FRP-wrapped cement-based composite grouting sleeve of sandwich structure and application method of FRP-wrapped cement-based composite grouting sleeve

Abstract

The invention discloses an FRP-wrapped cement-based composite grouting sleeve of a sandwich structure and an application method of the FRP-wrapped cement-based composite grouting sleeve. The FRP-wrapped cement-based composite grouting sleeve is composed of a tooth-shaped FRP sleeve, a double-tooth-surface UHPC pipe, a cement-based composite grouting material and bonding resin. The tooth-shaped FRP sleeve is arranged on the outermost side of the grouting sleeve, and the double-tooth-face UHPC pipe is located in the middle of the grouting sleeve. And the tooth-shaped FRP sleeve is bonded with the double-tooth-surface UHPC pipe through the bonding resin. The reinforcing steel bar is inserted into the double-tooth-surface UHPC pipe and is connected with the double-tooth-surface UHPC pipe through the cement-based composite material grouting material. According to the FRP-wrapped cement-based composite grouting sleeve of the sandwich structure and the application method of the FRP-wrapped cement-based composite grouting sleeve, through the tooth-shaped structures arranged outside the FRP sleeve and the UHPC pipe, enough binding power can be provided, and the steel bars are prevented from being pulled out of a cement-based composite grouting material. By utilizing the characteristics of multipoint cracking and high ductility of the cement-based composite material, the local high stress is reduced, the local crushing damage of the cement matrix caused by overlarge bonding stress is avoided, the application range is wide, and the standardization is high.

Description

TECHNICAL FIELD

[0001] The technical field of the present application relates to the multi-disciplinary intersection of material science, civil engineering and structural engineering, mainly applied in the fields of fabricated buildings, bridge engineering and seismic reinforcement, and particularly relates to a sandwich structure FRP wrapped cement-based composite grouting sleeve and its application method. BACKGROUND

[0002] Grouting sleeves play a crucial role in the field of structural steel connection in civil engineering. In the early days, steel or cast iron was the main material for making grouting sleeves. However, with the increasing requirements of the civil engineering industry for structural performance, cost control and durability, the defects of steel and cast iron have become increasingly prominent. On the one hand, steel and cast iron have a relatively high density, resulting in a heavy weight of the sleeve, which increases the self-weight of the building structure, puts higher requirements on the foundation bearing capacity, and also brings inconvenience to transportation and installation. On the other hand, such metal materials are prone to rust in humid and corrosive environments, which seriously affects the service life and safety of the structure. In addition, the cost of raw materials and processing is relatively high, which to some extent limits its large-scale application.

[0003] To address the above challenges, a new type of sleeve made of cement-based composite material has emerged. This new type of sleeve has obvious advantages in reducing material cost and improving corrosion resistance. Cement-based composite materials have relatively low prices and good chemical corrosion resistance, which can effectively resist environmental erosion and prolong the service life of the structure. However, the cement-based composite sleeve is not perfect. Its brittle nature makes the material prone to brittle fracture when subjected to external forces, lacking sufficient toughness. At the same time, the tensile strength is low, which makes it difficult to meet the requirements of some high-tensile stress structural connections, thereby limiting the expansion of its application scenarios.

[0004] Under this background, the present application utilizes the performance advantages of fiber-reinforced composite materials (FRP) and optimizes the structure through adjusting the fiber direction, layer number and resin type to customize the mechanical properties of the sleeve (such as hoop tensile, radial compression), thereby improving the mechanical properties of the sleeve and providing strong support for the wide application of grouting sleeves in different application scenarios. The present application combines the advantages of two materials, FRP and cement-based composite material, overcomes the brittleness of cement-based composite material, and has the characteristics of strong designability, high bearing capacity and superior anchoring performance. SUMMARY

[0005] The application provides a sandwich structure FRP wrapped cement-based composite grouting sleeve and an application method thereof.

[0006] The sandwich structure FRP wrapped cement-based composite grouting sleeve and the application method thereof are composed of a toothed FRP sleeve, a double-tooth surface UHPC pipe, cement-based composite grouting material and bonding resin. The toothed FRP sleeve is located at the outermost side of the grouting sleeve, and the double-tooth surface UHPC pipe is located at the middle of the grouting sleeve. The toothed FRP sleeve is bonded together with the double-tooth surface UHPC pipe through the bonding resin. The steel bar is inserted into the double-tooth surface UHPC pipe and connected with the double-tooth surface UHPC pipe through the cement-based composite grouting material.

