Reinforcing construction method for reinforced concrete column by adopting FRP (Fiber Reinforce Plastic) material

Abstract

The invention relates to a reinforcement construction method for a reinforced concrete column by adopting an FRP material, and belongs to the technical field of construction of water supply and drainage engineering in the fields of civil construction, bridge engineering, ancient buildings and water conservancy projects. When a reinforced concrete column is reinforced by adopting an FRP sleeve method, at present, FRP cloth is wound and pasted in multiple layers, or the FRP cloth is spliced, and clamps and the like are used as connecting devices at vertical joints. After a long time, the adhesive loses efficacy along with the aging of the adhesive, and then the adhesive falls off; the connecting device of the FRP sleeve transforms the linear load along the seam in the FRP sleeve into a plurality of concentrated loads, and the connecting device can also be corroded to lose efficacy. A self-made FRP strip is adopted, an FRP woven mesh is woven on site and coated with a matrix medium to form an FRP sleeve, and ultra-high performance concrete is poured on the inner side of the sleeve. The FRP sleeve manufactured according to the scheme is integrated, higher bearing capacity can be provided, workers with special skills are not needed, and cost is saved.

Description

Technical Field

[0001] The invention relates to a reinforcement construction method for a reinforced concrete column, in particular to a reinforcement construction method for a reinforced concrete column using FRP materials, and belongs to the technical field of maintenance and reinforcement construction of water supply and drainage projects in the fields of civil engineering, bridge engineering, ancient buildings, and hydraulic engineering. Background Art

[0002] The bearing capacity and durability of reinforced concrete columns such as frame columns in existing buildings, piers in bridges, and supporting columns of water aqueducts will be reduced during long-term service due to the influence of harsh external environment and human factors, so there is a large demand for reinforcement and repair. The traditional reinforcement methods mainly include increasing the cross-section reinforcement method and external bonding steel reinforcement method. The increasing cross-section method can effectively improve the bearing capacity of reinforced concrete columns, but at the same time it increases the deadweight and stiffness of the components, which will increase the seismic effects on the structure and is not conducive to earthquake resistance. The steel-cladding method effectively improves the bearing capacity of reinforced concrete columns by externally cladding steel plates, but in adverse environments, the external steel plates will rust, affecting the durability of the overall structure.

[0003] Fiber reinforced polymer (FRP) is a new generation of high-efficiency and energy-saving materials, and is the focus of research and development in my country. Fiber reinforced plastic (FRP) has the excellent characteristics of light weight, high strength and corrosion resistance. It has been widely used in the field of seismic reinforcement and reinforcement of civil engineering. According to the different fiber reinforcements, FRP can be divided into glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), aramid fiber reinforced plastic (AFRP), basalt fiber reinforced plastic (BFRP), etc. The FRP reinforcement method that has emerged in recent years is convenient for construction. The internal concrete is in a three-dimensional stress state under the constraint of the external FRP. Especially in seismic reinforcement, it can greatly improve the displacement ductility of the column and improve the energy dissipation capacity without basically increasing the bending strength of the column, and has been promoted and applied. Compared with the use of multiple FRP tapes or FRP strips, the sleeve method in the FRP reinforcement method can provide more effective lateral support for the internal concrete and provide better durability protection for the concrete, so it should be promoted and applied first.

[0004] When using FRP sleeves to reinforce reinforced concrete columns, the FRP coils are currently connected and fixed at the joints using a clamp or other connection device to form a sleeve, or multiple layers of FRP coils are wrapped and pasted, and then the ends are fixed with a fixing device to form a sleeve. After a long time, as the adhesive ages, the adhesive will fail, and the FRP material will fall off; the connection device or fixing device will also loosen due to corrosion, causing the FRP material to loosen or fall off. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the present invention has developed a reinforcement construction method for reinforced concrete columns using FRP materials, with the purpose of not using mechanical connection devices, through simple on-site operations by workers, using FRP sleeves to reinforce reinforced concrete columns, and avoiding the problem of easy delamination and failure of conventionally manufactured FRP sleeves.

