Damage Identification Of The Main Girder Of Cable-stayeded Bridge And Arch Bridge Based On The Cable Force Influence Line

As an important infrastructure, the bridge has been widely used in engineering. Cable supported bridges is the main form of the structure of long-span bridges, but in the process of long-term overload operation, the main girder of the bridge may appear different degrees of damage. To ensure the safety of bridge in the process of operation, damage identification technique is very important and become the focus and difficulty in the present study.According to the structure characteristics for cable supported bridges, change of cable force influence line can be used as index of damage. Damage identification of the main girder of cable supported bridges based on the cable force influence line is proposed in this thsis. The main works are as follows:1. The background and significance of topic selection of thesis is sketch, the research status about structural damage recognition at home and abroad is intrucded. Merits and drawbacks of damage identification method,such as structure dynamic response, static response, modal correction and artificial intelligence, is comparative analysed. The problem of existing in the current damage identification is stated.2.The bridge of the cable bearing system is simplified as the model of the continuous girder bridge supported by the spring support. The analytical expression of the influence line of elastic support on the elastic support before and after the damage is deduced, and the relationship between the support reaction force and the cable force(boom force) is one-to-one. In theory, the feasibility of identifying the main beam damage based on the cable force influence line is proved. And qualitative analysis of the influence rule of damage state on cable force influence line.3. Three dimensional space finite element model of HeDong is established, numerical study on damage identification of main girder of cable stayed bridge based on cable force, the method of reduc the structural stiffness is used to simulate the damage of the main beam,various conditions such as single damage, multiple damage and different degree of damage were analyzed. The results showed that it is difficult to identify the damage of the main beam by used to the cable force influence line directly, but the first derivative differential and second derivative differential of influence line Can better identify the damage of the main beam,the second differential of the cable force influence line is sensitive to the damage of the main beam, the recognition effect is good, not only can accurately locate the damage, but also can identify the degree of damage.4. Using Midas software to establish a spatial finite element model of beam arch combination system. Numerical study on the damage location and damage degree of the main girder and arch rib of arch bridge, the results of the study are similar to those of cable-stayeded bridges. That is, the first derivative differential and the second order difference of the influence line of the boom force have a good effect on the damage location and damage degree of the main beam.