High-ductility prestressed FRP-reinforced FRP-concrete composite beam

Abstract

The invention belongs to the technical field related to structural engineering, and discloses a high-ductility prestress FRP reinforced FRP-concrete composite beam which comprises a concrete beam (1), an FRP winding pipe (2), a beam bottom FRP plate (3), a prestress FRP rib (4), a ductility failure control device (5) and an end anchoring device (6). According to the high-ductility prestressed FRP reinforced FRP-concrete composite beam, the problem of steel bar corrosion existing in a common reinforced concrete beam is effectively solved by replacing steel bars with FRP materials, meanwhile, the bending ductility of the FRP bar reinforced concrete beam is remarkably improved through the ductility failure control device, and flexible control over the bending strength and ductility of the composite beam is achieved. Compared with a common reinforced concrete beam, the reinforced concrete beam has the advantages of light self weight, high strength, high ductility, high durability, no need of complex formwork engineering and the like, and has a quite wide practical engineering application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field related to structural engineering, and more specifically, relates to a high-ductility prestressed FRP reinforced FRP-concrete composite beam. Background Art

[0002] The rapid economic growth has brought about a large demand for infrastructure construction. With the in-depth promotion of high-quality infrastructure construction and the concept of sustainable development, higher requirements are placed on the mechanical properties and durability of infrastructure structures.

[0003] As the most common engineering structure, ordinary reinforced concrete structures face problems such as heavy weight, limited strength, complex steel and casting formwork engineering, and steel corrosion. Therefore, fiber-reinforced polymer (FRP), which has the advantages of light weight, high strength and corrosion resistance, is increasingly widely used in civil engineering structures. Among them, the use of FRP materials (sheets and bars) instead of steel bars as reinforcement materials for concrete beams is one of the mainstream applications. However, due to the linear elastic brittle fracture characteristics of FRP materials, FRP, as a completely linear elastic brittle material, has a low elastic modulus and no yield platform similar to steel bars, which makes the ductility of traditional FRP bar reinforced concrete bending members (such as beams) much lower than that of reinforced concrete bending members. In addition, FRP bar reinforced concrete beams still face complex reinforcement cages and casting formwork engineering. When assembling the reinforcement cage, special attention should be paid to the protection of FRP bars to avoid damage during processing and assembly. Steel bars may also need to be used in the reinforcement cage to fully utilize the ductility of steel bars and the high tensile strength of FRP bars, which increases the complexity of the reinforcement cage assembly. During the pouring process, special attention should also be paid to the vibration density of the concrete to ensure the bonding strength between the FRP bars and the concrete.

[0004] Therefore, there is an urgent need for a new type of FRP reinforced concrete beam with flexural ductility and convenient construction to promote the application of FRP materials in concrete structure engineering. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a high-ductility prestressed FRP reinforced FRP-concrete composite beam, the purpose of which is to improve the bending strength of the concrete beam and reduce its deadweight through the combined application of FRP plates and reinforcement materials, and at the same time adopt a ductile failure control device to overcome the defect of insufficient ductility of FRP, thereby providing bending ductility for the FRP-concrete composite beam.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a high-ductility prestressed FRP reinforced FRP-concrete composite beam is provided, comprising a concrete beam 1, an FRP wrapped tube 2, a beam bottom FRP plate 3, a prestressed FRP tendon 4, a ductility failure control device 5 and an end anchoring device 6; the FRP wrapped tube 2 is connected to the beam bottom FRP plate 3 and serves as a template for pouring the concrete beam 1; the bonding interface between the FRP wrapped tube 2, the beam bottom FRP plate 3 and the concrete beam 1 is shear-reinforced by steel nails or FRP anchors; there is no bonding between the prestressed FRP tendon 4 and the concrete beam 1, and the prestressed FRP tendon 4 passes through a PVC pipe pre-buried in the concrete beam 1 and is installed in the concrete beam 1; the ductility failure control device 5 is installed at the end of the prestressed FRP tendon 4; the end anchoring device 6 is composed of an anchor plate 61 and a sleeve 62, the sleeve 62 is connected to the end of the prestressed FRP tendon 4, and the anchor plate 61 is connected to the concrete beam 1 and the ductility failure control device 5.

