What are the advantages of carbon fiber cloth to strengthen the structure?

1. Bending and strengthening performance

Pasting carbon fiber in the tension zone of the concrete structure can effectively improve its bearing capacity and inhibit the propagation of cracks. The failure characteristics of carbon fiber reinforced concrete structures are quite different from those of ordinary concrete structures and concrete structures reinforced with bonded steel, and the calculation methods of their bearing capacity are also different. The research of domestic and foreign scholars mainly focuses on the flexural performance, failure form, bearing capacity calculation, influencing parameters of carbon fiber reinforced concrete beams, and the cross-sectional deformation and crack development of the carbon fiber reinforced concrete beams. In recent years, many scholars have carried out experimental research and theoretical analysis on the mechanical performance of carbon fiber reinforced beams under load, trying to establish calculation methods for flexural bearing capacity, hysteresis strain and mid-span deflection calculation formulas considering secondary forces.

2. Shear reinforcement performance

Pasting carbon fiber on the side of the concrete beam in the shear area can effectively improve its shear resistance. The commonly used shear reinforcement methods in engineering include side pasting, U-shaped pasting and wrapping pasting, among which the wrapping pasting effect is used. The main parameters that affect the performance of carbon fiber shear reinforcement include beam hoop ratio, concrete strength, carbon fiber reinforcement ratio, beam shear span ratio, carbon fiber bonding method and anchoring performance, carbon fiber and the material properties of the adhesive itself. At present, the research on shear reinforcement at home and abroad mainly includes the calculation of failure mechanism and bearing capacity. The theoretical model of bearing capacity calculation is generally based on the theoretical model of reinforced concrete member truss, adding carbon fiber shear bearing capacity Contribution items.

3. Seismic reinforcement performance

By wrapping the carbon fiber to confine the concrete in the plastic hinge area to increase the ultimate compressive strain of the concrete, the ductility of the member can be improved, which is beneficial to the seismic reinforcement of the structure. At present, many scholars at home and abroad have carried out experimental research, theoretical analysis and engineering application research on the seismic performance of outsourcing carbon fiber reinforced concrete columns, beam-column joints and even frames, and proposed corresponding calculation models for the stress-strain relationship of carbon fiber-confined concrete.

Fourth, anti-fatigue reinforcement performance

The fatigue of carbon fiber sheet reinforced components is divided into bending fatigue and shear fatigue. According to the load form, it can be divided into fatigue problems under constant amplitude load and variable amplitude load. The fatigue strength of carbon fiber sheet reinforced components is not only related to the fatigue resistance of the original concrete structure, but also related to the fatigue fracture capability of the carbon fiber reinforced part and the fatigue resistance of the carbon fiber sheet and concrete interface. Concrete flexural fatigue theory can be used to evaluate the fatigue resistance of the original concrete structure. The fatigue resistance of carbon fiber sheet itself can be solved by material mechanics experiments, but the research accumulation on the fatigue resistance of the interface between carbon fiber sheet and concrete Very few, there are only a few test results, these studies show that under repeated, moving loads, the bonding ability of the interface has a downward trend.

5. Durability reinforcement performance

A number of experimental studies have been carried out on the durability of carbon fiber reinforced concrete components at home and abroad. The research parameters include component types (beams, columns), carbon fiber types (AFRP, CFRP, GFRP), bonding methods (circular, axial), Environment type (room temperature, dry and wet, freeze-thaw), resin type, etc. Studies have shown that CFRP has better performance than GFRP in harsh environments. Under the action of dry and wet conditions, the strength and ductility of CFRP-constrained specimens are not reduced, and the stiffness is improved, while the strength and ductility of GFRP-constrained specimens are reduced, and the stiffness is not affected. ; Under the action of the freeze-thaw cycle, the strength and ductility of the CFRP and GFRP constrained specimens are significantly reduced, and the stiffness is not affected. Compared with the specimens under the action of room temperature and dry-wet cycles, the damage mode of the specimens subjected to the freeze-thaw action is more catastrophic sex. After seawater corrosion, the bearing capacity of ordinary reinforced concrete beams and columns and CFRP-reinforced reinforced concrete beams and columns are reduced, but the rigidity of CFRP-reinforced concrete beams is hardly affected in any way.