Method for reinforcing segmented self-locking type TRUHPC annularly-wrapped reinforced concrete column
The segmented self-locking TRUHPC ring-encased reinforced concrete column reinforcement method solves the problems of insufficient load-bearing capacity and poor durability of reinforced concrete structures during service, achieving improved load-bearing capacity, enhanced durability, and excellent seismic performance, and is suitable for various engineering sites.
Patent Information
- Application Number
- CN202511825281.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-02-24
AI Technical Summary
Existing reinforced concrete structures are prone to cracking, spalling, steel corrosion, insufficient load-bearing capacity, and decreased ductility during long-term service. In particular, reinforcement methods are difficult to simultaneously improve load-bearing capacity and ductility in humid and hot, coastal chloride and cold regions or under seismic loads.
The segmented self-locking TRUHPC ring-encased reinforced concrete column reinforcement method is adopted. Through base treatment, UHPC matrix configuration, CFRP mesh preparation and segmented reinforcement, the UHPC matrix and CFRP mesh form a composite system. The ends of the CFRP mesh are self-locking to prevent slippage. The construction is carried out in combination with the segmented coating process.
It significantly improves load-bearing capacity, durability, and seismic performance, and is suitable for various engineering sites, especially in hot and humid coastal areas and earthquake-prone regions. It is easy to construct and has a wide range of applications.
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Figure CN121556709A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building structure reinforcement technology, and in particular to a segmented self-locking TRUHPC ring-enclosed reinforced concrete column reinforcement method. Background Technology
[0002] Reinforced concrete structures are widely used in industrial and civil buildings, bridges, and infrastructure. However, during long-term service, due to factors such as increased load, environmental erosion, material aging, and seismic forces, concrete column members often experience problems such as cracking, spalling, steel corrosion, insufficient load-bearing capacity, and decreased ductility, which seriously threaten the durability and safety of the structure.
[0003] To address the aforementioned issues, commonly used reinforcement methods in the engineering field include steel sleeve reinforcement, CFRP external bonding reinforcement, and ordinary concrete or high-strength concrete cladding reinforcement. However, the durability and ductility of the reinforced structure remain key bottlenecks. In the humid and hot environment of southern regions, the chloride-rich coastal areas, and the freeze-thaw environment of cold regions, steel sleeves are prone to corrosion and failure, FRP interface bonding is prone to degradation, and ordinary concrete sleeve reinforcement carries the risk of cracking and seepage. For column members under seismic loading, traditional reinforcement methods struggle to simultaneously improve both load-bearing capacity and ductility. Summary of the Invention
[0004] To overcome the problems of poor durability and insufficient ductility in existing reinforcement methods, this invention provides a segmented self-locking TRUHPC ring-enclosed reinforced concrete column reinforcement method.
[0005] This invention provides a segmented self-locking TRUHPC ring-enclosed reinforced concrete column reinforcement method, employing the following technical solution:
[0006] S1. Base treatment: Roughen the surface of the reinforced concrete column to remove loose layers and contaminants;
[0007] S2, UHPC matrix configuration: Prepare UHPC slurry according to the design ratio, and add steel fiber;
[0008] S3. Prepare CFRP mesh: Pre-cut CFRP mesh according to the segmented design width and column cross-section size. Set two CFRP bars around the start and end points of each CFRP mesh for self-locking to prevent slippage and relaxation of the CFRP mesh during the pouring and service stages.
[0009] S4. Segmented reinforcement: Reinforce the column in segments according to its height. Spray water to moisten the surface of the reinforced concrete column, and evenly apply a UHPC layer with a thickness of half the designed circumferential layer thickness. Wrap the prepared CFRP mesh around the outer perimeter of the column and tighten it onto the UHPC layer. Continue to apply the UHPC layer to the designed circumferential layer thickness. After each segment is reinforced, immediately cover it with wet burlap sacks and sprinkle water for wet curing.
[0010] S5. Maintenance and Repair: After 28 days of water curing, the reinforced concrete column surface is ground and repaired, and the reinforcement is completed.
[0011] Optionally, in step S2, the water-binder ratio of the UHPC slurry is controlled at 0.18–0.22, the volume fraction of steel fibers is controlled at 3%, of which short fibers and long fibers each account for 1.5%, and the fiber diameter is uniformly 0.2 mm.
