Strengthening of concrete structures

The existing concrete structure is affected by various factors such as natural environment and use environment. It shows different degrees of defects such as insufficient bearing capacity and large denaturation. Structural reinforcement refers to strengthening the original stressed structure, so as to meet the new requirements and safety, and save costs and reduce investment.

When its required ?

1. the function of the original building is changed, and some structural members need reinforcement.

2. due to design alteration or construction errors, reinforcement and reinforcement of partial location are needed for in construction projects.

3. the original building is added to the roof or indoor. Due to the increase of load, the related structural components need reinforcement.

4. the existing buildings are in extended service, but there are no conditions to demolish and rebuild the buildings. The main body needs reinforcement.

5. the original parts in the building are obstructing the use and need to be demolished. The transmission way of the original structure is changing and needs reinforcement.

6. new mechanical and electrical equipment, elevators, escalators and other equipment will be added to the building. The load will increase until the equipment foundation is increased, so we need reinforcement.

7. the plane position of elevator and staircase has changed. The original staircase is demolished, and the openings and new openings of the sealing floors need reinforcement.

What are the methods of strengthening ?

1. carbon fiber reinforcement method

CFRP reinforcement is a new type of structural reinforcement technology. It uses resin cementing material to paste CFRP on the surface of concrete, and forms a whole force system with the structure to enhance the bending or shear ability of the reinforced structure, so as to achieve the purpose of strengthening and strengthening the structure and improving the mechanical properties of the structure.

2. enlarging section reinforcement method

The enlarging section reinforcement method is to increase the bearing capacity by adding the reinforced bar of the original component and adding the concrete on the outside to increase the section size of the member. The advantage is that it can increase the stiffness, bearing capacity and deformation capacity of the components, and in some cases, it can also enhance the reliability of the connection. Therefore, it is widely used to reinforce the beam and slab structure and column structure of reinforced concrete structure. The reinforced concrete may be in the tension zone, which can play a binding and protective effect on the reinforced bar; it may also be in the compression zone, increase the effective height of the component, thus improve the flexural and shear bearing capacity of the component, strengthen the stiffness of the component, and improve the force capacity of the component.

3. prestressing reinforcement method

The method of prestressed reinforcement is to reinforce the structure with prestressed carbon fiber sheet. It can improve the bearing capacity of normal section and oblique section of structural members almost without changing the space of use. At the same time, it can effectively eliminate or slow down the stress lag phenomenon of the rear member, reduce the width of the crack of the original beam, and even make it completely closed.

4. bonded steel reinforcement method

The adhesive steel reinforcement method is a kind of reinforcing method to improve the bearing capacity and deformation ability of the structure with a special building structure adhesive on the surface of the reinforced concrete member. The advantage of this method is simple and fast, and its influence on production activities and residents' life is relatively small during construction. The externally bonded steel plate reinforcement method is often used to reinforce the reinforced concrete members subjected to static loads.

Structural strengthening materials

Carbon fiber fabric, CFRP strip, steel plate adhesive, prestressed CFRP plate, structural pouring glue, anchoring adhesive, crack repair adhesive, crack injection adhesive and so on. They aim at different structural defects.