The procedures for strengthening and retrofitting existing structures：reliability identification of existing buildings — the selection of strengthening and retrofitting schemes – strengthening and retrofitting design — construction organization of reinforcement engineering — construction — inspection and acceptance of finished projects.

1.Reliability identification

Reliability evaluation is the basis for reinforcement or reconstruction of existing buildings. A comprehensive understanding of the structural performance and safety problems of the building (such as material strength, structural measures, cracks, deformation and use conditions) must be fully understood, and the reliability of the structure must be evaluated comprehensively.

2.A good choice of reinforcement (transformation) scheme

The choice of reinforcement scheme not only affects the investment of funds, but also affects the quality of reinforcement. For example, the reinforced concrete members with insufficient reinforcement and high reinforcement have no reinforcement function in the tensile area. The reasonable reinforcement plan should meet the following requirements: the strengthening effect is good, the use function is small, the technology is reliable, the construction is simple, the economy is reasonable and the appearance is neat.

3.The design of reinforcement (reconstruction)

Building reinforcement (transformation) design includes three parts: checking calculation of bearing capacity of reinforced component, construction processing and drawing construction drawing.

For carrying capacity calculation, special attention should be paid to the synergy between the new part and the original structural member. Generally speaking, the stress of the new part is lagged behind the original structure.

The structural treatment of reinforcement (retrofit) structure should not only satisfy the structural requirements of the new member, but also consider its connection with the original structural member. The new and old components should be accepted together.

4.Construction organization design

The following aspects should be taken into consideration in the construction organization design of reinforcement works.

(1) the construction site is narrow, the site is crowded, and the normal operation of the premises.

(2) restricted by production equipment, pipelines and original structures and components;

(3) reinforcement must be carried out without affecting or minimizing the use.

(4) during construction, the workload of demolition and cleaning is large, and the construction needs to be carried out in stages and stages.

Because most of the reinforcement works are carried out under load or partial load, the safety during construction is very important. One of the measures is to remove a part of the outer load as far as possible before construction and to apply prestressed pretension and to reduce the stress in the original component.

5.Construction

When the original components are removed or cleaned before reinforcement, special attention should be paid to whether there is any discrepancy with the original inspection and appraisal. Engineers and technicians should be at the scene to observe any accidents. In case of accidents, construction should be stopped immediately and proper treatment measures should be taken. During construction, attention should be paid to the connection quality between the old and new components.

The reinforcement of buildings should be decided in a quick and decisive manner, with minimal impact on the use and avoidance of accidents.

6.Acceptance of work

After the completion of the reinforcement project, the professional and technical personnel should be organized by the use unit or its competent department, and should be carried out in strict accordance with the relevant regulations on the construction or acceptance of the reinforcement project.