| Bridge is an important part of the road,it is also a key component of traffic engineering.Bridge is very important in the transportation development.Urban bridges refer to bridges within the city,which are on the river,overpasses between roads and roads,or even overpasses over roads and pedestrian bridges.With the age of the bridge structure is growing,the safety of the bridge structure and the use of performance is bound to degrade.In order to ensure the safe operation of bridges and to extend their service life,a bridge health monitoring system needs to be established.The bridge health monitoring system realizes the real-time monitoring by using sensors installed at the key position of the bridge structure for a long time and assesses the structural state of the bridge.When the natural environment,traffic conditions or operating conditions are serious abnormalities,the bridge health monitoring system provides basis and guidance to the bridge maintenance.The abnormalities can be found in the first time,then effectively avoid the vicious incidents.In this paper,under the background of the monitoring system of Xiawangbu overpass in Licang District of Qingdao City,the critical issues of the urban bridges health monitoring system are studied.The main contents are as follows:(1)The finite element model of the bridge is established to analyze and understand the stress characteristics and deformation of the bridge.Through the analysis of the force of the structural model,the critical force position of the structure is determined,which can provide the reference for the health monitoring sensor arrangement.And provide the corresponding reference data for the determination of the sensor range and the precision requirement.(2)The actual loading test of the bridge.When the bridge is ready to install the bridge monitoring system,it has been built 13 years.In order to avoid the finite element model calculation results and the actual structure of access is too large,to provide realistic technical indicators for the bridge monitoring system,the actual vehicle loading on the bridge is needed.(3)According to the characteristics of the bridge structure and the actual working condition,through the balance function and cost,choose the parameters which can reflect the working state of the structure and at the same time is easy to monitor the stability of the measurement.Determining the monitoring projects,monitoring methods,equipment selection and corresponding measuring points arrangement to realize the real-time monitoring of the main structural response of the bridge.(4)Setting early warning threshold and monitoring.The health monitoring threshold of the bridge is set according to the calculated value of the monitored project model,monitoring the actual measured values of the project,and the data of the standard limit value. |