[0007] Further, the FRP wrapped cement-based composite grouting sleeve is applied according to the following steps. Step 1: determining the required number of FRP wrapped cement-based composite grouting sleeves according to design requirements; Step 2: determining the height of the circular ring tooth rib of the toothed FRP sleeve h and the length of the circular ring tooth rib l ; Step 3: determining the height and length of the circular ring tooth rib one and the circular ring tooth rib two of the double-tooth surface UHPC pipe; Step 4: making the toothed FRP sleeve and embedding it in the concrete according to the design requirements, and setting the made double-tooth surface UHPC pipe in the toothed FRP sleeve cavity from the top surface to the bottom surface and injecting the bonding resin to bond the toothed FRP sleeve and the double-tooth surface UHPC pipe together; Step 5: inserting the steel bar into the grouting sleeve, pouring the cement-based composite grouting material into the hole from the top surface, and bonding and anchoring the steel bar.

[0008] Further, the toothed FRP sleeve is a circular ring structure, and the circular ring tooth rib is arranged in a ladder shape along the length direction A of the grouting sleeve. The circular ring tooth rib is in close connection between the bottom surface of the toothed FRP sleeve and the bottom surface of the double-tooth surface UHPC pipe, preventing the bonding resin from flowing out of the cavity between the toothed FRP sleeve and the double-tooth surface UHPC pipe.

[0009] Further, the height of the circular ring tooth rib h is determined according to the following formula:

[0010] In the formula, is the pulling force of the steel bar, N; is the front-rib extrusion stress of the annular tooth rib, MPa, determined by experiments; is the radius of the FRP sleeve, mm; n The number of annular tooth ribs is set for the FRP sleeve along the length direction A of the grouting sleeve.

[0011] Furthermore, the length of the annular tooth rib l Determine as follows:

[0012] Where: is the tensile strength of the steel bar, N; is the bonding stress between the annular tooth rib and the double-toothed UHPC tube, MPa, determined by experiment; is the radius of the FRP sleeve, mm; n The number of annular tooth ribs is set for the FRP sleeve along the length direction A of the grouting sleeve.

[0013] Furthermore, the double-toothed UHPC pipe has a circular ring structure, with circular tooth ribs 1 and 2 arranged symmetrically in a stepped pattern along the length direction A of the grouting sleeve. The position and number of circular tooth ribs 1 and 2 are consistent with the circular tooth ribs of the toothed FRP sleeve.

[0014] Beneficial effects of the present invention: 1) Stable and reliable connection. The toothed FRP sleeve and double-toothed UHPC tube are tightly bonded using a bonding resin. Both are equipped with stepped circular tooth ribs, which significantly increase the contact area and friction. This effectively withstands the pull-out force of the steel bars, prevents them from slipping or pulling out, and ensures the safety and durability of the building structure.

[0015] 2) Adjustable mechanical properties. The FRP sleeve can be customized to meet project requirements by adjusting the annular rib parameters and fiber layout to achieve customized mechanical properties, including circumferential tensile strength and radial compressive strength. The double-toothed UHPC pipe works in tandem to optimize the sleeve's overall mechanical properties, meeting diverse engineering requirements.

[0016] 3) Simple and efficient operation. The application method and steps are clear, and each component can be prefabricated and assembled on-site after standardized production in the factory. This reduces the amount of wet work, lowers the construction difficulty and environmental requirements, improves construction efficiency and flexibility, and adapts to different construction conditions.

[0017] 4) Prevent material leakage. The toothed FRP sleeve's circular tooth ribs are tightly connected to the bottom surface of the double-toothed UHPC pipe, effectively preventing leakage of the bonding resin and cement-based composite grouting material, ensuring bonding and grouting quality and reliable steel bar connection.

[0018] 5) Strong corrosion resistance. Both FRP materials and double-toothed UHPC pipes have excellent corrosion resistance, can resist chemical erosion, protect internal materials and steel bars, reduce external environmental damage, extend the service life of the sleeve, and reduce subsequent maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a side schematic diagram of the grouting sleeve structure of the present invention.

