Prestressed concrete beam and column joint reinforcing method and reinforcing structure thereof

Abstract

The invention relates to a prestressed concrete beam and column joint reinforcing method and structure. The method comprises the steps that column surface concrete is chiseled away to form a rough surface, and floor reinforcing steel bars are reserved; split steel hoops are installed, and beam bottom connecting steel plates are welded; after the pre-stressed pipeline is positioned through radar, the chemical anchor bolts are implanted, and the pre-stressed tendons are ensured to be avoided; welding a beam top steel plate to form a closed support; newly-added longitudinal bars are welded in unplugged welding holes of the upper steel plate and the lower steel plate, stirrups are bound, and the longitudinal bars outside the beam width range extend to a floor slab to be anchored; and finally, non-shrinkage grouting materials are poured under pressure, and maintenance is conducted for 7 days or above. The reinforcing structure is composed of steel hoops, upper and lower connecting steel plates, chemical anchor bolts and newly-added steel bars which are wrapped into a whole through grouting materials. The beam body does not need to be cut off, and the functions of the prestressed tendons are completely reserved; the steel hoop and the chemical anchor bolt cooperate to enhance the bearing capacity and the shock resistance of the joint; construction is convenient and efficient, cost is low, and normal use of a building is not affected; and the applicability is wide, and flexible adjustment can be achieved to meet different reinforcing requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of building structure reinforcement, in particular to a method for reinforcing a prestressed concrete beam and column node and a reinforcement structure thereof. Background Art

[0002] In the field of construction engineering, prestressed concrete structures artificially apply prestress before the components are subjected to external loads, using the excellent compressive properties of concrete to compensate for its lack of tensile strength, effectively delaying the cracking of concrete in the tensile zone, thereby significantly improving the structure's crack resistance and stiffness.

[0003] With socioeconomic development and shifting demands for building functionality, the renovation and reinforcement of existing buildings is increasing. For frame column reinforcement, the traditional method of increasing cross-sections often requires truncation of the frame beams connecting the columns. However, when the connecting beams are prestressed concrete beams, truncation can lead to failure of the prestressing tendons, damaging the original prestressing system and significantly weakening the load-bearing capacity. This makes it difficult to meet the requirements of modern building functional upgrades and increased loads, exposing the obvious limitations of traditional reinforcement methods for prestressed concrete beam-column joints.

[0004] At present, there is a technical gap in reinforcement technology for the special working conditions of prestressed concrete beam-column joints in ensuring the integrity of the prestressed system and structural safety. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for reinforcing prestressed concrete beam and column nodes and a reinforcement structure thereof, so as to solve the technical problem that traditional reinforcement methods lead to prestress failure in the construction of such nodes and meet the actual needs of the project.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for reinforcing prestressed concrete beam and column nodes, comprising the following steps:

[0007] S1. Joint area pretreatment: Chisel away 30-50mm of surface concrete within the full height of the frame column, creating a rough surface ≥6mm deep and spaced ≤100mm apart. Chisel away the floor slab 100mm on each side of the prestressed beam to the top surface of the slab bottom reinforcement, retaining the stress-bearing reinforcement.

[0008] S2. Install the lower steel collar assembly: Place the split annular collar on the outside of the frame column, temporarily secure with bolts, and then weld the groove. Weld the beam bottom connecting steel plate to the annular collar groove.

[0009] S3. Chemical anchor bolting: Drill holes in the connecting steel plate at the bottom of the beam, avoiding the prestressed reinforcement. Insert M16 high-strength chemical anchor bolts to a depth of ≥150mm and a drill hole spacing of ≥3 times the bolt diameter. Tighten with a torque wrench to a design tensile force of ≥60kN.

[0010] S4. Construct a closed support system: Install an upper steel plate on the top surface of the prestressed beam and weld its ends to the grooves of the annular hoop.

[0011] S5. New reinforcement connection: Create 25mm Φ perforated plug welding holes in the beam bottom connecting steel plate and the upper steel plate, with a spacing of ≤200mm. Pass the new longitudinal reinforcement through the plug welding holes and fully weld them, then tie with stirrups.

[0012] S6. Grouting: After supporting the formwork, pressure-inject non-shrinkage grouting material with a compressive strength of ≥60MPa, starting from the bottom and grouting until it overflows from the top.

[0013] Furthermore, in step S1 of the present invention, when removing the concrete on the surface of the frame column, a 10 mm artificial chiseling layer is reserved from the surface of the steel bars in the column.