[0007] Preferably, the cross-sectional shape of the concrete beam 1 is I-type or multi-box-type; the material of the concrete beam 1 is one of ordinary concrete, high-strength concrete, ultra-high performance concrete, fiber-reinforced concrete, rubber concrete and recycled aggregate concrete.

[0008] Preferably, the FRP winding tube 2 is made of fiber and resin-based materials, wherein the fiber is one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, polyethylene naphthalate synthetic fiber, the fiber direction is bidirectional winding, and the angle between the bidirectional fibers can be selected as any angle between 0 and 90 degrees.

[0009] Preferably, the beam bottom FRP plate 3 is made of fiber and resin-based materials, wherein the fiber is one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, polyethylene naphthalate synthetic fiber, and the fiber direction is unidirectional.

[0010] Preferably, the prestressed FRP tendons 4 are made of one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber.

[0011] Preferably, the material of the ductile failure control device 5 is selected from one of ordinary steel, high-strength steel and alloy steel, and its structural form is one of a circular cylinder, a square cylinder, a triangular cylinder and a plurality of square cylinders arranged side by side.

[0012] Preferably, the end anchoring device 6 is made of metal, and the length of the sleeve 62 is not less than 10 times the diameter of the prestressed FRP tendon 4 .

[0013] Preferably, the compressive yield strength of the ductile failure control device 5 is set to 70% to 90% of the tensile strength of the prestressed FRP tendon 4 .

[0014] Preferably, the prestressed FRP tendons 4 are tensioned after the concrete beam 1 has been cured to reach the design strength; and the ductility failure control device 5 is installed before the prestressed FRP tendons 4 are tensioned.

[0015] In general, compared with the prior art, the above technical solution conceived by the present invention provides a high ductility prestressed FRP reinforced FRP-concrete composite beam which mainly has the following beneficial effects:

[0016] 1. The high ductility prestressed FRP reinforced FRP-concrete composite beam of the present invention realizes flexible control of the bending strength and ductility of the composite beam by adjusting the concrete strength and cross-sectional size, the cross-sectional stiffness and strength of the FRP wrapped tube and the FRP plate at the bottom of the beam, the cross-sectional stiffness of the prestressed FRP tendons and the prestress tensioning grade, and the compressive performance of the ductility failure control device. Compared with ordinary reinforced concrete beams, it has the advantages of light weight, strong bearing capacity, high ductility, high durability, and corrosion resistance.

[0017] 2. The FRP tubes and FRP plates in the high-ductility prestressed FRP-reinforced FRP-concrete composite beam of the present invention can be used as casting templates for concrete beams, thereby saving a lot of template engineering and improving construction efficiency.

[0018] 3. The ductility failure control device in the high-ductility prestressed FRP reinforced FRP-concrete composite beam of the present invention overcomes the problem of insufficient ductility of the FRP-concrete composite beam. Through the flexible design of the ductility failure control device, the bending strength and ductility of the composite beam are controllable, which greatly improves its mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic elevation view of a high-ductility prestressed FRP-reinforced FRP-concrete composite beam structure of the present invention;

[0020] Figure 2 It is a schematic cross-sectional view of a high-ductility prestressed FRP-concrete composite beam structure of the present invention;

[0021] Figure 3 It is a schematic diagram of the ductile failure control device of the present invention.