[0020] Figure 2 It is a schematic diagram of the top surface of the grouting sleeve structure of the present invention.

[0021] Figure 3 It is a schematic structural diagram of the toothed FRP sleeve of the present invention.

[0022] Figure 4 Schematic diagram of the double-toothed UHPC tube structure of the present invention.

[0023] List of figures: 1 is a toothed FRP sleeve, 2 is a double-toothed UHPC pipe, 3 is a cement-based composite grouting material, 4 is a bonding resin, 5 is a grouting sleeve, 6 is a steel bar, 7 is a bottom surface, 8 is a cavity, 9 is a top surface, 10 is a hole, 11 is a circular tooth rib, 12 is the bottom surface of the toothed FRP sleeve, 21 is the bottom surface of the double-toothed UHPC pipe, 22 is a circular tooth rib one, 23 is a circular tooth rib two, 51 is the height of the circular tooth rib, and 52 is the length of the circular tooth rib. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0025] like Figure 1 、 Figure 2 As shown, this embodiment provides a sandwich-structured FRP-wrapped cementitious composite grouting sleeve and its application method 5. The sleeve comprises a serrated FRP sleeve 1, a double-serrated UHPC tube 2, a cementitious composite grouting material 3, and a bonding resin 4. The serrated FRP sleeve 1 is positioned at the outermost portion of the grouting sleeve 5, while the double-serrated UHPC tube 2 is positioned in the middle of the grouting sleeve 5. The serrated FRP sleeve 1 is bonded to the double-serrated UHPC tube 2 via the bonding resin. Rebar 6 is inserted into the double-serrated UHPC tube 2 and connected to the tube via the cementitious composite grouting material 3.

[0026] like Figure 1As shown, the toothed FRP sleeve 1 is an annular structure with annular tooth ribs 11 arranged in a stepped pattern along the length direction A of the grouting sleeve 5. The annular tooth ribs 11 are tightly connected between the bottom surface 12 of the toothed FRP sleeve 1 and the bottom surface 21 of the double-toothed UHPC tube 2, preventing the bonding resin 4 from flowing out of the cavity 8 between the toothed FRP sleeve 1 and the double-toothed UHPC tube 2.

[0027] like Figures 1 to 3 As shown, the height h51 of the annular tooth rib 11 is determined according to the following formula:

[0028] Where: is the pull-out force of steel bar 6, N; is the front-rib extrusion stress of the annular tooth rib 11, MPa, determined by experiments; is the radius of the FRP sleeve 1 , in mm; and n is the number of annular tooth ribs 11 provided on the toothed FRP sleeve 1 along the length direction A of the grouting sleeve 5 .

[0029] like Figures 1 to 3 As shown, the length l52 of the annular tooth rib 11 is determined according to the following formula:

[0030] Where: is the pull-out force of steel bar (6), N; is the bonding stress between the annular tooth rib 11 and the double-toothed UHPC tube 2, MPa, determined by experiments; is the radius of the FRP sleeve 1 , in mm; and n is the number of annular tooth ribs 11 provided on the FRP sleeve 1 along the length direction A of the grouting sleeve 5 .

[0031] like Figures 1 to 4 As shown, the double-toothed UHPC tube 2 is an annular structure, with annular tooth ribs 1 22 and 23 arranged symmetrically in a stepped pattern along the length direction A of the grouting sleeve 5. The positions and numbers of the annular tooth ribs 11 of the FRP sleeve 1 are consistent.

[0032] like Figures 1 to 4 As shown, the FRP wrapped cement-based composite grouting sleeve is applied according to the following steps: Step 1: Determine the required number of FRP-wrapped cement-based composite grouting sleeves according to design requirements; Step 2: Determine the height h51 and length l52 of the annular tooth rib 11 of the toothed FRP sleeve 1; Step 3: Determine the height and length of the annular tooth rib 1 22 and the annular tooth rib 2 23 of the double-toothed UHPC tube 2; Step 4: Prepare the toothed FRP sleeve 1 and embed it in the concrete according to the design requirements. At the same time, place the prepared double-toothed UHPC tube 2 in the toothed FRP sleeve 1 from the top surface 9 to the bottom surface 7. Inject the bonding resin 4 into the cavity 7 to bond the toothed FRP sleeve 1 and the double-toothed UHPC tube 2 together. Step 5: After the steel bar 6 is inserted into the grouting sleeve, pour the cement-based composite material grouting material 3 into the hole 10 from the top surface 9 to bond and anchor the steel bar 6.