[0014] Furthermore, in step S3 of the present invention, a radar detector is used to locate the prestressed pipe to ensure drilling avoidance.

[0015] Furthermore, in step S5 of the present invention, the longitudinal reinforcement outside the beam width extends upward through the floor slab area, and the anchorage length is ≥Lae.

[0016] Furthermore, the present invention further includes a curing step after step S6: covering with plastic film and curing for ≥7 days, and removing the mold after the strength of the grouting material reaches 80%.

[0017] At the same time, the present invention also provides a reinforcement structure used in a method for reinforcing prestressed concrete beam and column nodes, comprising:

[0018] Split steel hoop, consisting of multiple curved steel plates temporarily fixed to the outside of the frame column by high-strength bolts, with groove welds used at the butt joints to form a ring;

[0019] The lower connecting steel plate is horizontally welded and fixed to the bottom of the steel hoop, parallel to the bottom surface of the prestressed concrete beam;

[0020] The upper connecting steel plate covers the top surface of the prestressed concrete beam, and its two ends are welded to the top groove of the steel hoop;

[0021] Chemical anchor bolt assembly, which penetrates the lower part to connect the steel plate and anchor it to the side wall of the prestressed concrete beam;

[0022] New longitudinal reinforcements include: longitudinal reinforcement within the beam width, which passes through the plug welding holes of the lower connecting steel plate and is fully welded; and longitudinal reinforcement outside the beam width, which extends upward and is anchored in the floor slab cutout area;

[0023] The grouting material wrapping layer is filled between the frame column and the steel hoop.

[0024] Furthermore, the thickness of the arc-shaped steel plate of the split steel ferrule of the present invention is ≥20 mm, and the height of the butt groove weld is ≥8 mm.

[0025] Furthermore, the thickness of the lower connecting steel plate and the upper connecting steel plate of the present invention are both 20 mm, and the elevation error of the top surface of the upper connecting steel plate is ≤ 2 mm.

[0026] Furthermore, the chemical anchor assembly of the present invention includes an M16 high-strength chemical anchor, the drilling diameter of which is 2 mm larger than the anchor diameter, the anchoring depth is ≥150 mm, and the distance between the center of the anchor hole and the prestressed pipe in the beam is ≥3 times the anchor diameter.

[0027] Furthermore, the anchorage length of the newly added longitudinal reinforcement in the floor slab chiseled area of ​​the present invention is ≥Lae, and it is tied with the stirrups to form a grid; the diameter of the plug welding hole is 25mm, the spacing is ≤200mm, the newly added longitudinal reinforcement is HRB400 steel bar with a diameter ≥20mm, and the thickness of the plug welding weld with the steel plate is ≥8mm.

[0028] The beneficial effect of the present invention is to solve the defects existing in the background technology.

[0029] 1. The reinforcement device can better preserve the structural performance. For the prestressed concrete beams connected to the frame columns, there is no need to cut the beams, which avoids the failure of the prestressed tendons and fully preserves the prestressed performance of the beams, ensuring the rationality and safety of the force of the entire structure. Compared with traditional reinforcement methods, it greatly improves the reliability of the structure.

[0030] 2. The steel hoop tightly wraps the prestressed concrete beam and works together with the chemical anchor bolts to form a whole with the reinforcement device and the original structure. It can effectively transfer and distribute the load, improve the bearing capacity and seismic performance of the column-beam node, and enhance the overall stability of the building structure.

[0031] 3. The construction process is simple and quick, without the need for complex construction techniques and large equipment, which reduces construction difficulty and construction costs. At the same time, construction can be carried out without affecting the normal use of the building, reducing interference with users and having good economic and social benefits.

[0032] 4. It is not only suitable for the node reinforcement of prestressed concrete beams and frame columns, but also applicable to the reinforcement of other types of concrete beam-column nodes. The design of the steel hoop and the arrangement of the chemical anchor bolts can be flexibly adjusted according to different column and beam sizes and reinforcement requirements. It has strong versatility and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the reinforcement structure of the present invention;

[0034] Figure 2 It is a structural schematic diagram of the steel hoop of the present invention;

[0035] Figure 3 This is a schematic diagram of the connection structure between the steel hoop and the upper steel plate of the present invention;

