Prevention and reinforcement method of fatigue cracks caused by external deformation of railway steel bridge deck

Abstract

The invention discloses a method for preventing and reinforcing fatigue cracks caused by railway steel bridge out-plane deformation. The method includes the determination step, the hammering step, the crack preventing step and the reinforcing step. In the determination step, the railway steel bridge is examined, whether cracks exist or not is determined, if no cracks exist, stress at the ends of H-shaped beam web vertical stiffening ribs is analyzed, and whether the risk that cracks are generated or not is judged. In the hammering step, weld toes within 100 mm of the ends of weld joints of the vertical stiffening ribs on the two sides of a H-shaped beam web and inwards concave portions between weld passes are subjected to ultrasonic hammering. In the crack preventing step, a magnetic drill is used for drilling round holes in the tip ends of the cracks at the ends of the stiffening ribs, and meanwhile the tip ends of the cracks fall into the round holes. In the reinforcing step, a lower flange of an H-shaped beam is connected with the vertical stiffening ribs through angle steel and cushion plates to reduce out-plane deformation. The method has the advantages that welding fatigue strength can be improved, the service life can be prolonged, local rigidity of cracking portions is improved, out-plane deformation is reduced, and the cracks are effectively prevented from further extending.

Description

technical field [0001] The invention relates to the technical field of civil engineering, in particular to a method for preventing and reinforcing fatigue cracks caused by external deformation of a railway steel bridge. Background technique [0002] Heavy-duty railway transportation has obvious economic advantages in centralized, bulk and long-distance cargo transportation, and its transportation benefits have been confirmed by the performance of domestic and foreign railway transportation industries. In recent years, with the research and application of new technologies, heavy-duty railway transportation has developed rapidly, and the transportation efficiency has been continuously improved. It has become one of the main development directions of railway freight transportation in the world. With the construction and operation of my country's passenger railway network, it will be one of the main directions for the development of my country's railways to organize freight tran...

AI Technical Summary

Problems solved by technology

Fatigue cracks caused by principal stress can be effectively controlled by establishing appropriate fatigue design specifications and ensuring processing quality, but for fatigue cracks caused by out-of-plane deformation, due to the lack of deep research and high frequency of occurrence, etc It needs to be paid attention to, and the specific causes should be analyzed for different types of cracks, and reasonable and effective prevention and reinforcement methods should be selected

The crack at the end of the vertical stiffener of the I-shaped beam web is a typical fatigue crack caused by repeated out-of-plane deformation of the web. The crack is generally parallel to the stress field at first, and will not seriously affect the safety of the bridge. However, when the crack tip When the turning direction is perpendicular to the stress field, the crack may further extend to the flange, causing the main beam to lose its bearing capacity, so it should be repaired in time

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