[0033] This embodiment can effectively prevent material leakage. The toothed FRP sleeve annular tooth ribs are tightly connected to the bottom surface of the double-toothed UHPC pipe, effectively preventing leakage of bonding resin and cement-based composite grouting materials, ensuring bonding and grouting quality, and ensuring reliable connection of steel bars.

[0034] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method, characterized by: The grouting sleeve (5) is composed of a toothed FRP sleeve (1), a double-toothed UHPC tube (2), a cement-based composite grouting material (3) and a bonding resin (4); wherein the toothed FRP sleeve (1) is located at the outermost side of the grouting sleeve (5), and the double-toothed UHPC tube (2) is located in the middle of the grouting sleeve (5); the toothed FRP sleeve (1) is bonded to the double-toothed UHPC tube (2) through the bonding resin (4); and the steel bar (6) is inserted into the double-toothed UHPC tube (2) and connected to the double-toothed UHPC tube (2) through the cement-based composite grouting material (3).

2. The sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method according to claim 1, characterized in that: The toothed FRP sleeve (1) is a circular ring structure, and circular tooth ribs (11) are provided along the length direction A of the grouting sleeve (5) in a stepped arrangement; the circular tooth ribs (11) are tightly connected to the bottom surface (12) of the toothed FRP sleeve (1) and the bottom surface (21) of the double-toothed UHPC pipe (2) to prevent the bonding resin (4) from flowing out of the cavity (8) between the toothed FRP sleeve (1) and the double-toothed UHPC pipe (2).

3. The sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method according to claim 1 or 2, characterized in that: The double-toothed UHPC pipe (2) is a circular ring structure, and circular tooth ribs (22) and circular tooth ribs (23) are arranged along the length direction A of the grouting sleeve (5), and are arranged symmetrically in a stepped manner; the positions and numbers of the circular tooth ribs (22) and circular tooth ribs (23) are consistent with the circular tooth ribs (11) of the FRP sleeve (1).

4. The application method of the sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method according to claim 1 is characterized by: The specific steps of application include the following steps: Step 1: Determine the required number of FRP-wrapped cement-based composite grouting sleeves according to design requirements; Step 2: Determine the height h (51) and the length l (52) of the circular tooth rib (11) of the toothed FRP sleeve (1); Step 3: Determine the height and length of the annular tooth rib 1 (22) and the annular tooth rib 2 (23) of the double-toothed UHPC tube (2); Steps: Prepare a toothed FRP sleeve (1), embed it in concrete according to design requirements, and simultaneously arrange the prepared double-toothed UHPC tube (2) from the top surface (9) to the bottom surface (7) of the toothed FRP sleeve (1), inject bonding resin (4) into the cavity (7), so that the toothed FRP sleeve (1) and the double-toothed UHPC tube (2) are bonded together; Step 5: After the steel bar (6) is inserted into the grouting sleeve, the cement-based composite material grouting material (3) is poured into the hole (10) from the top surface (9) to bond and anchor the steel bar (6).

5. The application method of the sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method according to claim 4, characterized in that: The height h (51) of the annular tooth rib (11) is determined according to the following formula: Where: is the pull-out force of steel bar (6), N; is the front-rib extrusion stress of the annular tooth rib (11), MPa, determined by experiment; is the radius of the FRP sleeve (1), in mm; and n is the number of annular tooth ribs (11) provided on the toothed FRP sleeve (1) along the length direction A of the grouting sleeve (5).

6. The sandwich structure FRP-wrapped cement-based composite material grouting sleeve and its application method according to claim 4, characterized in that: The length l (52) of the annular tooth rib (11) is determined according to the following formula: ； Where: is the pull-out force of the steel bar (6), N; is the bonding stress between the annular tooth rib (11) and the double-toothed UHPC tube (2), MPa, determined by experiment; is the radius of the FRP sleeve (1), in mm; and n is the number of annular tooth ribs (11) provided on the FRP sleeve (1) along the length direction A of the grouting sleeve (5).

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