Prefabricated steel-concrete combined supporting structure and design and construction method thereof

Abstract

The invention relates to the technical field of supporting structures, and discloses a prefabricated steel-concrete combined supporting structure and a design and construction method thereof. Comprising an outer steel pipe, an inner steel pipe, ultra-high performance concrete, an inner ring plate, an outer ring plate, high-strength bolts, stiffening ribs, steel bar connectors, embedded steel bars, joint square steel plates, U-shaped joint steel bars, cast-in-place concrete joint beam reinforcing bars, a cast-in-place concrete beam, bolt holes and joint steel bar welding spots. The outer steel pipe and the inner steel pipe are large and small circular steel pipes which are concentrically arranged, ultra-high performance concrete is poured between the outer steel pipe and the inner steel pipe to form a body of the prefabricated support, and the multiple sections of supports are connected through the inner ring plate, the outer ring plate and the high-strength bolts, the steel bar connectors, the embedded steel bars, the joint square steel plates, the joint steel bars and the cast-in-place concrete joints form connecting joints of the prefabricated supports. Compared with a traditional reinforced concrete support, the steel-concrete combined support has the higher mechanical property, is detachable, convenient to construct and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of support structure technology, and in particular to a prefabricated assembled steel-concrete composite support structure and its design and construction method. Background Technology

[0002] With the development of prefabricated building technology, it is increasingly replacing traditional cast-in-place buildings due to its advantages such as low energy consumption, green and low carbon emissions, and high recyclability.

[0003] Prefabricated construction, which involves manufacturing prefabricated components off-site and assembling them on-site, offers significant environmental benefits. Many studies have found that prefabricated construction reduces carbon emissions compared to traditional construction. Furthermore, using recyclable materials instead of virgin materials can reduce overall environmental impact by up to 30%. For short-term foundation pit support structures, prefabricated structures offer advantages such as rapid and efficient construction, low cost, and light weight. Many scholars have proposed various forms of prefabricated supports, including multi-limb concrete-steel pipe supports (P-CFST) and assembled concrete slabs. However, existing prefabricated supports primarily use solid components combined into multi-limb structures with complex connection points, resulting in significant manufacturing and construction difficulties. This makes mass production and widespread adoption challenging. Additionally, stress concentration in the support cross-section is concentrated in areas far from the center; hollow components, compared to solid components, can better utilize their load-bearing capacity. Therefore, the area of ​​the support's central region should be minimized as much as possible.

[0004] Therefore, there is an urgent need for a prefabricated assembled steel-concrete composite support structure and its design and construction method, which can improve the mechanical performance of the support structure, be disassembled and reused, facilitate construction, and be green and environmentally friendly. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a prefabricated assembled steel-concrete composite support structure and its design and construction method, which can improve the mechanical properties of the support structure, is detachable and reusable, facilitates construction, and is environmentally friendly.

[0006] This invention provides a prefabricated assembled steel-concrete composite support structure, comprising the following steps: The outer steel pipe and the inner steel pipe form an annular cavity, which is filled with ultra-high performance concrete. Inner and outer ring plates are welded to both ends of the outer and inner steel pipes. The outer ring plate is also welded to the ends of the outer and inner steel pipes. The inner ring plate is welded to the outer wall of the outer steel pipe. Bolt holes are provided on the inner and outer ring plates. The inner and outer ring plates are connected by high-strength bolts. The outer ring plate at one end of the connection between the outer steel pipe and the inner steel pipe and the cast-in-place concrete beam is also connected to a joint square steel plate. The joint square steel plate is welded with multiple U-shaped joint steel bars. The two ends of the U-shaped joint steel bars are welding points, which are connected to the joint steel bar welding points on the joint square steel plate. The embedded steel bars are set in the cast-in-place concrete beams. The ends of the embedded steel bars are equipped with steel bar connectors, which are connected to the two ends of multiple U-shaped joint steel bars.

[0007] Furthermore, the outer steel pipe and the inner steel pipe are concentrically arranged circular steel pipes of different diameters.

