Development Of Bridge Rapid Test Method And System Based On Intelligent Tire And Microwave Radar

The civil infrastructure in China is huge and costly,and its safety is closely related to the national economy and people's livelihood.There are numerous short/middle span bridges on the national highway network,but some of them have serious safety problems due to limited maintenance budgets.The structural technical assessment based on regular inspection is the main means to evaluate the current service performance of the bridge,but it is mainly manual,which is time-consuming and laborious.Therefore,how to implement rapid tests and diagnoses of numerous bridges in the highway networks is a challenging problem home and abroad.Based on the unique advantages of the impact vibration,from three aspects of structure input,output monitoring and structure identification,this paper proposes a bridge rapid test method and system based on intelligent tire and microwave radar.It uses the moving vehicle to excite bridge structures while using a non-contact microwave radar to measure the time histories of the bridge displacement for the rapid tests of bridges.The main research work is as follows:(1)Vertical tire force identification of intelligent tire based on multi-sensor data fusion.In this paper,multiple sensors were mounted on the tire to accurately identify the moving loads acting on the bridge structure.It includes two aspects.The first one is the study of the tire mechanical properties,analysis model and the complex mapping relationship between the key parameters of the tire and the vertical tire force.The other aspect is a vertical tire force identification method based on the long and short-term memory(LSTM)depth learning algorithm,which can identify the vertical tire force without the explicit function relationship mapping only using the pre-model training.Finally,the static and high-speed tire experiments of the developed high-speed tire testing machine were used to verify the feasibility and effectiveness of the proposed method.(2)Continuous measurement of tire deformation using long-gauge strain sensors.Consider of real-time and continuous measuring the tire vertical deformation using the existing sensors in real project is very difficult,combined with the unique advantages of Fiber Bragg Dratings(FBG)sensors,this paper proposes a modified conjugate beam method,which transforms the problem of solving the tire deformation into a more convenient solution to the bending moment of the conjugate structure based on the SWIFT tire model.Furthermore,a vertical deformation monitoring system using FBG sensors was proposed,and the bridge impact monitoring vehicle static experiment,impact test and high-speed testing machine tire rolling experiment were used to verify the feasibility and effectiveness of the proposed system by comparing with traditional image processing method and laser sensor.Finally,this paper analyzes and discusses the selection of long gauge FBG sensors in practical project applications,and provides reference solutions for its specific implementation.(3)The principle of measuring deformation and the system of the microwave radar.Based on microwave technology and phase interferometry,the composition of microwave radar system and its measuring principle are briefly described.For the research and development of the actual microwave radar equipment system,technical program planning and calculation of main technical indicators were carried out.Then,the detailed design schemes of the microwave radar,the hardware and software implementation schemes are analyzed in detail.Finally,according to the requirements of bridge displacement monitoring,the selection method of pitch angle of microwave radar in real bridge project application is specifically analyzed.Through the indoor precision experiment and the actual bridge experiment,the accuracy of the developed microwave radar and the feasibility and effectiveness in the application of the real bridge project are verified.(4)Bridge deflection monitoring and modal parameter identification based on microwave radar.Yangzhou Beichengzi River Bridge was chosen for testing,the multi-target synchronous monitoring of microwave radar was verified,and the modal parameter identification of the bridge structure was further realized based on multi-reference point method under environmental vibration.In addition,in terms of Guangzhou Nansha Bridge test,a detailed plan for the application of microwave radar in the super-long-span bridge project was proposed,and a microwave radar point displacement inversion method based on multiple(dynamic)reference points was proposed to solve the problems of low net navigation height and low pitch angle of microwave radar test on the test site.The suppression and elimination of the "multipath effect" of microwave radar in extreme environments was furtherly discussed.Finally,compared with the traditional monitoring methods,the validity of the microwave radar test results was verified,and the advantages of high efficiency and rich test results was highlighted.(5)Synchronous cable force estimation of long-span cable-stayed bridge with microwave radar.Combined with the advantages of non-contact,multi-target,long-distance and high-precision of microwave radar,the research of simultaneous monitoring the cable tension force of multiple cables was carried out.Firstly,the various test conditions and problems that may occur in the cable tension test are analyzed in detail.Secondly,aiming at the signal aliasing problem of the multiple cables in the same range bin,a single channel signal blind source separation method combining fusion variational mode decomposition and time-frequency analysis was introduced,so that the simultaneous monitoring of the cable force can be realized.Finally,the "Nanjing Eye" cable-stayed footbridge was applied in the conduct of field measurement to validate the feasibility and effectiveness of the proposed method.(6)Structural flexibility identification using improved optimization algorithm.Since the structural inputs and outputs were known in the proposed rapid test described above,structural flexibility can be achieved in conjunction with the existing structural block impact testing methods.In actual project,microwave radar is difficult to realize the synchronous measurement of the overall bridge structure in real project due to the limitation of the pitch angle,and the traditional impact test method needs a large number of sensors deployed on the entire structure,which cannot meet the requirements of rapid bridge testing.This paper proposes a new mobile impact test method is proposed by sequentially testing the substructures then integrating the test data of all substructures for flexibility identification of the entire structure.The first novelty of the proposed method is that it doesn't require the reference measurement for integrating the mode shapes of substructures.The second novelty is that the quantum-inspired genetic algorithm(QIGA)is proposed to improve computational efficiency by transforming the scaling factor sign determination problem to an optimization problem.Experimental example of a steel-concrete composite slab and numerical example of a three-span continuous rigid-frame bridge are studied which successfully verify the effectiveness of the proposed method.