[0006] The technical solution proposed by the present invention includes the following construction steps:

[0007] S1. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced section of the reinforced concrete column to expose the internal concrete and make the surface rough;

[0008] S2. Construction of cement-based reinforcement layer: applying mortar or casting concrete in a formwork on the reinforcement section of the reinforced concrete column to form a cement-based reinforcement layer; polishing to make the surface of the cement-based reinforcement layer smooth or round;

[0009] S3, making an FRP woven mesh: using FRP strips to weave an FRP woven mesh around the cement-based reinforcement layer;

[0010] S4, making an FRP sleeve: applying FRP matrix glue on the surface of the cement-based reinforcement layer of the reinforcement section and the FRP woven mesh; fixing one end of the FRP woven mesh, stretching the other end in the direction in which the two ends depart from each other and fixing it, and forming an FRP sleeve after the FRP matrix glue solidifies.

[0011] Or the technical solution includes the following construction steps:

[0012] S1. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced section of the reinforced concrete column to expose the internal concrete and make the surface rough;

[0013] S2. Installing the inner lining tube: installing the inner lining sheet around the reinforcement section, and connecting the sides of the inner lining sheet to form the inner lining tube;

[0014] S3, making an FRP braided mesh: using FRP strips to weave an FRP braided mesh around the inner liner;

[0015] S4, making an FRP sleeve: coating the outer surface of the inner liner and the FRP woven net with FRP matrix glue; fixing one end of the FRP woven net, stretching the other end in the direction in which the two ends depart from each other, and forming the FRP sleeve after the FRP matrix glue solidifies;

[0016] S5, pouring cement-based reinforcement layer: taking out the inner liner, sealing the bottom of the FRP sleeve, pouring concrete into the FRP sleeve, and forming a cement-based reinforcement layer between the reinforced concrete column and the FRP sleeve.

[0017] Preferably, an additional construction step is added after step S4:

[0018] S4a: Around the formed FRP sleeve, another layer of FRP braided mesh is braided, and FRP matrix glue is applied to make a new FRP layer, which together with the previous FRP sleeve forms a new FRP sleeve; this operation can be performed multiple times until the FRP braided mesh reaches a predetermined number of layers.

[0019] Preferably, the manufacturing process of the FRP strip is as follows:

[0020] S2a: cutting out FRP cloth strips along the fiber direction of the FRP cloth; applying hot melt adhesive on one or both sides of the FRP cloth strips, and obtaining FRP strips after the adhesive solidifies.

[0021] Preferably, the manufacturing process of the FRP strip is as follows:

[0022] S2a: cutting out FRP cloth strips along the fiber direction of the FRP cloth; placing thermoplastic resin strips on one side or both sides of the FRP cloth strips, heating and pressing, so that the FRP cloth strips and the thermoplastic resin strips become one, and obtaining FRP strips.

[0023] Preferably, before pouring the concrete in the cement-based reinforcement layer, a steel cage in the cement-based reinforcement layer is manufactured.

[0024] Preferably, the concrete in the cement-based reinforcement layer is ultra-high performance concrete or self-compacting concrete.

[0025] Preferably, when starting to weave the FRP woven mesh, the metal strips are wrapped around the reinforced concrete column and connected to form a metal ring; the metal ring is placed at the lower port of the FRP woven mesh and woven into the lower port of the FRP woven mesh; a plurality of connection components are installed at equal intervals along the metal ring and connected to the corresponding embedded parts in the adjacent components at the bottom end of the reinforced concrete column.

[0026] Preferably, there is also a metal ring in the upper port of the FRP braided mesh; a plurality of connection components are installed at equal intervals along the metal ring and connected to the fixings on the reinforced concrete column above; vertical prestress can be applied to the FRP sleeve by operating the connection components.

[0027] Preferably, the FRP cloth is a unidirectional FRP cloth, the fibers of which are continuous fibers, and the material is any one of carbon fiber, glass fiber, aramid fiber or basalt fiber, or a combination thereof.

