A spiral annular prestressed and uhpc plate shell collaborative constrained concrete column ductility reinforcement structure and a reinforcement method thereof

Abstract

This invention discloses a ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC (Ultra-High-Pressure Polymer) panels, belonging to the field of building structure reinforcement technology. It includes a concrete column, with multiple arc-shaped prefabricated UHPC panels spliced ​​and covering the outside of the column. Prestressed ducts within each panel are sequentially connected to form a continuously extending helical annular path pipe along the column's height. Prestressed steel strands are threaded through and tensioned within this path. Interface spacing positioning supports control the interface pouring space between the panels and the concrete column. U-shaped interface limiting-slip short bars extend into the interface concrete to form a synergistic force transmission structure. A local debonding and rotation release zone and U-shaped interface limiting-slip short bars with a preset yield section are set in the potential plastic hinge zone to form a synergistic mechanism of continuous circumferential constraint, limited longitudinal release, and controlled energy dissipation at the interface. This invention can improve the load-bearing capacity and seismic ductility of concrete columns, and has the advantages of high assembly efficiency and good durability.

Description

Technical Field

[0001] This invention belongs to the field of building structure reinforcement technology, specifically relating to a ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestress and UHPC plate shell, and its reinforcement method. Background Technology

[0002] Structural columns not only directly affect the overall load-bearing capacity of a building, but also play a decisive role in its lateral stiffness, seismic performance, and overall stability. Therefore, the load-bearing capacity and ductility of column members have always been important research topics in seismic design and reinforcement of existing buildings. As buildings age, concrete columns are prone to problems such as concrete cracking, protective layer spalling, decreased load-bearing capacity, and insufficient ductility under long-term loads, environmental erosion, material aging, freeze-thaw cycles, steel corrosion, and changes in usage. Meanwhile, some existing buildings, due to their earlier construction, have relatively low seismic design standards, making it difficult to meet the requirements of current seismic codes. When buildings undergo functional modifications, increased loads, or seismic performance improvements, structural reinforcement of existing concrete columns is usually necessary to enhance their load-bearing capacity, seismic performance, and ductility, thereby extending the safe service life of the building structure.

[0003] Currently, common methods for reinforcing concrete columns in engineering and architectural design include increasing the cross-section, external steel cladding, bonding steel plates, fiber-reinforced polymer (FRP) wrapping, and external concrete ferrules. While increasing the cross-section effectively improves the column's load-bearing capacity, it involves a large amount of wet work, a long construction period, and significantly increases the component's cross-sectional dimensions and structural weight. External steel cladding and bonded steel plate methods require high construction precision, the steel is susceptible to environmental corrosion, and subsequent maintenance costs are high. FRP wrapping offers advantages such as convenient construction and light weight, but the material has poor fire resistance and relies primarily on passive restraint, making it prone to interface peeling or localized failure under strong earthquakes. While ordinary concrete or high-performance concrete ferrules can improve external restraint, they typically require on-site formwork, resulting in low assembly efficiency, and the interoperability between the cladding and the existing column is significantly affected by the quality of the interface construction.

[0004] While conventional technologies can improve load-bearing capacity or restraint capacity to varying degrees, they still suffer from problems such as large amounts of wet construction work, difficulties in durability maintenance, insufficient active restraint, or inadequate deformation coordination in the plastic hinge zone. For cladding layers with high stiffness, if they form a completely continuous bond with the existing column in the plastic hinge zone, the longitudinal tensile strain generated by the bending and rotation of the column will be directly transmitted to the cladding layer, potentially leading to premature cracking at the ends of the cladding layer. If the interface connection is too weak, uncontrollable slippage and sudden peeling may occur. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ductile reinforcement structure and reinforcement method for concrete columns under the synergistic constraint of helical circumferential prestressing and UHPC plate shell. This improves the compressive deformation capacity of the core concrete and the seismic ductility of the existing concrete column, reduces on-site formwork, demolding and assembly operations, and improves construction efficiency and prefabrication level. Furthermore, based on the prefabricated UHPC plate shell and helical circumferential prestressing constraint, by setting interface spacing positioning feet, interface pouring space, local debonding rotation release zone and controllable yielding U-shaped interface limiting short bars, a synergistic working mechanism is formed in which the potential plastic hinge zone forms circumferential continuous constraint, longitudinal limited release and interface controlled energy dissipation.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution: On the one hand, the present invention provides a ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestress and UHPC plate shell, including a concrete column; The concrete column is fitted with multiple pieces of arc-shaped prefabricated UHPC panels that are sequentially spliced ​​together to form an arc-shaped prefabricated UHPC shell that encloses the concrete column. The arc-shaped precast UHPC slab shell is provided with continuous or segmented prestressed ducts, and the prestressed ducts in multiple arc-shaped precast UHPC slab shells are connected sequentially along the circumference of the concrete column to form a spiral ring path pipeline along the height of the column. Prestressed steel strands are threaded through the spiral ring path pipeline and anchored and tensioned at both ends of the pipeline. At each of the two ends of the inner surface of the arc-shaped precast UHPC panel, an interface spacing positioning support is provided radially. The interface spacing positioning support is extended radially and abuts against the surface of the concrete column to control the formation of multiple circumferentially distributed interface casting spaces between the panel and the column. Furthermore, the inner surface of the arc-shaped precast UHPC panel is provided with a plurality of pre-embedded U-shaped interface slip limiting short ribs arranged in an array. The U-shaped ends of the interface slip limiting short ribs extend into the interface casting space in a radial direction and fill the interface casting space with casting interface concrete.

