The production method is to combine chopped polypropylene nitrile or pitch carbon fiber with pulp or synthetic pulp to make paper, and then use phenolic aldehyde, aldehyde, polyester, acrylonitrile-butadiene-styrene copolymer, Epoxy and other resin solutions – a kind of dipping treatment, can be made into soft films or rigid plates, etc., used as various energy-saving and heating bodies. According to the heat resistance of different resins and the different resistances of carbon fibers, it has the function of heating in different temperature zones after electrification, with stable thermal characteristics and energy saving, and can emit infrared rays of wavelength.
1. Corrosion resistance, fatigue resistance: Carbon fiber has high-strength corrosion resistance and fatigue resistance, and can last for a hundred years. 2. High and low temperature resistance: Suitable for use in various harsh environments, and can withstand low temperatures of -100°C and high temperatures of 150°C. 3. Small coefficient of thermal expansion: Small thermal expansion coefficient and anisotropy, good X-ray transparency, good electrical and thermal conductivity, and good electromagnetic shielding. 4. High axial strength: Carbon fiber has high axial strength and modulus, low density, high specific performance, and no creep.
Carbon fiber reinforced composite materials have the advantages of light weight, high strength, easy molding, good corrosion resistance and durability, good fatigue resistance, and convenient construction. They have been widely used in concrete structure repairs, and carbon fiber sheets are used to reinforce steel The structure can take advantage of these advantages of carbon fiber sheets, and can avoid the defects of traditional steel structure reinforcement methods, so it has broad application prospects in steel structure reinforcement.
Commonly used sheets in structural repair mainly include sheet and cloth. Carbon fiber cloth is woven directly from carbon fiber, while carbon fiber sheet is made by impregnating carbon fiber with resin, curing it in a mold and continuously pultruding it. The thickness is generally 1~ 1.6mm. Carbon fiber cloth is easy to shape and is suitable for surface reinforcement of various shapes; while carbon fiber sheet has the characteristics of good quality, stable performance, and convenient construction.
1. Repair of flexural members
The repair of the flexural member of the steel structure is usually to paste the carbon fiber sheet directly on the bottom of the tension flange. Carbon fiber is suitable for adding tension to various forms of steel beams and improving the bearing capacity of the beams. Carbon fiber is suitable for strengthening various forms of steel beams, including I-shaped section steel beams, rectangular section steel beams, steel plate beams, and steel-concrete composite beams.
2. Repair of tension (compression) members
Pasting carbon fiber reinforcement has a good effect on improving the bearing capacity of steel structure tension (compression) members.
Experimental research on carbon fiber reinforced hollow pipe columns shows that the reinforcement effect of sticking carbon fiber cloth along the circumferential direction of the square pipe is far better than that of the longitudinal direction, and the ultimate bearing capacity is increased by 18%.
3. Repair of steel pipe lines under internal pressure
The steel pipe line reinforced by carbon fiber winding, under the action of internal pressure, the pipe wall mainly bears the hoop stress, the steel pipe line expands, and the radial deformation is constrained by the externally wound carbon fiber, so that the carbon fiber and the steel pipe line are jointly stressed, reducing The hoop stress of the pipe wall is reduced, thereby improving the ability of the pipeline to withstand internal pressure.
4. Fatigue Repair of Steel Structures
The survey results show that steel members in practical engineering generally require a high number of cycles, and the stress cycles in 50 years, are nearly 10 million times.
Under the action of alternating load, the load-bearing capacity and stress amplitude are increased and the fatigue strength and fatigue life of the components are indirectly increased. The results show that the residual fatigue life of the steel structures with fatigue damage increases exponentially after the use of FRP, and the reinforcement effect is very obvious.
5. Prestressed carbon fiber reinforcement
As the elastic modulus is close to that of steel, the strength of carbon fiber can not be fully utilized in normal use, and the reinforcement has no significant effect on the performance improvement in normal use stage. After prestressing the carbon fiber sheet and then sticking it on the beam ramen for reinforcement, the above problems can be solved effectively.
