Anchoring device for TRC reinforcing fire damage beam in coastal environment and beam repairing method

Abstract

The invention relates to the technical field of fire damage beam reinforcement, in particular to an anchoring device and a beam repairing method for TRC reinforcement of a fire damage beam in a coastal environment, the anchoring device comprises a positioning unit, a clamping and tensioning unit, multiple layers of fiber grids and anchoring screws, the two ends of each layer of fiber grids are connected with the clamping and tensioning units through the positioning units, the clamping and tensioning units are connected with the anchoring screws, the anchoring screws are fixedly connected with the beam structure, the positioning units are used for adjusting the distances between the layers of fiber grids and keeping the distances between the layers of fiber grids fixed, and the clamping and tensioning units are connected with the anchoring screws. And the clamping and tensioning unit is used for clamping the end part of the fiber grid and tensioning the fiber grid. The ultimate bearing capacity of the beam can be remarkably improved by about 43.6%-88% through the reinforcing mode, stripping damage is avoided, and obvious damage omen are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of fire damaged beam reinforcement, and in particular to an anchoring device for TRC reinforced fire damaged beams in a coastal environment and a beam repair method. Background Art

[0002] In the field of civil engineering, facing the global background of increasingly scarce resources, how to effectively extend the service life of existing structures, especially those that can still be repaired and meet the requirements of current design standards after disasters such as fire, has become a highly-anticipated research focus. The damage caused by fire to concrete structures is often serious and complex, including but not limited to strength reduction, crack expansion, and steel corrosion, all of which pose a major threat to the stability and safety of the structure. Therefore, exploring efficient and economical reinforcement and repair technologies to restore and improve the performance of damaged concrete structures is crucial to maximize resource utilization and sustainable service of structures.

[0003] As an innovative reinforcement material, fiber mesh reinforced concrete (TRC) has shown great potential in the field of civil engineering reinforcement due to its excellent mechanical properties, including high strength, good toughness, and excellent anti-permeability, anti-carbonization and anti-freeze-thaw properties. Existing research results have clearly shown that compared with traditional reinforced concrete beams, composite beams reinforced with TRC have significantly improved cracking loads, yield loads and ultimate loads. At the same time, the crack width is effectively controlled and the crack development speed is slowed down, which is mainly due to the strong inhibitory effect of TRC on crack expansion. In addition, with the increase of TRC fabric distribution rate or reinforcement ratio, the residual deflection and strain damage accumulation of the tensile steel bars are significantly reduced, thereby extending the fatigue life of the structure and enhancing its long-term service capability.

[0004] Despite this, the application of TRC reinforcement technology also faces several challenges. On the one hand, although TRC can significantly improve the durability and crack control ability of the structure, its improvement in bearing capacity is still insufficient compared with other reinforcement methods (such as carbon fiber reinforced composite materials). On the other hand, although the increase in the number of TRC layers can theoretically further enhance the reinforcement effect, in practice, too many TRC layers are prone to peeling, affecting the reinforcement quality. In addition, although studies have pointed out that the anchoring system can effectively improve the reinforcement efficiency of TRC, especially in enhancing the bending or shear bearing capacity and ductility of the structure, such as U-type anchoring and nail anchoring, these studies are mostly limited to applications under normal temperature environments, and the research on the reinforcement of concrete beams (RC beams) after fire is still insufficient, especially in the optimal configuration of TRC combined with the anchoring system, the specific impact of fire damage on the TRC reinforcement effect, and how to effectively prevent TRC peeling. There are still many unknown and unresolved issues.

[0005] In summary, although the existing technology has made significant progress in TRC reinforcement of room temperature concrete beams, it still faces many challenges and unsolved mysteries in the field of strengthening RC beams after fire. Therefore, how to develop a more efficient and reliable TRC reinforcement technology for concrete structures damaged by fire, especially in combination with an optimized anchoring system to overcome the shortcomings of the existing technology, has become a key technical problem that needs to be solved urgently. Summary of the invention

[0006] The present invention provides an anchoring device and a beam repair method for TRC reinforced fire damaged beams in a coastal environment, the purpose of which is to reinforce the corroded concrete T-beams in a coastal environment after a fire occurs, mainly to address the following problems: 1. The corrosion problem in the coastal environment makes it unsuitable to use steel bars that are prone to rust for reinforcement; 2. There are problems such as loose layers and cracks on the surface after fire damage, and it is unsuitable to use external fiber cloth or fiberboard for reinforcement; 3. In the current TRC reinforcement technology, in the absence of anchoring, since the fiber grid is not initially tensioned and the force on each fiber bundle is inconsistent, it is easy to fail to coordinate force with the steel bars, the interface is peeled off prematurely, and the fiber grid strength utilization rate is not high.

