Damage Detection And Condition Assessment Of An Existing Cable Stayed Bridge Based On Structural Health Monitoring

Structural health monitoring is an international frontier,SHM system can do much more rather than locating a defect of the construction.It can describe a shape of damage,its size and orientation.Moreover,it can be used to describe and measure bridge’s physical characteristics.SHM system is a mixture of several systems and there are some other traditional techniques can be converted to SHM.Using SHM we can talk about evaluation of damage,residual life making diagnosis.In this paper,we apply for SHM system to make the data analysis of Tianjin Yonghe Bridge.The Bridge has a health system,including the envi ronmental monitoring subsystem,main beam stress monitoring subsystem,deformation monitoring subsystem,Structural dynamic response monitoring subsystem and traffic load monitoring subsystem.This paper analyzes the environmental monitoring subsystem and the structural dynamic response monitoring subsystem,mainly analyzes the structural dynamic response of the main beam.The complete data of the monitoring data from January to July 2008 are 101 days.During the monitoring period,the bridge experienced the stage from health to damage.Through analysis,the influence of wind speed and temperature on bridge modal parameters are proved to have great effect,so that the influence of environment is considered in subsequent analysis.In this paper,the acceleration time history analysis,spectrum analysis and mode analysis are carried out.This paper only makes a simple preliminary analysis of the monitoring data,but the monitoring data reflect the damage condition of the bridge and reflect the purpose and significance of the existence of the health monitoring system.By establishing and analyzing the ANSYS finite element model of Tianjin Yonghe Bridge,the stress condition of three bridge states(healthy state,side span auxiliary pier failure,plastic hinge formation in main span)and the dynamic characteristics of three bridge states are studied.In this paper,the vibration frequency and mode of Yonghe Bridge are extracted to provide theoretical data for health monitoring and damage identification of Yonghe Bridge.Ansys three-dimensional finite element model is only preliminary analyzed and the dynamic characteristics are extracted,but the finite element model analysis provides theoretical data and basis for the damage identification and judgment of Yonghe Bridge.It reflects the purpose and significance of finite element model analysis.