Design And Application Research Of Bridge Condition Real-time Monitoring And Evaluation System And Serviceability States Rapid Pre-evaluation System

Bridges,as the main hub of road transport,are very important.However,due to the overload of vehicles,natural disasters and aging structures,bridge safety accidents are common in our daily life.In order to avoid accidents,China has published codes and standards related to bridge inspection,including regular manual inspections and static load tests to evaluate the bearing capacity of bridges.Regular manual inspection has the disadvantages of poor real-time performance,poor economics,strong subjectivity,and poor storage.The cost of traditional bridge health monitoring system is high and it is difficult to cover existing bridges with them on a large scale.The system it's also not docked with current regulations which makes it difficult to meet the demand of bridge management units;traditional static load test is costly,timeconsuming,and easy to cause traffic jams.This thesis is docked with the current code and started from the perspectives of practicability and economy.Aiming at the shortcomings of regular inspection and traditional static load test,a real-time bridge condition monitoring and evaluation system and a rapid pre-evaluation system for serviceability states are proposed.Their principles are elaborated in detail and their practicability and economy are verified through engineering examples.The main contents include:(1)Aiming at the shortcomings of regular inspections,the concept of real-time monitoring and evaluation of the bridge condition are put forward,and the monitoring sensor requirements of the real-time monitoring and evaluation system of the bridge are introduced in detail;(2)Based on the wavelet packet decomposition,the structural response caused by the temperature field in the monitoring data is extracted,the strong linear relationship between the inclination and strain response of the bridge structure and the measured temperature value is found out,and a method to remove the temperature effect in real time from the monitoring data is proposed;(3)Three levels of early warning thresholds are set for real-time monitoring data.The yellow threshold is for the daily operation status of the bridge,the orange is for the value of the car load item under the serviceability limit state,and the red is for the value of the car load term at the limit state of the bearing capacity.According to these three warning thresholds,a bridge monitoring and early warning system is established,and a method for real-time bridge scoring based on monitoring data is proposed as well;(4)Taking a typical continuous girder bridge as an engineering example,the hardware composition of the monitoring system is introduced,and the validity of the early warning of the bridge state real-time monitoring and evaluation system is verified by loading tests.The long-term monitoring data of the bridge is taken as an example to analyze its safety status of the bridge during the monitoring period;(5)Aiming at the shortcomings of the traditional static load test,a concept of rapid pre-assessment of bearing capacity is proposed based on the basic principles of the static load test,which aims to reduce the time and number of inspectors for the assessment.The similarities and differences between rapid pre-assessment of bearing capacity and the traditional static load test are explained in detail;(6)The principle of measuring the bridge deflection by the inclination sensor is introduced in detail.The segmented superposition model is used to analyze the error composition of the inclination sensor when measuring the deflection of the bridge at a specific load.Based on the finite element calculation,polynomial fitting and Monte Carlo.Carlow method,methods for eliminating segmentation error and angle measurement error are proposed,and the feasibility of the inclination sensor to measure deflection is initially verified by laboratory tests;(7)Taking a typical continuous girder bridge as an engineering example,the traditional bridge static load test and the rapid pre-evaluation system for serviceability states are carried out simultaneously.A comparative analysis of these two from the aspects of evaluation conclusions,time-consuming and number of inspectors is done,verifying the effectiveness of the the rapid pre-evaluation system for serviceability states which also shows great advantages in terms of time-consuming and number of testing personnel.