A prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node

Abstract

This invention discloses a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node, relating to the field of building engineering technology. The node includes a prefabricated PVC-FRP pipe reinforced concrete column, a prefabricated node assembly, and a prefabricated reinforced concrete beam. The prefabricated node assembly includes an outer sleeve, a stiffening ring plate, bolts, cast-in-place concrete in the node area, and a threaded sleeve. The outer sleeve is fitted onto the outside of the node area of ​​the prefabricated PVC-FRP pipe reinforced concrete column, and the stiffening ring plate is arranged along the outer periphery of the outer sleeve, forming an outer sleeve-ring plate connector. This invention achieves a reliable prefabricated connection between the PVC-FRP pipe reinforced concrete column and the reinforced concrete beam by forming a clear force transmission path through pre-embedded steel, bolts, stiffening ring plate, outer sleeve, core concrete of the node, and column longitudinal reinforcement. It solves the problems of difficult direct connection between the two types of components and unclear force transmission at the node, and features good seismic performance, replaceability, prefabrication, and fast construction speed.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, specifically to a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node. Background Technology

[0002] Traditional reinforced concrete structures offer advantages such as economy and reliability. However, as modern engineering structures evolve towards taller, larger spans and service in various complex environments, the inherent disadvantages of traditional reinforced concrete, such as heavy weight, low construction efficiency, and poor durability, make it difficult for their load-bearing capacity and durability to meet the demands of modern engineering structures. Therefore, a material with stronger load-bearing capacity and corrosion resistance is needed to replace traditional reinforced concrete structures.

[0003] PVC-FRP pipe reinforced concrete columns are a novel composite structure formed by impregnating FRP strips with epoxy resin, wrapping them around the surface of a PVC pipe, and finally pouring concrete into the PVC pipe. This novel composite structure constrains the concrete inside the pipe through the PVC and FRP strips, placing the concrete in a triaxial stress state, which greatly improves the load-bearing capacity and ductility of the component. Furthermore, this composite structure is easy to construct, requires no formwork removal, and offers good economic benefits.

[0004] Prefabricated structures offer advantages such as convenient construction, low maintenance costs, environmental friendliness, and energy conservation and emission reduction. PVC-FRP pipes, as a lightweight, high-strength, and corrosion-resistant material, have significant application potential in prefabricated structures. However, when PVC-FRP pipes are used in main load-bearing components, improper design of the connection between them and reinforced concrete beams can lead to unclear force transmission paths and compromised reliability. Furthermore, the large self-weight and complex on-site construction of traditional prefabricated joints also limit their application in engineering projects. Therefore, there is an urgent need to develop a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection joint that features a clear force transmission path, convenient construction, and excellent seismic energy dissipation capabilities. Summary of the Invention

[0005] The main objective of this invention is to provide a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node that is easy to construct, reliable in connection, flexible in layout, and has good load-bearing capacity, so as to overcome the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node includes a prefabricated PVC-FRP pipe reinforced concrete column, a prefabricated node assembly, and a prefabricated reinforced concrete beam. The prefabricated node assembly includes an outer sleeve, a stiffening ring plate, bolts, cast-in-place concrete in the node area, and a straight threaded sleeve. The outer sleeve is fitted outside the node area of ​​the precast PVC-FRP pipe reinforced concrete column, and the stiffening ring plate is arranged along the outer periphery of the outer sleeve to form an outer sleeve-ring plate connector. The bolts pass through the reserved bolt holes in the outer sleeve and the PVC-FRP pipe node area to connect the prefabricated node assembly with the precast PVC-FRP pipe reinforced concrete column as a whole. The bolts also pass through the reserved bolt holes in the stiffening ring plate and the bolt connection holes at the ends of the pre-embedded steel sections in the prefabricated reinforced concrete beam to form an assemblable bolted connection between the prefabricated node assembly and the prefabricated reinforced concrete beam. The cast-in-place concrete in the node area is poured at the intersection of the outer sleeve, stiffening ring plate, embedded steel and precast PVC-FRP pipe reinforced concrete column, and is used to connect the precast PVC-FRP pipe reinforced concrete column, the prefabricated node component and the prefabricated reinforced concrete beam to form a whole. The connection node forms a beam-column joint force transmission system through the embedded steel, bolts, stiffening ring plate, outer sleeve, cast-in-place concrete in the joint area, and column longitudinal reinforcement. This system allows the beam end bending moment, shear force, and axial force to be sequentially transferred to the precast PVC-FRP pipe reinforced concrete column via the embedded steel, bolts, stiffening ring plate, outer sleeve, and cast-in-place concrete in the joint area, thus achieving a reliable prefabricated connection between the precast PVC-FRP pipe reinforced concrete column and the precast reinforced concrete beam.