[0007] To achieve the above object, the technical solution of the present invention is: An anchoring device for TRC reinforced fire damaged beams in a coastal environment comprises: a positioning unit, a clamping and tensioning unit, a fiber grid, and an anchoring screw. The fiber grid has multiple layers, and both ends of each layer of the fiber grid are connected to the clamping and tensioning unit through the positioning unit. The clamping and tensioning unit is connected to the anchoring screw, and the anchoring screw is fixedly connected to the beam structure. The positioning unit is used to adjust the spacing between each layer of the fiber grid and keep it fixed, and the clamping and tensioning unit is used to clamp the end of the fiber grid and tighten the fiber grid.

[0008] Preferably, the clamping and tensioning unit includes a U-shaped card, a tensioning screw, and a locking nut. The anchoring screw is anchored to the beam structure and arranged longitudinally. A guide sleeve is provided at the top of the anchoring screw. The tensioning screw passes through the guide sleeve. One end of the tensioning screw is fixedly connected to the back center position of the U-shaped card. The two side walls of the U-shaped card are arranged opposite to each other up and down. The other end of the tensioning screw is threaded with a locking nut, and the locking nut is used in conjunction with the end of the guide sleeve away from the U-shaped card.

[0009] Preferably, the positioning unit includes one or more first positioning holes provided on the two side walls of the U-shaped card, the first positioning holes on the two side walls are opposite to each other, the first positioning holes located on the lower side are provided with internal threads, and the positioning screws are passed through the first positioning holes opposite to each other, the lower end of the positioning screw is screwed with the first positioning hole opposite to the bottom, and multiple groups of positioning nuts are screwed on the rod arm of the positioning screw, each group of positioning nuts includes two nut bodies, and the upper end of the positioning screw is screwed with a limiting nut, and two clamping and tensioning units are respectively provided at both ends of the length direction of the fiber grid, and the two clamping and tensioning units on the same side are respectively provided at both ends of the width direction of the fiber grid, and the positioning unit also includes a number of positioning steel plates provided in the two U-shaped cards on the same side, and second positioning holes are respectively provided at the positions of the positioning steel plates opposite to the first positioning holes, and each positioning screw passes through the corresponding second positioning hole, and the spacing between adjacent positioning steel plates and between the positioning steel plates and the side walls of the U-shaped card is adjusted by two nut bodies.

[0010] Preferably, the spacing between adjacent positioning steel plates is the same, and the two ends of the fiber mesh are respectively tied and fixed to the positioning steel plates, and the locking nuts are tightened. Under the pulling of the tightening screw, the fiber mesh layers maintain the same spacing and are tightened.

[0011] Preferably, it also includes an anchoring fan structure, which includes a fiber anchor rod made of a high-performance fiber bundle material and a plurality of anchoring fans integrally connected to the top of the fiber anchor rod and folded outwards into a fan shape.

[0012] Preferably, the fiber anchor is a carbon fiber anchor formed by twisting multiple carbon fiber bundles, and the anchoring fan is a fan-shaped structure formed by unfolding the carbon fiber bundle at the top of the carbon fiber anchor through a yarn spreading process and folding the unfolded carbon fiber filaments or carbon fiber bundles outward.

[0013] A method for repairing a fire-damaged beam reinforced with TRC in a coastal environment comprises the following steps: 1) Chisel away the loose concrete on the surface of the T-beam structure that was exposed to fire, and clean the rusted steel bars with a wire brush: 2) Mixing of polymer cement mortar; 3) Apply the interface agent; clean the roughened base surface, remove the loose soil on the base surface, and then use a brush to apply the interface agent coating on the base surface; 4) Apply polymer cement mortar; Since the loose concrete caused by fire extends to the side of the web of the beam structure, it is necessary to repair the side of the web. Use a trowel to apply polymer cement mortar to the side of the web of the beam structure. The thickness of the mortar layer on both sides is controlled to be 30mm, and the bottom of the web is leveled to the outer edge of the stirrups. 5) Cutting fiber mesh; According to the length and width of the bottom end of the web of the beam structure, the fiber mesh is cut into the same size; 6) With the bottom end of the web of the beam structure facing upward, wooden formwork is laid on both sides of the web of the beam structure to prepare for repairing the bottom end of the web; 7) Fix the fiber grid through the anchoring device and pour the TRC; 8) Curing and demolding: After the TRC surface is smoothed, cover it with plastic film to prevent water evaporation; remove the mold within the 2nd to 3rd day of curing, and cover the surface with black felt to retain water; after the pouring is completed, the TRC board is watered and cured at room temperature for 28 consecutive days.

