FRP sleeve prestress device for reinforcing reinforced concrete column and construction method

Abstract

The invention relates to an FRP sleeve prestress device for reinforcing a reinforced concrete column and a construction method, and belongs to the technical field of construction of civil buildings, bridge engineering, ancient buildings, water supply and drainage engineering and the like. When the FRP sleeve method is adopted for reinforcement, the high-strength characteristic of the FRP material can be exerted only by applying prestress, and the utilization efficiency of the material is improved. The FRP sleeve is made of an FRP coiled material, circumferential prestress is applied to the whole FRP sleeve through a mechanism located in the sleeve, and ultra-high performance concrete is poured on the inner side of the FRP sleeve. The FRP sleeve is simple in appearance, durable and attractive after being reinforced, and the FRP sleeve is not provided with external connecting pieces such as a clamp and an anchorage device and is also not provided with butt joints, so that the durability of internal concrete is ensured. The construction does not need large tensioning equipment, and the operation is simple. The FRP sleeve manufactured in the scheme is integrated, the bearing capacity of the reinforced concrete column after reinforcement can be greatly improved, workers with special skills are not needed, and cost is saved.

Description

Technical Field

[0001] The present invention relates to a reinforcement construction method for a reinforced concrete column, in particular to an FRP sleeve prestressing device and a construction method for reinforcing a reinforced concrete column, and belongs to the technical field of construction maintenance and reinforcement 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 energy-saving materials and is the focus of research and development in my country. 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 of columns that has emerged in recent years is easy to construct. 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 without basically increasing the bending strength of the column, and improve the energy consumption capacity, and has been promoted and applied.

[0004] Compared with the use of multiple FRP sleeve belts or FRP strips, the use of a whole FRP sleeve can provide more effective lateral support for the internal concrete and better durability protection for the concrete, and should be promoted and applied first.

[0005] The general FRP outsourcing reinforcement method will make the stress of the FRP material lag behind the original structure. Only through prestressing can the internal force distribution of the original structure be changed and the stress-strain lag phenomenon be eliminated. The prestress generated in the FRP material by pouring micro-expansion concrete is too small; the longitudinal tensioning method along the winding direction, considering the large friction resistance, requires a large tensioning force, and has high requirements for tensioning equipment and construction. In addition, the construction sequence of tensioning first and then anchoring is adopted, and the setting of the anchor end is cumbersome, which greatly increases the difficulty of construction; the method of tensioning the transverse prestress at the vertical joint, the anchor end and the anchor are exposed on the column surface without a protective layer, which not only increases the shape of the column and affects the appearance, but also the loose joints affect the durability protection of the internal concrete, which is easy to fail in the natural environment and has low durability.

[0006] Therefore, finding a new method to apply transverse prestress to the entire FRP sleeve has important engineering application value. Summary of the invention

[0007] In order to overcome the deficiencies in the prior art, the present invention has developed an FRP sleeve prestressing device and a construction method for reinforcing reinforced concrete columns. The purpose is to reinforce the reinforced concrete columns with FRP sleeves through simple manual operations by workers on site without using lifting machinery or even hydraulic equipment, and the FRP sleeves have prestress applied by the prestressing device.

[0008] The FRP sleeve prestressing device in the present invention surrounds the reinforced concrete column, and includes a loading part and a transverse expansion part; the FRP sleeve is made by winding FRP cloth around the transverse expansion part; the loading part includes a loading unit composed of a jack and a reaction frame, and a support assembly for fixing the reaction frame; the transverse expansion part includes multiple groups of transverse expansion units, and is permanently cast in the reinforcement layer along with the reinforced concrete; the transverse expansion unit is a movable mechanism, including a vertical rod supporting the FRP sleeve in the longitudinal direction, and at least two connecting rods hinged to the vertical rod and the reinforced concrete column, and several connecting rods are at different heights; the jack pushes the vertical rod up and down, drives the connecting rod to rotate around the inner fixed hinge, changes the distance between the vertical rod and the reinforced concrete column, thereby generating transverse prestress in the FRP sleeve, and the corresponding strain is,