[0007] Furthermore, the arc-shaped precast UHPC panel shell is configured as four pieces, each of which is a quarter-circle arc structure; the radial thickness of each arc-shaped precast UHPC panel shell is consistent, the radius of curvature matches the outer circular curvature of the concrete column, the vertical height of the arc-shaped precast UHPC panel shell is uniform, and it is evenly distributed in segments along the vertical of the concrete column.

[0008] Furthermore, each of the two ends of the arc-shaped precast UHPC panel is provided with a reserved slot that is connected to the corresponding prestressing channel, and the reserved slots of each two adjacent arc-shaped precast UHPC panels are matched at the relative vertical joint of the two panels; the reserved slot is a concave rectangular groove structure, the size of the reserved slot is not less than the diameter of the prestressing channel, and the opening of the reserved slot faces the outside of the arc-shaped precast UHPC panel.

[0009] Furthermore, a local debonding and rotation release zone is set between the arc-shaped precast UHPC panel shell and the interface concrete within the height range corresponding to the potential plastic hinge zone of the concrete column, so that the arc-shaped precast UHPC panel shell and the interface concrete do not form a continuous direct bond within the range of the local debonding and rotation release zone, and maintain radial compression contact under the action of circumferential prestress. Furthermore, the U-shaped interface limiting ribs located within the range of the local debonding rotation release zone are provided with a preset yielding section to form a ductile-enhanced structure of the plastic hinge zone with continuous circumferential constraint, limited longitudinal release, and controlled energy dissipation at the interface.

[0010] Furthermore, the localized de-adhesion rotation release band is formed of at least one of an isolation film, a low-friction sheet, or a flexible anti-adhesion layer; The preset yield section is set in the middle connecting section of the U-shaped interface limiting short rib, and is made of low yield point steel or in the form of locally reduced cross section; the yield bearing capacity of the preset yield section is lower than the bearing capacity of the two anchoring sections of the U-shaped interface limiting short rib, so that plastic deformation is preferentially concentrated in the preset yield section.

[0011] Furthermore, adjacent arc-shaped prefabricated UHPC panels are joined together with flat joints, and the joints are coated with quick-drying oxygen-sealing rings or high-toughness sealing materials; after prestressing, the prestressing ducts are grouted and the prestressing slots are sealed, so that multiple arc-shaped prefabricated UHPC panels form a closed assembled circumferential constraint shell.