[0036] In the figure: 1-steel hoop, 11-arc steel plate 1, 12-arc steel plate 2, 13-upper connecting steel plate, 2-hole 1 (piercing plug welding hole), 3-hole 2 (chemical anchor hole), 4-chemical anchor, 5-longitudinal reinforcement outside the beam width, 6-longitudinal reinforcement within the beam width, 7-floor slab, 8-frame column, 9-prestressed concrete beam, 10-stirrups. DETAILED DESCRIPTION

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0038] like Figure 1-Figure 3 A prestressed concrete beam and column node reinforcement structure is shown, comprising:

[0039] The split steel hoop 1 is made of multiple curved steel plates (curved steel plate 11, curved steel plate 2 12) temporarily fixed to the outside of the frame column 8 by high-strength bolts, and the butt joints are connected into a ring by groove welds;

[0040] The lower connecting steel plate is horizontally welded and fixed to the bottom of the steel hoop, parallel to the bottom surface of the prestressed concrete beam 9;

[0041] The upper connecting steel plate 13 covers the top surface of the prestressed concrete beam, and its two ends are welded to the top of the steel hoop through the hole-2 groove;

[0042] Chemical anchor bolt 4 assembly, passing through the lower connecting steel plate and the side wall of the prestressed concrete beam and anchored through hole 2 3;

[0043] The newly added longitudinal reinforcement includes: longitudinal reinforcement 6 within the beam width, which passes through the plug welding holes of the lower connecting steel plate and is fully welded; and longitudinal reinforcement 5 outside the beam width, which extends upward and is anchored in the chiseled area of ​​the floor slab 7; there are stirrups 10 on the outside of the newly added longitudinal reinforcement.

[0044] The grouting material wrapping layer is filled between the frame column and the steel hoop.

[0045] The reinforcement steps are as follows:

[0046] 1. Set up the operating scaffolding: Build a full-height scaffolding around the frame columns to be reinforced and the connected prestressed concrete beams. The spacing between the scaffolding uprights and the crossbar pitches should be determined according to the construction plan. The scaffolding boards should be fully laid and secured. Protective railings and safety nets should be installed around the perimeter to create a safe operating platform. Use a level to measure and position the scaffolding to ensure that the height meets the clearance requirements for chiseling, installation, and other operations, with an error within ±5mm.

[0047] 2. Chisel away the floor slab around the prestressed beams: Using a hydraulic breaker and manual chiseling, remove the floor slab concrete 100 mm on each side of the prestressed beams, chiseling down to the top surface of the reinforcement at the bottom of the slab, leaving the load-bearing reinforcement within the slab. Use a rebar detector to locate the reinforcement within the slab to avoid damage during the chiseling process. After chiseling, clean up the debris, derust the exposed reinforcement at the slab edges, and apply epoxy anti-corrosion paint.

[0048] 3. Chisel away the concrete around the frame columns: Chisel away the loose concrete and protective layer along the entire height of the frame columns, removing a thickness of 30-50mm (depending on the designed reinforcement dimensions) to expose a solid base. When using a jackhammer, leave a 10mm artificial chiseling layer behind the longitudinal reinforcement and stirrups to prevent mechanical vibration from damaging the existing reinforcement. After chiseling, roughen the column surface to a depth of ≥6mm and a spacing of ≤100mm. Clean away any dust and debris.

[0049] 4. Install the lower steel collar assembly: The steel collar is made of hot-rolled steel (the specific steel type is determined by the design drawings). The lower collar consists of a column collar and a connecting steel plate at the bottom of the beam. First, place the collar (20mm thick, two-piece structure) on the outside of the frame column and temporarily secure it with bolts. Adjust the collar's verticality to ensure that its center deviates ≤3mm from the column center.

[0050] 5. Welding connection between ferrules: Bevel welding is used at the ferrule joints, with a weld height of ≥8mm. Before welding, remove oil and rust from the connection surface. Use a symmetrical welding method to reduce welding deformation. Perform weld flaw detection after welding to ensure effective force transmission between the ferrule and the beam bottom.

[0051] 6. Connect the hoop to the prestressed beam with chemical anchors: Drill holes (2mm larger than the anchor diameter) at the corresponding locations on the connecting steel plate on the beam side. Use M16 high-strength chemical anchors (anchoring depth 150mm, the chemical anchor model is determined according to the design drawings). Tighten with an electric torque wrench, ensuring the anchor tension is ≥ 60kN. Avoid the prestressed reinforcement in the beam when drilling. Use a radar detector to locate the prestressed pipes, and ensure that the drill hole spacing is ≥ 3d (d is the anchor diameter).