[0012] Optionally, the UHPC slurry in step S2 is formulated by weight as follows: 950-1050 parts silicate cement, 200-300 parts 3000-5000 mesh silica fume, 150-180 parts 325 mesh quartz powder, 950-1050 parts 20-40 mesh quartz sand, 100-130 parts 5mm long copper-plated short steel fibers, 100-130 parts 13mm long copper-plated long steel fibers, 240-260 parts water, and 20-30 parts polycarboxylate superplasticizer.
[0013] Optionally, the CFRP mesh used has a pore size of 20 mm × 20 mm, a single mesh width of 4 mm, a mesh tensile strength ≥2000 MPa, an elongation of 1.2-1.5%, and is arranged in single or double layers. The mesh pre-tension strain is controlled at ≤0.2% to prevent damage to the fibers and ensure stress coordination with the matrix.
[0014] Optionally, in step S3, two CFRP ribs are provided at both ends of the CFRP mesh to achieve self-locking. One end of the CFRP mesh is wrapped in an S-shape between the two CFRP ribs and encircles the outside once. Finally, it is fixed by applying epoxy resin adhesive.
[0015] Optionally, in step S4, after the CFRP mesh is wrapped circumferentially around the outer perimeter of the column and tightly attached to the UHPC layer, the two outermost CFRP bars at both ends of the CFRP mesh are tied and fixed with CFRP cable ties.
[0016] Optionally, in step S4, the thickness of the designed reinforcing ring cladding is approximately 1 / 20 of the cross-sectional dimensions of the reinforced concrete column.
[0017] Compared with the prior art, the present invention has the following beneficial technical effects:
[0018] 1. Significantly improved load-bearing capacity: The TRUHPC outer cladding layer forms a synergistic load-bearing system with the original column, improving the column's compressive, shear, and bending load-bearing capacity;
[0019] 2. Excellent ductility and seismic performance: The UHPC matrix and the self-locking CFRP mesh form a composite system with good synergistic stress distribution. The mesh is not prone to slippage and stress relaxation, ensuring the restraint effect of the cladding under large deformation. This can significantly improve the deformation capacity and energy dissipation performance of the column, making it suitable for reinforcement in seismic zones.
[0020] 3. Significantly improved durability: The TRUHPC matrix is dense, impermeable, chloride ion resistant, and freeze-thaw resistant, greatly extending the service life of the reinforced structure;
[0021] 4. Highly convenient construction: The method of this invention has a clear process and the segmented application process makes construction easier to operate. It does not require large-scale demolition and modification of the original structure and is suitable for engineering sites of different scales.
[0022] 5. Wide range of applications: It can be used for the reinforcement and repair of various reinforced concrete columns in buildings, bridges, ports, industrial plants, etc., and is especially suitable for coastal hot and humid, cold and earthquake-prone areas. Attached Figure Description
[0023] Figure 1 This is a schematic perspective view of the reinforced concrete column strengthening component in an embodiment of the present invention.
[0024] Figure 2 This is a schematic front view of the reinforced concrete column strengthening member in an embodiment of the present invention.
[0025] Figure 3 This is a schematic diagram of the self-locking of the CFRP mesh at both ends in an embodiment of the present invention.
[0026] Figure 4 This is a schematic diagram of CFRP reinforcement tied with CFRP cable ties in an embodiment of the present invention.
[0027] The labels in the diagram represent: 1. Reinforced concrete column; 2. UHPC layer; 3. CFRP mesh; 4. CFRP reinforcement; 5. CFRP cable tie. Detailed Implementation
[0028] The following is in conjunction with the appendix Figure 1-4 The present invention will be described in further detail below.
[0029] This invention discloses a method for reinforcing segmented self-locking TRUHPC (Textile Reinforced Ultra-high Performance Concrete) ring-enclosed reinforced concrete columns, including base treatment, UHPC matrix configuration, CFRP mesh preparation, segmented reinforcement, and curing and finishing.
[0030] The specific steps are as follows:
[0031] S1. Base treatment: Roughen the surface of the reinforced concrete column to remove loose layers and contaminants.
