The Damage Identification And Applied Research On Long-span Reinforced Concrete Arch Bridges

Much more complex structures,such as tall buildings and long span bridges,have been built with the development of economic. All of these load-carrying structures continuosly accumulated damage during their service life.Undetected damage may result in structural failure and loss of human lives.Therefore, it is important to detect the damage of the structure and make appropriate repair as early as possible.Visual inspection is the most common method for structural damage detection.This method,however,is unreliable for complex structures because certain critical damage may occur in inacccessible areas or may be concealed by paint or shin.Visual inspection also cannot provide a quantitative value for the remaining strength of the stucture,including ultrasonic,X-ray and acoustic emission.These traditional NDE methods,however,only give the effective deterioration state of local areas and tend to be impractical for large complicated structures.Additionally,none of these approaches provide a quantitative assessment of the damage.Vibration-based damage identification method is also a non-destructive testing methods. The structure have the inherent dynamic characteristics, such as:stiffness, quality and damping. Physical characteristics of the structure changing will result in the natural frequencies and modal information of the structure changing.Thus, the natural frequency and modal information of the structure can be used to locate and assess the damage.The main work of this thesis are the following:1. The damage identification methods were reviewed and compared, and the problems which we will meet in the practical application of the structural damage identification were bring forward.2. The natural vibration characteristics of the damaged structure was analysed by numerical simulation.3. Vibration mode-locating method was invented, which can locate the damage with low-level vibration mode information of the structure precise. 4. The damage identification procedures (SSZD) was invented, which is high universality and also can be used to locate and assess the structural damage.5. The numerical simulation analysis of the beams and Sweden's Arch Vindel verified the feasibility of this approach and some valuable conclusions were reached.