[0008] Furthermore, the outer and inner steel pipes are combinations of various types of round steel pipes, and the appropriate type of outer and inner steel pipe combination is selected according to the support bearing capacity requirements.

[0009] Furthermore, circumferential stiffening ribs are welded between the inner ring plate and the outer ring plate.

[0010] Furthermore, the joint square steel plate and the outer ring plate are tightly connected by multiple high-strength bolts.

[0011] Furthermore, a cast-in-place concrete joint is formed between the joint square steel plate and the cast-in-place concrete beam.

[0012] Furthermore, the cast-in-place concrete beams are reinforced with beam reinforcement.

[0013] Furthermore, multiple U-shaped joint steel bars connected to the steel bar connector are staggered with multiple U-shaped joint steel bars welded to the joint square steel plate to adjust the length of the cast-in-place concrete joint.

[0014] Furthermore, the cast-in-place concrete beam and the diaphragm wall form a T-beam structure. The minimum distance between the centerline of the current waist beam position of the cast-in-place concrete beam and the centerlines of the upper and lower adjacent supporting structures is used as the flange width of the T-beam structure, and the reinforcement in the diaphragm wall is locally densified within the current waist beam width range.

[0015] This invention also provides a design and construction method for a prefabricated assembled steel-concrete composite support structure, used to achieve any of the above-mentioned prefabricated assembled steel-concrete composite support structures, comprising the following steps: S1. After concentrically fixing the outer steel pipe and the inner steel pipe, pour ultra-high performance concrete into the formed annular cavity, weld the inner ring plate and the outer ring plate with bolt holes at both ends of the outer steel pipe and the inner steel pipe, and weld stiffening ribs between the inner ring plate and the outer ring plate to obtain the prefabricated support section. S2. Hoist the prefabricated support section to the working face of the foundation pit; S3. Connect the outer ring plate and inner ring plate of adjacent support sections by using high-strength bolts; S4. Connect the square steel plate with the welded U-shaped joint steel bars to the outer ring plate using high-strength bolts; S5. The multiple U-shaped joint steel bars connected to the steel bar connector are staggered and overlapped with the multiple U-shaped joint steel bars welded to the joint square steel plate. S6. Concrete is poured into the gap between the joint square steel plate and the cast-in-place concrete beam to form a cast-in-place concrete joint.

[0016] The embodiments of the present invention have the following technical effects: This invention utilizes a composite structure of concentric double steel tubes and ultra-high performance concrete to fully leverage the advantages of the annular cross-section in terms of load-bearing capacity, maximizing the compressive and bending bearing capacity of the components. This structural form not only improves overall stability but also enhances adaptability under complex loads. The concentric double steel tube composite support consists of a series of standardized, mass-produced prefabricated components. The appropriate support segment can be flexibly selected based on the bearing capacity requirements derived from engineering calculations, thus achieving precise matching of engineering needs and effectively reducing material waste. Through the bolt connection technology of inner and outer ring plates, rapid assembly and disassembly of the prefabricated support segments are achieved. The invention employs a flexible connection method using U-shaped joint steel bars and steel bar connectors. Through the synergistic effect of welded nodes and cast-in-place joints, it enhances the shear resistance and dimensional adaptability of the joint area (i.e., the length of the cast-in-place joint is adjustable), and also improves its overall load-bearing capacity and dimensional adaptability, ensuring the reliability and safety of the structural connection. The adjustable cast-in-place concrete joint design, based on the staggered lap joint principle of pre-embedded steel bars and joint steel bars, effectively compensates for dimensional deviations during foundation pit construction. Furthermore, the cast-in-place joint concrete uses ultra-high performance concrete, utilizing its high strength and early strength characteristics to ensure the joint's load-bearing capacity while significantly shortening the construction period. After construction is completed, the precast support section can be completely removed by dismantling the cast-in-place concrete joint, reducing the amount of on-site concrete pouring, significantly shortening the construction cycle, improving construction efficiency, achieving reusability, reducing building material consumption, and reducing carbon emissions, in line with the concept of green and low-carbon construction. This invention has a simple structure, is easy to construct, facilitates mass production, and is easy to implement in prefabricated construction, meeting the requirements of green building and circular economy development. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a precast steel-concrete composite support section connection provided in an embodiment of the present invention; Figure 2This is a schematic plan view of the connection node between a precast steel pipe concrete support section and a cast-in-place concrete beam provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the cross-sectional reinforcement of a cast-in-place concrete joint provided in an embodiment of the present invention; Figure 4 This is a schematic cross-sectional view of the connection node between a precast steel pipe concrete support section and a cast-in-place concrete beam provided in an embodiment of the present invention; Figure 5 This is a schematic cross-sectional view of a precast steel-concrete composite support section provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of a flange design provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the positioning of the weld point of the square steel plate rebar in a joint, provided by an embodiment of the present invention; Figure 8 This is a detailed drawing of a jointed steel bar provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of a T-beam structure provided in an embodiment of the present invention; Figure 10 This is a design flowchart of a prefabricated assembled steel-concrete composite support structure provided by an embodiment of the present invention; Figure 11 This is a schematic diagram of the construction method of a prefabricated assembled steel-concrete composite support structure provided by an embodiment of the present invention.