[0009]

[0010] L0 is the distance between the two hinge centers of the connecting rod;

[0011] h is the elevation of the hinge center on the outside of the connecting rod relative to the hinge center on the inside before wrapping the FRP cloth;

[0012] R0 is the distance from the inner side of the connecting rod to the center of the reinforced concrete column;

[0013] r0 is the distance from the hinge center to the outer edge of the adjacent connecting rod;

[0014] D0 is the thickness of the outer connecting rod branching to the outer edge of the vertical rod.

[0015] Preferably, the connecting rod is in a "Z" shape, with branches at both ends being parallel, the inner branch close to the reinforced concrete column being bent downward, and the outer branch being bent upward; the connecting rod is hinged to an anchor fixed on the inner side of the reinforced concrete column and an anchor fixed on the outer side of the vertical rod through hinge pin holes at two turning points; the outer shape of the two turning points of the connecting rod is an arc with the center of the hinge pin hole as the center, and the outer edge lines of each branch are tangent to the arc.

[0016] Preferably, the connecting rod is plate-shaped, and both ends of the longitudinal section are round ends; accordingly, the corresponding anchors at both ends are provided with corresponding horizontally arranged circular grooves; the ends of the connecting rod can rotate in the grooves of the anchors.

[0017] Preferably, the number of the transverse expansion units and the loading units is the same, and the transverse expansion units and the corresponding loading units are in the same vertical plane. The transverse expansion units are evenly arranged around the reinforced concrete column.

[0018] Preferably, all of the lateral expansion units are of the same shape, size and material and are the same components; and all of the reaction frames are the same components.

[0019] Preferably, the vertical rod is prefabricated from ultra-high performance concrete and has longitudinal reinforcement inside; the reinforcement layer is cast from ultra-high performance concrete with an expansion agent or self-compacting concrete.

[0020] Preferably, the loading portion is located above the transverse expansion portion; the supporting assembly is a clamp consisting of two identical semicircular rings, with both ends connected by connecting bolts.

[0021] The reinforced concrete column reinforcement construction method using the FRP sleeve prestressing device comprises the following construction steps:

[0022] S1. Construction preparation: Make various components, including connecting rods, vertical rods, reaction frames, etc., and prepare jacks;

[0023] S2. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced concrete columns to expose the internal concrete and making the surface rough;

[0024] S3. Fine treatment of anchoring parts: on the surface of reinforced concrete column, according to the position of each vertical rod and the anchoring parts thereon, roughly determine the position of the corresponding anchoring parts on the surface of reinforced concrete column, grind it, make the surface flat or round, and have a certain degree of roughness;

[0025] S4. Install the reaction frame: install the annular clamp, tighten the connecting bolts, and firmly fix the clamp on the reinforced concrete column; install the reaction frame, the top of the reaction frame presses against the clamp, and fixes the reaction frame with anchor bolts;

[0026] S5. Install the lateral expansion mechanism: accurately mark the vertical center line of each lateral expansion unit on the concrete surface; hinge the connecting rod and the vertical rod to form a vertical rod assembly, support the bottom end of the vertical rod assembly on the supporting surface of the reinforced concrete column, adjust the connecting rod so that the two hinge centers of the connecting rod are at the same height, thereby determining the position of the anchor on the surface of the reinforced concrete column, and install the anchor;

[0027] S6. Making FRP sleeves: push each vertical rod upwards and support the lower end of each vertical rod with a wedge; apply glue on the outer side of the vertical rod away from the reinforced concrete column; spirally wrap the FRP cloth around all the vertical rods to form a first cylindrical FRP layer; apply glue on the outer surface of the made FRP layer and wrap another FRP layer; repeat the operation until the FRP layer reaches the specified number of layers to form an FRP sleeve;

[0028] S7, applying prestress: removing the wedge; placing a jack on the top of the vertical rod, extending the jack to contact the reaction frame; extending all the jacks synchronously in multiple steps; the vertical rod moves downward, the connecting rod rotates, and the FRP sleeve expands outward and has a circumferential internal force;

[0029] S8. Casting reinforcement layer: pour concrete into the FRP sleeve to form a reinforcement layer; when the concrete strength reaches the predetermined requirement, remove the jack, and dismantle the reaction frame and clamp.