[0007] Furthermore, the precast PVC-FRP pipe reinforced concrete column includes column longitudinal bars, column stirrups, concrete inside the PVC pipe, FRP strips, and PVC pipe. The longitudinal bars of the upper and lower columns of the precast PVC-FRP pipe reinforced concrete column are connected by the straight threaded sleeve. The straight threaded sleeve is set within the cast-in-place concrete area of ​​the node area and is used to connect the longitudinal bars of the upper and lower columns to form a whole.

[0008] Furthermore, the column longitudinal reinforcement is evenly arranged within the concrete section of the PVC pipe, and is equidistant along the circumference. The column stirrups are positioned at least 20mm from the inner wall of the PVC pipe to ensure that the reinforcement is fully encased in concrete.

[0009] Furthermore, the column stirrups in the precast PVC-FRP pipe concrete column are densified near the joint area. The stirrup densification area uses closed circular stirrups or continuous spiral stirrups, which together with the FRP strip, outer sleeve and cast-in-place concrete in the joint area form a composite constraint system.

[0010] Furthermore, the FRP strip is made of any one of AFRP, BFRP, CFRP, GFRP or PFRP, and the FRP strip is reinforced near the node area; The number of layers of the FRP strip is determined by the following formula: (1) In the formula, The number of FRP stripe layers in the node region. The number of FRP layers is determined by the shear bearing capacity of the core area of ​​the node, and is determined by equation (2); The number of FRP layers, determined by the lateral restraint pressure required for FRP-confined concrete, is determined by equation (3); To ensure the minimum number of layers required for construction, the node area must have at least 2 layers. (2) In the formula, This is the seismic adjustment coefficient for bearing capacity. The total shear capacity of the node area, It contributes to the shear resistance of the concrete in the core area of ​​the node. Contributes to the shear resistance of the steel reinforcement and stirrups within the core area of ​​the node. The center-to-center spacing of the FRP strips The reduction factor contributes to the shear strength of FRP strips. For single-layer FRP strip thickness, For FRP strip width, The elastic modulus of FRP strip, For effective design of strain in FRP strips, The effective height of the beam section. This is the distance from the resultant point of the longitudinal compression reinforcement of the beam to the near edge of the cross section. (3) In the formula, The outer diameter of the PVC-FRP pipe or the equivalent diameter of the confined concrete. Lateral restraint pressure required to achieve the target confined concrete strength or ductility.

[0011] Furthermore, the prefabricated reinforced concrete beam includes gaskets, beam stirrups, beam longitudinal reinforcement, embedded steel sections, and concrete. The embedded steel sections are pre-embedded in the beam end connection area during the prefabrication of the prefabricated reinforced concrete beam. Bolt connection holes are provided at the ends of the embedded steel sections, and they are connected to the stiffening ring plate through the bolts and high-strength steel gaskets.

[0012] Furthermore, the strength grade of the gasket and the embedded steel section is not lower than the strength grade of the longitudinal reinforcement of the beam. The size of the embedded steel section is determined by calculation, and the size of the gasket is adjusted according to the size of its embedded steel section. The specific calculation formula is as follows: (4) In the formula, and These are the design bending moments about the x-axis and y-axis, respectively. and These are the net section moduli with respect to the x-axis and y-axis, respectively. When calculating, weakening components such as bolt holes on the section must be deducted. and These are the cross-sectional plastic development coefficients with respect to the x-axis and y-axis, respectively.

[0013] Furthermore, the embedded steel section adopts a uniform cross-section steel section or a dog-bone weakened steel section. When a dog-bone weakened steel section is used, a flange weakening section is set near the node connection area and away from the stiffening ring plate and bolt connection range. By reducing the plastic modulus of the section at the weakening section, the bending bearing capacity of the weakening section is lower than that of the beam-column connection interface and the core area of ​​the node. This is used to make the plastic hinge appear in the weakening section, realize the outward movement of the plastic hinge and protect the core area of ​​the node. The distance from the center of the dog-bone weakened section to the beam-column connection interface is determined by the following formula: (5) In the formula, This is the distance from the expected location of the plastic hinge to the beam-column connection interface. This is the distance from the beam-column connection interface to the starting position of the dog-bone weakened section. The length of the dog-bone weakened segment; The geometric dimensions of the dog-bone weakened segment can be determined by the following formula: (6) In the formula, This is the original width of the pre-embedded steel flange. The height of the embedded steel section, This represents the maximum weakening depth of a single wing edge; The minimum width of the dogbone-type weakened rear wing edge is: (7) In the formula, To reduce the remaining flange width at the minimum cross-section of the reduced section; The weakened section of the dog-bone structure should use a rounded transition, and the radius of the rounded transition should be determined by the following formula: (8) In the formula, The radius of the dog-bone circular arc is reduced.