[0052] 7. Install the upper connecting steel plate: Install a steel plate (20mm thick) on the top surface of the prestressed beam. The ends of the steel plate are welded to the lower steel hoop with grooves. The weld height is ≥10mm, forming a vertically connected steel hoop support system. During welding, a rigid fixing method is used to control deformation and ensure that the top surface elevation of the steel plate is consistent (error ≤2mm).

[0053] 8. Tie steel bars:

[0054] 1) Longitudinal reinforcement within the beam width: adopt the perforation plug welding process, open Φ25mm plug welding holes (spacing ≤200mm) in the steel plate below the steel hoop, pass the newly added longitudinal reinforcement (HRB400, diameter 20mm, determined according to the design drawing) through the plug welding holes, and fully weld to the bottom surface of the steel plate, with the weld thickness ≥8mm;

[0055] 2) Longitudinal reinforcement outside the beam width: The longitudinal reinforcement extends upward and passes through the removed floor slab area. The anchorage length is ≥Lae. The upper longitudinal reinforcement of the remaining prestressed beams is connected to the upper steel plate by perforation plug welding and is fully welded to the top surface of the upper steel plate. The weld thickness is ≥8mm;

[0056] 3) Tie stirrups and perform other operations according to the design drawings.

[0057] 9. Formwork Installation and Grouting: Wrap the column with formwork to pour high-strength, non-shrinkage grouting material (compressive strength ≥ 60 MPa). Apply sealing tape to the formwork joints to prevent grout leakage. Sprinkle water on the column surface 24 hours before grouting. Use pressure grouting to inject grout from the bottom grouting hole of the formwork until grout overflows from the top grouting hole. Vibrate and compact until grout is sealed.

[0058] 10. Maintenance and finished product protection:

[0059] 1) After grouting is completed, cover with plastic film for moisture preservation. When the ambient temperature is ≥15℃, the curing time should be ≥7 days, and water should be sprinkled 3-4 times a day. During the curing period, scaffolding vibration and construction load impact are prohibited. After the grouting material strength reaches 80% of the design value (passed the test of the same conditions test block), the formwork and scaffolding can be removed;

[0060] 2) Apply concrete interface treatment agent on the outside of the steel hoop, brushing one layer vertically and horizontally to enhance the bonding strength between the mortar and the steel. The mortar uses polymer cement mortar with a thickness of 20 to 30 mm (depending on the design drawings).

[0061] The innovation of this solution lies in:

[0062] 1. For the reinforcement of prestressed concrete beam and column nodes, a non-truncation reinforcement design is adopted, breaking through the limitation of traditional frame column reinforcement that requires truncation of connected beams. The concrete beam and column nodes are reinforced through steel hoops, avoiding the problem of prestressed reinforcement failure caused by truncation of prestressed concrete beams, retaining the original structural performance to the greatest extent, and providing a new solution for the reinforcement of prestressed concrete beam frame columns.

[0063] 2. Chemical anchor bolts are used to connect steel ferrules and prestressed concrete beams to achieve a collaborative connection. The beam steel ferrules can be customized according to the specific size and shape of the prestressed beam, and can fit tightly to the column-beam node and evenly transfer the load. Chemical anchor bolts use high-strength adhesives to firmly fix the steel ferrules on the concrete beam, forming a reliable connection system to ensure that the reinforcement device works in coordination with the original structure.

[0064] 3. The installation of the reinforcement device does not require large-scale construction equipment and is relatively simple to operate, greatly shortening the construction period. At the same time, it reduces the impact on the original building's use function and can be carried out without interrupting the normal use of the building, showing good adaptability to engineering applications.

[0065] As a result, significant results include:

[0066] 1. Solve the problem of prestressed tendon failure (compared with the traditional beam cutting method);

[0067] 2. Load transfer efficiency is increased by more than 40% (through three-dimensional force transmission of steel hoop);

[0068] 3. Construction period shortened by 50% (no need for beam repair process);

[0069] 4. Improved seismic performance: The stiffness of the node area is increased by 35%.

[0070] The above description only describes specific embodiments of the present invention. Various examples do not limit the essential content of the present invention. After reading the description, ordinary technicians in the relevant technical field can make modifications or variations to the specific embodiments described above without departing from the essence and scope of the invention.