[0030] Preferably, step S2 is replaced as follows, and in the absence of confusion, the reinforced concrete column with a repair layer in the reinforcement section is still called a reinforced concrete column:

[0031] S2. Repair layer construction: In the reinforcement section of the reinforced concrete column, the surface layer of the reinforced concrete column is ground to expose the internal concrete and make the surface rough; concrete is poured in a formwork to form a repair layer 3; the surface of the repair layer 3 is ground to make it flat or round and have a certain degree of roughness.

[0032] Preferably, the following steps are added after step S5:

[0033] S5a, making a reinforcement layer steel cage: drilling holes on the supporting surface of the reinforced concrete column, first installing spiral stirrups, and then anchoring vertical steel bars; adjusting the spiral stirrups to avoid the connecting rods and keep a certain distance from the connecting rods in the vertical direction.

[0034] The FRP sleeve in the technical solution of the present invention is made of FRP unidirectional 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.

[0035] Anchor steel plates can be embedded at the bottom of the vertical rods, which are connected to the supporting surface of the reinforced concrete column through anchor bolts after reinforcement. Between the two vertical rods, the lower edge of the FRP sleeve can be clamped with a clamp, and the FRP sleeve and the reinforced concrete supporting surface can be connected through the anchor bolts on the clamp. These two measures will fix the lower edge of the FRP sleeve and enhance the bending and shear resistance of the reinforced concrete column at the bottom.

[0036] The beneficial effects of the present invention include the following aspects:

[0037] (1) The technical solution of the present invention adopts the FRP sleeve method to strengthen the reinforced concrete column. The high-strength FRP material has prestress, which 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;

[0038] (2) The FRP sleeve of the present invention has no external connectors such as clamps and anchors, and no butt joints, and has a simple and beautiful appearance after reinforcement;

[0039] (3) The present invention does not use lifting machinery, the jack is mechanical, and even hydraulic equipment is not used. All reinforcement construction can be completed by simple manual operation by workers on site. No special skilled workers are required, which saves costs and reduces the cost;

[0040] (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.

[0041] (5) The present invention converts the vertical action of the jack into a lateral expansion force on the FRP sleeve through the designed lateral expansion mechanism, and does not require conventional tensioning equipment, thereby simplifying the prestressing construction;

[0042] (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;

[0043] (7) The reinforcement layer of the present invention adopts ultra-high performance concrete, combined with high-performance FRP materials, which can effectively improve the bearing internal force and seismic performance of the reinforced concrete column after reinforcement;

[0044] (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;

[0045] (9) By adding an expansion agent to the concrete, the volume shrinkage of the concrete during the hardening process can be avoided. After the concrete expands slightly, it can be more strongly bonded to the reinforced concrete column, and the prestress value in the outer FRP sleeve can be increased to avoid the debonding of the FRP sleeve and the concrete. The bending, shear and torsion resistance of the reinforced section can be greatly improved, which facilitates the optimization design of the reinforcement effect.