[0014] Furthermore, the outer sleeve, bolt, threaded sleeve, and gasket are all made of high-strength steel. The strength grade of the threaded sleeve is not lower than that of the longitudinal reinforcement of the beam, and the strength grade of the outer sleeve is one grade higher than that of the column stirrups. The strength grade of the cast-in-place concrete in the joint area is one grade higher than that of the concrete inside the PVC pipe and the concrete itself. The cast-in-place concrete in the joint area is steel slag concrete, recycled concrete, high-performance concrete, or grout.

[0015] Furthermore, the thickness of the straight threaded sleeve is not less than 1.2 times the thickness of the stiffening ring plate, and the outward extension height of the outer sleeve is not less than 3 times its thickness.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The connection node of the present invention is convenient and easy to construct. The PVC-FRP pipe can both bear the restraint function and bear the permanent column formwork. There is no need for later formwork removal, which simplifies the construction steps. (2) The connection node of the present invention has a clear force transmission path. The PVC-FRP pipe only has a restraining effect on the concrete inside the pipe, which improves the strength and ductility of the concrete. The outer sleeve and bolts of the node area can strengthen and enhance the node area, while improving the deformation coordination ability between the cast-in-place concrete and the PVC pipe in the node area. The pre-embedded steel and bolts in the beam transmit the bending moment, shear force and axial force to the core node area. (3) All the prefabricated components of the present invention can be prefabricated in each factory in advance, realizing full factory production and full assembly, which can ensure the quality of each component and improve the assembly accuracy, making it suitable for market promotion. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0018] Figure 2 This is a cross-sectional schematic diagram of the present invention.

[0019] Figure 3 This is a detailed view of the node region of the present invention.

[0020] Explanation of reference numerals in the attached drawings: 1-Precast PVC-FRP pipe reinforced concrete column; 2-Assembled node assembly; 3-Assembled reinforced concrete beam; 11-Column longitudinal reinforcement; 12-Column stirrups; 13-Concrete inside the PVC pipe; 14-FRP strip; 15-PVC pipe; 21-Outer sleeve; 22-Stiffening ring plate; 23-Bolt; 24-Cast-in-place concrete in the node area; 25-Straight threaded sleeve; 31-Gasket; 32-Beam stirrups; 33-Beam longitudinal reinforcement; 34-Embedded steel; 35-Concrete. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Combination Figures 1 to 3 This embodiment provides a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node, including a prefabricated PVC-FRP pipe reinforced concrete column 1, a prefabricated node component 2, and a prefabricated reinforced concrete beam 3.

[0023] In this embodiment, the prefabricated node assembly 2 includes an outer sleeve 21, a stiffening ring plate 22, bolts 23, cast-in-place concrete 24 in the node area, and a straight threaded sleeve 25. The outer sleeve 21 is sleeved on the outside of the node area of ​​the precast PVC-FRP pipe reinforced concrete column 1, and the stiffening ring plate 22 is arranged along the outer periphery of the outer sleeve 21 to form an outer sleeve-ring plate connector. Among them, bolt 23 passes through the reserved bolt hole in the outer sleeve 21 and the PVC-FRP pipe node area, and is used to connect the prefabricated node component 2 and the prefabricated PVC-FRP pipe reinforced concrete column 1 into a whole. Bolt 23 passes through the reserved bolt hole in the stiffening ring plate 22 and the bolt connection hole at the end of the pre-embedded steel 34 in the prefabricated reinforced concrete beam 3, and is used to form an assemblable bolt connection between the prefabricated node component 2 and the prefabricated reinforced concrete beam 3. The cast-in-place concrete 24 in the node area is poured at the intersection of the outer sleeve 21, the stiffening ring plate 22, the embedded steel 34 and the precast PVC-FRP pipe reinforced concrete column 1, and is used to connect the precast PVC-FRP pipe reinforced concrete column 1, the prefabricated node component 2 and the prefabricated reinforced concrete beam 3 to form a whole. The connection node forms a beam-column joint force transmission system through the pre-embedded steel section 34, bolts 23, stiffening ring plate 22, outer sleeve 21, cast-in-place concrete in the joint area 24, and column longitudinal reinforcement 11. This system allows the beam end bending moment, shear force, and axial force to be transmitted sequentially to the precast PVC-FRP pipe reinforced concrete column 1 via the pre-embedded steel section 34, bolts 23, stiffening ring plate 22, outer sleeve 21, and cast-in-place concrete in the joint area 24, thus achieving a reliable prefabricated connection between the precast PVC-FRP pipe reinforced concrete column 1 and the precast reinforced concrete beam 3.

