Frp double tube reinforced ultra high performance concrete composite bar and application thereof

Abstract

The application discloses a kind of FRP double-tube reinforced ultra-high performance concrete composite bars and its application, belong to building structure field, secondly, composite bar includes: external FRP pipe, internal FRP pipe, FRP stiffener and ultra-high performance concrete;External FRP pipe and internal FRP pipe are all hollow structure, internal FRP pipe is located in the inner wall of external FRP pipe, and there is no gap between the outer wall of internal FRP pipe and the inner wall of external FRP pipe, at least two FRP stiffeners are arranged on the inner wall of internal FRP pipe, and the inside of internal FRP pipe is filled with ultra-high performance concrete.FRP double-tube reinforced ultra-high performance concrete composite bar formed by using corrosion-resistant, high-performance, low-carbon FRP and ultra-high performance concrete material has the characteristics of good compressive ductility, corrosion resistance and strong tension and compression performance.The application can replace steel in reinforced concrete structure beam, plate, column component, FRP in FRP bar structure component and shaped steel in steel-concrete structure, steel pipe concrete to form new FRP structure, and is suitable for coastal and marine infrastructure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of building structures, and more particularly relates to a FRP double-pipe reinforced ultra-high performance concrete composite bar and application thereof. BACKGROUND

[0002] Steel and concrete are the main materials of current building structures, which meet the needs of social development, but also bring great challenges, among which the main challenge is the insufficient mechanical properties and short service life of traditional structures, especially in coastal and marine areas, due to the serious corrosion environment of seawater, marine atmosphere, splash zone, tidal zone, etc., which can significantly accelerate the corrosion of steel, thereby leading to a significant decline in structural performance. To solve the problem of structural performance degradation caused by corrosion of steel bars in traditional steel-concrete structures, the application of new structures composed of new materials in infrastructure construction has attracted much attention.

[0003] Fiber-reinforced polymer (FRP) has become a research hotspot in the field of civil engineering due to its light weight, high strength, corrosion resistance, and non-magnetic properties.

[0004] One of the main application forms is to replace steel bars with FRP bars to form FRP bar concrete structural members, but due to the brittle characteristics of FRP linear elasticity, the traditional FRP bar concrete structure has a sudden brittle failure, poor ductility, and very limited seismic energy dissipation capacity. On the other hand, FRP materials have fiber micro-buckling during compression, and their high strength cannot be fully utilized. For these reasons, the application of FRP in civil engineering has been greatly limited and is a problem to be solved.

[0005] Therefore, the prior art has the technical problems of sudden brittle failure, poor ductility, and low compressive strength. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the present application provides a FRP double-pipe reinforced ultra-high performance concrete composite bar and application thereof, thereby solving the technical problems of sudden brittle failure, poor ductility, and low compressive strength of the prior art.

[0007] To achieve the above-mentioned purpose, according to one aspect of the present application, a FRP double-pipe reinforced ultra-high performance concrete composite bar is provided, which comprises: an outer FRP pipe, an inner FRP pipe, an FRP stiffening rib, and ultra-high performance concrete.

[0008] The outer FRP pipe and the inner FRP pipe are both hollow structures, the inner FRP pipe is located on the inner wall of the outer FRP pipe, and there is no gap between the outer wall of the inner FRP pipe and the inner wall of the outer FRP pipe,

[0009] The inner wall of the internal FRP pipe is provided with at least two FRP stiffening ribs, and the internal FRP pipe is filled with ultra-high performance concrete.

[0010] Further, the cross-sectional area of the internal FRP pipe is greater than 10% of the cross-sectional area of the ultra-high performance concrete filled therein.

[0011] Further, the thickness of the external FRP pipe is greater than one-fifth of the thickness of the internal FRP pipe.

[0012] Further, the ultra-high performance concrete comprises cement, silica fume, fly ash, quartz sand, superplasticizer and water,

[0013] Alternatively, the ultra-high performance concrete comprises cement, silica fume, fly ash, quartz sand, superplasticizer, water and steel,

[0014] Alternatively, the ultra-high performance concrete comprises cement, silica fume, fly ash, quartz sand, superplasticizer, water and basalt fiber,

[0015] Alternatively, the ultra-high performance concrete comprises cement, silica fume, fly ash, quartz sand, superplasticizer, water, expansion agent and shrinkage reducing agent.

[0016] Further, the angle between the fiber winding direction of the external FRP pipe and the cross section of the composite bar is 0-30 degrees.