[0046] (10) In the present invention, the vertical rods are evenly distributed around the reinforced concrete column, so that the cross-section of the FRP sleeve is approximately a regular polygon, close to a circle, so that the prestress in the FRP sleeve is fully utilized to form a confining pressure on the reinforced concrete column, thereby improving the bearing capacity of the reinforced concrete column;

[0047] (11) By establishing an effective connection between the FRP sleeve and the reinforced concrete bearing surface at the bottom plate of the vertical rod and between the two vertical rods, the lower edge of the FRP sleeve will be fixed, thereby enhancing the bending and shear resistance of the reinforced concrete column at the bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the reinforced pier;

[0049] Figure 2 Schematic diagram of the pier column surface after roughening in the reinforcement section;

[0050] Figure 3 Schematic diagram after the repair layer is completed;

[0051] Figure 4 Schematic diagram of the anchors installed on the reinforced concrete column;

[0052] Figure 5 Figure 4 Schematic diagram of the top view of the middle BB section;

[0053] Figure 6 Figure 4 A partial enlarged schematic diagram in the middle;

[0054] Figure 7 A three-dimensional schematic diagram of an anchor;

[0055] Figure 8 A schematic diagram of the reinforcement components;

[0056] Fig. 9 Schematic diagram of connecting rod;

[0057] Fig.10 Schematic diagram of the cross section of the vertical rod passing through the reinforcement;

[0058] Fig.11 Schematic diagram of the FRP sleeve after positioning in Example 1;

[0059] Fig.12 Fig.11 Schematic diagram of the top view of the middle CC section;

[0060] Fig.13 A partial schematic diagram of the column foot after reinforcement in Example 2;

[0061] Fig.14 A schematic cross-sectional top view of a vertical rod of Example 2;

[0062] Fig.15 A schematic top view of the anchoring of the bottom of the FRP sleeve in Example 3;

[0063] Fig.16 A schematic diagram of a partial top view of the FRP anchor in Example 3;

[0064] Fig.17 Schematic diagram of the anchor box in Example 3;

[0065] Fig.18 Schematic diagram of the wedge-shaped anchor plug in Example 3;

[0066] Fig.19 Schematic diagram of the connecting rod in Example 4;

[0067] Fig. 20 Schematic diagram of the anchor in Example 4;

[0068] Fig.21 A schematic diagram of a reinforcement assembly in Example 4;

[0069] Fig. 22 Schematic diagram of the FRP sleeve after positioning in Example 2.

[0070] Figure numerals: top surface of the pedestal 1, pier 2, repair layer 3, FRP sleeve 4, first anchor 5, first base plate 501, first ear plate 502, first pin hole 503, hole 6, first anchor 7, clamp 8, reaction frame 9, jack 10, connecting rod 11, vertical rod 12, wire 13, second anchor 14, second base plate 1401, wedge 15, reinforcement layer 16, vertical rib 17, third anchor 18, anchor screw 1801, connecting plate 1802, connecting ring 19, fourth anchor 20, anchor box 2001, wedge-shaped anchor plug 2002, FRP notch 2003. DETAILED DESCRIPTION

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Example 1

[0075] The schematic diagram after the construction of this embodiment is shown in Figure 1 The reinforced concrete column to be reinforced is a bridge pier 2, with a diameter of 2.0m and a cap top surface 1. Figure 1 As shown, the reinforcement design is for a section of 3.0m at the bottom of the pier 2. A FRP sleeve 4 is made of carbon fiber material. The outside of the pier 2 is a repair layer 3. Between the repair layer 3 and the FRP sleeve 4 is a reinforcement layer 16 cast with ultra-high performance concrete. The thickness of the repair layer 3 is 5cm and the height is 2.0m; the thickness of the reinforcement layer 16 is 50cm and the height is 2.5m.