[0024] Using the above scheme, the connection node is composed of an outer sleeve 21, a stiffening ring plate 22, bolts 23, cast-in-place concrete in the node area 24, and a straight threaded sleeve 25, forming a prefabricated node component 2. The stiffening ring plate 22 improves the ductility and load-bearing capacity of the node area. Furthermore, the use of the stiffening ring plate 22 for beam connection greatly expands the applicability of the prefabricated node component 2, allowing it to connect with different beams and energy dissipation and vibration reduction systems. This makes the prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node simple in form, convenient in construction, flexible in layout, and strong in load-bearing capacity. It facilitates the connection of metal and non-metal materials, especially PVC-FRP-reinforced concrete structures. Moreover, it enables full factory production and prefabrication of beams, columns, and their node components, ensuring the quality of each component and improving assembly accuracy, making it suitable for market promotion.

[0025] The stiffening ring plate 22 is made of Q355B low-alloy high-strength structural steel plate, and the quality of the steel should comply with the provisions of the current national standard "Low-alloy High-strength Structural Steel" GB / T1591-2018. The stiffening ring plate 22 is welded to the outer sleeve 21 to form an integral sleeve-ring plate connector, and is connected to the pre-embedded steel 34 in the precast reinforced concrete beam by bolts 23. The use of Q355B steel ensures that the stiffening ring plate has high yield strength, good weldability and good plastic deformation capacity, enabling it to reliably transmit beam end bending moment, shear force and axial force, and improve the local stiffness and seismic bearing capacity of the joint area.

[0026] In a further embodiment, the thickness of the straight threaded sleeve 25 is not less than 1.2 times the thickness of the stiffening ring plate 22, and the outward extension height of the outer sleeve 21 is not less than 3 times its thickness.

[0027] In this embodiment, the precast PVC-FRP pipe reinforced concrete column 1 includes column longitudinal bars 11, column stirrups 12, concrete inside the PVC pipe 13, FRP strips 14, and PVC pipe 15. The column longitudinal bars 11 of the upper and lower columns of the precast PVC-FRP pipe reinforced concrete column 1 are connected by a straight threaded sleeve 25. The straight threaded sleeve 25 is set within the cast-in-place concrete 24 in the node area and is used to connect the column longitudinal bars 11 of the upper column and the column longitudinal bars 11 of the lower column to form a whole.

[0028] In a further embodiment, the column longitudinal reinforcement 11 is evenly arranged in the cross section of the concrete 13 inside the PVC pipe, and is equidistant along the circumference. The position of the column stirrup 12 is at least 20mm away from the inner wall of the PVC pipe 15, so as to ensure that the reinforcement is fully wrapped by the concrete.

[0029] In a further embodiment, the column stirrups 12 within the precast PVC-FRP pipe concrete column 1 are densified near the joint area. The densified stirrup area uses closed circular stirrups or continuous spiral stirrups, forming a composite constraint system together with the FRP strips 14, the outer sleeve 21, and the cast-in-place concrete 24 in the joint area. Specifically, when arranging the stirrups in the joint area, the densification method used in ordinary reinforced concrete frame joints is not directly adopted. Instead, local densification is implemented by combining the arrangement characteristics of the PVC-FRP pipe, high-strength steel outer sleeve, stiffening ring plate, and high-strength bolts. Since the high-strength bolt holes weaken the local continuity of the PVC-FRP pipe and the concrete in the joint area, the column stirrups should be arranged away from the bolt hole locations, and additional closed stirrups should be provided on both sides above and below the bolt holes. Because the high-strength steel straight thread sleeves are concentrated within the cast-in-place concrete area of ​​the joint area, additional stirrups or tie bars should be added to both ends of the sleeves to improve the local constraint capacity of the concrete in the longitudinal reinforcement connection area. The stirrups, FRP strips, and high-strength steel outer sleeve in the joint area together form a composite restraint system, thereby improving the shear bearing capacity, deformation coordination ability, and seismic performance of the joint core area.

