A high-ductility prestressed FRP-reinforced FRP-concrete composite beam

Abstract

The application belongs to the technical field of structural engineering, and discloses a high-ductility prestressed FRP reinforced FRP-concrete composite beam, which comprises a concrete beam (1), an FRP winding pipe (2), a beam bottom FRP plate (3), prestressed FRP bars (4), a ductility failure control device (5) and end anchoring devices (6). The high-ductility prestressed FRP reinforced FRP-concrete composite beam of the application effectively overcomes the problem of steel bar corrosion in ordinary reinforced concrete beams by using FRP material to replace steel bars, and significantly improves the flexural ductility of the FRP bar reinforced concrete beam through the ductility failure control device, so as to realize flexible control of the flexural strength and ductility of the composite beam. Compared with ordinary reinforced concrete beams, the application has the advantages of light weight, high strength, high ductility, high durability and no need for complex formwork engineering, and has quite broad practical engineering application prospects.

Description

Technical Field

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

[0002] Rapid economic growth has brought about a large demand for infrastructure construction. With the deepening of high-quality infrastructure construction and the concept of sustainable development, higher requirements have been placed on the mechanical performance 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 reinforcement and formwork engineering, and steel corrosion. Therefore, fiber-reinforced polymers (FRP), with advantages such as lightweight, high strength, and corrosion resistance, are increasingly widely used in civil engineering structures. One mainstream application is using FRP materials (sheets and reinforcing bars) to replace steel bars as reinforcement materials for concrete beams. However, due to the linear elastic brittle fracture characteristics of FRP, as a completely linear elastic brittle material, FRP has a low elastic modulus and lacks a yield plateau similar to steel bars. This results in the ductility of traditional FRP-reinforced concrete flexural members (such as beams) being significantly lower than that of reinforced concrete flexural members. Furthermore, FRP-reinforced concrete beams still face complex reinforcement cage and formwork engineering. Special care must be taken to protect the FRP bars during reinforcement cage assembly to avoid damage during processing and assembly. Steel bars may also need to be used in conjunction with the reinforcement cage to fully utilize the ductility of the steel bars and the high tensile strength of the FRP bars, which increases the complexity of reinforcement cage assembly. Special attention should be paid to the compaction of the concrete during the pouring process to ensure the bond strength between the FRP reinforcement and the concrete.

[0004] Therefore, there is an urgent need for a new type of FRP-reinforced concrete beam that is flexurally ductile and easy to construct, in order to promote the application of FRP materials in concrete structural engineering. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a high-ductility prestressed FRP reinforced FRP-concrete composite beam. The purpose is to improve the bending strength of the concrete beam and reduce its self-weight by combining FRP sheets and reinforcement. At the same time, a ductility failure control device is used to overcome the defect of insufficient FRP ductility, so as to provide bending ductility for the FRP-concrete composite beam.

[0006] To achieve the above objectives, 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 winding pipe 2, a bottom FRP plate 3, prestressed FRP reinforcement 4, a ductility failure control device 5, and an end anchoring device 6; the FRP winding pipe 2 and the bottom FRP plate 3 are connected and serve as a template for casting the concrete beam 1; the bonding interfaces between the FRP winding pipe 2, the bottom FRP plate 3, and the concrete beam 1 are reinforced with steel nails or FRP anchors for shear resistance; the prestressed FRP reinforcement 4 is not bonded to the concrete beam 1, and the prestressed FRP reinforcement 4 passes through a PVC pipe embedded 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 reinforcement 4; the end anchoring device 6 consists of an anchor plate 61 and a sleeve 62, the sleeve 62 is connected to the end of the prestressed FRP reinforcement 4, and the anchor plate 61 is connected to the concrete beam 1 and the ductility failure control device 5.

[0007] Preferably, the concrete beam 1 has an I-shaped or multi-box cross-section; 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 wound tube 2 is made of fiber and resin-based materials, wherein the fiber is one or more of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber, and the fiber direction is bidirectional winding, and the included angle between the bidirectional fibers can be any angle between 0 and 90 degrees.