[0014] Preferably, the step 7) comprises the following specific steps: ① Drilling and embedding reinforcement: Drill holes for installing anchor screws and carbon fiber anchors at the designated position at the bottom of the web of the beam structure, and embed anchor screws in the holes at both ends of the bottom of the web respectively. The remaining holes are reserved after cleaning; ②Install the clamping and tensioning unit: first connect the tensioning screw with the U-shaped card, and let the rear end of the tensioning screw pass through the guide sleeve. The length of each tensioning screw passing through the guide sleeve is consistent, and it is limited by the locking nut to ensure that the back of each U-shaped card on the same side is coplanar and parallel to the end of the web. Then apply the interface agent on the bottom surface of the web; ③ Binding the fiber mesh: Bind and fix the two ends of the fiber mesh to the corresponding positioning steel plates, so that the length of the fiber mesh between the two opposite positioning steel plates is the same, put each positioning steel plate into the U-shaped card on both sides, pass the positioning screw through the second positioning hole of each positioning steel plate, and adjust the position of the positioning nut to make the spacing of each layer of fiber mesh the same; ④Tension the fiber grid and install the anchor fan structure: After fixing the positioning steel plate, tighten the fiber grid by rotating the locking nut to ensure that the tensioning screw moves outward by the same distance, that is, to ensure that all fiber bundles of the fiber grid are tensioned at the same time and to the same degree; after the fiber grid is tensioned, insert the carbon fiber anchor rod into the reserved hole to complete the anchor fixation, and then unfold the fiber bundle or fiber filament at the top of the carbon fiber anchor rod to form multiple anchor fans around the axis of the carbon fiber anchor rod, and infiltrate the anchor fan with the top layer of the fiber grid through the resin matrix to form a fiber-resin composite transition layer with a thickness of 0.5-2mm; ⑤ Casting TRC: Cast the mixed polymer cement mortar on the top of the web between the wooden formworks on both sides, insert and vibrate the polymer mortar to fill the grid gaps with the mortar so that it and the fiber grid become a whole; after casting the last layer of fiber grid, smooth the exposed part of the CFRP bundle of the polymer cement mortar on the top layer of fiber grid, and continue to cast cement mortar after laying so that the cement mortar covers the anchor fan structure. After casting, smooth the surface of TRC with a trowel.

[0015] Beneficial effects of the anchoring device and beam repair method for TRC reinforced fire damaged beams in coastal environment of the present invention: 1. The present invention utilizes fiber mesh to supplement steel bar damage caused by corrosion, and utilizes the high durability of fiber to mitigate subsequent corrosion problems, and utilizes anchors to ensure or even improve the strength utilization of the fiber mesh; 2. For post-fire reinforcement, after the loose concrete is chiseled off, it is impossible to carry out external reinforcement, but the remaining space is just right for TRC reinforcement, which is convenient for construction and does not significantly increase the height of the original beam; 3. The reinforcement method of the present invention can significantly increase the ultimate bearing capacity of the beam by about 43.6%-88%, and no peeling failure will occur, with obvious signs of failure; 4. The anchoring fan structure provided by the present invention can be combined with the carbon fiber grid to form an integral structure, has a good elastic modulus, high toughness, and a large coverage area, and can provide obvious signs when the beam body is deformed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side structural schematic diagram of the anchoring device of the present invention.

[0017] Figure 2 It is a schematic diagram of the top structure of the anchoring device of the present invention.

[0018] Figure 3 It is a top view of the positional relationship between the positioning steel plate and the fiber grid of the present invention.

[0019] Figure 4 It is a schematic diagram of the anchoring fan structure of the present invention.

[0020] Figure 5 It is a schematic diagram of the installation of the anchoring fan structure of the present invention at the bottom of the beam.

[0021] Figure 6 It is the T-beam size and reinforcement diagram used in the test verification (unit: mm; a is the front view; b is the side view).

[0022] Figure 7 It is a three-dimensional diagram of the T-beam in the test verification.

[0023] Figure 8 It is a diagram of the ultimate failure effect of T-beam under different working conditions.

[0024] Fig. 9 It is the load-deflection curve of the T-beam (ABC in the figure refers to the specimen numbers of three groups of different working conditions, and the details of different working conditions are shown in Table 1).

[0025] Markings in the figure: 1. Beam structure; 2. U-shaped card; 3. Tension screw; 4. Anchor screw; 5. Guide sleeve; 6. Locking nut; 7. Positioning steel plate; 8. Binding part; 9. Fiber grid; 10. Positioning screw; 11. Positioning nut; 12. Second positioning hole; 13. Anchor fan; 14. Carbon fiber anchor rod; 15. Anchor fan structure. DETAILED DESCRIPTION

[0026] The following describes in detail the implementation mode of the present invention in a step-by-step manner. The description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the purpose of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, and a specific direction structure and operation, and therefore cannot be understood as a limitation on the present invention.