[0017] Further, the angle between the fiber winding direction of the internal FRP pipe and the cross section of the composite bar is 80-90 degrees.

[0018] Further, the shape of the internal FRP pipe is the same as that of the external FRP pipe, and the shape of the external FRP pipe is circular or rectangular.

[0019] Further, the shape of the FRP stiffening rib is rectangular, open-hole rectangular or rectangular with one side being wavy.

[0020] Further, the material of the external FRP pipe is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP;

[0021] The material of the internal FRP pipe is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP;

[0022] The material of the FRP stiffening rib is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP.

[0023] According to another aspect of the present application, there is provided an application of the FRP double-pipe reinforced ultra-high performance concrete composite bar, which replaces the steel bars in the reinforced concrete structure beams, plates, column members, the FRP bars in the FRP bar structure members, and the shaped steel and the steel pipe concrete in the steel-concrete structure to form a new FRP structure, which is applied to the coastal infrastructure, the infrastructure in the marine environment, or the structure member for isolating electromagnetism.

[0024] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0025] (1) The outer wall of the inner FRP pipe of the composite bar of the present application is seamless with the inner wall of the outer FRP pipe, the inner FRP pipe is tightly connected with the outer FRP pipe, at least two FRP stiffening ribs are arranged in the inner FRP pipe, and the inner FRP pipe is filled with ultra-high performance concrete. The ultra-high performance concrete is in a triaxial compression state under the constraint of the double-pipe reinforcement formed by the inner FRP pipe and the outer FRP pipe, and the compression strength and ductility of the ultra-high performance concrete are significantly improved. The inner FRP pipe is located between the outer FRP pipe and the ultra-high performance concrete, the fiber micro-buckling of the inner FRP pipe is limited, and the tensile and compressive strengths of the FRP material can be fully utilized. The inner wall of the inner FRP pipe is provided with at least two FRP stiffening ribs, which can ensure reliable bonding between the FRP pipe and the ultra-high performance concrete and work cooperatively, limit the fiber micro-buckling of the FRP pipe to a certain extent when the FRP pipe is compressed, and improve the ability of the member to withstand axial compression load, eccentric compression load, and bending moment. Compared with the brittle failure of the traditional FRP bar concrete structure, the new structure of the composite bar according to the present application is a gradual failure with signs when bearing load, and the ductility and seismic performance of the structure are significantly improved.

[0026] (2) The increase in the thickness of the inner pipe can improve the tensile strength of the composite bar, based on which the cross-sectional area of the inner FRP pipe in the present application is greater than 10% of the cross-sectional area of the ultra-high performance concrete filled therein, thereby limiting the minimum thickness of the inner FRP pipe. The increase in the thickness of the outer pipe can improve the tensile and compressive strengths of the composite bar, based on which the thickness of the outer FRP pipe is set to be greater than one-fifth of the thickness of the inner FRP pipe.

[0027] (3) The ultra-high performance concrete filled in the present application is composed of cement, silica fume, fly ash, quartz sand, high-efficiency water reducing agent, and water, and other types of fibers can be added to the ultra-high performance concrete according to requirements, and other additives can be added to the ultra-high performance concrete according to requirements. The composite bar of the present application uses ultra-high performance concrete with good extensibility, has flexible and variable size, is fast to prefabricate in the factory, is convenient to cast on site, has a wide range of applications, and can replace the steel bars in the traditional reinforced concrete structure members such as beams, plates, and columns, and can replace the shaped steel and the steel pipe concrete in the steel-concrete structure as a member.

[0028] (4) The angle between the fiber winding direction of the outer FRP pipe and the cross section of the composite bar in the application is 0-30 degrees. When the angle is 0 degree, the fiber winding direction of the outer FRP pipe is circumferential, and when the angle is greater than 0 degree to 30 degrees, the fiber winding direction of the outer FRP pipe is approximately circumferential. The ultra-high performance concrete is in a triaxial compression state under the constraint of the outer circumferential fiber FRP pipe, and the compression strength and ductility of the ultra-high performance concrete are significantly improved. The angle between the fiber winding direction of the inner FRP pipe and the cross section of the composite bar is 80-90 degrees. When the angle is 90 degrees, the fiber winding direction of the inner FRP pipe is longitudinal, and when the angle is between 80 degrees and 90 degrees, the fiber winding direction of the inner FRP pipe is approximately longitudinal. The inner longitudinal fiber FRP pipe is located between the outer circumferential fiber FRP pipe and the ultra-high performance concrete, and the fiber micro buckling of the inner longitudinal fiber FRP pipe is limited, and the tensile and compressive strength of the FRP material can be fully utilized. Compared with the brittle failure of the FRP bar, the composite bar has better compression ductility and higher tensile and compressive mechanical properties.

