FRP sleeve prestressing device and construction method for reinforcing reinforced concrete columns

Abstract

The present invention relates to an FRP sleeve prestressing device and construction method for reinforcing reinforced concrete columns, and belongs to the technical field of construction such as civil engineering, bridge engineering, ancient architecture, and water supply and drainage engineering. When the FRP sleeve method is used for reinforcement, only by applying prestress can the high strength characteristics of the FRP material be brought into play and the material utilization efficiency be improved. The present invention adopts FRP coils to make FRP sleeves, and applies circumferential prestress to the entire FRP sleeve through a mechanism located inside the sleeve, and casts ultra-high performance concrete on the inside of the FRP sleeve. After reinforcement, the appearance is simple, durable and beautiful. The FRP sleeve itself has no external connectors such as clamps and anchors, and no butt joints, ensuring the durability of the internal concrete. Construction does not require large-scale tensioning equipment and is simple to operate. The FRP sleeves made in this solution are integrated, which can greatly improve the bearing capacity of the reinforced concrete column after reinforcement, and do not require workers with special skills, saving costs.

Description

Technical Field

[0001] The present invention relates to a reinforcement construction method for reinforced concrete columns, and in particular to an FRP sleeve prestressed device and a construction method for reinforcing reinforced concrete columns, belonging 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] Reinforced concrete columns, such as frame columns in existing buildings, piers in bridges, and supporting columns in water aqueducts, will experience a reduction in their bearing capacity and durability during long-term service due to the influence of harsh external environments and human factors. Therefore, there is a large demand for reinforcement and repair. Traditional reinforcement methods mainly include increasing the cross-section reinforcement method and externally bonded steel reinforcement method. The increasing cross-section method can effectively improve the bearing capacity of reinforced concrete columns, but it also increases the deadweight and rigidity of the components, which will increase the seismic effects on the structure and be detrimental to earthquake resistance. The steel-cladding method effectively improves the bearing capacity of reinforced concrete columns by externally enclosing them with steel plates. However, 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 a key research and development area in my country. FRP boasts the excellent properties of lightweight, high strength, and corrosion resistance, making it widely used in seismic reinforcement and reinforcement of civil engineering projects. Depending on the fiber reinforcement, FRP can be classified into glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), aramid fiber reinforced plastic (AFRP), and basalt fiber reinforced plastic (BFRP). The FRP reinforcement method for columns, which has emerged in recent years, is easy to construct. The internal concrete is subjected to triaxial stress under the constraints of the external FRP. This method, particularly in seismic reinforcement, can significantly improve the column's displacement ductility and energy dissipation capacity while maintaining minimal flexural strength, leading to widespread application.

[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] Conventional FRP outsourcing reinforcement methods cause the stress of the FRP material to lag behind the original structure. Only prestressing can change the internal force distribution of the original structure and eliminate the stress-strain lag. The prestress generated in the FRP material by pouring micro-expansive concrete is too small. The longitudinal tensioning method along the winding direction requires a large tensioning force due to the large frictional resistance, which places high demands on tensioning equipment and construction. In addition, the construction sequence of tensioning first and then anchoring is adopted, and the anchor end setting is cumbersome, which greatly increases the construction difficulty. The method of tensioning the horizontal prestress at the vertical joint exposes the anchor end and anchor device on the column surface without a protective layer, which not only increases the column's appearance and affects the appearance, but also the loose joints affect the durability protection of the internal concrete, making it prone to failure in the natural environment and not very durable.

[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 construction method for reinforcing reinforced concrete columns. The purpose is to reinforce reinforced concrete columns with FRP sleeves through simple on-site manual operations by workers without the use of lifting machinery or even hydraulic equipment, and the FRP sleeves have prestress applied by the prestressing device.

[0008] The FRP sleeve prestressing device of the present invention surrounds the reinforced concrete column, and includes a loading part and a transverse expansion part; the FRP sleeve is made of FRP cloth wrapped 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 hingedly connecting 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, driving the connecting rod to rotate around the inner fixed hinge, changing 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 outer hinge center of the connecting rod relative to the inner hinge center 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 the anchor fixed on the inner side on the reinforced concrete column and the anchor fixed on the outer side on the vertical rod through the hinge pin holes at the two turning points; the outer shape of the two turning points of the connecting rod is an arc with the center of its hinge pin hole as the center, and the outer edge line of each branch is tangent to the arc.