[0032] S2, UHPC matrix configuration: Prepare UHPC slurry according to the design ratio, and add steel fiber.
[0033] S3. Prepare CFRP mesh: Pre-cut CFRP mesh according to the segmented design width and column cross-section size. Set two CFRP bars around the start and end points of each CFRP mesh for self-locking to prevent slippage and loosening of the CFRP mesh during the casting and service stages.
[0034] S4. Segmented Reinforcement: Reinforce the reinforced concrete column in segments according to its height. Moisten the surface of the reinforced concrete column by spraying water, then evenly apply a UHPC layer with a thickness half the designed circumferential cladding layer. Wrap the prepared CFRP mesh circumferentially around the column and taut it onto the UHPC layer. Continue applying the UHPC layer until the designed circumferential cladding layer thickness is reached. Immediately after each segment is reinforced, cover it with wet burlap sacks and spray water for wet curing.
[0035] S5. Maintenance and Repair: After 28 days of water curing, the reinforced concrete column surface is ground and repaired, and the reinforcement is completed.
[0036] The core innovations of this invention are mainly reflected in the following three aspects:
[0037] 1. Segmented construction process: The reinforced concrete column 1 is divided into several segments along the height direction. Each segment is independently subjected to "applying the bottom layer UHPC layer 2 - wrapping the end self-locking CFRP mesh 3 - applying the top layer UHPC layer 2", thereby reducing the difficulty of one-time construction and facilitating quality control and tensioning operation.
[0038] 2. Self-locking anchoring structure: An S-shaped path is formed around the end of the CFRP mesh 3 beforehand. The interface friction between the CFRP mesh 3 and the CFRP reinforcement 4, the mechanical interlocking formed by the CFRP reinforcement 4 embedded in the UHPC layer 2, and the constraint of the CFRP cable tie 5 on the CFRP reinforcement 4 are used to achieve self-locking at the end of the CFRP mesh 3, ensuring that the CFRP mesh 3 does not slip or loosen during construction and service.
[0039] 3. Layered positioning method: The layered construction process of "bottom layer application - mesh tensioning - top layer covering" is adopted to ensure that the CFRP mesh 3 is stably sandwiched in the middle of the UHPC layer 2, so as to avoid the mesh shifting due to its own weight or grout flow during the grouting construction process.
[0040] The following are specific usage examples:
[0041] A reinforced concrete column 1 with a cross-sectional dimension of 400 mm × 400 mm and a height of 3000 mm was selected. The original design strength grade of the concrete in column 1 was C30. After 20 years of service, testing revealed that the carbonation depth of the concrete exceeded 25 mm, the width of longitudinal cracks in the column reached 0.3 mm, some protective layers had peeled off, the corrosion rate of the reinforcing steel was approximately 5%, and the overall bearing capacity and ductility were significantly insufficient, no longer meeting the requirements of current seismic codes. Therefore, the segmented self-locking TRUHPC ring-wrapping reinforcement method proposed in this invention was used to reinforce column 1, with a designed ring-wrapping layer thickness of 20 mm.
[0042] Before reinforcement construction, the surface of reinforced concrete column 1 was treated. First, loose materials such as mortar, oil stains, and weathered layers were removed from the surface of reinforced concrete column 1 using a wire brush and high-pressure water gun. Then, an electric roughening machine was used to roughen the surface of reinforced concrete column 1, with the roughening depth controlled at 8–10 mm and the roughening rate at approximately 45%, to create a rough interface and enhance the mechanical bonding between the old concrete and UHPC layer 2.
[0043] After roughening, use an air compressor and clean water to rinse the surface of the reinforced concrete column 1 to ensure that the interface is free of dust.
[0044] The UHPC matrix material is prepared according to the designed proportions. In this embodiment, the UHPC is formulated by weight and includes the following components:
[0045] 950-1050 parts of silicate cement;
[0046] 200-300 parts of 3000-5000 mesh silica fume;
[0047] 150-180 parts of 325 mesh quartz powder;
[0048] 950-1050 parts of 20-40 mesh quartz sand;
[0049] 100-130 parts of 5mm long copper-plated short steel fiber;
[0050] 100-130 parts of 13mm long copper-plated steel fiber;
[0051] 240-260 parts water;
[0052] 20-30 parts of polycarboxylate superplasticizer.
