bearing component of deck load transferring to arch rib of half through arch bridge,stay cable is in alternating stress and harsh natural environment for a long time.It is easy to cause cumulative damage under environmental corrosion,load,fatigue and other effects,which seriously threatens the safety of arch bridge.Therefore,accurate measurement and evaluation of cable force is of great significance for bridge safety construction and operation management.There are many kinds of cable force measurement methods.Although the resistance strain gauge method is simple and convenient,it also has limitations.At present,the resistance strain sensing technology has some problems such as poor stability and insufficient sensitivity in cable force measurement.In this paper,a new type of polymer strain sensor is proposed,which is encapsulated by resistance strain gauge and polymer material(PTFE).The sensor has good deformation sensitivity,repeatability,reliability and durability;A new type of intelligent cable is designed,which is built in the cable body.It is proved to have excellent performance by theoretical analysis,finite element simulation and various sensing performance tests;Finally,the engineering applicability of the smart cable is verified.The main research work and results are as follows:1.Based on the resistance strain gauge,the sensitivity is reduced or the contact surface of the strain gauge is damaged due to the large elastic modulus and the uncoordinated deformation of the steel during the stress process.A method and packaging process for composite packaging of polymer material(PTFE)and resistance strain gauges to form a polymer strain sensor is proposed;the deformation state of the polymer substrate with the tension of the elastomer is analyzed by finite element simulation.2.The polymer strain sensor is pastered and encapsulated on the surface of high strength steel strand and parallel steel wire to make the polymer strain smart steel strand and smart parallel steel wire,and the sensing performance is tested under static load,fatigue,relaxation,temperature,etc.By using the wireless static strain acquisition system to collect data automatically,the polymer strain sensor has the advantages of excellent sensing performance,glorious linearity,high repetition and more accurate measurement.3.Combined with the common phenomenon that it is not easy to accurately measure the cable force of bridge cable at present,using the polymer strain sensor,it is proposed to build the sensor into the surface of steel strand or parallel steel wire at the anchor sleeve position at the end of the cable when making the cable,and further develop the polymer strain smart cable.The sensor makes full use of the internal safety space of the cable,which greatly improves the survival rate of the sensor;The solid model of the steel strand cable is established,and the finite element analysis of the smart cable is carried out,and the stress distribution of the outermost steel strand is obtained;Through the calibration test,the strain sensing of the cable shows good linearity,which verifies the feasibility of the research on the polymer strain intelligent cable.4.Finally,the smart cable is applied to the cable system of the world’s first arch No.3 Ping Nan Bridge.Through the cable force measurement data of Ping Nan No.3Bridge during construction and operation,the results show that the smart cable has high sensitivity,good linearity and repeatability.Through the establishment of the cable tension remote online health monitoring system,the long-term real-time monitoring of the bridge cable tension state shows that the polymer strain smart cable has excellent adaptability and good accuracy in engineering application.