[0029] (5) The new structure applied in the application is a full FRP material structure with excellent corrosion resistance, which solves the problem of steel corrosion in traditional steel and concrete material structures, and is very suitable for use in infrastructure in harsh corrosive environments, coastal and marine environments. At the same time, according to the new structure of the application, the structure does not contain steel, so it will not interfere with electromagnetic equipment, and can be used for the construction of structure parts that need to isolate electricity in hospitals, high-precision laboratories, aerospace bases and military projects. Using FRP material instead of steel for the construction of coastal / marine infrastructure not only can improve the durability of the structure, but also can use abundant seawater and sea sand resources as raw materials to manufacture concrete, solving the problems of lack of sand and stone resources and serious shortage of fresh water resources in coastal areas. The composite bar of the application is green, low-carbon, economical and environmentally friendly, the carbon emission of the raw material FRP is much lower than that of steel, and a large amount of waste slag (silica fume, fly ash) is recycled in the ultra-high performance concrete; at the same time, it has wide adaptability to concrete, and can use abundant seawater and sea sand resources to prepare concrete, reducing cost and saving fresh water and sand resources in coastal and marine areas. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a cross-sectional schematic view of the FRP double-pipe reinforced ultra-high performance concrete composite bar provided in Embodiment 1 of the application;

[0031] Figure 2 is a three-dimensional schematic view of the FRP double-pipe reinforced ultra-high performance concrete composite bar provided in Embodiment 1 of the application;

[0032] Figure 3 is a cross-sectional schematic view of the FRP double-pipe reinforced ultra-high performance concrete composite bar provided in Embodiment 2 of the application;

[0033] Figure 4is a structural cross-sectional schematic diagram of a concrete beam provided by the embodiment 3 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace the FRP bars in the compression side of the FRP bar concrete beam;

[0034] Figure 5 is a three-dimensional structural schematic diagram of a concrete beam provided by the embodiment 3 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace the FRP bars in the compression side of the FRP bar concrete beam;

[0035] Figure 6 is a structural cross-sectional schematic diagram of a reinforced concrete column provided by the embodiment 4 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace all the steel bars in the reinforced concrete column;

[0036] Figure 7 is a structural cross-sectional schematic diagram of a reinforced concrete slab provided by the embodiment 5 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace all the steel bars in the reinforced concrete slab;

[0037] Figure 8 is a structural cross-sectional schematic diagram of a concrete-filled steel tube structure provided by the embodiment 6 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace all the concrete-filled steel tubes in the concrete-filled steel tube structure;

[0038] Figure 9 is a three-dimensional structural schematic diagram of a concrete-filled steel tube structure provided by the embodiment 6 of the present application, in which the FRP double pipe reinforced ultra-high performance concrete composite bars are used to replace all the concrete-filled steel tubes in the concrete-filled steel tube structure;

[0039] Figure 10 is a cross-sectional schematic diagram of the FRP double pipe reinforced ultra-high performance concrete composite bar provided by the embodiment 7 of the present application;

[0040] In all the drawings, the same reference signs are used to represent the same elements or structures, in which:

[0041] 1 is an outer FRP pipe; 2 is an inner FRP pipe; 3 is an FRP stiffening rib; 4 is ultra-high performance concrete; 5 is an FRP double pipe reinforced ultra-high performance concrete composite bar; 6 is a GFRP longitudinal bar; 7 is a GFRP stirrup; 8 is seawater-sea sand concrete; and 9 is a GFRP plate. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0043] The application provides a FRP double-pipe reinforced ultra-high performance concrete composite bar, which comprises an outer FRP pipe 1, an inner FRP pipe 2, FRP stiffening ribs 3 and ultra-high performance concrete 4. Figures 1 to 3 As shown in the figure, the component comprises an outer FRP pipe 1, an inner FRP pipe 2, FRP stiffening ribs 3 and ultra-high performance concrete 4. There is no gap between the outer FRP pipe 1 and the inner FRP pipe 2, the inner FRP pipe 2 is provided with the FRP stiffening ribs 3, and the longitudinal fiber FRP pipe is filled with the ultra-high performance concrete 4.