[0022] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0023] 1-concrete beam; 2-FRP wrapped tube; 3-beam bottom FRP plate; 4-prestressed FRP tendons; 5-ductility failure control device; 6-end anchoring device; 61-anchor plate; 62-sleeve. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] This embodiment proposes a high ductility prestressed FRP reinforced FRP-concrete composite beam, such as Figure 1 and Figure 2 As shown, it includes a concrete beam 1, an FRP wrapped tube 2, a beam bottom FRP plate 3, a prestressed FRP tendon 4, a ductile failure control device 5 and an end anchoring device 6; the FRP wrapped tube 2 is connected to the beam bottom FRP plate 3 and serves as a template for pouring the concrete beam 1; the bonding interface between the FRP wrapped tube 2, the beam bottom FRP plate 3 and the concrete beam 1 is shear-reinforced by steel nails or FRP anchors; there is no bonding between the prestressed FRP tendon 4 and the concrete beam 1, and the prestressed FRP tendon 4 passes through the PVC pipe pre-buried in the concrete beam 1 and is installed in the concrete beam 1; the ductile failure control device 5 is installed at the end of the prestressed FRP tendon 4; the end anchoring device 6 is composed of an anchor plate 61 and a sleeve 62, the sleeve 62 is connected to the end of the prestressed FRP tendon 4, and the anchor plate 61 is connected to the concrete beam 1 and the ductile failure control device 5.

[0026] Specifically, the pouring of the concrete beam 1 is carried out after the FRP wrapped tube 2 and the beam bottom FRP plate 3 are formed by epoxy resin gluing, and no additional formwork engineering is required. Furthermore, the cross-sectional type of the concrete beam 1 can be selected as a multi-box type or an I type according to the actual transverse and longitudinal span requirements of the beam, such as Figure 2 shown.

[0027] Furthermore, the material of the concrete beam 1 is one of ordinary concrete, high-strength concrete, ultra-high performance concrete, fiber-reinforced concrete, rubber concrete and recycled aggregate concrete.

[0028] Furthermore, the FRP winding tube 2 and the beam bottom FRP plate 3 are made of fiber and resin-based materials, wherein the fiber is one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber. Preferably, glass fiber material is selected because glass fiber material has excellent performance, low cost, and is widely used, which can effectively reduce the economic cost of the composite beam.

[0029] Furthermore, the fiber direction of the FRP wrapped tube 2 is bidirectional, and the fiber direction of the beam bottom FRP plate 3 is unidirectional. Preferably, the angle between the bidirectional fibers of the FRP wrapped tube 2 is 90 degrees, and the angle between the fibers and the longitudinal axis of the beam is 45 degrees.

[0030] Furthermore, the contact surface between the FRP wrapped tube 2 and the concrete beam 1 should be roughened, and shear keys should be reasonably set to improve the interface shear resistance between the FRP wrapped tube and the concrete beam, thereby ensuring the overall performance of the composite beam. Preferably, the interface shear key between the FRP wrapped tube and the concrete beam can be a steel nail or an FRP anchor.

[0031] Further, the prestressed FRP tendons 4 are made of one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, polyethylene naphthalate synthetic fiber. Carbon fiber material is preferably selected because the carbon fiber material has high tensile strength and rigidity, which can effectively ensure the bending rigidity and strength of the prestressed FRP tendons to enhance the composite beam.

[0032] Furthermore, the material of the ductile failure control device 5 is selected from one of ordinary steel, high-strength steel, and alloy steel, and its structural form is one of a cylinder, a square cylinder, a triangular cylinder, and a plurality of square cylinders arranged side by side. Figure 3 As shown, when a single prestressed FRP tendon is used, a cylindrical ductile failure control device is selected; when multiple prestressed FRP tendons are arranged side by side, multiple square cylinder-type ductile failure control devices are used.

[0033] Furthermore, the end anchoring device 6 is made of metal material. Preferably, ordinary steel with low cost is used. The length of the sleeve 62 is set according to the diameter of the prestressed FRP tendon 4 to ensure the bonding strength between the sleeve 62 and the prestressed FRP tendon 4 before the prestressed FRP tendon 4 reaches the designed tensile strength. Preferably, the length of the sleeve 62 is not less than 10 times the diameter of the prestressed FRP tendon 4.