[0028] The beneficial effects of the present invention include the following aspects:

[0029] (1) The technical solution of the present invention adopts the FRP sleeve method to reinforce reinforced concrete columns. The high-strength FRP material can effectively constrain the internal concrete, so that the concrete is in a three-dimensional stress state, thereby improving the bearing capacity of the column;

[0030] (2) In the technical solution of the present invention, the FRP sleeve is made of FRP woven mesh, and the FRP sleeve has good integrity. Compared with the FRP sleeve made of multi-layer winding of FRP cloth, the FRP sleeve avoids the failure of viscose aging and the resulting debonding; compared with the FRP sleeve spliced ​​with FRP cloth and clamps, the FRP sleeve avoids the failure of clamps due to corrosion;

[0031] (3) The present invention adopts FRP strips and manufactures FRP sleeves by weaving FRP woven mesh on site, thus avoiding difficult operations such as on-site tensioning, greatly reducing the technical requirements for workers, and thus reducing the cost;

[0032] (4) The construction method of the present invention does not require large or bulky construction tools and machinery, thus reducing labor intensity and facilitating operations in places with inconvenient construction environments. It has strong adaptability to construction sites and a wide range of applications.

[0033] (5) The present invention has a low requirement for the weaving error of the FRP braided mesh. Even if the woven FRP braided mesh is relatively loose, it can be stretched longitudinally to make the FRP braided mesh close to the surface of the inner component or member, thereby reducing the difficulty of weaving the FRP braided mesh, that is, the difficulty of manufacturing the FRP sleeve is low;

[0034] (6) The FRP sleeve made on site can also serve as the formwork for the subsequent pouring of inner concrete, and the reinforcement construction method is efficient;

[0035] (7) The FRP materials available on the market are in the form of cloth, plate, wire (or rod), and tube. The present invention obtains FRP cloth strips by cutting FRP cloth, and combines the FRP cloth strips with thermoplastic resin strips by heating and pressing to obtain FRP strips, thereby speeding up the production of FRP strips and reducing the production cost.

[0036] (8) The self-compacting concrete used in the present invention can avoid quality problems such as voids, facilitate the pouring of concrete, and improve the reinforcement speed and quality;

[0037] (9) By using multiple layers of FRP braided mesh to make FRP sleeves, each layer can be braided in a different way, which can greatly improve the bending, shear and torsion resistance of the reinforced section, making it easier to achieve the optimal design of the reinforcement effect;

[0038] (10) Adding expansion agent to concrete can prevent the volume shrinkage of concrete during the hardening process. After the concrete expands slightly, it can bond more strongly with the reinforced concrete column. It can also generate prestress in the outer FRP sleeve to prevent the FRP sleeve from debonding from the concrete. The prestress can make full use of the high strength characteristics of the FRP material to improve the bearing capacity of the reinforced concrete column after reinforcement.

[0039] (11) By adding metal rings as ports in the FRP woven mesh, it is convenient to connect the FRP sleeve with the pedestal, thereby improving the bearing capacity of the reinforced concrete column after reinforcement; by adding metal rings in the upper and lower ports of the FRP woven mesh, it is convenient to apply vertical prestress to the FRP sleeve, thereby improving the bearing capacity of the reinforced concrete column after reinforcement and saving the cost of clamps and anchors.

[0040] (12) The use of ultra-high performance concrete in the cement-based reinforcement layer can achieve a perfect combination of two new materials, high-performance concrete and FRP, in the reinforced structure, reduce the size of the newly added section, and greatly improve the bearing capacity of the reinforced component. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the reinforced pier;

[0042] Figure 2 Schematic diagram of the pier column surface after roughening in the reinforcement section;

[0043] Figure 3 Schematic diagram of the repair layer after the completion of Example 1;

[0044] Figure 4 Schematic diagram of the first layer of woven mesh when starting to weave the first diagonal strip;

[0045] Figure 5 Schematic diagram of the first layer of woven mesh when it starts to weave the second diagonal strip;

[0046] Figure 6 Schematic diagram of the first layer of woven mesh with all diagonal strips in place;

[0047] Figure 7 Schematic diagram of the spiral rise of the transverse strips in the first layer of woven mesh;

[0048] Figure 8 Schematic diagram of the first layer of braided mesh after it is woven;

[0049] Fig. 9 Schematic diagram of Example 1 after the first FRP layer is completed;

[0050] Fig.10 Schematic diagram of the second braided mesh in Example 1;

[0051] Fig.11 Schematic diagram of Example 1 after the second FRP layer is completed;

[0052] Fig.12 Schematic diagram of the liner after installation in Example 2;

[0053] Fig.13 A schematic cross-sectional view of the reinforcement section after the liner is installed in Example 2;

[0054] Fig.14 Schematic diagram of the FRP sleeve after being formed in Example 2;

[0055] Fig.15 Schematic diagram of FRP strips;

[0056] Fig.16 Schematic diagram of the FRP strip manufacturing process (part one);

[0057] Fig.17 Schematic diagram of the FRP strip production process (part 2);

[0058] Fig.18 Schematic diagram of installation of metal ring of lower port;

[0059] Fig.19 Schematic diagram of the first layer of woven mesh;

[0060] Fig. 20 Schematic diagram of the lower part of the first FRP layer;

[0061] Fig.21 Schematic diagram of the upper part of the first FRP layer of Example 4.

