Applications Projects

The No. 1 building of Beijing Julong Company is a newly built 8-story reinforced concrete frame structure, which has not been put into use after completion, and its use function has changed. The first and second floors were converted into production workshops, and heavier equipment was arranged; the loads on the air-conditioning machine rooms at both ends of the first to third floors also increased a lot. The structure is recalculated according to the load after reconstruction, and the results are as follows. The mid-span flexural capacity of some beams on the first to third floors cannot meet the requirements, and the mid-span flexural capacity and shear capacity of the beams in the air-conditioning machine room cannot meet the requirements. There is also an open room in the basement, due to the centralized placement of equipment, there is a concentrated load, and the top slab has insufficient flexural bearing capacity, so it needs to be reinforced.

Frame beam reinforcement scheme with fiber composite materials

The frame beam has a span of 9m and a cross-sectional size of 300mmx950mm. After calculation and analysis, the mid-span bending capacity of 20 frame beams cannot meet the requirements and the shear capacity of 5 frame beams cannot meet the requirements. The proposed reinforcement method is as follows. The flexural bearing capacity of part of the frame beams needs to be improved not much, and a layer of carbon fiber composite materials with a width of 250mm is pasted along the entire length of the beam bottom. Another part of the frame beam needs to be greatly improved in bending resistance, and two layers of carbon fiber composite materials with a width of 300mm are pasted along the entire length of the beam bottom. In addition, the U-shaped carbon fiber hoops are pasted at the end of the frame beam and the places where the shear resistance on both sides of the secondary beam is insufficient. And attach a 20omm wide bead on both ends of the u-shaped carbon fiber hoop for anchoring and reinforcement effect: the stiffness and bearing capacity of the carbon fiber composite reinforced beam are improved to a certain extent. And with the difference in the number of layers of the carbon fiber composite materials, the increase in the deflection in the middle of the span is also different, and the ductility of the beam is obviously increased.

Sum up about strengthening concrete structure using fibre compoisite material

The structure is reinforced by the method of pasting carbon fiber composite materials, the structure is reasonably stressed, and the purpose of safety, economy, reliability and application is achieved. In recent years, with the improvement of living standards, people's requirements for the safety, applicability and durability of buildings have gradually increased, and the repair and reinforcement of existing structures have also attracted extensive attention from the engineering community. There are many earthquake disasters in the vast area of my country, and the requirements for the seismic performance of structures are also high. Therefore, the reinforcement of buildings and the repair of earthquake-damaged structures are also the main research directions of structural engineers. Therefore, the development and promotion of fiber-reinforced concrete and other new materials and technologies have been generally recognized. Carbon fiber composite materials is widely used in the reinforcement of damaged reinforced concrete structures, which has a positive role in promoting the development of reinforcement projects.

Application of strengthening concrete structure using fibre compoisite material

In the range of h/4-h/3 (h is the height of the column) at the end of the column, the carbon fiber composite materials is wrapped horizontally with a spacing of 200mm, so that the fiber direction is parallel to the ground, which can produce hoop restraint and reduce the buckling coefficient of the column. Thereby improving the compression resistance of the column and effectively improving the ductility of the member. This damage reinforcement method has a significant reinforcement effect. The reason why the carbon fiber composite materials wraps the reinforced concrete column transversely to increase the ductility is that the outer carbon fiber composite materials can well constrain the deformation of the high-strength concrete column in the circumferential direction, and the outer carbon fiber composite materials has a more direct and effective restraint on the concrete members than the stirrups. . Therefore, carbon fiber composite materials can significantly increase the strength of the component, improve the ductility, and increase its seismic energy consumption.

Reinforcing damaged reinforced concrete beams with carbon fiber composite materials, carbon fiber composite materials can not only effectively limit the extension of cracks and the development of crack width, but also can make the beam work normally when there are many cracks. Furthermore, the integrity of the beam is enhanced, and the bearing capacity of the beam is improved. It shows the good ductility of carbon fiber composite materials, the reinforced concrete beam reinforced by carbon fiber composite materials still has a large deformation space, and the carbon fiber composite materials has better energy consumption capacity. Although carbon fiber composite materials is a brittle material, this large deformation can still give signs of damage to the bending beam to a certain extent.

Reinforced concrete flexural members are reinforced with oblique sections, and the use of carbon fiber composite materials to improve the shear capacity of concrete members is effective. After the carbon fiber cloth is pasted, the cracking load and shear capacity of the beam are obviously improved, and the increase in shear capacity is more significant. The mechanism of carbon fiber composite materials in improving the shear capacity is similar to that of stirrups. Therefore, while increasing the shear capacity of reinforced concrete beams, it can also significantly improve the deformation capacity of the component and increase the ductility of the component. For the oblique section of the concrete beam reinforced with carbon fiber, before failure, the carbon fiber strips will show signs of tearing, bulging, wrinkling, etc., thereby improving the brittle failure of the original concrete beam's shear resistance. While improving the shear resistance, it can increase the anchoring of the bent carbon fiber

In addition, after carbon fiber composite materials are used for seismic reinforcement of bridge piers and building columns, the bending and shear resistance, bearing capacity, fatigue resistance and seismic performance of the columns have been significantly improved. At the same time, carbon fiber composite materials is also suitable for the anti-vibration reinforcement of large and medium-sized structures that are subjected to dynamic loads such as bridges.