[0012] On the other hand, the present invention provides a method for ductile reinforcement of concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell, comprising the following steps: Step S1: Measure the dimensions and treat the surface of the concrete column to be reinforced. Determine the radius of curvature, number of segments and arrangement of prestressed ducts of the arc-shaped precast UHPC panel shell according to the outer contour dimensions of the concrete column. Determine the vertical arrangement range corresponding to the local debonding rotation release zone according to the location of the potential plastic hinge zone of the concrete column. Step S2: Install each arc-shaped prefabricated UHPC panel shell in sequence on the outer periphery of the concrete column, so that each arc-shaped prefabricated UHPC panel shell forms a closed ring-shaped covering structure around the concrete column. Step S2-1: During the installation process, the interface spacing positioning support feet abut against the outer surface of the concrete column in the radial direction. The interface spacing positioning support feet together define a uniform interface pouring space between the arc-shaped precast UHPC panel shell and the concrete column. Step S2-2: Simultaneously, make the reserved slots at both ends of the adjacent arc-shaped prefabricated UHPC panels connect with each other, so that the prestressed ducts inside each panel are continuously connected in the circumferential direction to form a spiral ring-shaped path pipe that extends continuously along the height of the column, and use temporary clamps or fixtures to fix the spatial position of each arc-shaped prefabricated UHPC panel. Step S3: Within the height range corresponding to the potential plastic hinge zone of the concrete column, a local debonding and rotation release zone is set on the inner surface of the arc-shaped precast UHPC panel shell, so that the arc-shaped precast UHPC panel shell and the interface concrete formed by subsequent pouring do not form a continuous direct bond in this area; at the same time, the U-shaped interface limiting short bars located within the range of the local debonding and rotation release zone adopt a preset yield section, while ordinary U-shaped interface limiting short bars are used in other areas, so that the plastic hinge zone forms a circumferential continuous constraint, longitudinal limited release, and interface controlled energy dissipation structure; Step S4: Continuously pour interface concrete into the interface pouring space formed between each arc-shaped precast UHPC slab shell and the concrete column, so that the interface concrete covers the U-shaped ends of each U-shaped interface limiting short bar and fills the entire interface pouring space; wherein a continuous interface force transmission layer is formed in the ordinary area, while the corresponding area of ​​the local debonding rotation release zone maintains a discontinuous bonded state and maintains radial compression contact. Step S5-1: After the interface concrete reaches the design strength, the long prestressed steel strands are passed sequentially through the interconnected prestressed ducts inside each arc-shaped precast UHPC slab shell from one end of the spiral ring path pipe, so that the prestressed steel strands form a continuous spiral ring arrangement along the height direction of the concrete column. Step S5-2: Then, the prestressed steel strands are tensioned and permanently anchored at both ends of the spiral annular path pipe, so that the prestressed steel strands apply continuous circumferential preload to each arc-shaped precast UHPC slab shell, and each arc-shaped precast UHPC slab shell then transmits radial constraint force to the concrete column through the interface concrete. Step S6: After completing the prestressing tensioning, pressure grouting is performed on the prestressing ducts to form an integral bond between the prestressing steel strands and the prestressing ducts; the tensioning reserved slots and the joints of each plate and shell are sealed to form a continuous and closed assembled UHPC constraint shell from multiple arc-shaped prefabricated UHPC plates and shells.

[0013] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: The ductile reinforcement structure and reinforcement method for concrete columns under the synergistic constraint of helical annular prestressed steel strands and UHPC slab shells provided by this invention utilizes a multi-level synergistic constraint system formed by helical annular prestressed steel strands, precast UHPC slab shells, and interface concrete. The prestressed steel strands continuously apply circumferential active prestress to the UHPC slab shell, and then the UHPC slab shell and interface concrete transmit radial constraint stress to the existing concrete column. This transforms the concrete column from a traditional passive constraint to a combined active and passive constraint stress mode, effectively suppressing lateral expansion and crack development in the core concrete, and improving the axial bearing capacity, ductility, and seismic energy dissipation capacity of the concrete column. Simultaneously, the helical annular prestress is continuously distributed along the column height, ensuring continuous and uniform circumferential constraint at all height positions, which is beneficial for improving overall stress uniformity and long-term service performance.

[0014] This invention also utilizes interface spacing positioning supports to control the interface pouring space between the UHPC slab and the concrete column, ensuring uniform and controllable interface concrete thickness. Combined with pre-embedded U-shaped interface anti-slip reinforcements, a reliable interface-coordinated force transmission system is formed between the UHPC slab, the interface concrete, and the existing concrete column. The interface spacing positioning supports serve multiple functions, including assembly positioning, temporary support, and interface thickness control, significantly improving assembly accuracy and construction efficiency. The U-shaped interface anti-slip reinforcements effectively limit relative interface slippage, enhance interface shear force transmission capacity, and strengthen the overall working performance between the UHPC slab and the concrete column, creating a stable and reliable integrated load-bearing structure between the reinforcement layer and the original structure.

[0015] Furthermore, local debonding and rotation release zones are set up for the potential plastic hinge zone of the concrete column, and U-shaped interface limiting short bars with preset yield sections are used in the corresponding areas to form a synergistic working mechanism of "continuous circumferential constraint, limited longitudinal release, and controlled energy dissipation at the interface" in the plastic hinge zone. When the column undergoes large bending and rotation under seismic loading, the local debonding and rotation release zones can release part of the longitudinal deformation and reduce stress concentration at the ends of the UHPC plate and shell; the U-shaped interface limiting short bars with preset yield sections can preferentially undergo plastic yielding and dissipate seismic energy while limiting excessive interface slippage, thereby avoiding sudden interface peeling and brittle failure of the plate and shell, further improving the seismic ductility, structural safety, and durability of the existing concrete column, and realizing the synergistic enhancement of prefabricated rapid reinforcement and high-performance seismic resistance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a concrete column ductility reinforcement structure under the synergistic constraint of helical annular prestress and UHPC plate shell according to an embodiment of the present invention.