[0030] In a further embodiment, the FRP strip 14 is any one of AFRP, BFRP, CFRP, GFRP or PFRP, and the FRP strip 14 is reinforced near the node area; The number of layers of the FRP strip 14 is determined by the following formula: (1) In the formula, The number of FRP stripe layers in the node region. The number of FRP layers is determined by the shear bearing capacity of the core area of ​​the node, and is determined by equation (2); The number of FRP layers, determined by the lateral restraint pressure required for FRP-confined concrete, is determined by equation (3); To ensure the minimum number of layers required for construction, the node area must have at least 2 layers. (2) In the formula, This is the seismic adjustment coefficient for bearing capacity. The total shear capacity of the node area, It contributes to the shear resistance of the concrete in the core area of ​​the node. Contributes to the shear resistance of the steel reinforcement and stirrups within the core area of ​​the node. The center-to-center spacing of the FRP strips The reduction factor contributes to the shear strength of FRP strips. For single-layer FRP strip thickness, For FRP strip width, The elastic modulus of FRP strip, For effective design of strain in FRP strips, The effective height of the beam section. This is the distance from the resultant point of the longitudinal compression reinforcement of the beam to the near edge of the cross section. (3) In the formula, The outer diameter of the PVC-FRP pipe or the equivalent diameter of the confined concrete. Lateral restraint pressure required to achieve the target confined concrete strength or ductility.

[0031] In this embodiment, the prefabricated reinforced concrete beam 3 includes a gasket 31, beam stirrups 32, beam longitudinal reinforcement 33, embedded steel 34, and concrete 35. The embedded steel 34 is pre-embedded in the beam end connection area during the prefabrication of the prefabricated reinforced concrete beam 3. The end of the embedded steel 34 is provided with bolt connection holes and is connected to the stiffening ring plate 22 through bolts 23 and high-strength steel gaskets 31.

[0032] In a further embodiment, the strength grade of the gasket 31 and the embedded steel 34 is not lower than the strength grade of the longitudinal reinforcement 33 of the beam. The size of the embedded steel 34 is determined by calculation, and the size of the gasket 31 is adjusted according to the size of its embedded steel 34. The specific calculation formula is as follows: (4) In the formula, and These are the design bending moments about the x-axis and y-axis, respectively. and These are the net section moduli with respect to the x-axis and y-axis, respectively. When calculating, weakening components such as bolt holes on the section must be deducted. and These are the cross-sectional plastic development coefficients with respect to the x-axis and y-axis, respectively.

[0033] In a further embodiment, the embedded steel 34 is a steel with a uniform cross-section or a dog-bone weakened steel. When a dog-bone weakened steel is used, a flange weakening section is set near the node connection area and away from the stiffening ring plate 22 and the bolt 23 connection range. By reducing the plastic modulus of the section at the weakening section, the bending bearing capacity of the weakening section is lower than that of the beam-column connection interface and the node core area. This is used to make the plastic hinge appear in the weakening section, realize the outward movement of the plastic hinge and protect the node core area. The distance from the center of the dog-bone weakened section to the beam-column connection interface is determined by the following formula: (5) In the formula, This is the distance from the expected location of the plastic hinge to the beam-column connection interface. This is the distance from the beam-column connection interface to the starting position of the dog-bone weakened section. The length of the dog-bone weakened segment; The geometric dimensions of the dog-bone weakened segment can be determined by the following formula: (6) In the formula, This is the original width of the pre-embedded steel flange. The height of the embedded steel section, This represents the maximum weakening depth of a single wing edge; The minimum width of the dogbone-type weakened rear wing edge is: (7) In the formula, To reduce the remaining flange width at the minimum cross-section of the reduced section; The weakened section of the dog-bone structure should use a rounded transition, and the radius of the rounded transition should be determined by the following formula: (8) In the formula, The radius of the dog-bone circular arc is reduced.

