A hollow sandwich GFRP pipe

Abstract

This utility model discloses a hollow sandwich GFRP pipe, belonging to the field of engineering structure technology. The hollow sandwich GFRP pipe comprises several individual pipe components, each including a GFRP pipe, a high-strength square steel pipe, and a UHPC layer. The GFRP pipe is the outermost layer, the high-strength square steel pipe is the innermost layer, and the UHPC layer fills the space between the GFRP pipe and the high-strength square steel pipe. A first flange and a second flange are fixed to one outer end of the GFRP pipe. Adjacent individual pipe components are interlocked by the first and second flanges and secured with bolts. The outer side of the GFRP pipe is threaded with oblique studs, and a perforated steel plate is fixedly installed at the inner end of the GFRP pipe. This design effectively solves the problem of corrosion of traditional high-strength steel in marine environments, enhances the performance of the internal UHPC, ensures the stability and rigidity of the entire structure, reduces the cost of subsequent periodic maintenance and repair, and is suitable for normal use in marine engineering structures.

Description

Technical Field

[0001] This utility model relates to the field of engineering structure technology, and more specifically, to a hollow sandwich GFRP pipe. Background Technology

[0002] The glass fiber reinforced polymer (GFRP) tube-ultra-high performance concrete (UHPC)-high-strength steel composite component is a novel composite component developed based on solid steel tube concrete components. This component consists of an inner high-strength steel tube with coincident cross-sections and an outer glass fiber reinforced polymer (GFRP) tube, with ultra-high performance concrete filling the gap between the two tubes to ensure all three components share the load. This novel glass fiber reinforced polymer (GFRP) tube-ultra-high performance concrete (UHPC)-high-strength steel composite component possesses the excellent characteristics of ordinary solid steel tube concrete components, while also offering advantages such as light weight and high bending stiffness.

[0003] In the field of marine engineering, structures must withstand harsh conditions such as extreme climate, seawater corrosion, and wave impact over long periods. While traditional materials such as high-strength steel possess excellent high-strength properties and can withstand large loads, providing strong protection for structural stability, their poor corrosion resistance necessitates significant investment of manpower, resources, and funds for regular maintenance and repair, and can also negatively impact the normal use of marine engineering structures.

[0004] Therefore, in view of this, we have studied and improved the existing structure to provide a hollow sandwich GFRP pipe, in order to achieve a more practical purpose. Utility Model Content

[0005] In view of the problems existing in the prior art, the purpose of this utility model is to provide a hollow sandwich GFRP pipe, which can effectively solve the problem of easy corrosion of traditional high-strength steel in marine environment, enhance the performance of internal UHPC, ensure the stability and rigidity of the whole structure, reduce the cost of subsequent regular maintenance and repair, and is suitable for normal use in marine engineering structures.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A hollow sandwich GFRP pipe includes a hollow sandwich GFRP pipe composed of several individual pipe components. Each individual pipe component includes a GFRP pipe, a high-strength square steel pipe, and a UHPC layer. The GFRP pipe is located in the outermost layer, the high-strength square steel pipe is located in the innermost layer, and the UHPC layer is filled between the GFRP pipe and the high-strength square steel pipe.

[0008] One flange is fixed to one outer end of the GFRP pipe, and another flange is fixed to one outer end of the GFRP pipe. The first and second flanges are interlocked between two adjacent individual pipe components and fixed by bolts. The outer side of the GFRP pipe is threaded with oblique studs, and the inner end of the GFRP pipe is fixed with a perforated steel plate. The oblique studs pass through the GFRP pipe and the perforated steel plate in sequence and extend into the UHPC layer.

[0009] Furthermore, the end faces of the GFRP pipe, the high-strength square steel pipe, and the UHPC layer are flush and their cross-sectional geometric centers coincide.

[0010] Furthermore, the GFRP tube is made of glass fiber reinforced polymer material.

[0011] Furthermore, the outer diameter Do of the GFRP pipe is 600mm, and the side length Di of the high-strength square steel pipe is 400mm.