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

[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 transverse 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 rods are prefabricated from ultra-high performance concrete and have 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 hoop, which is composed of two identical semicircular rings, and the two ends are connected by connecting bolts.

[0021] The reinforced concrete column reinforcement construction method using the FRP sleeve prestressing device includes 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 inner concrete and roughening the surface;

[0024] S3. Fine treatment of anchoring parts: On the surface of reinforced concrete column, roughly determine the position of the corresponding anchors on the surface of reinforced concrete column according to the position of each vertical rod and the anchors on it, and polish it to make the surface flat or rounded with 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, tighten the clamp with the top of the reaction frame, and fix the reaction frame with anchor bolts;

[0026] S5. Install the lateral expansion mechanism: Accurately mark the vertical centerline 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. This determines the position of the anchor on the surface of the reinforced concrete column and installs the anchor.

[0027] S6. Fabricate the FRP sleeve: Push each vertical rod upward and support the lower end of each vertical rod with a wedge; apply glue to the outer side of the vertical rod away from the reinforced concrete column; spirally wrap FRP cloth around all vertical rods to form the first cylindrical FRP layer; apply glue to the outer surface of the prepared FRP layer and wrap another FRP layer; repeat the process until the specified number of FRP layers is reached to form the FRP sleeve;

[0028] S7. Apply prestress: remove the wedge; place a jack on the top of the vertical rod, extend the jack, and push it against the reaction frame; extend 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 hoop 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 clamps.

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

[0031] S2. Repair layer construction: In the reinforced section of the reinforced concrete column, the surface 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 polished 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. Fabricate a reinforcement cage: drill holes on the supporting surface of the reinforced concrete column, install spiral stirrups first, and then anchor the vertical steel bars; adjust the spiral stirrups to avoid the connecting rods and maintain a certain vertical distance from the connecting rods.

[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 are made of 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. After reinforcement is complete, these plates are connected to the supporting surface of the reinforced concrete column via anchor bolts. Between the two vertical rods, a clamp can be used to hold the lower edge of the FRP sleeve, which is then connected to the reinforced concrete supporting surface via anchor bolts on the clamp. These two measures secure the lower edge of the FRP sleeve and enhance the bending and shear resistance of the reinforced concrete column at its base.

[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 reinforced concrete columns. The high-strength FRP material has prestressed stress, 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 joints, and its appearance after reinforcement is simple and beautiful;

[0039] (3) The present invention does not use any 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 construction 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 locations 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 prestressed 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 uses 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. It can also increase the prestress value in the outer FRP sleeve, avoiding the debonding of the FRP sleeve and the concrete. It 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.

[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 as to fully utilize the prestress in the FRP sleeve 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 supporting 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 end. 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 installed anchors 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] Figure 9 Connecting rod diagram;

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

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

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

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

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

[0062] Figure 15 Schematic top view of the anchoring at the bottom of the FRP sleeve in Example 3;

