The bridge structure directly bears various loads from the bridge deck, and various diseases will inevitably appear during operation. With the rapid increase of traffic flow and heavy vehicles, the rate of appearance and deterioration of bridge structure diseases is gradually accelerating.

Bridge Overview

Wuhan Second Yangtze River Bridge is the second Yangtze River Bridge in Wuhan. It was completed and opened to traffic in June 1995. The bridge has a total length of 4,678 m, of which the main bridge is 1,876. 1 m and the bridge is 26.5 m wide. The main girder is a straight-web double-box single-chamber box girder, arranged symmetrically according to the center line of the bridge. After it was completed and opened to traffic, the bridge has been overwhelmed due to overloaded operations. After a comprehensive inspection of the bridge from 2000 to 2005, it was found that the cumulative damage of the bridge has reduced the stiffness of the bridge to a certain extent, and the concrete surface inside the beam is densely cracked. The most serious is the continuous rigid frame span of the bridge. The part deflection accumulated 82 mm, and the test data showed that the crack and deflection continued to develop. Therefore, from the perspective of safety, timely and effective repair and reinforcement of the bridge appear to be very necessary.

In the process of maintenance and reinforcement of the bridge, the external pre-stressed tensioning method and the reinforcement method of adding a web stiffness frame were implemented on the bridge as a whole, which played a great role in maintaining the overall structure of the bridge and maintaining the overall stability of the bridge. For the local area, crack sealing treatment and the method of sticking steel plate and carbon fiber wrap are adopted to strengthen the disease according to the disease and the location of the disease. This article mainly introduces the reinforcement technology of sticking unidirectional carbon fiber wrap to the continuous beam on the Hankou side of the bridge.

Concrete structure repair method

As far as the current situation is concerned, the main technical methods for strengthening, reforming and repairing concrete structures include: reinforced concrete thickening method; external prestressing method; outer steel and sticking steel plate method; carbon fiber sheet reinforcement method and seismic isolation and damping .

The carbon fiber wrap sheet reinforcement method has the characteristics of low relative density, high fatigue strength, good durability, abrasion resistance, and convenient construction. There is no need for formwork and large mechanical equipment, and it is not restricted by construction conditions, and basically does not affect the shape of the original structure. It is the latest development of concrete structure repair and reinforcement technology.

In a comprehensive comparison, the continuous beams on the Hankou side of the Wuhan Yangtze River Second Bridge are patched with carbon fiber wrap to repair local diseases.

The main material for carbon fiber wrap reinforcement

1) The bridge reinforcement uses unidirectional fabric (wrap), high-strength type I carbon fiber wrap.

2) Grade A glue is used in the bridge reinforcement

Construction Notes

The reinforced structure should have a certain strength, because the box girder of Wuhan Yangtze River Second Bridge is made of C50 concrete, it can meet the strength requirements. In the actual structural reinforcement, the fiber is a secondary force, and there is a strain hysteresis. Therefore, during the reinforcement construction, the load on the structure should be removed as much as possible to reduce the strain hysteresis of the fiber. In order to prevent the occurrence of adhesive peeling damage, two aspects should be noted:

1) Choose the right binder

2) Ensure that the carbon fiber wrap has sufficient traceability.

A total of 14 000 m2 of carbon fiber wrap was used in the maintenance of the continuous beams on the Hankou side of the Wuhan Second Yangtze River Bridge. The externally pasted carbon fiber wrap played a very important role in the reinforcement of the bridge, and the reinforcement effect was good. With people's further in-depth research on carbon fiber materials and the practice and promotion of carbon fiber reinforcement technology, carbon fiber materials are used as a new type of building reinforcement material. Its excellent performance and excellent reinforcement effect will be further manifested. Carbon fiber reinforcement theory and reinforcement technology will gradually mature, and carbon fiber reinforcement technology will play an increasingly important role in the field of engineering reinforcement.