[0028] Embodiment 1: An anchoring device for TRC reinforced fire damaged beams in a coastal environment, such as Figure 1-Figure 4 As shown, it includes: a positioning unit, a clamping and tensioning unit, a fiber grid 9, and an anchoring screw 4. The fiber grid 9 has multiple layers, and both ends of each layer of fiber grid 9 are connected to the clamping and tensioning unit through the positioning unit. The clamping and tensioning unit is connected to the anchoring screw 4, and the anchoring screw 4 is fixedly connected to the beam structure 1. The positioning unit is used to adjust the spacing between each layer of fiber grid and keep it fixed. The clamping and tensioning unit is used to clamp the end of the fiber grid and tighten the fiber grid 9. In this embodiment, during the specific construction, the distance between each layer of fiber grid can be adjusted as needed to achieve the best repair effect.

[0029] Embodiment 2: Based on Example 1, this embodiment discloses: Figure 1-Figure 4 As shown, the clamping and tensioning unit includes a U-shaped card 2, a tensioning screw 3, and a locking nut 6. The anchoring screw 4 is anchored to the beam structure 1 and arranged longitudinally. A guide sleeve 5 is provided at the top of the anchoring screw 4. The tensioning screw 3 passes through the guide sleeve 5. One end of the tensioning screw 3 is fixedly connected to the back center position of the U-shaped card 2. The two side walls of the U-shaped card 2 are arranged opposite to each other up and down. The other end of the tensioning screw 3 is threaded with a locking nut 6. The locking nut 6 is used in conjunction with the end of the guide sleeve 5 away from the U-shaped card 2, that is, the U-shaped card can be pulled to move by rotating the locking nut.

[0030] Embodiment 3: Based on Example 2, this embodiment discloses: Figure 1-Figure 4 As shown, the positioning unit includes one or more first positioning holes (such as Figure 2 As shown, not marked in the figure), the first positioning holes on the two side walls are opposite to each other, the first positioning holes on the lower side are provided with internal threads, and the positioning screws 10 are passed through the first positioning holes opposite to each other. The lower ends of the positioning screws 10 are screwed with the first positioning holes opposite to the bottom, and the rod arms of the positioning screws 10 are screwed with multiple groups of positioning nuts 11, each group of positioning nuts includes two nut bodies, and the upper ends of the positioning screws 10 are screwed with limited position nuts (such as Figure 1 As shown, not marked in the figure), two clamping and tensioning units are respectively provided at both ends of the length direction of the fiber grid, and the two clamping and tensioning units on the same side are respectively provided at both ends of the width direction of the fiber grid 9, and the positioning unit also includes a plurality of positioning steel plates 7 arranged in the two U-shaped cards 2 on the same side, and a plurality of positioning steel plates 7 are respectively provided with second positioning holes at the positions opposite to the first positioning holes, and each positioning screw 10 passes through the corresponding second positioning holes, and the spacing between adjacent positioning steel plates 7 and between the positioning steel plates 7 and the side walls of the U-shaped card 2 is adjusted by two nut bodies; taking the adjustment of the spacing between adjacent positioning steel plates as an example: the upper nut body is abutted against the bottom of the upper positioning steel plate, and the lower nut body is abutted against the top of the adjacent positioning steel plate below, so that the precise control of the spacing is achieved, and the control of the spacing between the positioning steel plates helps to achieve precise control of the spacing between each layer of fiber grids. In this embodiment, the number of the first or second positioning holes can be set as needed to make the positioning steel plate evenly stressed and avoid local deformation.

[0031] Embodiment 4: Based on Example 3, this embodiment discloses: Figure 1-Figure 4 As shown, the spacing between adjacent positioning steel plates 7 is the same, and the two ends of the fiber mesh 9 are respectively tied and fixed to the positioning steel plates 7, and the locking nuts 6 are tightened. Under the pulling of the tightening screw 2, the fiber meshes 9 of each layer maintain a consistent spacing and are tightened. This embodiment shows a situation where the spacing between each layer of fiber mesh is consistent. It can be understood that it can also be set to decrease the spacing gradient between adjacent fiber meshes from the outside to the inside. Such a design can achieve a step-by-step increase in the structural strength of the repair structure from the outside to the inside. By setting it in this way, it can cope with different levels of vibration damage and provide staged protection for the core position of the beam structure.