[0012] Furthermore, the outer surface of the high-strength square steel pipe is sandblasted or polished to form an outer rough mesh.

[0013] Furthermore, between two adjacent individual pipe components, six obliquely inserted studs are provided, and the six obliquely inserted studs are evenly distributed in a ring.

[0014] Furthermore, the corners of the high-strength square steel pipe are processed to form a rounded corner structure.

[0015] Furthermore, both flange No. 1 and flange No. 2 are fixed with protruding retaining rings on their sides.

[0016] The sides of flange No. 1 and flange No. 2 are provided with annular snap-fit ​​openings, and the outwardly protruding snap-fit ​​rings engage with the corresponding annular snap-fit ​​openings.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] ① This solution effectively solves the problem of easy corrosion of traditional high-strength steel in marine environments by using glass fiber reinforced polymer (GFRP) pipes as the outer pipe material, and also enhances the performance of the internal UHPC through the constraint effect;

[0019] ② This scheme achieves synergistic stress distribution through a triple-combination structure of GFRP pipe, UHPC layer, and high-strength square steel pipe. The outer GFRP pipe provides tensile strength and corrosion resistance protection, the middle UHPC layer provides ultra-high compressive strength (actual tests have shown that the compressive strength can reach more than 150MPa), and the inner high-strength square steel pipe provides core support stiffness, so that the hollow ratio α is controlled within the optimal range of 0.1-0.65 (the load-bearing capacity is optimal when α≈0.45). Compared with a solid structure, the weight is reduced by more than 30%, ensuring the stability of the entire structure.

[0020] ③ This solution uses a dual connection mechanism of flanges and oblique studs to achieve a joint strength of over 95% of the pipe body strength, far exceeding traditional welded connections. In addition, the multi-layered sealing protection mechanism reduces the cost of subsequent regular maintenance and repair. The dual connection mechanism can resist 10MPa water pressure penetration during testing, making it suitable for deep-sea engineering. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a single pipe component in this utility model;

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of the two individual pipe components spliced ​​together in this utility model;

[0023] Figure 3 This is a schematic diagram of the high-strength square steel pipe and the outer rough mesh in this utility model;

[0024] Figure 4 This is a schematic diagram of the overall structure of the two individual pipe components after being spliced ​​together in this utility model.

[0025] Explanation of the labels in the diagram:

[0026] 1. GFRP pipe; 101. No. 1 flange; 1011. Outer convex retaining ring; 1012. Annular bayonet; 102. No. 2 flange; 103. Bolt; 2. High-strength square steel pipe; 201. Outer rough mesh; 3. UHPC layer; 4. Angled studs; 5. Perforated steel plate. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model. Example 1

[0028] Please see Figure 1 - Figure 4 A hollow sandwich GFRP pipe is composed of several individual pipe components. Each individual pipe component includes a GFRP pipe 1, a high-strength square steel pipe 2, and a UHPC layer 3. The GFRP pipe 1 is located in the outermost layer, the high-strength square steel pipe 2 is located in the innermost layer, and the UHPC layer 3 is filled between the GFRP pipe 1 and the high-strength square steel pipe 2.

[0029] One flange 101 is fixed to one outer end of GFRP pipe 1, and another flange 102 is fixed to one outer end of GFRP pipe 1. Between two adjacent individual pipe components, flange 101 and flange 102 are interlocked and fixed by bolts 103. GFRP pipe 1 is threaded with oblique studs 4 on its outer side, and a perforated steel plate 5 is fixedly installed on the inner end of GFRP pipe 1. The oblique studs 4 pass through GFRP pipe 1 and perforated steel plate 5 in sequence and extend into the UHPC layer 3.

[0030] See Figure 1 Specifically, the end faces of GFRP pipe 1, high-strength square steel pipe 2, and UHPC layer 3 are flat and their cross-sectional geometric centers coincide.

[0031] This ensures stress balance within each individual pipe component and facilitates connection between adjacent individual pipe components.

[0032] Specifically, GFRP pipe 1 is made of glass fiber reinforced polymer material.

[0033] Glass fiber reinforced polymer materials have corrosion resistance and high strength, and can effectively resist seawater erosion.