[0017] Figure 2This is a front view schematic diagram of the assembly of prefabricated UHPC panels and the arrangement of spiral prestressed steel strands according to an embodiment of the present invention.

[0018] Figure 3 This is a cross-sectional schematic diagram of the UHPC shell, interface concrete, existing concrete column, and interface spacing positioning support provided according to an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of a partial structure of the positioning support for the interface spacing of the inner surface of a prefabricated UHPC panel shell and the arrangement of short U-shaped interface limiting ribs, provided by an embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram of the arrangement of a localized debonding and rotation release zone in a potential plastic hinge region according to an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram showing the positions of an existing column and a prefabricated UHPC panel shell according to an embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram illustrating the construction steps of a method for ductile reinforcement of concrete columns under the synergistic constraint of helical annular prestress and UHPC plate shell according to an embodiment of the present invention.

[0023] In the picture: 1. Precast UHPC panel shell; 2. Steel strand; 3. Prestressed ducts; 4. Interface concrete; 5. Interface spacing positioning support; 6. Interface anti-slip short reinforcement; 7. Local debonding and rotation release zone; 8. Reserved groove; 9. Plastic hinge zone; 10. Concrete column; 11. Joint. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figures 1 to 7 As shown in the figure, this embodiment of the invention provides a ductile reinforcement structure for concrete columns under the synergistic constraint of spiral annular prestressing and UHPC plate shell. It is suitable for the seismic reinforcement, bearing capacity improvement and ductility enhancement of existing reinforced concrete columns 10, and can also be used for the prefabricated reinforcement of building structural columns, frame columns, underground engineering support columns and other concrete structural compression column members, such as reinforced concrete columns (RC columns), steel-concrete composite columns (SRC columns), steel-concrete composite columns (CFST columns), steel columns (H-shaped steel columns, circular steel columns), masonry columns (brick columns, block columns), etc.

[0028] The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestress and UHPC plate shell provided in this embodiment includes a concrete column; The concrete column is fitted with multiple pieces of arc-shaped prefabricated UHPC panels that are sequentially spliced ​​together to form an arc-shaped prefabricated UHPC shell that encloses the concrete column. The arc-shaped precast UHPC slab shell is provided with continuous or segmented prestressed ducts, and the prestressed ducts in multiple arc-shaped precast UHPC slab shells are connected sequentially along the circumference of the concrete column to form a spiral ring path pipeline along the height of the column. Prestressed steel strands are threaded through the spiral ring path pipeline and anchored and tensioned at both ends of the pipeline. At each of the two ends of the inner surface of the arc-shaped precast UHPC panel, an interface spacing positioning support is provided radially. The interface spacing positioning support is extended radially and abuts against the surface of the concrete column to control the formation of multiple circumferentially distributed interface casting spaces between the panel and the column. Furthermore, the inner surface of the arc-shaped precast UHPC panel is provided with a plurality of pre-embedded U-shaped interface slip limiting short ribs arranged in an array. The U-shaped ends of the interface slip limiting short ribs extend into the interface casting space in a radial direction and fill the interface casting space with casting interface concrete.

[0029] In this embodiment, the concrete column 10 is preferably a circular reinforced concrete column, with four arc-shaped prefabricated UHPC shells 1 installed sequentially along the circumference on its outer side. Each UHPC shell adopts a quarter-circle arc structure, and the four shells enclose a complete closed ring. The inner radius of curvature of the shell is consistent with the outer contour of the concrete column 10, so that the UHPC shell can uniformly cover the outer periphery of the concrete column.

[0030] Each UHPC panel has a consistent thickness and vertical height, and can be arranged in vertical segments according to the height of the reinforced column to meet the requirements of transportation, hoisting, and on-site assembly. For columns with larger cross-sectional dimensions, the number of UHPC panel segments can be appropriately increased; for irregularly shaped columns such as elliptical columns and rounded rectangular columns, the radius of curvature and splicing method of each panel can be adjusted accordingly so that the panels can still work together to form a continuous closed constraint shell.