[0062] Figure numerals: top surface of the pedestal 1, pier 2, repair layer 3, FRP sleeve 4, transverse FRP strip 5, oblique FRP strip 6, first woven mesh 7, first FRP layer 8, vertical FRP strip 9, horizontal FRP strip 10, second woven mesh 11, second FRP layer 12, inner lining tube 13, FRP wire 15, FRP cloth strip 16, nylon belt 17, electric soldering iron 18, upper roller cylinder 19, lower roller cylinder 20, lower port metal ring 21, lower screw 22, lower connecting ring 23, lower connecting sleeve 24, upper connecting sleeve 25, upper connecting ring 26, upper screw 27, clamp 28, upper port metal ring 29. DETAILED DESCRIPTION

[0063] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0064] The directional words in the embodiments are based on the customary terms in engineering and are not strictly defined. For example, "upper" means the upper surface of the built part of the structure, and also includes the upper surface of the auxiliary components located obliquely above its influence range; when indicating the direction, "upper" includes both directly above and obliquely above. Directional words such as "left" and "right", "upper" and "lower" are only used to facilitate the description in conjunction with the drawings. The directional words used are only for the convenience of describing this patent, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as a limitation on this patent.

[0065] The present invention has no limitation on the cross-sectional shape of the reinforced concrete column. The reinforcement method is applicable to reinforced concrete columns with cross-sectional shapes of various shapes. In the embodiment, only a circular cross-sectional shape is used for description.

[0066] Example 1

[0067] This embodiment sees Figure 1 The reinforced concrete column to be reinforced is a pier 2 of a bridge, and its cap top surface 1 is as shown in Figure 1 As shown, the reinforcement design is aimed at the bottom of the pier 2, and a FRP sleeve 4 made of carbon fiber material is prepared. Between the FRP sleeve 4 and the pier 2 is a repair layer 3 cast with ultra-high performance concrete. The thickness of the repair layer 3 is 15 cm and the height is 1.2 m.

[0068] The construction process includes the following construction steps:

[0069] S1. Surface treatment of reinforced concrete column: Because the surface concrete of pier 2 has been carbonized to a certain depth, and in order to strengthen the bonding strength between ultra-high performance concrete and pier 2, the surface of the reinforced section of pier 2 is grinded with an angle grinder. The depth is controlled to be about half of the thickness of the protective layer of pier 2, and the depth is ensured to be greater than the carbonization depth. Figure 2 ; If cracks still exist and the depth does not exceed 2 cm, carve a "V" shaped groove and fill it with epoxy resin sealant; if the depth is deeper, use the "Bi Ke method" to inject epoxy resin sealant.

[0070] S2. Construction of cement-based reinforcement layer: erect formwork, make and install steel cage, pour ultra-high performance concrete with expansion agent in the reinforcement section of pier 2 to form cement-based reinforcement layer, also called repair layer 3; polish and make the surface of repair layer 3 round, see Figure 3 .

