What is prestressing really? Prestressing is the pre applied compressive stress to the structure during construction to improve its service performance. During the service period, the pre applied stress can completely or partially offset the tensile stress caused by the load, avoiding structural damage.

The prestressed carbon fiber plate reinforcement technology and steel strand reinforcement belong to the external prestressing reinforcement method. Its reinforcement principle is to apply external prestressing to the reinforced components, which is an indirect reinforcement method that improves or adjusts the stress situation of the original structure and components. Their scope of application is also roughly the same, and they are mostly used for strengthening reinforced concrete flexural, tensile, and large eccentric compression components with small reinforcement sections or insufficient reinforcement, to improve the bearing capacity of building sections, etc.

Although they all belong to the external prestressing reinforcement method and the reinforcement principle is basically the same, what are the obvious differences between them?

Difference 1: In terms of material, when reinforcing reinforced concrete, the elastic modulus of carbon fiber material is similar to that of steel bars, but its strength is 5 times that of steel bars, while steel strands do not possess this characteristic. Therefore, when the structure undergoes significant deformation, prestressed carbon fiber reinforcement technology can greatly improve the strength utilization rate of carbon fiber materials, while steel strands with similar strength to steel bars cannot achieve this effect.

Difference 2: In terms of layout, the reinforcement of prestressed steel strands is external prestressed reinforcement with unbonded steel strands, which has a small change in stress and is beneficial for structural stress. The prestressed arrangement is flexible and can be used for local reinforcement, facilitating component replacement and later maintenance operations.

However, the prestressed carbon fiber plate reinforcement system requires the use of structural adhesive to bond the carbon fiber plate and concrete components together, making it a whole with superior overall performance. While increasing the strength and stiffness of the structure, it can also reduce the deflection and deformation of the structure, and reduce and seal the cracks caused by insufficient bearing capacity of concrete components.

Difference 3: In terms of construction technology, the prestressed carbon fiber plate reinforcement technology has certain temperature requirements during construction due to the need to be used in conjunction with structural adhesive. At the same time, in order to achieve the reinforcement effect, there may be some limitations on the distance between the tension end and the fixed end of the carbon fiber plate reinforcement system. When strengthening large-span components, segmented construction is required; The prestressed steel strand has relatively small requirements in this regard and is more suitable for reinforcement of complex sections, but has strict requirements for later maintenance.

In summary, we can conclude that the reinforcement and strengthening technologies of prestressed steel strands and prestressed carbon fiber sheets have their respective application ranges and advantages.

In short, there is no universal method for strengthening buildings. We need to choose suitable reinforcement methods based on the actual situation to truly ensure the safety of the structure.