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

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

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

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

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

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

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

[0070] Figure 1: Cap top surface 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 reinforcement 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 terms used in the embodiments are based on common engineering terminology and are not strictly defined. For example, "upper" refers to the upper surface of the completed portion of a structure, and also includes the upper surfaces of auxiliary components located diagonally above its range of influence. When expressing a direction, "upper" includes both directly above and diagonally above. Directional terms such as "left," "right," "upper," and "lower" are used solely to facilitate description in conjunction with the accompanying drawings. The directional terms used are intended solely to facilitate the description of this patent and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations 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 various cross-sectional shapes. In the embodiment, only circular cross-sectional shapes are 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 that needs to be reinforced is a bridge pier 2 with a diameter of 2.0m. The top surface 1 of the pedestal is as follows: Figure 1 As shown, the reinforcement design is for the bottom 3.0m section 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 prestressed device of the present invention surrounds the reinforced concrete column, including a loading part and a transverse expansion part. Figure 4 、 Figure 8 and Figure 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, the two ends of which 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 along with the reinforced concrete; the lateral expansion unit is a movable mechanism, including a vertical rod 12 that supports the FRP sleeve 4 in the longitudinal direction, and two connecting rods 11 that hinge 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, thereby generating internal force in the FRP sleeve 4; after concrete is poured in the FRP sleeve 4 and solidified, the FRP sleeve 4 in the reinforced structure formed has 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 is bent downward, and the outer branch is 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 of the circle, and the outer edge line of each branch is tangent to the arc. Figure 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 and 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 from ultra-high performance concrete and has vertical reinforcement 17 inside. Figure 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 with a first anchor bolt 7. The first anchor 5 comprises a first base plate 501 and a first ear plate 502. 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 base plate 1401 is embedded in the inner surface of the vertical rod 12. Figure 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 outer hinge center of the connecting rod relative to the inner hinge center 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 ground with an angle grinder, the depth of which is controlled at about 20mm, while the thickness of the protective layer of pier 2 is 40mm; if cracks still exist and the depth does not exceed 20mm, a "V"-shaped groove is carved and filled with epoxy resin sealant; if the depth is deeper, epoxy resin sealant is injected according to the "Bi Ke method", see Figure 2 . Cast concrete in a formwork to form a repair layer 3; polish the surface of the repair layer 3 to make it smooth or round and have a certain degree of roughness. Figure 3 . In the absence of confusion, the reinforced concrete column with the reinforced section and repair layer 3 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 anchoring part thereon, roughly determine the position of the first anchoring part 5 on the surface of the corresponding reinforced concrete column, and polish it to make the surface flat or rounded with a certain degree of roughness;

[0089] S4. Install the reaction frame: Install the annular hoop 8, tighten the connecting bolts, and firmly fix 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 centerline of each lateral expansion unit on the concrete surface; hinge the connecting rod 11 and the vertical rod 12 to form 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. Make the FRP sleeve: push each vertical rod 12 upwards 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 the first cylindrical FRP layer; apply glue to the outer surface of the prepared FRP layer and wrap another FRP layer; repeat the operation until the FRP layer reaches the specified 4 layers to form the FRP sleeve 4. Figure 12 ;

[0092] S7. Apply prestress: remove the wedge 15; place the mechanical jack 10 on the top of the vertical rod 12, and manually extend the jack 10 until it reaches the reaction frame 9; extend all the jacks 10 synchronously in three 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: pour ultra-high performance concrete with expansion agent into FRP sleeve 4 to form reinforcement layer 16; when the concrete strength reaches the predetermined requirement, remove jack 10, remove reaction frame 9 and clamp 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. Figure 13 、 Figure 14 and Figure 22 The bottom end of the vertical rod 12 has a third anchor 18. After prestressing, the vertical rod 12 is anchored to the top surface 1 of the pedestal via a foundation screw 1801. The connecting plate 1802 of this anchor is welded to the vertical reinforcement 17 during the prefabrication process of the vertical rod 12 and before concrete is poured. The bolt holes in the connecting plate 1802 are rectangular holes with rounded ends to accommodate the estimated error caused by the outward movement of the vertical rod 17 during the prestressing process. After installing the lateral expansion unit, the following construction steps are added:

[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 maintain a certain vertical distance from the connecting rod 11.

[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 base, improving the bending and shear resistance of the bottom of the reinforced section.

[0099] Example 3

[0100] This embodiment is a modification of embodiment 2. The bottom of the FRP sleeve 4 is connected to the base at multiple locations. Figure 15 、 Figure 16 、 Figure 17 and Figure 18 Two fourth anchors 20 are arranged between adjacent vertical rods 12. These anchors include an anchor box 2001 and a wedge-shaped anchor plug 2002 installed inside. The anchor box 2001 has an FRP notch 2003 that allows the FRP sleeve 4 to pass through. 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. A drill bit is drilled through the hole in the bottom plate of the anchor box 2001 to secure the anchor bolt. The wedge-shaped anchor plug 2002 is installed and the nut is tightened firmly to secure it. The resulting FRP sleeve 4 is connected to the base at multiple points at the lower end, enhancing the bending and shear resistance of the reinforced reinforced concrete column.