[0032] Embodiment 5: Based on Example 4, this embodiment discloses: Figure 1-Figure 5As shown, it also includes an anchoring fan structure 15, which includes a fiber anchor made of high-performance fiber bundle material and a plurality of anchoring fans 13 integrally connected to the top of the fiber anchor and folded outward to form a fan shape; the fiber anchor is a carbon fiber anchor 14 formed by twisting multiple carbon fiber bundles, and the anchoring fan 13 is a fan-shaped structure formed by unfolding the carbon fiber bundle at the top of the carbon fiber anchor 14 through a yarn spreading process, and the unfolded carbon fiber filaments or carbon fiber bundles are folded outward.

[0033] Embodiment 6: Based on the above embodiments, this embodiment discloses a method for repairing a TRC reinforced fire damaged beam in a coastal environment, comprising the following steps: 1) Chisel away the loose concrete on the surface of the T-beam structure that was exposed to fire, and clean the rusted steel bars with a wire brush: 2) Mixing of polymer cement mortar; Mix the polymer mortar at a water-cement ratio of about 17%, mechanically stir for about 3 minutes, and manually stir for about 5 minutes. Too short a mixing time will cause problems such as uneven mortar mixing, low viscosity, and slurry sagging; stir until the slurry is uniform and free of lumps; the mixed mortar should be used up within 30-60 minutes; do not add additional water after the construction process begins; strictly control the water-cement ratio in the mortar. Too much water will cause the slurry to flow and cannot be adhered to the substrate in large quantities; on the contrary, too little water will cause problems such as poor mortar application performance; 3) Apply interface agent; Clean the roughened base surface, remove the loose soil on the base surface, and then use a brush to apply the interface agent coating on the base surface. Apply it once, and then apply the polymer cement mortar without waiting for the interface layer to dry; 4) Apply polymer cement mortar; Since the loose concrete caused by fire extends to the side of the web of the beam structure, it is necessary to repair the side of the web. Use a trowel to apply polymer cement mortar to the side of the web of the beam structure. The thickness of the mortar layer on both sides is controlled to be 30mm, and the bottom of the web is leveled to the outer edge of the stirrups. 5) Cutting the fiber mesh; in this embodiment, the fiber mesh is a carbon fiber woven mesh; according to the length and width of the bottom end of the web of the beam structure, the fiber mesh is cut into the same size; 6) With the bottom end of the web of the beam structure facing upward, wooden formwork is laid on both sides of the web of the beam structure to prepare for repairing the bottom end of the web; 7) Fix the fiber grid through the anchoring device and pour the TRC; 8) Curing and demolding: After the TRC surface is smoothed, cover it with plastic film to prevent water evaporation; remove the mold within the 2nd to 3rd day of curing, and cover the surface with black felt to retain water; after the pouring is completed, the TRC board is watered and cured at room temperature for 28 consecutive days.

[0034] Embodiment 7: Based on Example 6, this embodiment discloses: The step 7) includes the following specific steps: ① Drilling and rebar planting: First, mark the drilling position on the bottom surface of the web of the beam structure, and then use a drilling machine to drill holes. 8.8-grade articulated screws with a diameter of 10mm are implanted at both ends of the bottom of the web (the fish eyes form the guide sleeve 5) to fix the holes of the anchoring fan structure. Carbon fiber anchor rods are not implanted temporarily; the process of rebar planting is as follows: after the drilling is completed, pour clean water into the hole to clean the inside of the hole until all the mud is completely removed; after the hole is completely dry, squeeze the rebar planting glue into the hole, and then immediately insert the prepared articulated screw into the hole and wipe off the overflowed rebar planting glue; the subsequent implantation of carbon fiber anchor rods is the same; ②Install the clamping and tensioning unit: first connect the tensioning screw 3 with the U-shaped card 2, and let the rear end of the tensioning screw 3 pass through the guide sleeve 5. The lengths of the tensioning screws 3 passing through the guide sleeve 5 are consistent, and they are limited by the locking nut 6 to ensure that the backs of the U-shaped cards 2 on the same side are coplanar and parallel to the ends of the webs. Then, apply the interface agent on the bottom surface of the webs; ③ Binding the carbon fiber mesh: Bind and fix the two ends of the carbon fiber mesh with the corresponding positioning steel plates 7, so that the length of the carbon fiber mesh between the positioning steel plates 7 at the two ends is the same, put each positioning steel plate 7 into the U-shaped card 2 on both sides, make the positioning screw 10 pass through the second positioning hole of each positioning steel plate 7, adjust the position of the positioning nut 11, so that the spacing of each layer of carbon fiber mesh is the same; wherein, the method of binding the carbon fiber mesh can be to connect the carbon fiber mesh with a binding belt and fix it with the positioning steel plate 7, or to wrap the two ends of the carbon fiber mesh around the positioning steel plate 7; ④Tension the fiber grid and install the anchor fan structure: After fixing the positioning steel plate, tighten the fiber grid by rotating the locking nut to ensure that the tensioning screw moves outward by the same distance, that is, to ensure that all fiber bundles of the fiber grid are tensioned at the same time and to the same degree; after the fiber grid is tensioned, insert the carbon fiber anchor rod into the reserved hole to complete the anchor fixation, and then unfold the fiber bundle or fiber filament at the top of the carbon fiber anchor rod to form multiple anchor fans around the axis of the carbon fiber anchor rod, and infiltrate the anchor fan with the top layer of the fiber grid through the resin matrix to form a fiber-resin composite transition layer with a thickness of 0.5-2mm; ⑤ Casting TRC: Cast the mixed polymer cement mortar on the top of the web between the wooden formworks on both sides, insert and vibrate the polymer mortar to fill the grid gaps with the mortar so that it and the carbon fiber grid form a whole; after casting the last layer of carbon fiber grid, smooth the exposed part of the CFRP bundle of the polymer cement mortar on the top layer of carbon fiber grid. After laying, continue to cast cement mortar so that the cement mortar covers the anchor fan structure. After casting, smooth the surface of TRC with a trowel.