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

[0010] Preferably, the prestressed FRP reinforcement 4 is made of one or more 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 ordinary steel, high-strength steel, and alloy steel, and its structural form is selected from cylindrical, square, triangular, or multiple square tubes 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 bar 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 tensioning of the prestressed FRP reinforcement 4 is carried out after the concrete beam 1 has reached its design strength; the installation of the ductility failure control device 5 is carried out before the tensioning of the prestressed FRP reinforcement 4.

[0015] In summary, compared with the prior art, the high-ductility prestressed FRP-reinforced FRP-concrete composite beam provided by the present invention has the following beneficial effects:

[0016] 1. The high-ductility prestressed FRP-reinforced FRP-concrete composite beam of the present invention achieves flexible control over the bending strength and ductility of the composite beam by adjusting the concrete strength and cross-sectional dimensions, the cross-sectional stiffness and strength of the FRP winding tube and the FRP plate at the bottom of the beam, the cross-sectional stiffness and prestressing tension level of the prestressed FRP reinforcement, and the compressive performance of the ductility failure control device. Compared with ordinary reinforced concrete beams, it has advantages such as light weight, high load-bearing capacity, high ductility, high durability, and corrosion resistance.

[0017] 2. The FRP pipes 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 formwork work 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 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. Attached Figure Description

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

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

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

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

[0023] 1-Concrete beam; 2-FRP spiral wound pipe; 3-FRP plate at the bottom of the beam; 4-Prestressed FRP reinforcement; 5-Ductility failure control device; 6-End anchoring device; 61-Anchor plate; 62-Sleeve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this 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, the structure includes a concrete beam 1, an FRP spiral wound pipe 2, an FRP bottom plate 3, prestressed FRP reinforcement 4, a ductility failure control device 5, and an end anchoring device 6. The FRP spiral wound pipe 2 and the FRP bottom plate 3 are connected and serve as a template for pouring the concrete beam 1. The bonding interfaces between the FRP spiral wound pipe 2, the FRP bottom plate 3, and the concrete beam 1 are reinforced with steel nails or FRP anchors for shear resistance. The prestressed FRP reinforcement 4 is not bonded to the concrete beam 1; it passes through a PVC pipe embedded in the concrete beam 1 and is installed within the beam. The ductility failure control device 5 is installed at the end of the prestressed FRP reinforcement 4. The end anchoring device 6 consists of an anchor plate 61 and a sleeve 62. The sleeve 62 is connected to the end of the prestressed FRP reinforcement 4, and the anchor plate 61 is connected to the concrete beam 1 and the ductility failure control device 5.

[0026] Specifically, the concrete beam 1 is poured after the FRP spiral wound pipe 2 and the FRP plate 3 at the bottom of the beam are bonded together with epoxy resin, without the need for additional formwork. Furthermore, the cross-sectional type of the concrete beam 1 can be selected as a multi-box type or an I-type, depending on the actual transverse and longitudinal span requirements of the beam. Figure 2 As shown.

[0027] Furthermore, the material of 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 spiral wound tube 2 and the FRP plate 3 at the bottom of the beam are made of fiber and resin-based materials, wherein the fibers are 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 is chosen because it has excellent performance, low cost, and wide application, which can effectively reduce the economic cost of the composite beam.

[0029] Furthermore, the fiber direction of the FRP spiral tube 2 is bidirectional, while the fiber direction of the FRP sheet 3 at the bottom of the beam is unidirectional. Preferably, the included angle between the two-way fibers of the FRP spiral tube 2 is 90 degrees, and the included angle with the longitudinal axis of the beam is 45 degrees.

[0030] Furthermore, the contact surface between the FRP spiral wound tube 2 and the concrete beam 1 should be roughened, and shear keys should be appropriately set to improve the interfacial shear resistance between the FRP spiral wound tube and the concrete beam, thereby ensuring the overall performance of the composite beam. Preferably, the interfacial shear keys between the FRP spiral wound tube and the concrete beam can be steel nails or FRP anchors.

[0031] Furthermore, the prestressed FRP reinforcement 4 is made of one or more of the following: carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber. Carbon fiber is preferably chosen because it has high tensile strength and stiffness, effectively ensuring the bending stiffness and strength of the prestressed FRP reinforcement-reinforced composite beam.