[0053] This embodiment uses a carbon fiber FRP mesh with the following basic physical properties: tensile strength of approximately 230 MPa, elastic modulus of approximately 230 GPa, and ultimate elongation of approximately 1.5%. The mesh aperture size is 20 mm × 20 mm, and the width of a single mesh bundle is 4 mm. A single-layer mesh arrangement is adopted, and it is laid continuously in the circumferential direction.
[0054] Considering that the height of reinforced concrete column 1 is 3000 mm, in order to facilitate the application of UHPC layer 2 and the wrapping of CFRP mesh 3, reinforced concrete column 1 is divided into three sections of equal height for segmented reinforcement, each section being 1000 mm long.
[0055] Cut CFRP mesh 3 into strips with a width of 900 mm (each mesh strip is slightly shorter than the length of the column segment it is divided into), with a length equal to the perimeter of the cross-section of reinforced concrete column 1 (approximately 2000 mm) plus 200 mm × 2 self-locking winding portions at both ends, for a total of 2400 mm.
[0056] Prepare two CFRP reinforcing bars 4, each 900 mm long and 10 mm in diameter. Wrap one end of the CFRP mesh 3 around the first CFRP reinforcing bar 4 and fold it back, then wrap it around the second CFRP reinforcing bar 4, forming an S-shaped path. Attach the folded end to the CFRP mesh 3 body to form a self-locking mechanism, and secure it by applying epoxy resin adhesive. Similarly, perform the same steps on the other end of the CFRP mesh 3 to achieve self-locking. See the schematic diagram of the self-locking mechanism of the CFRP mesh 3 end wrapped around the CFRP reinforcing bar 4. Figure 3 .
[0057] First, apply the bottom layer UHPC layer 2, with a thickness half the designed cladding thickness (10 mm in this example). Spread it evenly using a wooden trowel and compact it until it adheres to the reinforced concrete column 1. During the application process, round off the corners of the reinforced concrete column 1 with a radius of 10-15 mm to avoid stress concentration and damage to the CFRP mesh 3 during service. The surface of the bottom UHPC layer 2 should be slightly roughened and moderately textured to facilitate the embedding of the CFRP mesh 3 and good bonding with the upper UHPC layer 2.
[0058] Once the bottom UHPC layer 2 reaches a semi-solid state (finger indentation 3-5 mm, not sticky, penetration resistance around 0.5 MPa), the CFRP mesh 3 winding operation begins.
[0059] The prepared CFRP mesh 3, with self-locking reinforcement at both ends, is continuously wound around the perimeter of the reinforced concrete column 1, maintaining uniform tension. The CFRP reinforcement bars 4 are lightly pressed at both ends of the CFRP mesh 3 to allow them to adhere and slightly embed into the UHPC matrix 2. The two outermost CFRP reinforcement bars 4 at both ends of the CFRP mesh 3 are then tightly secured together with CFRP cable ties 5 at 300 mm intervals to prevent the CFRP mesh 3 from shifting or loosening during subsequent construction. A schematic diagram of the CFRP cable ties 5 securing the CFRP reinforcement bars 4 at both ends is shown below. Figure 4 .
[0060] After the CFRP mesh 3 is fixed, continue to lay the second UHPC layer 2, also 10 mm thick, so that the CFRP mesh 3 is completely sandwiched between the upper and lower UHPC layers 2. During laying, use a pressure roller to lightly press, ensuring a tight bond between the CFRP mesh 3 and the UHPC layer 2, without any voids or air bubbles. Special attention should be paid to ensuring the UHPC matrix is densely filled within the self-locking area at the ends of the CFRP mesh 3.
[0061] After completing the first section, immediately proceed with wet curing by covering with wet burlap sacks and sprinkling water. Then proceed with the construction of the second and third sections, following the same process. At the junctions of each section, careful attention should be paid to ensure that the boundaries are level and that there are good, seamless contacts to achieve good vertical continuity of the cladding.
[0062] After construction is completed, the covered wet burlap sacks should be regularly sprayed with water and kept wet for 28 days to prevent shrinkage cracks.
