First, the principle of bonding steel plate strengthening method

The bonding steel plate reinforcement method is to apply epoxy resin series adhesive on the steel plate, and then paste it into the weak part of the reinforced concrete structure's tensile area, the steel plate and the structure form the whole, and the additional reinforcing bar is added. Through the combined action of steel plate and reinforcement structure, the stiffness is improved, the crack changes are prevented, the stress state of reinforcing steel and concrete is improved, and the bearing capacity of beam is improved.

Two. usage of bonding steel plate strengthening method

Anchored in the tensile edge or weak part of the concrete structure to make it and structure form a whole, with bodning steel plate instead of additional reinforcing bar.

Three, advantages and disadvantages

advantages of bonding steel plate strengthening method

1. advanced technology and good performance

The high strength steel plate is bonded to the reinforced concrete beams strengthened by parts, not only can guarantee the concrete and steel plate as a whole new force, but also can give full play to the strength of steel stick, crack closure paste position of the reinforcing member, constrained deformation of concrete, so as to effectively improve the structural stiffness and reinforcement crack resistance.

At the same time, it can be pasted in any way according to design needs and possibilities. It can effectively exert flexural, shear and compressive properties of bonded steel members, and its force is even, so it does not cause stress concentration in concrete.

2. of the space is small and does not affect the appearance of the reinforced structure and the use of space

Because adding solid is mostly a layer of 3~4mm thick steel plate, which is pasted on the structure with relatively large shape or thickness, so adding solid occupies little space and basically doesn't affect appearance. To reinforce the space required for the construction, and also to meet the requirements of the clearance, use the top and anchor bolt to press and paste.

3. short construction period is short

By cleaning, repairing and reinforcing the surface of the members, the steel plates are pasted on the components to press and solidify for about 1~2 days. Compared with other reinforcement methods, the construction time can be greatly saved.

4. material consumption is small

The steel can be attached to the reinforcing parts of the component according to the required amount of calculation and co ordinate the force with the original component.

5. process is simple and convenient

The process of bonded steel reinforcement is to clean and repair the surface of the reinforced component, remove rust from the steel plate, glue and paste, press and solidify, and expose the rust paint on the outer surface of the steel plate. The construction technology is simple and convenient. As long as we are careful and meticulous, every process is easy to meet the requirements of the operation rules.

At the same time, there is no need to destroy the original structure that is reinforced. Reinforcement works hardly increase the size of the original structure, and can hardly change the original artistic characteristics of the historic value building.

disadvantages of bonding steel plate strengthening method

The disadvantage of the method is the stress hysteresis phenomenon in the stress of the bonded steel plate, and the greater the load of the original structure is, the more the stress lag is. The quality and durability of the binder are the main factors affecting the reinforcement effect, and the influence of the construction quality is obvious.

Steel plate reinforcement

Four. application of bonding steel plate strengthening method

The commonly used forms of pasting steel plate reinforcement are: plate girder bridge or T beam bridge, bottom sticking longitudinal steel plate reinforcement, box girder or T beam (or I-beam), beam abdomen sticking inclined steel plate reinforcement, cantilever beam corbel or hanging beam end sticking steel plate reinforcement, arch bridge arch ring sticking steel plate reinforcement and so on.

In order to ensure that the steel plate is formed with the reinforced component, the steel plate must have sufficient anchorage length, and the binder has sufficient bond strength and durability. In order to avoid the degumming of steel plate, the end part can be tightened with bolt to be fixed, but it must be paid attention to not causing unnecessary damage to the section of the component. The following is as follows:

(1) suitable for bending and pulling members;

(2) the bridge structure is adapted to the external environment, which is not more than 60, the relative humidity is not more than 70% and no chemical corrosion area.

(3) use the mature structure glue and treat the new glue carefully.

(4) test shows that the shear bond strength and the tensile strength of concrete is greater than the shear strength, tensile strength, damage occurred in the concrete and not in the adhesive layer, the bond strength of steel plate and concrete depends entirely on concrete strength, concrete strength can not be too low, otherwise it can not play the role of adhesives and steel plate.

Five, material requirements

1. steel plate adhesive has high strength, good thixotropy, more toughness and good durability.

2. the strength design value of steel plate, connecting bolt and weld seam should be adopted according to the current design specification of steel structure.