[0044] The ultra-high performance concrete is also called reactive powder concrete.

[0045] Specifically, the cross-sectional shape of the outer FRP pipe 1 can be circular, rectangular or the like, and the cross-sectional shape of the inner FRP pipe 2 is the same as that of the outer FRP pipe 1; the fiber winding direction of the outer FRP pipe 1 is circumferential (i.e. the included angle with the cross section of the composite bar is 0 degree), or is approximately circumferential (i.e. the included angle with the cross section of the composite bar is less than 30 degrees); and the fiber winding direction of the inner FRP pipe 2 is longitudinal (i.e. the included angle with the cross section of the composite bar is 90 degrees), or is approximately longitudinal (i.e. the included angle with the cross section of the composite bar is greater than 80 degrees). Preferably, the outer FRP pipe 1 and the inner FRP pipe 2 adopt the circular shape with the best constraint effect, the fiber winding direction of the outer FRP pipe 1 is circumferential, and the fiber winding direction of the inner FRP pipe 2 is longitudinal.

[0046] Specifically, the inner FRP pipe 2 is provided with at least two FRP stiffening ribs 3, the FRP stiffening ribs 3 are in the shape of rectangle, open-hole rectangle, rectangle with one side being wavy or the like; the inner FRP pipe 2 and the FRP stiffening ribs 3 can be respectively prefabricated by pultrusion and then bonded by high-performance structural adhesive, or can be integrally pultruded; the outer FRP pipe 1 can be prefabricated by winding and then bonded with the inner FRP pipe 2 by high-performance structural adhesive, or can be directly wound on the outer surface of the inner FRP pipe 2. Preferably, the FRP part of the composite bar is made by the method of integral prefabrication, the inner FRP pipe 2 and the FRP stiffening ribs 3 are integrally pultruded, the outer FRP pipe 1 is directly wound on the outer surface of the inner FRP pipe 2, and the shape of the FRP stiffening ribs 3 is rectangle with one side being wavy.

[0047] Specifically, the material of the outer FRP pipe 1, the inner FRP pipe 2 and the FRP stiffening ribs 3 is one or a combination of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP or aramid fiber reinforced composite material AFRP. Preferably, the glass fiber reinforced composite material GFRP with good ductility, low cost and wide application is selected.

[0048] Specifically, the ultra-high performance concrete 4 is poured in the interior FRP pipe 2; the axial compressive strength of the ultra-high performance concrete 4 is greater than 100 MPa, and the extension degree is greater than 750 mm; the ultra-high performance concrete 4 is composed of cement, silica fume, fly ash, quartz sand, high-efficiency water reducing agent and water, and the mass ratio is 1:0.3:0.14:1.48:0.05:0.3; the ultra-high performance concrete adds steel or basalt fiber and other types of fibers according to requirements. The cross-sectional area of the interior FRP pipe 2 should be greater than 10% of the cross-sectional area of the ultra-high performance concrete. A rubber hammer is used to gently knock the exterior FRP pipe 1 during pouring to compact the ultra-high performance concrete 4, and the pouring is completed under standard curing conditions for 28 days.

[0049] Further, the thickness of the exterior FRP pipe 1 and the interior FRP pipe 2, the size, shape and number of the FRP stiffening ribs 3, and the water-cement ratio, fiber type and dosage of the ultra-high performance concrete 4 can be appropriately adjusted according to engineering design requirements.

[0050] The combined rib of the application has strong tensile and compressive performance, good compressive ductility, flexible size, and is easy to prefabricate, and is widely applicable. The application method includes: replacing the steel in the traditional reinforced concrete structural members such as beams, slabs and columns, replacing the FRP rib in the FRP rib structural member, and replacing the profiled steel and steel pipe concrete in the steel-concrete structure as a member. Based on the new FRP structure of the application, the problem of steel corrosion in traditional steel and concrete structures is completely solved, and the problems of poor ductility and low seismic performance of traditional FRP rib concrete structures are overcome. It is very suitable for coastal and marine infrastructure, and can use abundant sea sand and seawater as raw materials to prepare concrete, saving freshwater and sand resources, and having good economic and environmental benefits. At the same time, the new structure according to the application does not contain steel, does not interfere with electromagnetic equipment, and can be used for the construction of special facilities such as hospitals, high-precision laboratories, aerospace bases and military projects.