Claims

1. A method for reinforcing prestressed concrete beam and column nodes, characterized by: The following steps are included: S1. Joint area pretreatment: Chisel away 30-50mm of surface concrete within the full height of the frame column, creating a rough surface ≥6mm deep and spaced ≤100mm apart. Chisel away the floor slab 100mm on each side of the prestressed beam to the top surface of the slab bottom reinforcement, retaining the stress-bearing reinforcement. S2. Install the lower steel collar assembly: Place the split annular collar on the outside of the frame column, temporarily secure with bolts, and then weld the groove. Weld the beam bottom connecting steel plate to the annular collar groove. S3. Chemical anchor bolting: Drill holes in the connecting steel plate at the bottom of the beam, avoiding the prestressed reinforcement. Insert M16 high-strength chemical anchor bolts to a depth of ≥150mm and a drill hole spacing of ≥3 times the bolt diameter. Tighten with a torque wrench to a design tensile force of ≥60kN. S4. Construct a closed support system: Install an upper steel plate on the top surface of the prestressed beam and weld its ends to the grooves of the annular hoop. S5. New reinforcement connection: Create 25mm Φ perforated plug welding holes in the beam bottom connecting steel plate and the upper steel plate, with a spacing of ≤200mm. Pass the new longitudinal reinforcement through the plug welding holes and fully weld them, then tie with stirrups. S6. Grouting: After supporting the formwork, pressure-inject non-shrinkage grouting material with a compressive strength of ≥60MPa, starting from the bottom and grouting until it overflows from the top.

2. A method for reinforcing prestressed concrete beam and column nodes according to claim 1, characterized in that: In step S1, when removing the concrete on the surface of the frame column, a 10 mm artificial chiseling layer is reserved from the surface of the steel bars in the column.

3. A method for reinforcing prestressed concrete beam and column nodes according to claim 1, characterized in that: In step S3, a radar detector is used to locate the prestressed pipe to ensure drilling avoidance.

4. A method for reinforcing prestressed concrete beam and column nodes according to claim 1, characterized in that: In step S5, the longitudinal reinforcement outside the beam width extends upward through the floor slab area, and the anchorage length is ≥Lae.

5. A method for reinforcing prestressed concrete beam and column nodes according to claim 1, characterized in that: The step S6 also includes a curing step: covering with plastic film and curing for 7 days or more, and removing the mold after the strength of the grouting material reaches 80%.

6. A reinforcement structure used in the method for reinforcing prestressed concrete beam and column joints according to claim 1, characterized in that: include: Split steel hoop, consisting of multiple curved steel plates temporarily fixed to the outside of the frame column by high-strength bolts, with groove welds used at the butt joints to form a ring; The lower connecting steel plate is horizontally welded and fixed to the bottom of the steel hoop, parallel to the bottom surface of the prestressed concrete beam; The upper connecting steel plate covers the top surface of the prestressed concrete beam, and its two ends are welded to the top groove of the steel hoop; Chemical anchor bolt assembly, which penetrates the lower part to connect the steel plate and anchor it to the side wall of the prestressed concrete beam; New longitudinal reinforcement, including: longitudinal reinforcement within the beam width, passing through the plug welding holes of the lower connecting steel plate and fully welded; and, longitudinal reinforcement outside the beam width, extending upward and anchored in the floor slab chiseled area; The grouting material wrapping layer is filled between the frame column and the steel hoop.

7. The prestressed concrete beam and column joint reinforcement structure according to claim 6, characterized in that: The thickness of the arc-shaped steel plate of the split steel hoop is ≥20 mm, and the height of the butt groove weld is ≥8 mm.

8. The prestressed concrete beam and column joint reinforcement structure according to claim 6, characterized in that: The thickness of the lower connecting steel plate and the upper connecting steel plate are both 20 mm, and the elevation error of the top surface of the upper connecting steel plate is ≤2 mm.

9. The prestressed concrete beam and column joint reinforcement structure according to claim 6, characterized in that: The chemical anchor assembly includes an M16 high-strength chemical anchor, the drilling diameter of which is 2 mm larger than the anchor diameter, the anchoring depth is ≥150 mm, and the distance between the center of the anchor hole and the prestressed pipe in the beam is ≥3 times the anchor diameter.

10. The prestressed concrete beam and column joint reinforcement structure according to claim 6, characterized in that: The anchorage length of the newly added longitudinal reinforcement in the floor slab chiseled area is ≥Lae, and it is tied with the stirrups to form a grid; the diameter of the plug welding holes is 25mm, the spacing is ≤200mm, the newly added longitudinal reinforcement is HRB400 steel bar with a diameter ≥20mm, and the thickness of the plug welding weld with the steel plate is ≥8mm.

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