[0032] Furthermore, the ductile failure control device 5 is made of one of the following materials: ordinary steel, high-strength steel, or alloy steel, and its structural form is one of the following: cylindrical, square, triangular, or multiple square cylinders arranged side by side. Preferably, as shown below... Figure 3 As shown, when using a single prestressed FRP bar, a cylindrical ductile failure control device is selected; when using multiple prestressed FRP bars arranged in parallel, multiple square tube-type ductile failure control devices are used.

[0033] Furthermore, the end anchoring device 6 is made of metal. Preferably, it is made of ordinary steel, which has a lower cost. The length of the sleeve 62 is set according to the diameter of the prestressed FRP bar 4 to ensure the bond strength between the sleeve 62 and the prestressed FRP bar 4 before the prestressed FRP bar 4 reaches its design tensile strength. Preferably, the length of the sleeve 62 is not less than 10 times the diameter of the prestressed FRP bar 4.

[0034] Furthermore, the tensioning of the prestressed FRP reinforcement 4 should be carried out after the installation of the ductility failure control device 5 and the anchoring device 6, and after the concrete beam 1 has cured to the design strength. Its initial tension strength should be determined based on the cracking strength of the concrete at the top of the beam. Preferably, the tension strength of the prestressed FRP reinforcement 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 dimensions, the cross-sectional stiffness and strength of the FRP winding tube 2 and the FRP plate 3 at the bottom of the beam, the cross-sectional stiffness and prestressing tension level of the prestressed FRP reinforcement 4, and the compressive performance of the ductility failure control device 5.

[0036] Those skilled in the art will readily understand that the above are merely 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 within the scope of protection of the present invention.

Claims

1. A high-ductility prestressed FRP-reinforced FRP-concrete composite beam, characterized in that: The structure includes a concrete beam (1), an FRP spiral pipe (2), a bottom FRP plate (3), prestressed FRP reinforcement (4), a ductility failure control device (5), and an end anchoring device (6). The FRP spiral pipe (2) and the bottom FRP plate (3) are connected and serve as a template for casting the concrete beam (1). The bonding interface between the FRP spiral pipe (2), the bottom FRP plate (3), and the concrete beam (1) is reinforced with steel nails or FRP anchors for shear resistance. The prestressed FRP reinforcement (4) is not bonded to the concrete beam (1). The prestressed FRP reinforcement (4) passes through a PVC pipe embedded 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 bar (4); the end anchoring device (6) consists of an anchor plate (61) and a sleeve (62), the sleeve (62) is connected to the end of the prestressed FRP bar (4), and the anchor plate (61) is connected to the concrete beam (1) and the ductility failure control device (5); the compressive yield strength of the ductility failure control device (5) is set to 70% to 90% of the tensile strength of the prestressed FRP bar (4); the tensioning of the prestressed FRP bar (4) is carried out after the concrete beam (1) has reached the design strength; the installation of the ductility failure control device (5) is carried out before the tensioning of the prestressed FRP bar (4).

2. The high-ductility prestressed FRP-reinforced FRP-concrete composite beam as described in claim 1, characterized in that: The concrete beam (1) has an I-shaped or multi-box cross-section; 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. The high-ductility prestressed FRP-reinforced FRP-concrete composite beam as described in claim 1, characterized in that: The FRP wound tube (2) is made of fiber and resin-based materials, wherein the fiber is one or more of carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber, and the fiber direction is bidirectional winding, and the included angle between the bidirectional fibers can be any angle between 0 and 90 degrees.

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

5. A high-ductility prestressed FRP-reinforced FRP-concrete composite beam as described in claim 1, characterized in that: The prestressed FRP reinforcement (4) is made of one or more of the following: carbon fiber, glass fiber, aramid fiber, basalt fiber, polyethylene terephthalate synthetic fiber, and polyethylene naphthalate synthetic fiber.

6. A high-ductility prestressed FRP-reinforced FRP-concrete composite beam as described in claim 1, characterized in that: The ductility failure control device (5) is made of one of ordinary steel, high-strength steel, or alloy steel, and its structural form is one of cylindrical, square, triangular, or multiple square tubes arranged side by side.

7. A high-ductility prestressed FRP-reinforced FRP-concrete composite beam as described in 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 bar (4).

Images