[0034] The high-strength square steel pipe 2 serves as the internal support structure, providing the necessary strength and rigidity. The UHPC layer 3, with its ultra-high compressive strength and good durability, fills the space between the GFRP pipe 1 and the high-strength square steel pipe 2, forming a tight assembly.

[0035] Specifically, the outer diameter Do of GFRP pipe 1 is 600mm, the side length Di of high-strength square steel pipe 2 is 400mm, and the wall thickness is the design standard value.

[0036] By controlling the specifications of each structure, the resulting composite column performed excellently in durability tests under simulated marine conditions, exhibiting superior corrosion resistance and load-bearing capacity compared to traditional structures.

[0037] See Figure 3 Specifically, the outer surface of the high-strength square steel pipe 2 is sandblasted or ground to form an outer rough mesh 201.

[0038] By increasing the roughness, the bonding strength between the high-strength square steel pipe 2 and the UHPC layer 3 is increased, ensuring that the high-strength square steel pipe 2 and the UHPC layer 3 can work together better during the stress process, thereby improving the load-bearing capacity of the overall structure.

[0039] See Figure 4 Specifically, between two adjacent individual pipe components, there are six obliquely inserted studs 4, and the six obliquely inserted studs 4 are evenly distributed in a ring.

[0040] On the outer wall of the high-strength square steel pipe 2, a certain number of oblique studs 4 are evenly arranged along its length direction. Together with the perforated steel plate 5, they form shear connectors. These shear connectors can penetrate into the UHPC layer 3 to effectively transmit shear force, prevent relative slippage between the high-strength square steel pipe 2 and the UHPC layer 3, and further enhance the integrity of the composite structure.

[0041] See Figure 1 , Figure 2 Specifically, the corners of the high-strength square steel pipe 2 are processed to form a rounded corner structure.

[0042] Square cross-sections with rounded corners or beveled edges are used to reduce stress concentration and improve the durability and safety of the structure.

[0043] See Figure 1 Specifically, both flange 101 and flange 202 are fixed with protruding retaining rings 1011 on their sides.

[0044] Annular snap-fit ​​1012 is provided on the side of flange 101 and flange 202, and the outwardly protruding snap ring 1011 is engaged with the corresponding annular snap-fit ​​1012.

[0045] This improves the tightness of the mating between flange 101 and flange 102, and also increases the sealing between the two individual pipe components after connection.

[0046] Furthermore, flange connections provide reliable axial and shear bearing capacity, making them suitable for applications subject to large loads.

[0047] Working principle:

[0048] When using hollow sandwich GFRP pipes, the external load is first borne by the GFRP pipe 1 under bending stress, and the shear force is transferred to the UHPC layer 3 through the obliquely inserted studs 4. The UHPC layer 3 then evenly transfers the pressure to the high-strength square steel pipe 2.

[0049] The circumferential constraint of GFRP pipe 1 puts UHPC in a triaxial compression state, which increases its compressive strength by 50%. The filling of UHPC layer 3 effectively suppresses the local buckling of high-strength square steel pipe 2. The coincident design of the cross-sectional geometric center ensures no eccentric force. The deformation space reserved in UHPC layer 3 can absorb shrinkage deformation of 0.3 to 0.5 mm / m.

[0050] Furthermore, actual testing has shown that GFRP pipe 1 forms a corrosion barrier with a corrosion rate of <0.01mm / year, the sealing system is ISO12944 certified, and the protective lifespan reaches 50 years. Example 2

[0051] Referring to Embodiment 1 above, further description is provided.

[0052] In individual pipe components, the void ratio is calculated using the following formula:

[0053] α=V2 / V1

[0054] Where V2 is the volume of the square steel tube and V1 is the volume of the GFRP tube. The void ratio α ranges from 0.1 ≤ α ≤ 0.65.