[0031] refer to Figure 2 Each arc-shaped precast UHPC panel 1 has pre-embedded continuous or segmented prestressed ducts 3 inside, and each prestressed duct is arranged at a predetermined spiral angle along the length of the panel. After the UHPC panels are assembled circumferentially, the reserved slots 8 on the sides of adjacent panels correspond to each other, so that adjacent prestressed ducts 3 are connected to each other, thereby forming a continuous spiral ring-shaped pipeline along the height of the concrete column.

[0032] Specifically, the reserved slot 8 preferably adopts a rectangular concave structure, with its width and depth not less than the diameter of the prestressing duct, to ensure smooth threading of the steel strands and facilitate the entry and operation of the tensioning equipment. Adjacent shell plates are connected by a flat joint 11. After installation, epoxy adhesive or high-toughness sealing material can be applied to the joint to improve the overall integrity of the shell plates and the sealing performance of subsequent grouting.

[0033] like Figure 3 and Figure 4As shown, interface spacing positioning supports 5 are prefabricated integrally at both edges of the inner surface of each UHPC panel 1. The interface spacing positioning supports 5 extend radially inward along the panel, and their ends abut against the outer surface of the concrete column 10 during installation, so that the panel always maintains the designed radial spacing, thereby forming multiple circumferentially continuously distributed interface casting spaces between the UHPC panel and the concrete column.

[0034] Specifically, the interface spacing positioning support 5 is preferably cast integrally with the UHPC plate shell, or it can be fixed to the inside of the plate shell by post-installation connection. This not only ensures that the interface concrete thickness is uniform, but also provides temporary support and radial positioning during the plate shell installation stage, avoiding plate shell installation deviation and improving assembly accuracy.

[0035] Simultaneously, a number of U-shaped interface anti-slip short bars 6 are uniformly embedded in a matrix pattern on the inner side of the UHPC slab shell 1. One end of each U-shaped interface anti-slip short bar is anchored inside the UHPC slab shell, and its U-shaped end extends radially into the interface pouring space. After the interface concrete 4 is poured, the U-shaped end is completely covered inside the interface concrete, forming a reliable mechanical interlocking effect between the UHPC slab shell, the interface concrete, and the concrete column. Under normal working conditions, the interface concrete bears the continuous interface force transmission, and the U-shaped interface anti-slip short bars bear the interface shear force transmission and anti-slip function. Together, they ensure that a stable and reliable overall force-bearing system is formed between the UHPC slab shell and the original column.

[0036] refer to Figure 5 For the potential plastic hinge zone 9 of the concrete column, a local debonding and rotation release zone 7 is provided in this embodiment. Specifically, the local debonding and rotation release zone 7 is preferably formed by an isolation film, a low-friction polytetrafluoroethylene sheet, or a flexible anti-adhesive layer. It is set between the inner surface of the UHPC shell and the interface concrete, so that the area does not form a continuous rigid bond, but maintains radial compression contact. At the same time, the U-shaped interface limiting short ribs 6 located in the local debonding area are provided with a preset yield section. The preset yield section can be formed by locally reducing the cross section or by low yield point steel. Its yield bearing capacity is lower than the bearing capacity of the anchoring sections at both ends, so that plastic deformation is preferentially concentrated in the preset yield section. When plastic rotation occurs at the column end, the local debonding area can release part of the longitudinal deformation, avoiding large tensile strain concentration at the end of the UHPC shell; while the preset yield section restricts interface slip while preferentially dissipating plastic energy, thus forming a ductility enhancement mechanism of "circumferential continuous constraint, longitudinal limited release, and interface controlled energy dissipation".

[0037] During construction, the outer contour dimensions, vertical height, and location of the potential plastic hinge zone 9 of the concrete column 10 are first measured based on the on-site test results. This information is then used to determine the segment dimensions of the UHPC shell, the arrangement of prestressed ducts, and the extent of local debonding areas. Subsequently, the surface of the concrete column is cleaned, repaired, and roughened to improve subsequent interfacial bonding performance.

[0038] Then, each UHPC sheet 1 is sequentially installed on the outside of the concrete column, and the interface spacing positioning supports 5 are used to maintain a uniform distance between the sheet and the concrete column. Temporary clamps or special fixtures are used to fix the position of the sheet, ensuring that all prestressed ducts 3 are accurately connected to form a complete spiral ring path. Subsequently, interface concrete 4 is continuously poured into each interface pouring space, ensuring that the interface concrete fully covers each U-shaped interface limiting short reinforcement 6 and fills the entire interface space. During the pouring process, the position of the local debonding and rotation release zone should be kept stable, without displacement or damage.

