Research on Single Damage Identification of Multi-span Bridge Based on Influence Line

Abstract

Bridges are an important part of traffic engineering. They play an irreplaceable role in developing national economy, promoting cultural exchanges and consolidating national defense. The structural safety of bridges is the primary prerequisite for their role. However, due to the influence of many factors such as material aging, external environmental corrosion, longterm load action and accidental impact, the bridge structure will be damaged to different degrees, and the bridge will be destroyed when the damage accumulates to a certain degree. Once the bridge is damaged, it will have a great negative impact on human life safety, property safety, and social stability. Therefore, studying the method of rapid and accurate identification of bridge structure damage has great theoretical significance and engineering value. Based on the current status and existing problems of existing bridge structure damage identification, this paper proposes a continuous beam bridge structure damage identification technology based on deflection influence lines. Firstly, using graph multiplication and other theories, the expression of influence line function on the deflection of multi-span continuous beam bridge is derived. The influence line function of continuous beam bridge without structural damage is derived from the theoretical level, and the graph is drawn. Through the formula of the deflection influence line of healthy structure, it can be confirmed that the deflection influence line obtained quickly under the visual tracking technology can identify the damage of the structure. We use software modeling to find the best identification parameters. Using MIDAS/Civil software can establish the model and simulate the deflection influence lines of different measuring points of continuous beam bridge structures with different positions and different degrees of damage under the action of moving loads. Taking the continuous beam bridge deflection influence line, the difference between the deflection influence line of the first derivative and the second derivative, the first derivative and the second derivative and other parameters as the research objects, we explore how to use the deflection influence line to identify damage. Finally, after the comparison of multiple working conditions and multiple measuring points, it is found that the damage identification effect of the first derivative of the deflection influence line difference is the best.