[0051] The following is a specific example:

[0052] Example 1

[0053] As Figures 1 to 2As shown, the dimensions of the FRP double-tube reinforced ultra-high performance concrete composite reinforcement 5 are as follows: the composite reinforcement is 1000mm long and circular in shape; the outer FRP tube 1 has an outer diameter of 35mm and a thickness of 1mm; the inner FRP tube 2 has an outer diameter of 33mm and a thickness of 2mm; it is equipped with two rectangular FRP stiffening ribs 3, with a cross-sectional length of 7mm and a width of 2mm; the ultra-high performance concrete 4 is composed of cement, silica fume, fly ash, quartz sand, high-efficiency water-reducing agent, and water, with a mass ratio of 1:0.3:0.14:1.48:0.05:0.3. The inner FRP tube 2 and FRP stiffening ribs 3 are integrally pultruded, and the outer FRP tube 1 is directly wound onto the outer surface of the inner FRP tube 2. After preparing the ultra-high performance concrete 4, slowly pour it into the inner FRP pipe 2. During the pouring process, use a rubber hammer to gently tap the outer FRP pipe 1 until it is compacted. After pouring, cure under standard curing conditions for 28 days to complete the fabrication of the FRP double-pipe reinforced ultra-high performance concrete composite reinforcement.

[0054] Example 2

[0055] like Figure 3 As shown, the dimensions of the FRP double-tube reinforced ultra-high performance concrete composite reinforcement 5 are as follows: the composite reinforcement is 1000mm long and rectangular in shape; the outer FRP tube 1 has an outer surface length of 100mm, a width of 100mm, and a thickness of 4mm; the inner FRP tube 2 has an outer surface length of 92mm, a width of 92mm, and a thickness of 6mm; it is equipped with four rectangular FRP stiffening ribs 3 with one side toothed, the maximum cross-section length being 20mm and the width being 6mm, and the minimum cross-section length being 10mm and the width being 6mm; the ultra-high performance concrete 4 is composed of cement, silica fume, fly ash, quartz sand, high-efficiency water-reducing agent, and water, with a mass ratio of 1:0.3:0.14:1.48:0.05:0.3. The inner FRP tube 2 and the FRP stiffening ribs 3 are integrally pultruded, and the outer FRP tube 1 is directly wound onto the outer surface of the inner FRP tube 2. After preparing the ultra-high performance concrete 4, slowly pour it into the inner FRP pipe 2. During the pouring process, use a rubber hammer to gently tap the outer FRP pipe 1 until it is compacted. After pouring, cure under standard curing conditions for 28 days to complete the fabrication of the FRP double-pipe reinforced ultra-high performance concrete composite reinforcement.

[0056] Example 3

[0057] like Figures 4 to 5As shown, two FRP double-tube reinforced ultra-high performance concrete composite bars replace the FRP bars on the compression side of the FRP-reinforced concrete beam, forming a new type of FRP composite beam. The parameters of the FRP double-tube reinforced ultra-high performance concrete composite bars 5 are the same as in the first embodiment, and they are prefabricated in advance. The dimensions of the new FRP composite beam are as follows: the beam cross-section is rectangular, 200mm wide and 400mm high; the beam length is 3000mm, the clear span is 2700mm, and the concrete cover thickness is 20mm; four GFRP longitudinal bars 6 with a diameter of 20mm are arranged on the tension side, and three FRP double-tube reinforced ultra-high performance concrete composite bars 5 are arranged on the compression side. The stirrups are rectangular GFRP stirrups 7 with a height of 360mm, a width of 160mm, and a spacing of 100mm, and the diameter of the GFRP bars in the stirrups is 12mm. After binding the FRP double-tube reinforced ultra-high performance concrete composite bars 5, GFRP longitudinal bars 6, and GFRP stirrups 7 according to the design requirements, the entire assembly is placed into the mold, with a 20mm protective layer reserved at the bottom and sides and fixed to prevent movement and displacement during the pouring process. Subsequently, C40 strength grade seawater and sea sand concrete 8 is prepared, with the same formula as C40 ordinary concrete, except that fresh water and sand are replaced with the same mass of seawater and sea sand. After pouring, it is cured at room temperature.