[0039] After the interface concrete reaches its design strength, the continuous prestressed steel strands 2 are sequentially inserted into each prestressed duct 3 from one end of the spiral path and continuously arranged along the spiral path to the other end. Then, tensioning equipment is used to tension the steel strands, and permanent anchorages are implemented at both ends of the steel strands, allowing the prestressed steel strands to continuously apply circumferential active preload to the UHPC shell. After tensioning, pressure grouting is performed into the prestressed ducts 3, forming an integral bond between the steel strands and the ducts. Simultaneously, the pre-reserved tensioning slots 8 and joints 11 are sealed, ultimately forming a continuous, closed prefabricated UHPC circumferentially constrained shell.

[0040] During structural service, the prestressed steel strands 2 continuously apply circumferential active constraints to the UHPC shell 1. The UHPC shell, through the interface concrete 4, uniformly transfers the circumferential constraint force to the concrete column 10, ensuring that the column is always in a state of combined active and passive constraints. This effectively suppresses the lateral expansion of the core concrete and improves the axial bearing capacity and ductility. When subjected to repeated seismic loads, the interface concrete and U-shaped interface limiting short reinforcements in the ordinary area ensure overall coordinated operation. In the potential plastic hinge zone 9, the local debonding and rotation release zone releases the longitudinal deformation of the column, and the pre-set yield section preferentially enters the plastic state and dissipates seismic energy, thereby avoiding sudden interface peeling and brittle cracking at the ends of the UHPC shell. This significantly improves the ductility, energy dissipation capacity, and seismic performance of the concrete column.

[0041] It should be noted that this invention is not limited to the embodiments described above. For concrete columns with different cross-sectional shapes and sizes, the number of UHPC shell segments, the helical angle of prestressed ducts, the size of the interface spacing positioning supports, the density of the U-shaped interface limiting short reinforcements, and the range of the local debonding and rotation release zone can be adjusted according to engineering design requirements; the number of prestressed steel strands, tension force, and duct arrangement can also be adjusted according to the structural stress requirements. Without departing from the technical concept of this invention, all equivalent substitutions and conventional improvements described above should fall within the protection scope of this invention.

[0042] Furthermore, this invention also provides a method for ductile reinforcement of concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell, comprising the following steps: Step S1: Dimension measurement and surface treatment of the concrete column to be reinforced. Determine the radius of curvature, number of segments and arrangement of prestressed ducts of the arc-shaped precast UHPC panel shell according to the outer contour dimensions of the concrete column. Determine the vertical arrangement range corresponding to the local debonding rotation release zone according to the position of the potential plastic hinge zone 9 of the concrete column. Step S2: Install each arc-shaped prefabricated UHPC panel shell in sequence on the outer periphery of the concrete column, so that each arc-shaped prefabricated UHPC panel shell forms a closed ring-shaped covering structure around the concrete column. Step S2-1: During the installation process, the interface spacing positioning support feet abut against the outer surface of the concrete column in the radial direction. The interface spacing positioning support feet together define a uniform interface pouring space between the arc-shaped precast UHPC panel shell and the concrete column. Step S2-2: Simultaneously, make the reserved slots at both ends of the adjacent arc-shaped prefabricated UHPC panels connect with each other, so that the prestressed ducts inside each panel are continuously connected in the circumferential direction to form a spiral ring-shaped path pipe that extends continuously along the height of the column, and use temporary clamps or fixtures to fix the spatial position of each arc-shaped prefabricated UHPC panel. Step S3: Within the height range corresponding to the potential plastic hinge zone 9 of the concrete column, a local debonding and rotation release zone is set on the inner surface of the arc-shaped precast UHPC panel shell, so that the arc-shaped precast UHPC panel shell and the interface concrete formed by subsequent pouring do not form a continuous direct bond in this area; at the same time, the U-shaped interface limiting short bars located within the range of the local debonding and rotation release zone adopt a preset yield section, while ordinary U-shaped interface limiting short bars are used in other areas, so that the plastic hinge zone 9 forms a structure of continuous circumferential constraint, limited longitudinal release, and controlled energy dissipation at the interface; Step S4: Continuously pour interface concrete into the interface pouring space formed between each arc-shaped precast UHPC slab shell and the concrete column, so that the interface concrete covers the U-shaped ends of each U-shaped interface limiting short bar and fills the entire interface pouring space; wherein a continuous interface force transmission layer is formed in the ordinary area, while the corresponding area of ​​the local debonding rotation release zone maintains a discontinuous bonded state and maintains radial compression contact. Step S5-1: After the interface concrete reaches the design strength, the long prestressed steel strands are passed sequentially through the interconnected prestressed ducts inside each arc-shaped precast UHPC slab shell from one end of the spiral ring path pipe, so that the prestressed steel strands form a continuous spiral ring arrangement along the height direction of the concrete column. Step S5-2: Then, the prestressed steel strands are tensioned and permanently anchored at both ends of the spiral annular path pipe, so that the prestressed steel strands apply continuous circumferential preload to each arc-shaped precast UHPC slab shell, and each arc-shaped precast UHPC slab shell then transmits radial constraint force to the concrete column through the interface concrete. Step S6: After completing the prestressing tensioning, pressure grouting is performed on the prestressing ducts to form an integral bond between the prestressing steel strands and the prestressing ducts; the tensioning reserved slots and the joints of each plate and shell are sealed to form a continuous and closed assembled UHPC constraint shell from multiple arc-shaped prefabricated UHPC plates and shells.