[0071] S3, making FRP woven mesh: buy unidirectional carbon fiber cloth, which is made of continuous fiber, cut FRP cloth strips 16 along the fiber direction of the FRP cloth, and the direction of the FRP line 15 is shown in FIG. Fig.15; Apply hot melt adhesive on one or both sides of the FRP strip 16, and after the colloid solidifies, an FRP strip with a thickness of about 1.5 mm is obtained. Next, the prepared FRP strip is used to surround the cement-based reinforcement layer and weave the FRP woven mesh. See the schematic diagram of the process. Figure 4 — Fig. 9 . First, wrap a circle of transverse FRP strip 5 around the bottom and connect it with hot melt adhesive. One end of the FRP strip forms a closed ring around the repair layer 3. The average gap between the closed ring and the repair layer 3 is 2mm. Take another FRP strip as the first oblique FRP strip 6. This strip passes under the transverse FRP strip 5. The outer end extends to the upper left and the inner end extends to the upper right. The lengths of the two ends are roughly equal. Adjust them so that the angles between the two and the horizontal plane are roughly equal, and fix them to the transverse FRP strip 5 with hot melt adhesive; take another FRP strip as the second oblique FRP strip 6, fix it in the same way, and adjust it so that the right branch of the oblique FRP strip 6 on the left presses on the left branch of the oblique FRP strip 6 on the right; repeat this operation until the oblique FRP strip 6 around the column is fixed. The protruding end of the transverse FRP strip 5 is spirally inclined, as shown in sequence. Figure 7 As shown above the intersection of the upper oblique FRP strips 6. The first woven mesh 7 is woven in this way, and the oblique FRP strips 6 are folded back downward at the upper end and fixed with the transverse FRP strips sealed at the upper end port with hot melt adhesive. The lower end of the first woven mesh 7 is fixed, and the upper end is pulled upward so that the first woven mesh 7 is close to the surface of the cement-based reinforcement layer, and the intersection of the FRP strips is connected with hot melt adhesive.

[0072] S4, making FRP sleeve: coating FRP matrix glue on the surface of cement-based reinforcement layer of reinforcement section and first woven mesh 7, the matrix glue adopts one of epoxy resin, vinyl resin or polyamine resin, covering the surface of cement-based reinforcement layer of all reinforcement sections; fixing the lower end of first woven mesh 7, pulling up the upper end, making first woven mesh 7 close to the surface of cement-based reinforcement layer, after FRP matrix glue solidifies, forming first FRP layer 8, see Fig. 9 .

[0073] S4a: Around the first FRP layer 8, another layer of FRP woven mesh is woven, such as Fig.10 As shown. The second woven mesh 11 is composed of vertical FRP strips 9 and horizontal FRP strips 10. First, the horizontal FRP strips 10 are made into a hoop with hot melt adhesive, and the bottom end of the vertical FRP strips 9 is fixed to the hoop at the bottom with hot melt adhesive. The spacing between each vertical FRP strip 9 is roughly equal. Fig.10The upper end of the vertical FRP strip 9 is also fixed to the uppermost hoop with hot melt adhesive. The second woven mesh 11 is used to obtain the second FRP layer 12 as described above. The second FRP layer is integrated with the first FRP layer 8. Fig.11 Continue to weave the third layer of woven mesh that is the same as the first woven mesh 7, and make the third FRP layer, thereby completing the production of the FRP sleeve 4 of the reinforced concrete column.

[0074] A 5 mm thick protective layer is sprayed on the surface of the FRP sleeve 4 to ensure the appearance quality and durability after reinforcement. The protective layer is sprayed with an adhesive and mortar or directly painted with a paint color consistent with the original pier concrete.

[0075] During this reinforcement construction, the original surface defects of the reinforced concrete columns were also treated: ultra-high performance concrete with expansion agent was used to facilitate firm bonding with the original concrete inside.

[0076] Example 2

[0077] This embodiment sees Figure 1 The reinforced concrete column to be reinforced is a pier 2 of a bridge, and its cap top surface 1 is as shown in Figure 1 As shown, the reinforcement design is aimed at the bottom of the pier 2, and a FRP sleeve 4 made of carbon fiber material is prepared. Between the FRP sleeve 4 and the pier 2 is a repair layer 3 cast with self-compacting concrete. The thickness of the repair layer 3 is 15 cm and the height is 1.2 m.

[0078] The construction process includes the following construction steps:

[0079] S1. Surface treatment of reinforced concrete column: Because the surface concrete of pier 2 has been carbonized to a certain depth, and in order to strengthen the bonding strength between the self-compacting concrete and pier 2, the surface of the reinforced section of pier 2 is grinded with an angle grinder. The depth is controlled to be about half of the thickness of the protective layer of pier 2, and ensure that the depth is greater than the carbonization depth. Figure 2 ; If cracks still exist and the depth does not exceed 2 cm, carve a "V" shaped groove and fill it with epoxy resin sealant; if the depth is deeper, use the "Bi Ke method" to inject epoxy resin sealant.

