Wrap the reinforced concrete column with carbon fiber material so that the fiber direction is perpendicular to the column axis, which can effectively improve the ductility and bearing capacity of the column and increase its seismic energy dissipation capacity. In addition, the shear wall as the main anti-side force member, its failure form is nothing more than bending ductility failure (medium-high shear wall) or shear brittle failure (low shear wall). The use of carbon fiber to reinforce shear walls can also significantly increase their ductility and bearing capacity as long as the method is appropriate. Therefore, the seismic reinforcement of reinforced concrete structures is an effective field for the application of carbon fiber materials. However, it should be pointed out that when carbon columns are used to reinforce columns or shear walls, the carbon fibers themselves are flexible materials and are bonded to the reinforced structure by structural glue. This requires that the reinforced structure concrete must meet certain strength requirements. Only then is it possible to exert the reinforcement effect of carbon fiber. The following uses actual engineering as an example to illustrate the method of strengthening reinforced concrete columns with carbon fiber and improving seismic performance.

Project Overview

In a certain multi-layer reinforced concrete frame structure, during construction acceptance, it was found that the concrete strength of 9 frame columns could not meet the design requirements, resulting in an excessive axial compression ratio and unable to meet the ductility requirements required by the axial compression ratio limit. In this regard, a reinforcement scheme for wrapping the column with carbon fiber fabric was determined. The reason for this is that on the one hand, the carbon fiber wrapping has a hoop effect on the column concrete, which can increase the axial compressive strength of the concrete to a certain extent. On the other hand, the lateral restraint effect of carbon fiber on the column can also significantly improve the ductility of the column under horizontal loads and meet the ductility requirements of the axial compression ratio.

Reinforcement plan

The reinforcing material is Horse unidirectional carbon fiber fabric and carbon glue. Through calculation of bearing capacity and ductility, the three columns with lower strength are wrapped with three layers of carbon fiber fabric along the entire column height, and the other six columns are wrapped with two layers of carbon fiber fabric along the entire column height. The reinforcement scheme is shown in Figure 1.

After being reinforced with carbon fiber, the shear capacity and ductility of the frame column can be significantly improved. When reinforced concrete columns are reinforced with carbon fiber to improve seismic resistance, the amount of carbon fiber fabric should be determined according to the bearing capacity and ductility index.