[0043] After grouting and sealing are completed, the spiral annular prestressed steel strands, the arc-shaped precast UHPC slab shell, the interface concrete, the U-shaped interface limiting short bars, and the concrete column form a multi-level collaborative load-bearing structure. Among them, the spiral annular prestressed steel strands continuously provide active circumferential constraints to the arc-shaped precast UHPC slab shell, and the arc-shaped precast UHPC slab shell transmits radial compressive stress to the concrete column through the interface concrete. In ordinary areas, the interface concrete and the U-shaped interface limiting short bars achieve overall collaborative work. In the potential plastic hinge zone 9, longitudinal deformation is released by the local debonding rotation release zone, and the U-shaped interface limiting short bars with preset yield sections limit the relative slippage of the interface and dissipate seismic energy, so that the concrete column obtains continuous circumferential constraints, controlled interface force transmission, and ductility enhancement effects.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell, characterized in that, Including concrete columns; The concrete column is fitted with multiple pieces of arc-shaped prefabricated UHPC panels that are sequentially spliced ​​together to form an arc-shaped prefabricated UHPC shell that encloses the concrete column. The arc-shaped precast UHPC slab shell is provided with continuous or segmented prestressed ducts, and the prestressed ducts in multiple arc-shaped precast UHPC slab shells are connected sequentially along the circumference of the concrete column to form a spiral ring path pipeline along the height of the column. Prestressed steel strands are threaded through the spiral ring path pipeline and anchored and tensioned at both ends of the pipeline. At each of the two ends of the inner surface of the arc-shaped precast UHPC panel, an interface spacing positioning support is provided radially. The interface spacing positioning support is extended radially and abuts against the surface of the concrete column to control the formation of multiple circumferentially distributed interface casting spaces between the panel and the column. Furthermore, the inner surface of the arc-shaped precast UHPC panel is provided with a plurality of pre-embedded U-shaped interface slip limiting short ribs arranged in an array. The U-shaped ends of the interface slip limiting short ribs extend into the interface casting space in a radial direction and fill the interface casting space with casting interface concrete.

2. The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell as described in claim 1, characterized in that, The arc-shaped precast UHPC panel shell is configured as four pieces, each of which is a quarter-circle arc structure; the radial thickness of each arc-shaped precast UHPC panel shell is consistent, the radius of curvature matches the outer circular curvature of the concrete column, the vertical height of the arc-shaped precast UHPC panel shell is uniform, and it is evenly distributed in segments along the vertical of the concrete column.

3. The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell as described in claim 2, characterized in that, Each of the two ends of the arc-shaped precast UHPC panel is provided with a reserved slot that is connected to the corresponding prestressing channel. The reserved slots of each two adjacent arc-shaped precast UHPC panels are matched at the vertical joint between the two panels. The reserved slot is a concave rectangular slot structure, the size of the slot is not less than the diameter of the prestressing channel, and the slot opening faces the outside of the arc-shaped precast UHPC panel.

4. The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell as described in claim 3, characterized in that, A local debonding and rotation release zone is set between the arc-shaped precast UHPC panel and the interface concrete within the height range corresponding to the potential plastic hinge zone of the concrete column, so that the arc-shaped precast UHPC panel and the interface concrete do not form a continuous direct bond within the local debonding and rotation release zone, and maintain radial compression contact under the action of circumferential prestress. Furthermore, the U-shaped interface limiting ribs located within the range of the local debonding rotation release zone are provided with a preset yielding section to form a ductile-enhanced structure of the plastic hinge zone with continuous circumferential constraint, limited longitudinal release, and controlled energy dissipation at the interface.