[0035] Embodiment 8: The anchoring fan structure is composed of a high-performance fiber bundle anchor rod (such as carbon fiber), and a composite system is formed with a carbon fiber woven grid; the anchor rod body is made of multiple strands of carbon fiber filaments with a diameter of 2-8 mm, and the end of the anchor rod is formed into a fan-shaped anchoring end through a yarn spreading process, and an umbrella-shaped structure with a diameter of 80-100 mm is unfolded, and the fiber monofilaments are distributed radially at 15-30 degrees; the anchoring end and the outer layer of the fiber grid are infiltrated and composited through a resin matrix to form a fiber-resin composite transition layer with a thickness of 0.5-2 mm; the advantages are: 1) the fan-shaped anchoring end and the fiber grid form a three-dimensional interlocking structure, and the stress is transmitted through the fiber-resin interface shear; 2) the normal stress generated in the direction of the anchor rod axis and the radial constraint stress form a bidirectional anchoring effect; 3) Flexible fiber materials achieve gradient deformation coordination and convert interface shear stress into tensile stress of the anchoring system. The anchoring function of the fiber anchor fan at the bottom of the beam is similar to that of the U-shaped hoop anchor, which prevents premature peeling of TRC from the concrete surface and improves the bearing capacity. The anchor rod spacing is equidistantly distributed at 50-150mm, and the bottom area of ​​the beam is encrypted to 30-80mm. The difference from ordinary anchor rods is that it has good elastic modulus, high toughness, large anchor fan coverage area, and can form a composite structure with the fiber grid. When the beam structure is damaged, there are obvious signs of destruction.

[0036] Embodiment 9: Experimental verification: The length, width and height of the beam in this test are 2900mm, 200mm and 350mm respectively, and the flange width and height are 400mm and 100mm respectively. In the flange part, the distance from the center of the longitudinal reinforcement to the outer edge of the concrete is 30mm, and the distance from the center of the longitudinal reinforcement to the outer edge of the concrete in the beam body is 30mm; the beam size and reinforcement diagram are as follows Figure 6 As shown, the three-dimensional diagram is Figure 7 As shown; The specimens were cast with C30 commercial concrete and HRB400 steel bars. The longitudinal tensile steel bars were 20mm in diameter. During the production process, wires were connected to one end of the two tensile steel bars and led out for electrification accelerated corrosion test. The diameter of the 6 frame bars was 10mm, the diameter of the stirrups was 8mm, and the spacing was 150mm. The total length of the longitudinal tensile steel bars was 2960mm, the total length of the frame bars was 2880, and the total length of the stirrups was 1000mm. A total of 9 T-shaped reinforced concrete beams with the same size and reinforcement were made, and 3 groups A to C were set. Among them, the corrosion rate change value was 0.05 / 0.1, the fire exposure time change value was 90min / 120min, and the TRC anchoring mode of the reinforced beam changed to no anchoring and new combined anchoring. The test groups are shown in Table 1: Table 1 T-beam test grouping: .

