Study On Hanger Rod Damage Identification Of Tied Arch Bridge Based On Cable Force Monitoring

The hanger rod is an important force transmission component of the tied arch bridge.When the bridge is in long-term operation,environmental erosion of the hanger rod and fatigue damage from traffic loads can cause changes in the stiffness of the hanger rod resulting in a redistribution of internal forces in the structure,affect the safety of bridge operation,and may even lead to bridge collapse,resulting in the loss of national life and property.It is important for the safe operation of the structure to correctly identify the damage status of the hanger rod using the data collected by the bridge health monitoring system.In this thesis,the increment of cable force before and after the damage of the hanger rod is used as the identification parameter,by the given assumptions,the mechanical relationship between the hanger rod cable force increment due to hanger rod damage and the stiffness of the hanger rod after damage is derived for the bridge self-weight,hanger rod initial tension,the overall temperature rise and fall and other loads acting individually and jointly on the tied arch bridge,and the damage identification process is summarized.And establish the nonlinear finite element model of Caofeidian ore quay trestle bridge to verify the correctness of the method in this thesis,and from the verification results it can be seen that the method has high recognition accuracy.The main research contents are as follows :Firstly,based on the simplified model of tied arch bridge,the mechanical relationship between the cable force increment of hanger rod and the stiffness and active cable force increment after hanger rod damage was studied when single hanger rod is damaged and multiple hanger rods are damaged at the same time under the action of bridge self-weight,and to summarize the damage identification process.The nonlinear finite element model of Caofeidian ore quay trestle bridge is established by Ansys software.The method is validated using a finite element model under self-weight loading.Secondly,the mechanical relationship between the hanger rod cable force increment and the hanger rod post-damage stiffness and active cable force increment of the hanger rod after damage was studied for tied arch bridges under the action of the hanger rod initial tension alone and under the joint action of the hanger rod initial tension and self-weight when a single hanger rod was damaged and multiple hanger rods were damaged at the same time,and the damage identification process was summarized,and the finite element model of Caofeidian ore quay trestle bridge is used to validate the method.Thirdly,the mechanical relationship between the hanger rod cable force increment and hanger rod stiffness and active cable force increment after damage to a tied arch bridge under the action of temperature alone and under the combined action of temperature,hanger rod initial tensile force and self-weight when damage occurs to a single hanger rod and to multiple hanger rods at the same time was studied,and the damage identification process was summarize,the finite element model was used to verify the method and to investigate the stability of damage identification under the combined effects of self-weight,initial tension and temperature loads for single hanger rod damage and multiple hanger rods with simultaneous damage under different operating conditions.