[0063] After curing, the surface of the cladding layer is ground and repaired, and the reinforcement is complete. The schematic three-dimensional view and front view of the reinforced concrete column 1 reinforcement component in this embodiment are shown below. Figure 1 and Figure 2 As shown.
[0064] This embodiment employs a "segmented self-locking + layered application" construction method to ensure that the CFRP mesh 3 is positioned in the middle of the UHPC layer 2, and achieves self-locking around the CFRP reinforcement 4 at both ends. This effectively solves the problems of stress relaxation and mesh displacement caused by end slippage of the CFRP mesh 3. It achieves good overall coordination between the CFRP mesh 3 and the UHPC layer 2, and between the TRUHPC cladding layer and the original reinforced concrete column 1. This process offers strong construction controllability and significantly enhances the load-bearing capacity and ductility of reinforced concrete columns. It is suitable for various reinforced concrete column reinforcement projects in buildings, bridges, and other applications, and is particularly suitable for earthquake zones and humid coastal environments.
[0065] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A method for reinforcing segmented self-locking TRUHPC circumferential reinforced concrete columns, characterized in that... Includes the following steps: S1. Base treatment: Roughen the surface of the reinforced concrete column to remove loose layers and contaminants; S2, UHPC matrix configuration: Prepare UHPC slurry according to the design ratio, and add steel fiber; S3. Prepare CFRP mesh: Pre-cut CFRP mesh according to the segmented design width and column cross-section size. Set two CFRP bars around the start and end points of each CFRP mesh for self-locking to prevent slippage and relaxation of the CFRP mesh during the pouring and service stages. S4. Segmented reinforcement: Reinforce the column in segments according to its height. Spray water to moisten the surface of the reinforced concrete column, and evenly apply a UHPC layer with a thickness of half the designed circumferential layer thickness. Wrap the prepared CFRP mesh around the outer perimeter of the column and tighten it onto the UHPC layer. Continue to apply the UHPC layer to the designed circumferential layer thickness. After each segment is reinforced, immediately cover it with wet burlap sacks and sprinkle water for wet curing. S5. Maintenance and Repair: After 28 days of water curing, the reinforced concrete column surface is ground and repaired, and the reinforcement is completed.
2. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 1, characterized in that: In step S2, the water-cement ratio of the UHPC slurry is controlled at 0.18–0.22, the volume fraction of steel fibers is controlled at 3%, of which short fibers and long fibers each account for 1.5%, and the fiber diameter is uniformly 0.2 mm.
3. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 2, characterized in that: The UHPC slurry in step S2 is formulated by weight as follows: 950-1050 parts silicate cement, 200-300 parts 3000-5000 mesh silica fume, 150-180 parts 325 mesh quartz powder, 950-1050 parts 20-40 mesh quartz sand, 100-130 parts 5mm long copper-plated short steel fibers, 100-130 parts 13mm long copper-plated long steel fibers, 240-260 parts water, and 20-30 parts polycarboxylate superplasticizer.
4. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 1, characterized in that: In step S3, two CFRP ribs are provided at both ends of the CFRP mesh to achieve self-locking; one end of the CFRP mesh is wrapped in an S-shape between the two CFRP ribs and encircles the outside once, and finally fixed by applying epoxy resin glue.
5. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 4, characterized in that: The CFRP mesh used has a pore size of 20 mm × 20 mm, a single mesh width of 4 mm, a tensile strength of ≥2000 MPa, an elongation of 1.2-1.5%, and is arranged in single or double layers. The pre-tension strain of the mesh is controlled at ≤0.2% to prevent damage to the fibers and ensure stress coordination between the fibers and the matrix.
6. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 1, characterized in that: In step S4, after the CFRP mesh is wrapped circumferentially around the outer perimeter of the column and stretched and attached to the UHPC layer, the two CFRP ribs at both ends of the CFRP mesh are tied and fixed with CFRP cable ties.
7. The method for strengthening a segmented self-locking TRUHPC circumferential reinforced concrete column according to claim 1, characterized in that: In step S4, the thickness of the reinforced ring cladding is approximately 1 / 20 of the cross-sectional dimensions of the reinforced concrete column.