[0058] Example 4

[0059] like Figure 6 As shown, eight FRP (fiberglass reinforced plastic) double-tube reinforced ultra-high performance concrete composite bars replace all the steel bars in the reinforced concrete column to form a new type of FRP composite column. The parameters of the FRP double-tube reinforced ultra-high performance concrete composite bars 5 are the same as in the first embodiment, and they are prefabricated. The dimensions of the new FRP composite column are: a circular cross-section with a diameter of 300mm; a column length of 2000mm; and a concrete cover thickness of 20mm. Eight FRP double-tube reinforced ultra-high performance concrete composite bars 5 are evenly arranged along the circumference. The stirrups are circular GFRP stirrups 7 with a diameter of 260mm and a spacing of 150mm, and the GFRP bars of the stirrups have a diameter of 12mm. After the FRP double-tube reinforced ultra-high performance concrete composite bars 5 and GFRP (glass fiber reinforced composite material) stirrups 7 are tied according to the design requirements, the entire column is placed in a mold, with a 20mm protective layer reserved at the bottom and sides and fixed to prevent movement and displacement during the pouring process. Then, C40 strength grade seawater sand concrete 8 is prepared. Its formula is the same as that of C40 ordinary concrete. The fresh water and sand are replaced with the same mass of seawater and sand. After pouring, it is cured at room temperature.

[0060] Example 5

[0061] like Figure 7As shown, a new type of FRP composite slab is formed by replacing the FRP reinforcement on the compression side of the FRP-reinforced concrete slab with FRP double-tube reinforced ultra-high performance concrete composite bars. The parameters of the FRP double-tube reinforced ultra-high performance concrete composite bars 5 are the same as in Example 1, and they are prefabricated in advance. The dimensions of the new FRP composite slab are: rectangular cross-section, 100mm high, 500mm wide, and a clear span of 3000mm; the concrete cover thickness is 10mm; seven GFRP longitudinal bars 6 with a diameter of 20mm are evenly arranged on the tension side, and seven FRP double-tube reinforced ultra-high performance concrete composite bars 5 are evenly arranged on the compression side. After the FRP double-tube reinforced ultra-high performance concrete composite bars 5 and GFRP longitudinal bars 6 are tied according to the design requirements, the entire slab is placed in a mold, with a 15mm protective layer reserved at the bottom and sides and fixed to prevent movement and displacement during the pouring process. Subsequently, C40 strength grade seawater and sea sand concrete 8 is prepared, with the same formula as C40 ordinary concrete, except that fresh water and sand are replaced with the same mass of seawater and sea sand. After pouring, it is cured at room temperature.

[0062] Example 6

[0063] like Figure 8 and Figure 9 As shown, FRP double-tube reinforced ultra-high performance concrete composite bars replace all steel-concrete composite bars in steel-concrete composite structures, forming a novel FRP composite bar structure. The dimensions of the FRP double-tube reinforced ultra-high performance concrete composite bar 5 are as follows: the composite bar length is 2000mm, and the shape is circular; the outer FRP tube 1 has an outer diameter of 100mm and a thickness of 4mm; the inner FRP tube 2 has an outer diameter of 92mm and a thickness of 6mm; it is equipped with four rectangular FRP stiffening ribs 3, with a cross-sectional length of 20mm and a width of 6mm; the ultra-high performance concrete 4 is composed of cement, silica fume, fly ash, quartz sand, high-efficiency water-reducing agent, and water, in a mass ratio of 1:0.3:0.14:1.48:0.05:0.3. The inner FRP tube 2 and FRP stiffening ribs 3 are integrally pultruded, and the outer FRP tube 1 is directly wound onto the outer surface of the inner FRP tube 2. After preparing the ultra-high performance concrete 4, slowly pour it into the inner FRP pipe 2. During the pouring process, gently tap the outer FRP pipe 1 with a rubber mallet until it is compacted. After pouring, cure for 28 days under standard curing conditions to complete the fabrication of three FRP double-pipe reinforced ultra-high performance concrete composite bars 5. Temporarily fix the three FRP double-pipe reinforced ultra-high performance concrete composite bars 5 to the three vertices of an equilateral triangle with a side length of 400mm. Use GFRP plates 9 (300mm long, 60mm wide, and 15mm thick) and high-performance structural adhesive to bond the FRP double-pipe reinforced ultra-high performance concrete composite bars 5 in pairs. The vertical spacing of the GFRP plates 9 is 500mm. After bonding, cover with a rainproof cloth and cure for 7 days.