[0034] In this design, the embedded steel section 34 in the prefabricated reinforced concrete beam can be a dog-bone weakened steel section, with weakening methods including circular arc weakening, straight line weakening, or a combination of circular arc and straight line weakening. By weakening the local width of the upper and lower flanges of the embedded steel section, the plastic modulus of the section at the weakened section is made smaller than that at the beam-column connection interface. This allows the plastic deformation at the beam end under seismic loading to preferentially concentrate within the dog-bone weakened section, preventing plastic hinges from directly appearing in the stiffening ring plate, high-strength bolt connection area, and joint core area. This allows the plastic hinge at the beam end to be moved from the beam-column connection interface to the interior of the prefabricated reinforced concrete beam, reducing damage to the joint core area and improving the joint's seismic energy dissipation capacity and post-earthquake repairability.

[0035] Weakening depth The bending capacity of the weakened section should be determined based on its target bending capacity, and should meet the requirements that the bending capacity of the weakened section is less than the bending capacity of the connection interface and the bending capacity of the node connection area is greater than the bending capacity of the weakened section.

[0036] In this embodiment, the outer sleeve 21, bolt 23, threaded sleeve 25, and washer 31 are all made of high-strength steel. The strength grade of the threaded sleeve 25 is not lower than the strength grade of the longitudinal reinforcement 33 of the beam. The strength grade of the outer sleeve 21 is one grade higher than the strength grade of the column stirrup 12. The strength grade of the cast-in-place concrete 24 in the joint area is one grade higher than the strength grade of the concrete 13 and concrete 35 inside the PVC pipe. The cast-in-place concrete 24 in the joint area is steel slag concrete, recycled concrete, high-performance concrete, or grout.

[0037] The high-strength steel outer sleeve, stiffening ring plate 22, and embedded steel 34 used in the prefabricated node component 2 can be made of different steel materials, and the yield strength of the steel in the node area is not lower than the yield strength of the embedded steel 34. The contact surface of the cast-in-place concrete 24 in the node area is roughened.

[0038] One specific application of this embodiment is as follows: The width and spacing lines of the FRP strip 14 are drawn on the surface of the PVC pipe 15 using a marker to determine the bonding position of the FRP strip 14. Before bonding, the FRP roll is cut to the predetermined length and width, with an overlap length of 100mm for the FRP strip 14.

[0039] Subsequently, the curing agent and impregnating adhesive are mixed evenly at a ratio of 1:3 (by weight). The impregnating adhesive is then evenly applied to the surface of the FRP strip 14 using a brush. The FRP strip 14 is then adhered to the surface of the PVC pipe 15 according to the marked positions, and smoothed circumferentially with a scraper to ensure a tight bond between the FRP strip 14 and the PVC pipe 15, preventing air bubbles. After adhesion, a layer of epoxy resin is evenly applied to the surface of the outer FRP strip 14 for protection. The completed PVC-FRP pipe is then cured at room temperature until the surface adhesive is completely hardened, forming the PVC-FRP pipe, which is then disconnected at the joint area. The tied reinforcing cage is then placed inside the PVC-FRP pipe, followed by the pouring of the PVC-FRP pipe. The concrete used for pouring can be steel slag concrete, recycled concrete, or various types of concrete with micro-expansion properties.

[0040] The width, spacing, and number of layers of the FRP strips 14 can be determined based on the design load-bearing capacity of the nodes. Shear bolt holes are drilled along the height and circumferential directions of the PVC-FRP pipe, ensuring a center-to-center distance of at least three times the bolt diameter to prevent tearing of the sheet metal between holes and to guarantee sufficient operating space for the wrench.

[0041] A specific application of this embodiment is as follows: High-strength steel outer sleeve 21, stiffening ring plate 22, high-strength steel bolts 23, high-strength steel straight thread sleeve 25, high-strength steel gasket 31, and embedded steel 34 are fabricated in a steel structure processing plant, and the longitudinal reinforcement 11 of the column is threaded. Stiffening ring plate 22 is welded around the high-strength steel outer sleeve 21 to form a connector, and bolt holes are drilled in corresponding locations according to the design load-bearing capacity and specifications. The longitudinal reinforcement 11 and column stirrups 12 of the column are tied to form a reinforcing cage, then PVC-FRP pipes are installed, and concrete is poured to form a precast PVC-FRP pipe reinforced concrete column 1. Then, beam stirrups 32 and beam longitudinal reinforcement 31 are tied, and the position of the embedded steel 34 is determined. A template is fabricated, and a precast reinforced concrete beam 3 is poured. The precast PVC-FRP pipe reinforced concrete column 1 and precast reinforced concrete beam 3 are then cured at room temperature.