[0076] The FRP sleeve 4 prestressing device of the present invention surrounds the reinforced concrete column, including a loading part and a lateral expansion part. Figure 4 , Figure 8 and Fig.11; The FRP sleeve 4 is made of CFRP cloth wrapped around the lateral expansion part; the loading part includes a loading unit composed of a jack 10 and a reaction frame 9, and a clamp 8 for fixing the reaction frame 9; the clamp 8 is composed of two identical semicircular rings, and the two ends are connected by connecting bolts and tightly clamp the repair layer 3; the lateral expansion part includes multiple groups of lateral expansion units, and is permanently cast in the reinforcement layer 16 with the reinforced concrete; the lateral expansion unit is a movable mechanism, including a vertical rod 12 supporting the FRP sleeve 4 in the longitudinal direction, and two connecting rods 11 hinged to the vertical rod 12 and the reinforced concrete column, the connecting rod 11 is divided into two layers above and below and is at different heights; the jack 10 can push the vertical rod 12 to move up and down, drive the connecting rod 11 to rotate around the inner fixed hinge, change the distance between the vertical rod 12 and the reinforced concrete column, so that internal force can be generated in the FRP sleeve 4; after the concrete is poured in the FRP sleeve 4 and solidified, the FRP sleeve 4 in the formed reinforced structure has a lateral prestress. The connecting rod 11 is in a "Z" shape, with branches at both ends being parallel, the inner branch close to the reinforced concrete column being bent downward, and the outer branch being bent upward; the connecting rod 11 is hinged to the first anchor 5 fixed on the inner side of the reinforced concrete column and the second anchor 14 fixed on the outer side of the vertical rod 12 through the hinge pin holes at the two turning points; the outer shape of the two turning points of the connecting rod 11 is an arc with the center of the hinge pin hole as the center, and the outer edge line of each branch is tangent to the arc, see Fig. 9 There are 6 transverse expansion units and 6 loading units. Each transverse expansion unit and its corresponding loading unit are called a group of reinforcement components, which are located in the same vertical plane. Each group of reinforcement components is evenly arranged around the reinforced concrete column. All transverse expansion units have the same shape, size, and material, and are the same components; all reaction frames 9 are the same components. The vertical rod 12 is prefabricated with ultra-high performance concrete and has vertical reinforcement 17 inside. Fig.10 The reinforcement layer 16 is cast by ultra-high performance concrete with expansion agent. Figure 5 , Figure 6 and Figure 7 As shown, a hole 6 is punched in the repair layer 3, and the first anchor 5 is anchored by a first anchor bolt 7. The first anchor 5 includes a first bottom plate 501 and a first ear plate 502, and the first ear plate 502 has a first pin hole 503. When the second anchor 14 is prefabricated as the vertical rod 12, the second bottom plate 1401 is pre-buried on the inner surface of the vertical rod 12. Fig.10 .

[0077] The strain corresponding to the transverse prestress in the FRP sleeve is:

[0078]

[0079] L0 is the distance between the two hinge centers of the connecting rod;

[0080] h is the elevation of the hinge center on the outside of the connecting rod relative to the hinge center on the inside before wrapping the FRP cloth;

[0081] R0 is the distance from the inner side of the connecting rod to the center of the reinforced concrete column;

[0082] r0 is the distance from the hinge center to the outer edge of the adjacent connecting rod;

[0083] D0 is the thickness of the outer connecting rod branching to the outer edge of the vertical rod.

[0084] From the given design strain, h can be calculated from this formula, which is the pre-lift of the vertical bar during construction, equal to the height to which the bottom of the vertical bar is supported.

[0085] The construction process includes the following construction steps:

[0086] S1. Construction preparation: Make various components, including connecting rod 11, vertical rod 12, reaction frame 9, etc., and prepare jack 10;

[0087] S2. Surface treatment of reinforced concrete column: Because the surface concrete of pier 2 has carbonized about 15mm, 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, and the depth is controlled at about 20mm, while the thickness of the protective layer of pier 2 is 40mm; if there are still cracks, if the depth does not exceed 20mm, a "V"-shaped groove is carved and filled with epoxy resin sealant; if the depth is deeper, the epoxy resin sealant is injected according to the "Bi Ke method", see Figure 2 . Cast concrete in a mold to form a repair layer 3; polish the repair layer 3 to make it smooth or round with a certain degree of roughness. Figure 3 In the absence of confusion, the reinforced concrete column with the repair layer 3 in the reinforcement section can still be called a reinforced concrete column.

