"Prestress" is designed to improve the service performance of the structure. During the construction period, the pressure is applied to the structure in advance. The precompression stress in the structure during service can completely or partially counteract the tensile stress caused by the load and avoid structural damage.

In recent years, the concept of prestress in the field of building structure has been mentioned by more and more people. In the field of structural reinforcement, the application of prestressed reinforcement technology is developing faster and faster. There are two main ways of prestressed reinforcement: prestressed FRP laminate and Prestress wire.

The reinforcement technology of Prestressed CFRP plate and steel stranded wire is the external prestressing reinforcement method, and its strengthening principle is an indirect reinforcement method for improving or adjusting the force condition of the original structure and component by applying external prestress to the reinforced component. Their scope of application is also roughly the same. Most of them are used in the reinforcement of reinforced concrete members with small reinforcement section or lack of reinforcement because of bending, drawing and large eccentric compression, which can be used to improve the bearing capacity of the building section.

The difference between prestress CFRP plate and prestressed strand

1.From the material, the modulus of elasticity of the carbon fiber material is similar to that of the steel, but the strength is 5 times that of the steel, but the steel strand does not have this characteristic. Therefore, when the deformation of the structure is large, the reinforcement technology of prestressed carbon fiber can greatly improve the strength utilization of carbon fiber material, but the steel wire with similar strength can not achieve this effect.

2.In terms of layout, the prestressed steel strand is strengthened to the non adhesive steel strand in external prestressing force, the stress change is small, the stress is favorable to the structure, the prestress is arranged flexibly, the local reinforcement can be carried out, the parts change and the later maintenance operation is convenient.

However, the prestressed CFRP reinforcement system needs to use structural adhesive to bond the CFRP with the concrete components to make it a whole, and the overall performance is superior. While increasing the strength and rigidity of the structure, it can reduce the deflection and deformation of the structure, and can reduce and seal the cracks caused by the insufficient bearing capacity of the concrete members.

3.In the construction technology, the prestressed CFRP reinforcement technology needs to be used together with the structural adhesive, and the temperature is required at the time of construction. At the same time, in order to achieve the reinforcement effect, the distance between the tensile end and the fixed end of the CFRP reinforcement system may be limited, for the large span components. The construction of the reinforcement should be segmented while the prestressed steel strand is relatively small, and it is more suitable for the reinforcement of the complex section, but it is more strict for the later maintenance.