The reliability design benchmark period of the building structure in my country is set at 50 years, but the reliability of the structure will gradually decrease over time. If we can scientifically analyze the law and extent of this deterioration and damage, and take effective treatment measures in time, we can delay the damage process of the structure and achieve the purpose of prolonging the service life of the structure.

Therefore, reliable appraisal and evaluation of buildings is the basis for building reinforcement and the primary issue of engineering reinforcement. For buildings that are inherently inadequate or poorly managed, improper use or post-disaster building repairs and buildings that need to be added or renovated, investigations, inspections, and scientific identification and evaluation are required.

Throughout the development process of the construction industry in major developed countries in the world, it can be divided into three main stages: large-scale new construction stage, new construction and renovation stage, and a large number of old building maintenance and restoration stages.

During the period of equal emphasis on new construction and maintenance and renovation, on the one hand, in order to meet the needs of social development, new buildings are constantly being constructed. At the same time, the low-standard buildings built in the past can no longer meet the needs of society after decades of use, and need to be repaired, reinforced and remodeled, so that the construction industry transitions to a period of development where both new construction and maintenance are equally important. This has to a large extent promoted the correct identification of buildings in use and the research on effective reinforcement techniques.

Since then, with the development of society and the improvement of people's living standards, people have higher and higher requirements for building functions, and structural safety issues caused by the gradual weakening of the scale and function of existing buildings have begun to attract people's attention. However, the high cost of demolition and the serious impact on normal life and the environment hindered the rise of a new round of new construction. So people turned their attention to the maintenance, reinforcement and transformation of existing buildings. This kind of reinforcement and transformation measures to modernize the functions of internal facilities while improving structural safety has low investment, small impact, and quick results. It not only has considerable economic benefits, but also has huge social benefits. Therefore, the construction industry has stepped into the third development period focusing on modernization, repair and reinforcement.

After the founding of the People’s Republic of my country in 1949, a large-scale construction phase began, which reached its peak in the 1990s and the first ten years of the 20th century. With the passage of time, the buildings built in the early days of the founding of the People's Republic of China and before and after the reform and opening up have approached or even exceeded the design base period.

In view of my country's basic national conditions, my country's construction industry should be in the stage of both new construction and renovation, and gradually develop to the third stage. A large number of buildings already have obvious safety hazards, and there is an urgent need for reinforcement and renovation design.

Moreover, due to the shortage of urban and rural construction land in my country, the housing problem is quite prominent. The addition of floors to low-rise houses built before the 1990s with a large floor area has improved the housing and production technology or use functions of incomplete sanitary equipment or shared units. The transformation and reconstruction of the changed factory building is a very realistic subject.

Taking the road of sustainable development, as the theme of human social development in the 21st century, has formed a consensus around the world. Building a building requires a lot of materials and consumes a lot of resources, many of which are non-renewable.

The maintenance and renovation of buildings to extend their service life as much as possible is in line with the strategy of sustainable development, and therefore has broad prospects.

The three stages experienced by the construction industry in western developed countries are also the three necessary stages for our country. Research on the maintenance and transformation of existing buildings should arouse our attention.

The detection and reinforcement technology in my country started relatively late. These technologies have experienced the development process from scratch, from simple to comprehensive, from partial construction to overall structure. This also makes the detection technology and reinforcement technology continue to be updated to meet the needs of modern buildings. New requirements for quality. Structural identification and reinforcement technology have also developed a lot and are beginning to take shape. As a new discipline, it is gradually taking shape.

There are many reinforcement methods for existing buildings in our country. In the structure, there are enlarged cross-section reinforcement methods, external post-tensioned prestress reinforcement methods, and structural force transmission system reinforcement methods. Among the foundations, there are pile underpinning, foundation treatment, and strengthening of the foundation area. These methods have been used in large quantities in our country for a long time and have obtained a lot of mature experience. With the application of some new technologies such as the bonding steel reinforcement method, the planting reinforcement method, and the carbon fiber reinforcement method, other new technologies are also more and more widely used in engineering reinforcement.

At the same time, my country promulgated the "Technical Specifications for the Reinforcement of Concrete Structures" in 1991 and the "Technical Regulations for the Reinforcement of Concrete Structures with Carbon Fiber Sheets" in 2003. my country's codes and regulations for the maintenance, reconstruction and reinforcement of buildings also include: "Masonry and Concrete Structures" "Technical Specifications for Building Stories", "Technical Specifications for Foundation Reinforcement of Existing Buildings", "Technical Standards for On-site Inspection of Masonry Engineering", etc. The promulgation and implementation of norms and regulations on the maintenance, renovation and reinforcement of buildings further shows that we are paying more and more attention to the maintenance, renovation, reinforcement and reuse of buildings in use. At the same time, it has also promoted the research and development of the renovation and reinforcement industry in my country. Become an important part of my country's construction industry.

In recent years, as the pace of urban transformation in my country has been accelerating, the demand for maintenance of buildings in use has also increased. The development of production does not only rely on new construction, but also the technological transformation of old projects is very necessary.