[0088] S3, fine processing of the anchoring part: on the surface of the reinforced concrete column, according to the position of each vertical rod 12 and the anchor thereon, roughly determine the position of the first anchor 5 on the surface of the corresponding reinforced concrete column, and grind it to make the surface smooth or round and have a certain roughness;

[0089] S4, installing the reaction frame: installing the annular hoop 8, tightening the connecting bolts, and firmly fixing the hoop 8 on the reinforced concrete column; the reaction frame 9, the top of the reaction frame 9 presses against the hoop 8, and fixes the reaction frame 9 with anchor bolts;

[0090] S5. Install the lateral expansion mechanism: accurately mark the vertical center line of each lateral expansion unit on the concrete surface; hinge the connecting rod 11 and the vertical rod 12 into a vertical rod assembly, support the bottom end of the vertical rod assembly on the top surface 1 of the pedestal, adjust the connecting rod 11 so that the two hinge centers of the connecting rod 11 are at the same height, thereby accurately determining the position of the first anchor 5 on the surface of the reinforced concrete column, and install the first anchor 5;

[0091] S6, making FRP sleeves: push each vertical rod 12 upward, and support the lower end of each vertical rod 12 with a wedge 15; apply glue to the outer side of the vertical rod 12 away from the reinforced concrete column; spirally wrap the CFRP cloth around all vertical rods 12 to form a first cylindrical FRP layer; apply glue to the outer surface of the prepared FRP layer, and then wrap another FRP layer; repeat the operation until the FRP layer reaches the specified 4 layers, forming an FRP sleeve 4, see Fig.12 ;

[0092] S7, applying prestress: remove the wedge 15; place the jack 10 at the top of the vertical rod 12, the jack 10 is a mechanical jack, and the jack 10 is extended by hand to reach the reaction frame 9; all the jacks 10 are extended synchronously in 3 steps; the vertical rod 12 moves downward, the connecting rod 11 rotates, and the FRP sleeve 4 expands outward and has a circumferential internal force;

[0093] S8, pouring reinforcement layer: pouring ultra-high performance concrete with expansion agent into the FRP sleeve 4 to form a reinforcement layer 16; when the concrete strength reaches the predetermined requirement, remove the jack 10, and dismantle the reaction frame 9 and the hoop 8.

[0094] Finally, the surface of the FRP sleeve 4 is layered and sprayed multiple times to form a 5mm thick wrapping layer to ensure the appearance quality and durability after reinforcement. The protective layer is sprayed with adhesive and mortar or directly painted with paint that is consistent with the original pier concrete color.

[0095] Example 2

[0096] This embodiment is an improvement on embodiment 1. Fig.13 , Fig.14 and Fig. 22 , a third anchor 18 is provided at the bottom of the vertical rod 12. After the prestress is applied, the vertical rod 12 is anchored to the top surface 1 of the pedestal through the anchor bolt 1801. The connecting plate 1802 of the anchor is welded to the vertical reinforcement 17 before pouring concrete during the prefabrication process of the vertical rod 12. The bolt holes on the connecting plate 1802 are round-ended rectangular holes, which are convenient for accommodating the estimated error caused by the outward movement of the vertical rod 17 during the application of prestress. After installing the lateral expansion unit, add the following construction steps:

[0097] S5a, making a reinforcement layer steel cage: drilling holes on the supporting surface of the reinforced concrete column, first installing spiral stirrups, and then anchoring vertical steel bars; adjusting the spiral stirrups to avoid the connecting rod 11 and keep a certain distance from the connecting rod 11 in the vertical direction.

[0098] Subsequently, the position of the anchor bolt 1801 is roughly determined, holes are drilled, and the anchor bolt 1801 is fixed with epoxy resin glue. After the prestressing is completed, it is fixed with bolts. This measure connects the FRP sleeve 4 and the pedestal, and improves the bending and shear resistance of the bottom of the reinforcement section.