[0080] S2. Install the inner lining tube: Install the inner lining sheet around the reinforcement section; the inner lining sheet is made of plastic with a thickness of 10 mm. The cross-sections of the sheets on both sides of the joint have corresponding sharpened bevels, which are connected with hot melt adhesive. Fig.12 and Fig.13 The outer surface of the inner liner 13 is pasted with aluminum foil, or coated with a release agent to facilitate demoulding of the inner liner 13.

[0081] S3, making FRP woven mesh: buy unidirectional carbon fiber cloth, which is made of long-line fibers, cut FRP cloth strips 16 along the fiber direction of the FRP cloth, and the direction of the FRP line 15 is shown in FIG. Fig.15 ;like Fig.16 To make FRP strips, a nylon belt 17 is placed on an electric soldering iron 18, and an FRP cloth strip 16 is placed on the nylon belt 17. An upper roller 19 is pressed on the FRP cloth strip 16 with a certain pressure and rotates to press the FRP cloth strip 16 into the hot-melt nylon belt 17 to obtain an FRP strip. Fig.17 As shown in the figure, the FRP strip is made, the nylon belt 17 is placed on the electric soldering iron 18, and the FRP cloth strip 16 is placed on the nylon belt 17. The upper roller 19 and the lower roller 20 are provided on the left side of the electric soldering iron 18. Fig.17 The upper roller 19 and the lower roller 20 maintain a certain pressure, and the two rotate in opposite directions, so that the FRP cloth strip 16 and the nylon belt 17 are integrated to obtain an FRP strip. The thickness of the FRP strip is about 1.5 mm.

[0082] Next, the prepared FRP strips are used to surround the inner liner 13 and weave the FRP woven mesh. The process diagram is shown in FIG. Figure 4 — Figure 7 . First, wrap a circle of transverse FRP strip 5 around the bottom and connect it with hot melt adhesive. One end of the FRP strip forms a closed ring around the inner liner 13. The average gap between the closed ring and the inner liner 13 is 2mm. Take another FRP strip as the first oblique FRP strip 6. The strip passes under the transverse FRP strip 5. The outer end extends to the upper left and the inner end extends to the upper right. The lengths of the two ends are roughly equal. Adjust them so that the angles between the two and the horizontal plane are roughly equal, and fix them to the transverse FRP strip 5 with hot melt adhesive; take another FRP strip as the second oblique FRP strip 6, fix it in the same way, and adjust it so that the right branch of the oblique FRP strip 6 on the left presses on the left branch of the oblique FRP strip 6 on the right; repeat this operation until the oblique FRP strip 6 around the column is fixed. The protruding end of the transverse FRP strip 5 is spirally inclined, as shown in sequence. Figure 7 As shown, the first woven mesh 7 is woven above the intersection of the oblique FRP strips 6 above. In this way, the first woven mesh 7 is woven, and the oblique FRP strips 6 are folded back downward at the upper end and fixed with the transverse FRP strips sealed at the upper end port with hot melt adhesive. The lower end of the first woven mesh 7 is fixed, and the upper end is pulled upward so that the first woven mesh 7 is close to the surface of the inner liner 13, and the intersection of the FRP strips is connected with hot melt adhesive.

[0083] S4. Make an FRP sleeve: apply FRP matrix glue on the surface of the inner liner 13 of the reinforcement section and the first woven mesh 7. The matrix glue uses one of epoxy resin, vinyl resin or polyamine resin to cover the surface of the inner liner 13 of all reinforcement sections; fix the lower end of the first woven mesh 7, and pull up the upper end to make the first woven mesh 7 close to the surface of the inner liner 13. After the FRP matrix glue solidifies, the first FRP layer 8 is formed.

[0084] S4a: Around the first FRP layer 8, another layer of FRP woven mesh is woven, such as Fig.10 As shown. The second woven mesh 11 is composed of vertical FRP strips 9 and horizontal FRP strips 10. First, the horizontal FRP strips 10 are made into a hoop with hot melt adhesive, and the bottom end of the vertical FRP strips 9 is fixed to the hoop at the bottom with hot melt adhesive. The spacing between each vertical FRP strip 9 is roughly equal. Fig.10 The upper end of the vertical FRP strip 9 is also fixed to the uppermost hoop with hot melt adhesive. The second woven mesh 11 is used to obtain the second FRP layer 12 as described above. The second FRP layer is integrated with the first FRP layer 8. The third woven mesh 7 is woven the same as the first woven mesh 7, and the third FRP layer is made. The inner liner 13 is removed, thereby completing the production of the FRP sleeve 4 of the reinforced concrete column. Fig.14 .