[0042] The specific application of this embodiment is as follows: the prefabricated precast PVC-FRP pipe reinforced concrete column 1 and the prefabricated node component 2 are fixedly connected by high-strength steel bolts. Then, the longitudinal reinforcement 11 of the upper and lower columns of the precast PVC-FRP pipe reinforced concrete column 1 is connected by straight threaded sleeves 25. Then, the prefabricated node component 2 connected to the precast PVC-FRP pipe reinforced concrete column 1 is connected to the embedded steel 34 by high-strength steel bolts, so as to realize the connection between the prefabricated node component 2 and the prefabricated reinforced concrete beam 3. A template is made in the node area, a protective layer of 15mm is reserved, and then concrete is poured. Finally, room temperature curing is carried out to form a prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node.

[0043] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node, characterized in that, It includes a precast PVC-FRP pipe reinforced concrete column (1), an assembled node assembly (2) and an assembled reinforced concrete beam (3). The assembled node assembly (2) includes an outer sleeve (21), a stiffening ring plate (22), bolts (23), cast-in-place concrete in the node area (24) and a straight threaded sleeve (25). The outer sleeve (21) is fitted on the outside of the node area of ​​the precast PVC-FRP pipe reinforced concrete column (1), and the stiffening ring plate (22) is arranged along the outer periphery of the outer sleeve (21) to form an outer sleeve-ring plate connector. The bolt (23) passes through the reserved bolt hole in the outer sleeve (21) and the PVC-FRP pipe node area, and is used to connect the prefabricated node assembly (2) and the prefabricated PVC-FRP pipe reinforced concrete column (1) into a whole. The bolt (23) passes through the reserved bolt hole in the stiffening ring plate (22) and the bolt connection hole at the end of the pre-embedded steel section (34) in the prefabricated reinforced concrete beam (3), and is used to form an assemblable bolt connection between the prefabricated node assembly (2) and the prefabricated reinforced concrete beam (3). The cast-in-place concrete (24) in the node area is poured at the intersection of the outer sleeve (21), stiffening ring plate (22), embedded steel (34) and precast PVC-FRP pipe reinforced concrete column (1), and is used to connect the precast PVC-FRP pipe reinforced concrete column (1), the prefabricated node component (2) and the prefabricated reinforced concrete beam (3) to form a whole. The connection node forms a beam-column joint force transmission system through the pre-embedded steel (34), bolts (23), stiffening ring plate (22), outer sleeve (21), cast-in-place concrete in the joint area (24), and column longitudinal reinforcement (11). The bending moment, shear force, and axial force at the beam end are transmitted sequentially to the precast PVC-FRP pipe reinforced concrete column (1) through the pre-embedded steel (34), bolts (23), stiffening ring plate (22), outer sleeve (21), and cast-in-place concrete in the joint area (24), thereby realizing a reliable prefabricated connection between the precast PVC-FRP pipe reinforced concrete column (1) and the prefabricated reinforced concrete beam (3).

2. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 1, characterized in that, The precast PVC-FRP pipe reinforced concrete column (1) includes column longitudinal bars (11), column stirrups (12), concrete inside the PVC pipe (13), FRP strips (14) and PVC pipe (15). The column longitudinal bars (11) of the upper and lower columns of the precast PVC-FRP pipe reinforced concrete column (1) are connected by the straight threaded sleeve (25). The straight threaded sleeve (25) is set within the cast-in-place concrete (24) of the node area and is used to connect the column longitudinal bars (11) of the upper column and the column longitudinal bars (11) of the lower column to form a whole.

3. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 2, characterized in that, The column longitudinal reinforcement (11) is evenly arranged in the cross section of the concrete (13) inside the PVC pipe, and is equidistant along the circumference. The column stirrup (12) is located at least 20mm away from the inner wall of the PVC pipe (15) to ensure that the reinforcement is fully wrapped by the concrete.

4. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 2, characterized in that, The column stirrups (12) in the precast PVC-FRP pipe concrete column (1) are densified near the node area. The stirrup densification area adopts closed circular stirrups or continuous spiral stirrups, and together with the FRP strip (14), the outer sleeve (21) and the cast-in-place concrete (24) in the node area, they form a composite constraint system.

5. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 2, characterized in that, The FRP strip (14) is made of any one of AFRP, BFRP, CFRP, GFRP or PFRP, and the FRP strip (14) is reinforced near the node area; The number of layers of the FRP strip (14) is determined by the following formula: (1) In the formula, The number of FRP stripe layers in the node region. The number of FRP layers is determined by the shear bearing capacity of the core area of ​​the node, and is determined by equation (2); The number of FRP layers, determined by the lateral restraint pressure required for FRP-confined concrete, is determined by equation (3); To ensure the minimum number of layers required for construction, the node area must have at least 2 layers. (2) In the formula, This is the seismic adjustment coefficient for bearing capacity. The total shear capacity of the node area, It contributes to the shear resistance of the concrete in the core area of ​​the node. Contributes to the shear resistance of the steel reinforcement and stirrups within the core area of ​​the node. The center-to-center spacing of the FRP strips The reduction factor contributes to the shear strength of FRP strips. For single-layer FRP strip thickness, For FRP strip width, The elastic modulus of FRP strip, For effective design of strain in FRP strips, The effective height of the beam section. This is the distance from the resultant point of the longitudinal compression reinforcement of the beam to the near edge of the cross section. (3) In the formula, The outer diameter of the PVC-FRP pipe or the equivalent diameter of the confined concrete. Lateral restraint pressure required to achieve the target confined concrete strength or ductility.

6. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 2, characterized in that, The prefabricated reinforced concrete beam (3) includes a gasket (31), beam stirrups (32), beam longitudinal reinforcement (33), embedded steel (34) and concrete (35). The embedded steel (34) is pre-embedded in the beam end connection area during the prefabrication of the prefabricated reinforced concrete beam (3). The end of the embedded steel (34) is provided with bolt connection holes and is connected to the stiffening ring plate (22) through the bolt (23) and the high-strength steel gasket (31).

7. A prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 6, characterized in that, The strength grade of the gasket (31) and the embedded steel (34) is not lower than the strength grade of the longitudinal reinforcement (33) of the beam. The size of the embedded steel (34) is determined by calculation, and the size of the gasket (31) is adjusted according to the size of its embedded steel (34). The specific calculation formula is as follows: （4） In the formula, and These are the design bending moments about the x-axis and y-axis, respectively. and These are the net section moduli with respect to the x-axis and y-axis, respectively. When calculating these, weakening components such as bolt holes on the cross-section must be deducted. and These are the cross-sectional plastic development coefficients with respect to the x-axis and y-axis, respectively.

8. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 6, characterized in that, The embedded steel (34) adopts a uniform cross-section steel or a dog-bone weakened steel. When a dog-bone weakened steel is used, a flange weakening section is set at a position close to the node connection area and avoiding the connection range of the stiffening ring plate (22) and bolt (23). By reducing the plastic resistance moment of the section at the weakening section, the bending bearing capacity of the weakening section is lower than that of the beam-column connection interface and the core area of ​​the node, so that the plastic hinge appears in the weakening section, realizing the outward movement of the plastic hinge and protecting the core area of ​​the node. The distance from the center of the dog-bone weakening section to the beam-column connection interface is determined by the following formula: （5） In the formula, This is the distance from the expected location of the plastic hinge to the beam-column connection interface. This is the distance from the beam-column connection interface to the starting position of the dog-bone weakened section. The length of the dog-bone weakened segment; The geometric dimensions of the dog-bone weakened segment can be determined by the following formula: （6） In the formula, This is the original width of the pre-embedded steel flange. The height of the embedded steel section, This represents the maximum weakening depth of a single wing edge; The minimum width of the dogbone-type weakened rear wing edge is: （7） In the formula, To reduce the remaining flange width at the minimum cross-section of the weakened section; The weakened section of the dog-bone structure should use a rounded transition, and the radius of the rounded transition should be determined by the following formula: （8） In the formula, The radius of the dog-bone circular arc is reduced.

9. A prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 6, characterized in that, The outer sleeve (21), bolt (23), straight thread sleeve (25) and gasket (31) are all made of high-strength steel. The strength grade of the straight thread sleeve (25) is not lower than the strength grade of the longitudinal reinforcement (33) of the beam. The strength grade of the outer sleeve (21) is one grade higher than the strength grade of the column stirrup (12). The strength grade of the cast-in-place concrete (24) in the node area is one grade higher than the strength grade of the concrete (13) in the PVC pipe and the concrete (35). The cast-in-place concrete (24) in the node area is steel slag concrete, recycled concrete, high-performance concrete or grout.

10. The prefabricated PVC-FRP pipe reinforced concrete column-reinforced concrete beam connection node as described in claim 1, characterized in that, The thickness of the straight threaded sleeve (25) is not less than 1.2 times the thickness of the stiffening ring plate (22), and the outward extension height of the outer sleeve (21) is not less than 3 times its thickness.

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