[0034] Furthermore, the tensioning of the prestressed FRP tendons 4 should be carried out after the ductility failure control device 5 and the anchoring device 6 are installed, and after the concrete beam 1 is cured to reach the design strength, and its initial tensioning strength should be determined according to the cracking strength of the concrete at the top of the beam. Preferably, the tensioning strength of the prestressed FRP tendons 4 does not exceed 30% of its tensile strength.

[0035] Therefore, the high-ductility prestressed FRP reinforced FRP-concrete composite beam of this embodiment can achieve flexible control of the bending strength and ductility of the composite beam by adjusting the concrete strength and cross-sectional size, the cross-sectional stiffness and strength of the FRP wrapped tube 2 and the beam bottom FRP plate 3, the cross-sectional stiffness and prestress tension grade of the prestressed FRP tendons 4, and the compressive performance of the ductility failure control device 5.

[0036] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high ductility prestressed FRP reinforced FRP-concrete composite beam, characterized in that: The invention comprises a concrete beam (1), an FRP wrapped tube (2), an FRP plate (3) at the bottom of the beam, a prestressed FRP tendon (4), a ductile failure control device (5) and an end anchoring device (6); the FRP wrapped tube (2) and the FRP plate (3) at the bottom of the beam are connected and serve as a template for pouring the concrete beam (1); the bonding interface between the FRP wrapped tube (2), the FRP plate (3) at the bottom of the beam and the concrete beam (1) is reinforced with steel nails or FRP anchors for shear resistance; the prestressed FRP tendon (4) and the concrete There is no bonding between the soil beams (1); the prestressed FRP tendons (4) pass through the PVC pipe pre-buried in the concrete beam (1) and are installed in the concrete beam (1); the ductility failure control device (5) is installed at the end of the prestressed FRP tendons (4); the end anchoring device (6) is composed of an anchor plate (61) and a sleeve (62); the sleeve (62) is connected to the end of the prestressed FRP tendons (4); the anchor plate (61) is connected to the concrete beam (1) and the ductility failure control device (5).

2. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The cross-sectional shape of the concrete beam (1) is I-type or multi-box-type; the material of the concrete beam (1) is one of ordinary concrete, high-strength concrete, ultra-high performance concrete, fiber-reinforced concrete, rubber concrete and recycled aggregate concrete.

3. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The FRP winding tube (2) is made of fiber and resin-based materials, wherein the fiber is one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, polyethylene naphthalate synthetic fiber, the fiber direction is bidirectional winding, and the angle between the bidirectional fibers can be selected as any angle between 0 and 90 degrees.

4. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The beam bottom FRP plate (3) is made of fiber and resin-based materials, wherein the fiber is one or more combinations of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, polyethylene naphthalate synthetic fiber, and the fiber direction is unidirectional.

5. A high ductility prestressed FRP reinforced FRP-concrete composite beam as claimed in claim 1, characterized in that: The prestressed FRP tendons (4) are made of one or more combinations of carbon fibers, glass fibers, aramid fibers, basalt fibers, polyethylene terephthalate synthetic fibers, and polyethylene naphthalate synthetic fibers.

6. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The material of the ductile failure control device (5) is selected from one of ordinary steel, high-strength steel and alloy steel, and its structural form is one of a circular cylinder, a square cylinder, a triangular cylinder and a plurality of square cylinders arranged side by side.

7. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The end anchoring device (6) is made of metal, and the length of the sleeve (62) is not less than 10 times the diameter of the prestressed FRP tendon (4).

8. A high ductility prestressed FRP reinforced FRP-concrete composite beam as claimed in claim 1, characterized in that: The compressive yield strength of the ductile failure control device (5) is set to 70% to 90% of the tensile strength of the prestressed FRP tendons (4).

9. A high ductility prestressed FRP reinforced FRP-concrete composite beam according to claim 1, characterized in that: The prestressed FRP tendons (4) are tensioned after the concrete beam (1) has been cured to reach the designed strength; and the ductility failure control device (5) is installed before the prestressed FRP tendons (4) are tensioned.

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