5. The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell as described in claim 4, characterized in that, The localized de-adhesion rotation release band is formed of at least one of an isolation film, a low-friction sheet, or a flexible anti-adhesion layer; The preset yield section is set in the middle connecting section of the U-shaped interface limiting short rib, and is made of low yield point steel or in the form of locally reduced cross section; the yield bearing capacity of the preset yield section is lower than the bearing capacity of the two anchoring sections of the U-shaped interface limiting short rib, so that plastic deformation is preferentially concentrated in the preset yield section.

6. The ductile reinforcement structure for concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell as described in claim 5, characterized in that, The adjacent arc-shaped prefabricated UHPC panels are joined together with flat joints, and the joints are coated with quick-drying oxygen-sealing rings or high-toughness sealing materials. After prestressing, the prestressing ducts are grouted and the tensioning slots are sealed, so that multiple arc-shaped prefabricated UHPC panels form a closed assembled circumferential constraint shell.

7. A method for ductile reinforcement of concrete columns under the synergistic constraint of helical annular prestressing and UHPC plate shell, characterized in that, Includes the following steps: Step S1: Measure the dimensions and treat the surface of the concrete column to be reinforced. Determine the radius of curvature, number of segments and arrangement of prestressed ducts of the arc-shaped precast UHPC panel shell according to the outer contour dimensions of the concrete column. Determine the vertical arrangement range corresponding to the local debonding rotation release zone according to the location of the potential plastic hinge zone of the concrete column. Step S2: Install each arc-shaped prefabricated UHPC panel shell in sequence on the outer periphery of the concrete column, so that each arc-shaped prefabricated UHPC panel shell forms a closed ring-shaped covering structure around the concrete column. Step S2-1: During the installation process, the interface spacing positioning support feet abut against the outer surface of the concrete column in the radial direction. The interface spacing positioning support feet together define a uniform interface pouring space between the arc-shaped precast UHPC panel shell and the concrete column. Step S2-2: Simultaneously, make the reserved slots at both ends of the adjacent arc-shaped prefabricated UHPC panels connect with each other, so that the prestressed ducts inside each panel are continuously connected in the circumferential direction to form a spiral ring-shaped path pipe that extends continuously along the height of the column, and use temporary clamps or fixtures to fix the spatial position of each arc-shaped prefabricated UHPC panel. Step S3: Within the height range corresponding to the potential plastic hinge zone of the concrete column, a local debonding and rotation release zone is set on the inner surface of the arc-shaped precast UHPC panel shell, so that the arc-shaped precast UHPC panel shell and the interface concrete formed by subsequent pouring do not form a continuous direct bond in this area; at the same time, the U-shaped interface limiting short bars located within the range of the local debonding and rotation release zone adopt a preset yield section, while ordinary U-shaped interface limiting short bars are used in other areas, so that the plastic hinge zone forms a circumferential continuous constraint, longitudinal limited release, and interface controlled energy dissipation structure; Step S4: Continuously pour interface concrete into the interface pouring space formed between each arc-shaped precast UHPC slab shell and the concrete column, so that the interface concrete covers the U-shaped ends of each U-shaped interface limiting short bar and fills the entire interface pouring space; wherein a continuous interface force transmission layer is formed in the ordinary area, while the corresponding area of ​​the local debonding rotation release zone maintains a discontinuous bonded state and maintains radial compression contact. Step S5-1: After the interface concrete reaches the design strength, the long prestressed steel strands are passed sequentially through the interconnected prestressed ducts inside each arc-shaped precast UHPC slab shell from one end of the spiral ring path pipe, so that the prestressed steel strands form a continuous spiral ring arrangement along the height direction of the concrete column. Step S5-2: Then, the prestressed steel strands are tensioned and permanently anchored at both ends of the spiral annular path pipe, so that the prestressed steel strands apply continuous circumferential preload to each arc-shaped precast UHPC slab shell, and each arc-shaped precast UHPC slab shell then transmits radial constraint force to the concrete column through the interface concrete. Step S6: After completing the prestressing tensioning, pressure grouting is performed on the prestressing ducts to form an integral bond between the prestressing steel strands and the prestressing ducts; the tensioning slots and the joints of each plate and shell are sealed to form a continuous and closed assembled UHPC constraint shell from multiple arc-shaped prefabricated UHPC plates and shells.

Images