[0037] Test results and analysis: Through static load tests, the ultimate failure effect diagram and load-deflection curve under different working conditions were obtained, such as Figure 8 , Fig. 9 As shown; after comparative analysis, we can get: (1) From the perspective of the ultimate load failure mode, the corroded concrete T-beams in the coastal environment are prone to shear failure after fire, without obvious signs, which is brittle failure; the beams reinforced with TRC materials are normal bending failures, and the upper concrete is crushed only after the fiber mesh at the bottom of the beam is pulled off, with obvious signs of failure; the reinforced beams without anchoring measures will suffer large-scale peeling failure after the fiber mesh is pulled off, while the beams reinforced with new anchoring measures will not suffer large-scale peeling failure; (2) From the load-deflection curve, under three different working conditions (a), b and c), the ultimate bearing capacity of the reinforced beams using TRC and the new anchoring method increased by 43.6%, 87.5% and 88% respectively compared with the unreinforced beams, and increased by 7.69%, 15.38% and 8.46% respectively compared with the unanchored beams. It can be seen that the reinforcement method of the present invention significantly improves the ultimate bearing capacity of the beams and can ensure the continued service of the rusted beams after the fire.

[0038] During operation, the two ends of the pre-processed and optimized carbon fiber grid are precisely wound on a special steel sheet (positioning steel plate). The precise control of the fiber grid spacing is ensured by precisely controlling the thickness of the steel sheet or the position of the positioning nut. By rotating the locking nut, the three-layer carbon fiber grid can be synchronously tensioned, thereby ensuring the flatness of the grid and the uniformity of the prestress distribution, and significantly improving the utilization efficiency of the carbon fiber material.

[0039] The present invention introduces a circular fiber anchor fan anchoring design in the critical load-acting area at the bottom of the beam, that is, 200 mm on both sides of the load point. Compared with the traditional U-shaped hoop anchoring method, this design not only maintains the excellent performance of preventing TRC (fiber woven mesh reinforced concrete) from premature debonding and peeling from the concrete base, but also shows a more significant effect in improving the bearing capacity of the overall structure.

[0040] In summary, the combined anchoring device of the present invention ensures the flatness and prestressing of the carbon fiber grid, and at the same time effectively improves the overall stability and bearing capacity of the reinforced structure through the enhanced design of the fiber anchor fan anchoring at the bottom of the beam.

Claims

1. An anchoring device for TRC reinforced fire damaged beams in a coastal environment, characterized by: A positioning unit, a clamping and tensioning unit, a fiber grid, and an anchoring screw. The fiber grid has multiple layers, and both ends of each layer of the fiber grid are connected to the clamping and tensioning unit through the positioning unit. The clamping and tensioning unit is connected to the anchoring screw, and the anchoring screw is fixedly connected to the beam structure. The positioning unit is used to adjust the spacing between the layers of fiber grid and keep it fixed. The clamping and tensioning unit is used to clamp the ends of the fiber grid and tighten the fiber grid.

2. The anchoring device for TRC reinforced fire damaged beams in a coastal environment as claimed in claim 1, characterized in that: The clamping and tensioning unit includes a U-shaped card, a tensioning screw, and a locking nut. The anchoring screw is anchored to the beam structure and arranged longitudinally. A guide sleeve is provided at the top of the anchoring screw. The tensioning screw passes through the guide sleeve. One end of the tensioning screw is fixedly connected to the back center position of the U-shaped card. The two side walls of the U-shaped card are arranged opposite to each other up and down. The other end of the tensioning screw is threaded with a locking nut. The locking nut is used in conjunction with the end of the guide sleeve away from the U-shaped card.

3. The anchoring device for TRC reinforced fire damaged beams in a coastal environment as claimed in claim 2, characterized in that: The positioning unit includes one or more first positioning holes arranged on the two side walls of the U-shaped card, the first positioning holes on the two side walls are opposite to each other, the first positioning holes located on the lower side are provided with internal threads, and the positioning screws are passed through the first positioning holes opposite to the upper and lower parts, the lower end of the positioning screw is screwed with the first positioning hole opposite to the bottom, and multiple groups of positioning nuts are screwed on the rod arm of the positioning screw, each group of positioning nuts includes two nut bodies, and the upper end of the positioning screw is screwed with a limiting nut, and two clamping and tensioning units are respectively provided at the two ends of the length direction of the fiber grid, and the two clamping and tensioning units on the same side are respectively provided at the two ends of the width direction of the fiber grid, and the positioning unit also includes a number of positioning steel plates arranged in the two U-shaped cards on the same side, and the positions of the positioning steel plates opposite to the first positioning holes are respectively provided with second positioning holes, and each positioning screw passes through the corresponding second positioning hole, and the spacing between adjacent positioning steel plates and between the positioning steel plates and the side walls of the U-shaped card is adjusted by two nut bodies.

4. The anchoring device for TRC reinforced fire damaged beams in a coastal environment as claimed in claim 3, characterized in that: The spacing between adjacent positioning steel plates is the same, and the two ends of the fiber grid are respectively tied and fixed to the positioning steel plates, and the locking nuts are tightened. Under the pulling of the tightening screw, the fiber grid layers maintain the same spacing and are tightened.