[0099] Example 3

[0100] This embodiment is a modification of the embodiment 2. The bottom of the FRP sleeve 4 is connected to the abutment at multiple locations. Fig.15 , Fig.16 , Fig.17 and Fig.18 Two fourth anchors 20 are arranged between adjacent vertical rods 12, and the anchors include an anchor box 2001 and a wedge-shaped anchor plug 2002 installed inside. The anchor box 2001 has an FRP notch 2003, through which the FRP sleeve 4 can pass. Before pouring the concrete of the reinforcement layer 16, the anchor box 2001 is rotated to allow the FRP sleeve 4 to enter the FRP notch 2003, and the drill bit is drilled through the hole on the bottom plate of the anchor box 2001 to fix the anchor bolt, install the wedge-shaped anchor plug 2002, and tighten the nut to fix it. The lower end of the FRP sleeve 4 finally obtained is connected to the abutment at multiple locations to enhance the bending and shear resistance of the reinforced concrete column after reinforcement.

[0101] Example 4

[0102] This embodiment is a modification of the embodiment 1, and adopts a different type of connecting rod. Fig.19 , Fig. 20 and Fig.21 The connecting rod is plate-shaped, with round ends at both ends of the longitudinal section; accordingly, the corresponding anchors at both ends are also replaced, and the anchors are provided with corresponding horizontal circular grooves; the ends of the connecting rod can rotate in the grooves of the anchors. Connecting rings 19 are installed on the anchors at both ends. After the connecting rod and the vertical rod are installed, the corresponding connecting rings 19 are connected with iron wires 13, and the iron wires 13 are tightened to temporarily fix the vertical rods 12. This measure improves the stress state of the connecting rod in the lateral expansion unit, the connecting rod and the anchor have a larger surface contact area, and avoids the use of pins or bolts, saving materials.

[0103] 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. An FRP sleeve prestressing device for reinforcing reinforced concrete columns, characterized in that: The prestressed device surrounds the reinforced concrete column and includes a loading part and a transverse expansion part; the FRP sleeve is made by winding FRP cloth around the transverse expansion part; the loading part includes a loading unit composed of a jack and a reaction frame, and a support assembly for fixing the reaction frame; the transverse expansion part includes multiple groups of transverse expansion units, and is permanently cast in the reinforcement layer along with the reinforced concrete; the transverse expansion unit is a movable mechanism, including a vertical rod supporting the FRP sleeve in the longitudinal direction, and at least two connecting rods hinged to the vertical rod and the reinforced concrete column, and several connecting rods are at different heights; the jack pushes the vertical rod up and down, drives the connecting rod to rotate around the inner fixed hinge, changes the distance between the vertical rod and the reinforced concrete column, thereby generating transverse prestress in the FRP sleeve, and the corresponding strain is, L0 is the distance between the two hinge centers of the connecting rod; h is the elevation of the hinge center on the outside of the connecting rod relative to the hinge center on the inside before wrapping the FRP cloth; R0 is the distance from the inner side of the connecting rod to the center of the reinforced concrete column; r0 is the distance from the hinge center to the outer edge of the adjacent connecting rod; D0 is the thickness of the outer connecting rod branching to the outer edge of the vertical rod.

2. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: The connecting rod is in a "Z" shape, with branches at both ends being parallel and perpendicular to the middle section, the inner branch close to the reinforced concrete column being bent downward, and the outer branch being bent upward; the hinge hole of the connecting rod is located on the center line of the connecting rod, and the connecting rod is hinged to an anchor fixed on the inner side of the reinforced concrete column and an anchor fixed on the outer side of the vertical rod through hinge pin holes at two turning points; the outer shape of the two turning points of the connecting rod is an arc with the center of the hinge pin hole as the center, and the outer edge lines of each branch are tangent to the arc.

3. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: The connecting rod is plate-shaped, and the two ends of the longitudinal section are round ends; accordingly, the corresponding anchor pieces at the two ends are provided with corresponding horizontally arranged circular grooves; the ends of the connecting rod can rotate in the grooves of the anchor pieces.

4. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: The number of the lateral expansion units and the loading units is the same, and the lateral expansion units and the corresponding loading units are in the same vertical plane, which is called a group of reinforcement components; the lateral expansion units are evenly arranged around the reinforced concrete column.

5. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: All of the lateral expansion units are of the same shape, size, and material and are the same components; all of the reaction frames are the same components.

6. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: The vertical rod is prefabricated from ultra-high performance concrete and has longitudinal reinforcement inside; the reinforcement layer is cast from ultra-high performance concrete with expansion agent or self-compacting concrete.

7. The FRP sleeve prestressing device for reinforcing a reinforced concrete column according to claim 1, characterized in that: The loading part is located above the transverse expansion part; the supporting assembly is a clamp, which is composed of two identical semicircular rings, and the two ends are connected by connecting bolts.

8. A reinforced concrete column reinforcement construction method using the FRP sleeve prestressing device according to claim 1, characterized in that: The construction steps include: S1. Construction preparation: Make various components, including connecting rods, vertical rods, reaction frames, etc., and prepare jacks; S2. Surface treatment of reinforced concrete columns: grinding the surface of the reinforced concrete columns to expose the internal concrete and making the surface rough; S3. Fine treatment of anchoring parts: on the surface of reinforced concrete column, according to the position of each vertical rod and the anchoring parts thereon, roughly determine the position of the corresponding anchoring parts on the surface of reinforced concrete column, grind it, make the surface flat or round, and have a certain degree of roughness; S4. Install the reaction frame: install the annular clamp, tighten the connecting bolts, and firmly fix the clamp on the reinforced concrete column; install the reaction frame, the top of the reaction frame presses against the clamp, and fixes the reaction frame with anchor bolts; S5. Install the lateral expansion mechanism: accurately mark the vertical center line of each lateral expansion unit on the concrete surface; hinge the connecting rod and the vertical rod to form a vertical rod assembly, support the bottom end of the vertical rod assembly on the supporting surface of the reinforced concrete column, adjust the connecting rod so that the two hinge centers of the connecting rod are at the same height, thereby determining the position of the anchor on the surface of the reinforced concrete column, and install the anchor; S6. Making FRP sleeves: push each vertical rod upwards and support the lower end of each vertical rod with a wedge; apply glue on the outer side of the vertical rod away from the reinforced concrete column; spirally wrap the FRP cloth around all the vertical rods to form a first cylindrical FRP layer; apply glue on the outer surface of the made FRP layer and wrap another FRP layer; repeat the operation until the FRP layer reaches the specified number of layers to form an FRP sleeve; S7, applying prestress: removing the wedge; placing a jack on the top of the vertical rod, extending the jack to contact the reaction frame; extending all the jacks synchronously in multiple steps; the vertical rod moves downward, the connecting rod rotates, and the FRP sleeve expands outward and has a circumferential internal force; S8. Casting reinforcement layer: pour concrete into the FRP sleeve to form a reinforcement layer; when the concrete strength reaches the predetermined requirement, remove the jack, and dismantle the reaction frame and clamp.

9. A construction method for reinforcing a reinforced concrete column according to claim 8, characterized in that: Step S2 is replaced as follows, and in the absence of confusion, the reinforced concrete column with a repair layer in the reinforcement section is still called a reinforced concrete column: S2. Repair layer construction: In the reinforcement section of the reinforced concrete column, the surface layer of the reinforced concrete column is ground to expose the internal concrete and make the surface rough; concrete is poured in a formwork to form a repair layer 3; the surface of the repair layer 3 is ground to make it flat or round and have a certain degree of roughness.

10. A construction method for reinforcing a reinforced concrete column according to claim 8, characterized in that: Add the following steps after step S5: S5a, making a reinforcement layer steel cage: drilling holes on the supporting surface of the reinforced concrete column, first installing spiral stirrups, and then anchoring vertical steel bars; adjusting the spiral stirrups to avoid the connecting rods and keep a certain distance from the connecting rods in the vertical direction.

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