CFRP composite strengthening bridge

General situation of Engineering

The maintenance renovation of the irrigation canal bridge of the North Jiangsu Expressway has been the first maintenance since the bridge was opened to traffic in December 8, 2000. In order to ensure the normal, safe and smooth transportation of this important north-south highway, the bridge maintenance repair project adopts non closed construction method with a construction period of 1 months.

Reinforcement time

September 2014

Reinforcement method

Strengthening method by bonding carbon fiber cloth

Material selection

HM carbon fiber cloth, HM carbon fiber glue

Strengthening concrete column reinforced with carbon fiber wrap

column reinforced with carbon fiber wrap

column reinforced with carbon fiber wrap

Since most of the engineering building structures use reinforced concrete columns as their primary load-bearing form, it has practical engineering significance for their reinforcement research.

Technical characteristics of reinforced concrete column with carbon fiber wrap

First, the characteristics of carbon fiber materials. 

Carbon fiber wrap has small thickness, light weight, good flexibility, acid and alkali resistance, high temperature resistance, fatigue resistance and creep resistance. It can meet the requirements of bending, compression and earthquake resistance, and at the same time can resist the corrosion of various acids, alkalis and salts that the reinforced column is often subjected to. Carbon fiber wrap forms a second protective layer on the surface of the concrete column, which enhances the durability of the concrete. It has little effect on increasing the weight of the column and the cross-sectional size, and meets the appearance requirements of the reinforcement.

Secondly, in terms of stress characteristics.

Carbon fiber wrap has high tensile strength and is easy to bond well with the concrete surface. After transversely surrounding the column, the stress state of the concrete is changed from two directions to three directions, becoming constrained concrete, which has been greatly improved in both bearing capacity and ductility

Finally, engineering application.

It has the characteristics of non-destructive reinforcement of the original structure, easy construction and easy guarantee of construction quality. Unlike other reinforcement methods, carbon fiber wrap reinforces the entire construction process without large machines and wet operations, does not require a large number of fixed safeguards, and has a small occupation rate and high work efficiency. In terms of reinforcement quality, even if the surface of the reinforcement member is not flat, due to the flexibility of the carbon fiber wrap material, the adhesion efficiency can be guaranteed, and the maintenance cost of the investment in the later period is lower and the service life is longer.

carbon-fiber-is-an-effective-seismic-reinforcement-material

Carbon fiber is the mainstream seismic reinforcement material in the world.

But do you know why carbon fiber can be used for seismic reinforcement?

Let's do a little experiment.

Usually when we eat food in plastic packaging bags, there will be a small mouth on the side. It is especially easy to tear the packaging bag when it is torn from this mouth.

Concrete is a brittle material. If there are cracks in the concrete wall, it is easy to cause the entire wall or floor to crack. So in the event of an earthquake, if there is a crack, it will be fatal to the whole building.

Therefore, carbon fiber will be used for seismic reinforcement.

The carbon fiber contains a large number of carbon fiber bundles, and is a ductile material. If an earthquake occurs, hard steel or concrete will be damaged. However, there is carbon fiber cloth attached to the wall. The wall will not be broken directly, but will be linked by carbon fiber. The entire structure is connected as a whole to absorb the force released by the earthquake. Even if the deformation is large, the floor or wall will not collapse or fall directly, and it will win time for people to survive.

The carbon fiber has many excellent properties, the weight is very low, significantly reducing the load and saving materials. And the anti-corrosion performance is outstanding, the durability is far beyond the level of the steel structure, and it is a rare material for seismic reinforcement. Can greatly improve building safety and save costs.

Prestressed carbon plate reinforcement vs carbon fiber

Compared with the traditional reinforcement technology, carbon fiber cloth reinforcement and prestressed carbon plate reinforcement technology have many significant advantages. The most notable feature is that it reduces the difficulty of construction and guarantees the construction effect.

Carbon Fiber

Carbon fiber reinforcement technology is a new type of reinforcement technology that is reinforced by carbon fiber cloth to improve the stress state of components and limit the occurrence and development of cracks.

When carbon fiber cloth first entered China, many people felt it looked like a "magic cloth", looking thin, but full of energy. Take Horse carbon fiber cloth as an example. Can you imagine that it only has 23% of the weight of steel, but can exert a strength of up to 4300 MPa?

Carbon fiber's characteristics

1.Light self-weight, can operate in a narrow and small space, not affect the normal use of the houses in the construction;

2.High strength, can be used in bending, closed hoop and shear reinforcement flexibly;

3.Has the flexibility, can wrap components with complex shape;

4.Suitable for surface of various components (beams, columns, ventilation tube, pipe, wall);

5.Anti-acid alkali and other chemical corrosion and rugged environments (have no environmental pollution in themselves);

6.Long storage life, allow long operational deadline;

7.High strength, high modulus;

8.Can be the substrates of concrete, masonry structure, wood structure, and many other structures;

9.High temperature resistance, creep resistance under permanent load, corrosion resistance and good seismic resistance performance

Prestressed Carbon Plate

For the reinforcement of large-span beam-slab members, although the construction cost of carbon fiber cloth is low, it is actually a passive reinforcement, and the problem of stress lag will occur. 

The prestressed carbon fiber plate reinforcement technology overcomes this problem. It can improve the bending stiffness of the flexural member, reduce the deflection of the original member, limit the development of structural cracks, and solve the contradiction between the carbon fiber strength and the elastic modulus ratio is too high. Horse's prestressed carbon fiber plate has a tensile strength more than 10-15 times that of ordinary steel, and it performs well in major bridge reinforcement projects. Has been successfully used in Chile, India, Thailand, Malaysia, Indonesia and other markets.

Prestressed carbon plate characteristics

1.High strength carbon fiber plate, increase loading tremendously

2.Achieve high strength of carbon fiber by prestress

3.Active loading by prestress, no train lagging

4.Achieve Reverse bending moment, offset part of loading, increase stiffness, reduce distortion and deflection of members.

5.Reduce cracks, avoid and stop cracking.