[0101] Example 4

[0102] This embodiment is a modification of embodiment 1, using a different type of connecting rod. Figure 19 、 Figure 20 and Figure 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 horizontally arranged 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 wires 13, and the 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 are only preferred embodiments of the present invention and are 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 scope of protection of the present invention.

Claims

1. An FRP sleeve prestressing device for reinforcing reinforced concrete columns, characterized by: The prestressed device surrounds the reinforced concrete column and includes a loading part and a transverse expansion part; the FRP sleeve is made of FRP cloth wrapped 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, which are 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 hingedly connecting the vertical rod and the reinforced concrete column, and several connecting rods are at different heights; the connecting rod is "Z" shaped, with branches at both ends parallel, They are all perpendicular to the middle section, with the inner branch close to the reinforced concrete column bent downward and the outer branch 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 the anchor fixed on the inner side of the reinforced concrete column and the anchor fixed on the outer side of the vertical rod through the hinge pin holes at the 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 of the circle, and the outer edge line of each branch is tangent to the arc; the jack pushes the vertical rod up and down, driving the connecting rod to rotate around the inner fixed hinge, changing 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 outer hinge center of the connecting rod relative to the inner hinge center 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 reinforced concrete columns according to claim 1, characterized in that: The connecting rod is plate-shaped, with round ends at both ends of the longitudinal section; accordingly, corresponding horizontal circular grooves are provided on the corresponding anchoring pieces at both ends; the ends of the connecting rod can rotate in the grooves of the anchoring pieces.

3. The FRP sleeve prestressing device for reinforcing reinforced concrete columns according to claim 1, characterized in that: 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, which is called a group of reinforcement components; the transverse expansion units are evenly arranged around the reinforced concrete column.

4. The FRP sleeve prestressing device for reinforcing reinforced concrete columns 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.

5. The FRP sleeve prestressing device for reinforcing reinforced concrete columns according to claim 1, characterized in that: The vertical rods are prefabricated from ultra-high performance concrete and have longitudinal reinforcement inside; the reinforcement layer is cast from ultra-high performance concrete with an expansion agent or self-compacting concrete.

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

7. 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 inner concrete and roughening the surface; S3. Fine treatment of anchoring parts: On the surface of reinforced concrete column, roughly determine the position of the corresponding anchors on the surface of reinforced concrete column according to the position of each vertical rod and the anchors on it, and polish it to make the surface flat or rounded with 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, tighten the clamp with the top of the reaction frame, and fix the reaction frame with anchor bolts; S5. Install the lateral expansion mechanism: Accurately mark the vertical centerline 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. This determines the position of the anchor on the surface of the reinforced concrete column and installs the anchor. S6. Fabricate the FRP sleeve: Push each vertical rod upward and support the lower end of each vertical rod with a wedge; apply glue to the outer side of the vertical rod away from the reinforced concrete column; spirally wrap FRP cloth around all vertical rods to form the first cylindrical FRP layer; apply glue to the outer surface of the prepared FRP layer and wrap another FRP layer; repeat the process until the specified number of FRP layers is reached to form the FRP sleeve; S7. Apply prestress: remove the wedge; place a jack on the top of the vertical rod, extend the jack, and push it against the reaction frame; extend 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 hoop 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 clamps.

8. A construction method for reinforcing reinforced concrete columns according to claim 7, characterized in that: Step S2 is replaced as follows, and in order to avoid confusion, the reinforced concrete column with a repair layer in the reinforced section is still referred to as a reinforced concrete column: S2. Construction of repair layer: Grind the surface of the reinforced concrete column in the reinforced section to expose the internal concrete and make the surface rough; cast concrete in a formwork to form a repair layer; and grind the repair layer to make the surface smooth or round with a certain degree of roughness.

9. A construction method for reinforcing reinforced concrete columns according to claim 7, characterized in that: Add the following steps after step S5: S5a. Fabricate a reinforcement cage: drill holes on the supporting surface of the reinforced concrete column, install spiral stirrups first, and then anchor the vertical steel bars; adjust the spiral stirrups to avoid the connecting rods and maintain a certain vertical distance from the connecting rods.

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