Fracture Analysis of Bridge Anchor Plate

Analysis of Fracture Failure of Anchor Plate in Large-Span Bridge

Fracture failure is a typical failure form of anchor plates in large-span bridge construction. It is a critical failure form for the life-time safety of the structure, and it is also a buzzword in the bridge failure analysis field. Among them, the fracture failure of anchor plate is one of the typical failure forms of bridge structure. In order to ensure the stability and safety of large bridges, it is necessary to analyze thoroughly the cause and mechanism of the fracture of the anchor plate, so that effective measures can be taken to prevent and solve the related problems.

In the past few years, the fracture failure of anchor plate in large-span bridge has become an important issue in bridge engineering construction. The main reason for this phenomenon is the overloading caused by external or internal forces, or the stress concentration caused by the adjacent members stiffness incompatibility and load path. The load of the large-span bridge is not only concentrated on the anchor plate, but also through the connection and force transmission of the joint system. Therefore, the external forces and internal forces of the anchor plate bear the force at the same time, and the combination of these forces will inevitably lead to serious stress concentration in the anchor plate, resulting in the fracture failure of the anchor plate.

In view of the fracture failure of anchor plates in large-span bridges, it is necessary to identify the cause and mechanism of the failure in order to take effective measures to prevent and solve the related problems. In order to analyze the fracture failure of anchor plates in large-span bridges, it is necessary to accurately evaluate the distribution of stress and strain within the anchor plate, so as to understand the general distribution of the stress and strain, and to grasp the specific location or trend of the fracture in advance. The evaluation of the internal stress and strain of the anchor plate can be conducted based on the fracture mechanics theories such as stationary fracture mechanics, dynamic fracture mechanics, linear fracture mechanics and ductile fracture mechanics. Through the analysis and evaluation of fracture mechanics theories, it is possible to understand the fracture failure process of anchor plate, and to better judge whether the anchor plate should be replaced or strengthened.

By analyzing the fracture failure of the anchor plates in large-span bridges, it can be found out that there are still many problems in the design and construction of large-span bridges, such as unreasonable design of the joint system, insufficient calculation of the bearing capacity of the member, and insufficient attention to the stress concentration of the joints, etc., all of which are due to the lack of experience, insufficient understanding and immature technology. Therefore, in order to reduce the fracture failure of the anchor plate in large-span bridge and ensure the stability and safety of the bridge, it is necessary to strengthen the design and construction management of the bridge, formulate corresponding design standards to control anchor plate fracture incident, and constantly improve the calculation standards of bridge construction so as to the reduce the risk of fracture failure of the anchor plate.

In conclusion, the fracture failure of anchor plates in large-span bridges is a very important and influential phenomenon, which needs to be taken seriously by all parties in the engineering construction. Only by analyzing and evaluating the fracture failure of anchor plates in large-span bridges in a comprehensive and systematic way, can the causes and failure mechanisms of anchoring plates be accurately identified, and effective and feasible measures be taken to prevent and solve the related problems, so as to ensure the safe operation of the bridge and the health and safety of the surrounding people.

The Soryu-Oohashi bridge is one of the most important large bridges in Japan. It is a suspension bridge carrying more than 50,000 vehicles each day connecting Osaka and Wakayama Prefectures. Its weight of 35,000 tonnes supports the roadway, which is suspended by cables, connected to the main anchor piers of the bridge.

However, it occurred in 2013 that several anchor plates of the bridge have cracked due to the constant movement caused by seismic activities. The initial inspection of the plates revealed that they were cut at an angle of 45 degrees, which made them more prone to deformation. In consequence, the anchor plates were unable to with stand the seismic activity and this led to their fracture.

Several factors have been attributed to the fracture of the bridge anchor plates, including the inadequate design, the poor quality of steel material and the welding technique used to forge the plates. In addition, the thickness of the plates used was not enough to withstand the continuous vibrations generated by the seismic activities.

To fix the issue, the engineering team of the bridge decided to reinforce the main anchor piers in order to disperse the concentrated stresses development. The reinforcement involved the addition of some thicker plates as well as steel plates with better fatigue resistance. This approach allowed to redistribute the stresses and increases the overall resistance of the main anchor piers.

Overall, the fracture of the Soryu-Oohashi bridges anchor plates was caused by the combination of inadequate design, poor material quality and the welding technique of the plates. However, the bridge engineers managed to effectively rescue the bridge structure from collapse by reinforcing the anchor plates in an appropriate manner.