[0064] Example 7

[0065] likeFigure 10 As shown in the figure, the FRP double-tube reinforced ultra-high performance concrete composite bar 5 has a size of: the length of the composite bar is 1000 mm, and the shape is circular; the outer FRP tube 1 has an outer diameter of 35 mm and a thickness of 1 mm; the inner FRP tube 2 has an outer diameter of 33 mm and a thickness of 2 mm; four rectangular FRP stiffening ribs 3 are arranged, each having a cross-sectional length of 7 mm and a width of 2 mm; the ultra-high performance concrete 4 is configured by cement, silica fume, fly ash, quartz sand, high-efficiency water reducing agent and water, and the mass ratio is 1:0.3:0.14:1.48:0.05:0.3. The inner FRP tube 2 and the FRP stiffening ribs 3 are integrally pultruded, and the outer FRP tube 1 is directly wrapped on the outer surface of the inner FRP tube 2. After the ultra-high performance concrete 4 is configured, it is slowly poured into the inner FRP tube 2, and a rubber hammer is used to gently knock the outer FRP tube 1 to be dense during the pouring process. After the pouring is completed, the FRP double-tube reinforced ultra-high performance concrete composite bar is completed after being cured for 28 days under standard curing conditions.

[0066] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An FRP double tube reinforced ultra-high performance concrete composite bar, characterized by, The combined bar comprises an outer FRP pipe (1), an inner FRP pipe (2), an FRP stiffening rib (3) and ultra-high performance concrete (4); The outer FRP pipe (1) and the inner FRP pipe (2) are both hollow structures, the inner FRP pipe (2) is located on the inner wall of the outer FRP pipe (1), and there is no gap between the outer wall of the inner FRP pipe (2) and the inner wall of the outer FRP pipe (1), The inner wall of the inner FRP pipe (2) is provided with at least two FRP stiffening ribs (3), and the inner part of the inner FRP pipe (2) is filled with ultra-high performance concrete (4); The fiber winding direction of the outer FRP pipe (1) forms an angle of 0-30 degrees with the cross section of the combined bar, and the fiber winding direction of the inner FRP pipe (2) forms an angle of 80-90 degrees with the cross section of the combined bar; The ultra-high performance concrete (4) comprises cement, silica fume, fly ash, quartz sand, high efficiency water reducing agent and water, Alternatively, the ultra-high performance concrete (4) comprises cement, silica fume, fly ash, quartz sand, high efficiency water reducing agent, water and steel fiber, Alternatively, the ultra-high performance concrete (4) comprises cement, silica fume, fly ash, quartz sand, high efficiency water reducing agent, water and basalt fiber, Alternatively, the ultra-high performance concrete (4) comprises cement, silica fume, fly ash, quartz sand, high efficiency water reducing agent, water, expansion agent and shrinkage reducing agent.

2. The FRP double tube reinforced ultra-high performance concrete composite bar according to claim 1, wherein The cross-sectional area of the inner FRP pipe (2) is greater than 10% of the cross-sectional area of the ultra-high performance concrete (4) filled therein.

3. The FRP double tube reinforced ultra-high performance concrete composite bar according to claim 1 or 2, wherein The thickness of the outer FRP pipe (1) is greater than one fifth of the thickness of the inner FRP pipe (2).

4. The FRP double tube reinforced ultra-high performance concrete composite bar according to claim 1 or 2, wherein The shape of the inner FRP pipe (2) is the same as that of the outer FRP pipe (1), and the shape of the outer FRP pipe (1) is circular or rectangular.

5. The FRP double tube reinforced ultra-high performance concrete composite bar according to claim 1 or 2, wherein The shape of the FRP stiffening rib (3) is rectangular, open-hole rectangular or rectangular with one side being wavy.

6. The FRP double tube reinforced ultra-high performance concrete composite bar according to claim 1 or 2, wherein The material of the outer FRP pipe (1) is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP; The material of the inner FRP pipe (2) is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP; The material of the FRP stiffening rib (3) is at least one of carbon fiber reinforced composite material CFRP, glass fiber reinforced composite material GFRP and aramid fiber reinforced composite material AFRP.

7. The use of the FRP double-tube reinforced ultra-high performance concrete composite bar according to any one of claims 1 to 6, characterized in that, The combined bar replaces the steel bars in the reinforced concrete structure beams, plates and column members, the FRP bars in the FRP bar structure members and the shaped steel and concrete-filled steel tube in the steel-concrete structure to form a new FRP structure, which is applied to coastal infrastructure, infrastructure in marine environment or electromagnetic isolation structural members.

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