5. The anchoring device for TRC reinforced fire damaged beams in a coastal environment as claimed in claim 4, characterized in that: It also includes an anchoring fan structure, which includes a fiber anchor rod made of high-performance fiber bundle material and a plurality of anchoring fans integrally connected to the top of the fiber anchor rod and folded outward to form a fan shape; the fiber anchor rod is a carbon fiber anchor rod formed by twisting multiple carbon fiber bundles, and the anchoring fan is a fan-shaped structure formed by unfolding the carbon fiber bundle at the top of the carbon fiber anchor rod through a yarn spreading process, and folding the unfolded carbon fiber filaments or carbon fiber bundles outward.

6. A method for repairing a TRC reinforced fire damaged beam in a coastal environment, using the anchoring device for a TRC reinforced fire damaged beam in a coastal environment as claimed in claim 5, characterized in that: The steps include: 1) Chisel away the loose concrete on the surface of the T-beam structure that was exposed to fire, and clean the rusted steel bars with a wire brush: 2) Mixing of polymer cement mortar; 3) Apply the interface agent; clean the roughened base surface, remove the loose soil on the base surface, and then use a brush to apply the interface agent paint on the base surface; 4) Apply polymer cement mortar; Since the loose concrete caused by fire extends to the side of the web of the beam structure, it is necessary to repair the side of the web. Use a trowel to apply polymer cement mortar to the side of the web of the beam structure. The thickness of the mortar layer on both sides is controlled to be 30mm, and the bottom of the web is leveled to the outer edge of the stirrups. 5) Cutting fiber mesh; According to the length and width of the bottom end of the web of the beam structure, the fiber mesh is cut into the same size; 6) With the bottom end of the web of the beam structure facing upward, wooden formwork is laid on both sides of the web of the beam structure to prepare for repairing the bottom end of the web; 7) Fix the fiber grid through the anchoring device and pour the TRC; 8) Curing and demolding: After the TRC surface is smoothed, cover it with plastic film to prevent water evaporation; remove the mold within the 2nd to 3rd day of curing, and cover the surface with black felt to retain water; after the pouring is completed, the TRC board is watered and cured at room temperature for 28 consecutive days.

7. A method for repairing a TRC reinforced fire damaged beam in a coastal environment as claimed in claim 6, characterized by: The step 7) includes the following specific steps: ① Drilling and embedding reinforcement: Drill holes for installing anchor screws and carbon fiber anchors at the designated position at the bottom of the web of the beam structure, and embed anchor screws in the holes at both ends of the bottom of the web respectively. The remaining holes are reserved after cleaning; ②Install the clamping and tensioning unit: first connect the tensioning screw with the U-shaped card, and let the rear end of the tensioning screw pass through the guide sleeve. The length of each tensioning screw passing through the guide sleeve is consistent, and it is limited by the locking nut to ensure that the back of each U-shaped card on the same side is coplanar and parallel to the end of the web. Then apply the interface agent on the bottom surface of the web; ③ Binding the fiber mesh: Bind and fix the two ends of the fiber mesh to the corresponding positioning steel plates, so that the length of the fiber mesh between the two opposite positioning steel plates is the same, put each positioning steel plate into the U-shaped card on both sides, pass the positioning screw through the second positioning hole of each positioning steel plate, and adjust the position of the positioning nut to make the spacing of each layer of fiber mesh the same; ④Tension the fiber grid and install the anchor fan structure: After fixing the positioning steel plate, tighten the fiber grid by rotating the locking nut to ensure that the tensioning screw moves outward by the same distance, that is, to ensure that all fiber bundles of the fiber grid are tensioned at the same time and to the same degree; after the fiber grid is tensioned, insert the carbon fiber anchor rod into the reserved hole to complete the anchor fixation, and then unfold the fiber bundle or fiber filament at the top of the carbon fiber anchor rod to form multiple anchor fans around the axis of the carbon fiber anchor rod, and infiltrate the anchor fan with the top layer of the fiber grid through the resin matrix to form a fiber-resin composite transition layer with a thickness of 0.5-2mm; ⑤ Casting TRC: Cast the mixed polymer cement mortar on the top of the web between the wooden formworks on both sides, insert and vibrate the polymer mortar to fill the grid gaps with the mortar so that it and the fiber grid become a whole; after casting the last layer of fiber grid, smooth the exposed part of the CFRP bundle of the polymer cement mortar on the top layer of fiber grid, and continue to cast cement mortar after laying so that the cement mortar covers the anchor fan structure. After casting, smooth the surface of TRC with a trowel.

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