[0085] A 5 mm thick protective layer is sprayed on the surface of the FRP sleeve 4 to ensure the appearance quality and durability after reinforcement. The protective layer is sprayed with an adhesive and mortar or directly painted with a paint color consistent with the original pier concrete.

[0086] S5. Casting cement-based reinforcement layer: a steel cage is made around the reinforced concrete column and lowered into the FRP sleeve 4 , and self-compacting concrete with expansion agent is cast to form a cement-based reinforcement layer between the reinforced concrete column and the FRP sleeve 4 .

[0087] Example 3

[0088] This embodiment is a modification of the embodiment 1, and the bottom of the FRP sleeve is connected to the cap. When weaving the FRP woven mesh, the metal strips are wrapped around the reinforced concrete column and connected to form a lower end metal ring 21, see Fig.18 The lower port metal ring 21 is placed at the lower port of the FRP braided mesh and woven into the lower port of the FRP braided mesh; a plurality of connection components are installed at equal intervals along the lower port metal ring 21, connected to the lower screw 22 embedded in the cap, see Fig.19 The lower connecting ring 23 is buckled on the lower port metal ring 21, and the corresponding lower screw 22 and the lower connecting ring 23 are connected by the lower connecting sleeve 24. Fig. 20, there is no glue coating near the metal ring 21 at the lower end, and measures are taken to cover it to prevent glue from flowing in. When the second FRP braided mesh and subsequent FRP braided meshes are woven, the FRP strips still bypass the metal ring 21 at the lower end. The lower end of the final FRP sleeve is connected to the cap to enhance the bending resistance of the reinforced concrete column after reinforcement.

[0089] If one wishes to increase the bending resistance of the reinforced concrete column at the bottom as much as possible, the number of connection components can be increased.

[0090] Example 4

[0091] This embodiment is a modification of the embodiment 2, and vertical prestress can be applied to the FRP sleeve. The bottom of the FRP sleeve is connected to the cap. When weaving the FRP woven mesh, the metal strips are wrapped around the reinforced concrete column and connected to form a metal ring 21 at the lower end. Fig.18 The lower port metal ring 21 is placed at the lower port of the FRP braided mesh and woven into the lower port of the FRP braided mesh; a plurality of connection components are installed at equal intervals along the lower port metal ring 21, connected to the lower screw 22 embedded in the cap, see Fig.19 The lower connecting ring 23 is buckled on the lower port metal ring 21 , and the corresponding lower screw rod 22 and the lower connecting ring 23 are connected by the lower connecting sleeve 24 .

[0092] The top of the FRP sleeve is connected to the hoop 28 on the reinforced concrete column 2. When weaving the FRP woven mesh, the metal strips are wrapped around the reinforced concrete column and connected to form an upper end metal ring 29, see Fig.21 ; The upper port metal ring 29 is placed at the upper port of the FRP braided mesh and woven into the upper port of the FRP braided mesh; multiple connecting components are installed at equal intervals along the upper port metal ring 29, the clamp 28 is connected by the upper screw 27, the upper connecting ring 26 is buckled on the upper port metal ring 29, and the corresponding upper screw 27 and upper connecting ring 26 are connected by the upper connecting sleeve 25.

[0093] After the first FRP layer is formed, Fig. 20 and Fig.21 , there is no glue coating near the lower port metal ring 21, and measures are taken to cover it to prevent glue from flowing in. When the second FRP braided mesh and the subsequent FRP braided mesh are prepared, the FRP strips still bypass the lower port metal ring 21 and the upper port metal ring 29.

[0094] After the FRP sleeve is manufactured, vertical prestress is applied to the FRP sleeve through the lower connecting sleeve 24 and the upper connecting sleeve 25, and then concrete is poured. The high-strength FRP material can be fully utilized to further improve the bending resistance of the reinforced concrete column.