[0055] To further verify the effectiveness, comparative tests were conducted on GFRP pipe-UHPC-high-strength steel composite columns with different void ratios. The test results show that the composite column exhibits stable performance when the void ratio α is within the range of 0.1 to 0.65. In particular, the load-bearing capacity of the composite column reaches its optimal level when the void ratio α is approximately 0.45. Example 3

[0056] Referring to Embodiment 1 above, further description is provided.

[0057] When filling the UHPC layer 3 between the GFRP pipe 1 and the high-strength square steel pipe 2, a certain amount of deformation space can be reserved to accommodate the shrinkage of UHPC during the hardening process and the deformation caused by temperature changes, reduce the internal stress caused by deformation incoordination, and protect the integrity of the combined structure.

[0058] After the mechanical connection of two adjacent individual pipe components is completed, a layer of special corrosion-resistant adhesive is applied to the joint. The adhesive fills the tiny gaps in the joint, enhances the adhesion between components, and improves the overall sealing and durability of the structure.

[0059] During assembly, ensure that the end faces of each component are flat, smooth, and free of impurities and oil. Apply sealing strips or sealant to the joints to prevent seawater and corrosive media from seeping in. The sealing strips or sealant should have good corrosion resistance and aging resistance.

[0060] After assembly, non-destructive testing techniques (such as ultrasonic testing) are used to inspect the joints for quality. This ensures the joints are free of cracks, gaps, and other defects, and that the connection is reliable. Regular inspections and maintenance of the joints are conducted to promptly identify and address any potential connection problems. Adhesives and sealing strips are periodically replaced or repaired to maintain their optimal performance.

[0061] The above description is merely a preferred embodiment of this utility model; however, the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and its improved concept, should be included within the protection scope of this utility model.

Claims

1. A hollow sandwich GFRP pipe, wherein the hollow sandwich GFRP pipe is composed of a plurality of individual pipe components, characterized in that: The single pipe component includes a GFRP pipe (1), a high-strength square steel pipe (2), and a UHPC layer (3). The GFRP pipe (1) is the outermost layer, the high-strength square steel pipe (2) is the innermost layer, and the UHPC layer (3) is filled between the GFRP pipe (1) and the high-strength square steel pipe (2). One flange (101) is fixed to one outer end of the GFRP pipe (1), and another flange (102) is fixed to one outer end of the GFRP pipe (1). The first flange (101) and the second flange (102) are interlocked between two adjacent individual pipe components and fixed by bolts (103). The outer side of the GFRP pipe (1) is threaded with a stud (4). A perforated steel plate (5) is fixedly installed at the inner end of the GFRP pipe (1). The stud (4) passes through the GFRP pipe (1) and the perforated steel plate (5) in sequence and extends into the UHPC layer (3).

2. The hollow sandwich GFRP pipe according to claim 1, characterized in that: The end faces of the GFRP pipe (1), the high-strength square steel pipe (2), and the UHPC layer (3) are flat and their cross-sectional geometric centers coincide.

3. The hollow sandwich GFRP pipe according to claim 1, characterized in that: The GFRP tube (1) is made of glass fiber reinforced polymer material.

4. A hollow sandwich GFRP pipe according to claim 1, characterized in that: The outer diameter Do of the GFRP pipe (1) is 600mm, and the side length Di of the high-strength square steel pipe (2) is 400mm.

5. A hollow sandwich GFRP pipe according to claim 1, characterized in that: The outer surface of the high-strength square steel pipe (2) is formed by sandblasting or grinding to create an outer rough mesh (201).

6. A hollow sandwich GFRP tube according to claim 1, characterized in that: Between two adjacent single pipe components, there are six oblique studs (4), and the six oblique studs (4) are evenly distributed in a ring.

7. A hollow sandwich GFRP pipe according to claim 1, characterized in that: The corners of the high-strength square steel pipe (2) are processed to form a rounded corner structure.

8. A hollow sandwich GFRP pipe according to claim 1, characterized in that: Both flange No. 1 (101) and flange No. 2 (102) are fixed with external convex retaining rings (1011) on their sides. The first flange (101) and the second flange (102) have annular snap-fit ​​(1012) on their sides, and the outwardly protruding snap ring (1011) engages with the corresponding annular snap-fit ​​(1012).

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