What is structural reinforcement strengthening?

Structural strengthening refers to strengthening the existing stressed structure to meet the new requirements and safety, save costs and reduce investment. It is an activity to strengthen or adjust the internal force of load-bearing structures, components and their related parts with insufficient reliability to make them have sufficient safety and durability, and strive to maintain their applicability. The existing concrete structures are affected by various factors, such as natural environment and service environment, showing various defects, such as insufficient bearing capacity and excessive variability. Researchers at home and abroad have proposed different repair and reinforcement methods for the damaged engineering structures.

Why do structural reinforcement strengthening?

In the 1950s and 1960s, a large number of reinforced concrete plants, public buildings and office buildings were built. These houses have been used for thirty or forty years. Due to improper use and maintenance or construction quality, many houses have problems of one kind or another, some of which are quite serious, endangering the structural safety. However, due to the large investment in civil engineering, although there are some problems in the house, it is often not to demolish and rebuild the house, but to adopt the method of structural reinforcement. As long as a small amount of investment is spent on maintenance and reinforcement, its bearing capacity can be restored to ensure safe use.

In addition, 1. Due to the new use requirements, the original structure also needs to be reinforced if the house is to be changed in use or sandwich.

2. The design has reached the service life, or the original structure can not meet the requirements under the existing specifications, and it needs to be reinforced after the structural identification. After the Sichuan earthquake in 2008, a new anti-seismic code was issued, but the existing buildings cannot meet the requirements of the existing code, so anti-seismic reinforcement is required.

Characteristics of structural reinforcement

1. Carry out targeted reinforcement for components.

2. It has a wide range of similar mechanical performance indicators with concrete members.

3. Good aging resistance and fatigue resistance.

4. The building structural adhesive shall pass the impact peeling toughness test.

Principles of structural reinforcement

1. Before the structural reinforcement plan, determine the content and plan of the reinforcement plan according to the judgment results; At the same time, according to the severity of the structural damage results and the detailed request of the application unit, the safety level of the strengthened structure is determined.

2. The original structures and components shall be preserved and used as far as possible to avoid unnecessary cancellation and replacement. Some shall be preserved to ensure their safety and durability; Withdrawal of some materials should consider the possibility of recovery and application.

3. The technical and economic indicators shall be summarized, and useful methods shall be adopted from the aspects of planning and construction organization to shorten the construction period as much as possible, reduce the shutdown and production stoppage, and try not to affect or less affect the normal operation.

4. Since high temperature, corrosion, freeze-thaw, vibration, uneven settlement of foundation and other factors constitute structural damage, it is necessary to reduce, reduce, or resist these unfortunate factors together during reinforcement, so as to avoid further damage to the reinforced structure and secondary reinforcement.

5. In addition to meeting the requirements for bearing capacity, the strengthening of structures or components should also have the ability to meet the requirements for earthquake resistance. There should be no thin layers or thin parts that form new bad luck for earthquake resistance due to some strengthening or sudden changes in stiffness. At the same time, attention should be paid to the impact of the increase in seismic force due to the increase in structural stiffness. The structural reinforcement shall meet the requirements related to earthquake resistance and the ductility and integrity of the advancing structure.

6. In addition to the analysis of the structure and the calculation of the bearing capacity, the structural strengthening plan also demands reasonable structure and reliable connection.

7. In the structural reinforcement plan, the architectural beauty shall be considered under possible conditions, the facade appearance and interior decoration shall be combined, and the necessary architectural art treatment shall be carried out to avoid the traces of reinforcement.

8. Structural reinforcement construction is often carried out under the condition of load, so it is necessary to adopt useful methods, such as setting temporary supports, unloading treatment, etc., to avoid and avoid safety accidents in the reinforcement construction.

9. When it is really difficult to strengthen the structure or it is really unreasonable through economic summary and comparison, and the original structure is not seriously damaged, the method of changing the use of the structure or reducing and restraining the load can be used for treatment. The method of load reduction can be changed to light materials, and the superstructure can be changed to steel structure; Reduce or restrict the service load of the structure.

How to do structural reinforcement strengthening?

Building reinforcement is an effective method to extend the service life of buildings. During the use of the building, the building structure is damaged due to improper use or long disrepair, or the building structure is damaged due to the occurrence of disaster events, which cannot meet the current use requirements, or reduce the safety value of the building structure. When these problems occur, the building must be reinforced to greatly improve the use quality of the building, so as to ensure the safety and stability of people's daily life.

Before the construction of building reinforcement, it is necessary to conduct the reliability appraisal and seismic appraisal of the building structure. According to the conclusion of the house safety appraisal report issued by the house safety appraisal institution, combined with the specific characteristics of the building structure and the reinforcement construction conditions, it is determined according to the principle of safety, reliability, economy and rationality. Building reinforcement focuses on improving the bearing capacity of structural members, while seismic reinforcement focuses on improving the ductility of the structure and enhancing the integrity of the house; For the reinforcement of concealed works, the principle of "no move, no move" shall be adopted.

After the reinforcement scheme is determined, it is necessary to design the construction drawings and review the drawings after the design is completed. The design of drawings is to have a goal and standard in the construction process; The purpose of drawing review is to check whether the design is reasonable, whether there is possibility of optimization and whether the design is safe and reliable.

Before construction, the construction organization design shall be prepared according to the design requirements and structural characteristics. The construction shall be carried out in strict accordance with the corresponding process standards. In the process, measures shall be taken to avoid or reduce the damage to the original structural components, so as to avoid secondary damage to the original components and adversely affect the later treatment

Reinforcement process: reliability appraisal of existing buildings - selection of reinforcement (reconstruction) schemes - reinforcement (reconstruction) design - construction organization design of reinforcement works - construction - project acceptance.

Methods of structural reinforcement

Enlarge the section, add reinforcement, prestress, change the force transmission path, change the stress system, stick steel, wrap steel, stick carbon fiber, etc.

For concrete members with cracks, crack repair and chemical grouting shall be carried out first. Whether additional reinforcement is required depends on the actual situation and the actual bearing capacity!