[0095] It is also possible to continuously weave three layers of FRP braided mesh and then glue them together to form an FRP sleeve.

[0096] The preferred embodiments listed above further illustrate the objectives, technical solutions and advantages of the present invention in detail. It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for reinforcing a reinforced concrete column using FRP material, characterized in that: The construction steps include: S1. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced section of the reinforced concrete column to expose the internal concrete and make the surface rough; S2. Construction of cement-based reinforcement layer: applying mortar or casting concrete in a formwork on the reinforcement section of the reinforced concrete column to form a cement-based reinforcement layer; polishing to make the surface of the cement-based reinforcement layer smooth or round; S3, making an FRP woven mesh: using FRP strips to weave an FRP woven mesh around the cement-based reinforcement layer; S4, making an FRP sleeve: applying FRP matrix glue on the surface of the cement-based reinforcement layer of the reinforcement section and the FRP woven mesh; fixing one end of the FRP woven mesh, stretching the other end in the direction in which the two ends depart from each other and fixing it, and forming an FRP sleeve after the FRP matrix glue solidifies.

2. A method for reinforcing a reinforced concrete column using FRP material, characterized in that: The construction steps include: S1. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced section of the reinforced concrete column to expose the internal concrete and make the surface rough; S2. Installing the inner lining tube: installing the inner lining sheet around the reinforcement section, and connecting the sides of the inner lining sheet to form the inner lining tube; S3, making an FRP braided mesh: using FRP strips to weave an FRP braided mesh around the inner liner; S4, making an FRP sleeve: coating the outer surface of the inner liner and the FRP woven net with FRP matrix glue; fixing one end of the FRP woven net, stretching the other end in the direction in which the two ends depart from each other, and forming the FRP sleeve after the FRP matrix glue solidifies; S5, pouring cement-based reinforcement layer: taking out the inner liner, sealing the bottom of the FRP sleeve, pouring concrete into the FRP sleeve, and forming a cement-based reinforcement layer between the reinforced concrete column and the FRP sleeve.

3. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: Additional construction steps after step S4: S4a: Around the formed FRP sleeve, another layer of FRP braided mesh is braided, and FRP matrix glue is applied to make a new FRP layer, which together with the previous FRP sleeve forms a new FRP sleeve; this operation can be performed multiple times until the FRP braided mesh reaches a predetermined number of layers.

4. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: The production process of the FRP strip is as follows: S2a: cutting out FRP cloth strips along the fiber direction of the FRP cloth; applying hot melt adhesive on one or both sides of the FRP cloth strips, and obtaining FRP strips after the adhesive solidifies.

5. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: The production process of the FRP strip is as follows: S2a: cutting out FRP cloth strips along the fiber direction of the FRP cloth; placing thermoplastic resin strips on one side or both sides of the FRP cloth strips, heating and pressing, so that the FRP cloth strips and the thermoplastic resin strips become one, and obtaining FRP strips.

6. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: Before pouring the concrete in the cement-based reinforcement layer, a steel cage in the cement-based reinforcement layer is manufactured.

7. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: The concrete in the cement-based reinforcement layer is ultra-high performance concrete or self-compacting concrete.

8. A method for reinforcing a reinforced concrete column using FRP material according to claim 1 or claim 2, characterized in that: When weaving the FRP mesh, the metal strips are wrapped around the reinforced concrete column and connected to form a metal ring; the metal ring is placed at the lower port of the FRP mesh and woven into the lower port of the FRP mesh; a plurality of connection components are installed at equal intervals along the metal ring and connected to the corresponding embedded parts in the adjacent components at the bottom end of the reinforced concrete column.

9. A method for reinforcing a reinforced concrete column using FRP material according to claim 2 and claim 8, characterized in that: There is also a metal ring inside the port of the FRP braided mesh; a plurality of connection components are installed at equal intervals along the metal ring and connected to the fixings on the reinforced concrete column above; vertical prestress can be applied to the FRP sleeve by operating the connection components.

10. A method for reinforcing a reinforced concrete column using FRP material according to claim 4 or claim 5, characterized in that: The FRP cloth is a unidirectional FRP cloth, the fibers of which are continuous fibers, and the material is any one of carbon fiber, glass fiber, aramid fiber or basalt fiber, or a combination thereof.

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