[0019] In the picture: 1-Outer steel pipe; 2-Inner steel pipe; 3-Ultra-high performance concrete; 4-Inner ring plate; 5-Outer ring plate; 6-High-strength bolt; 7-Stiffening rib; 8-Rebar connector; 9-Embedded rebar; 10-Joint square steel plate; 11-Joint rebar; 11-1-U-shaped rebar connected to the rebar connector; 11-2-U-shaped rebar connected to the square steel plate of the support section; 11-3-Ordinary rebar; 11-4-Joint stirrup; 12-Cast-in-place concrete joint; 13-Beam reinforcement; 14-Cast-in-place concrete beam; 15-Bolt hole; 16-Joint rebar weld point. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] This invention proposes a prefabricated assembled steel-concrete composite support structure, see [link to relevant documentation]. Figures 1-9Specifically, it includes: Outer steel pipe 1 and inner steel pipe 2 form an annular cavity between the outer steel pipe 1 and the inner steel pipe 2. The annular cavity is filled with ultra-high performance concrete 3 (Ultra-High Performance Concrete, abbreviated as UHPC). Inner ring plate 4 and outer ring plate 5 are welded to both ends of outer steel pipe 1 and inner steel pipe 2. Outer ring plate 5 is simultaneously welded to the ends of outer steel pipe 1 and inner steel pipe 2. Inner ring plate 4 is welded to the outer wall of outer steel pipe 1. Bolt holes 15 are provided on inner ring plate 4 and outer ring plate 5. Inner ring plate 4 and outer ring plate 5 are connected by high-strength bolts 6. The outer ring plate 5 at one end of the outer steel pipe 1 and inner steel pipe 2 that are connected to the cast-in-place concrete beam 14 is also connected to a joint square steel plate 10. The joint square steel plate 10 is welded with multiple U-shaped joint steel bars 11. The two ends of the U-shaped joint steel bars 11 are welding points, which are connected to the joint steel bar welding points 16 on the joint square steel plate 10. The embedded steel bars 9 are set in the cast-in-place concrete beam 14. The ends of the embedded steel bars 9 are provided with steel bar connectors 8, which are connected to the two ends of multiple U-shaped joint steel bars 11.

[0022] In some embodiments, the outer steel pipe 1 and the inner steel pipe 2 are concentrically arranged circular steel pipes of different diameters.

[0023] The outer steel pipe 1 and the inner steel pipe 2 are combinations of various types of round steel pipes. The appropriate type of outer steel pipe 1 and inner steel pipe 2 combination is selected according to the support bearing capacity requirements. This type of support is a series with various combinations of round steel pipes of different sizes. Different support models can be selected according to the support bearing capacity requirements obtained from the engineering calculations to meet different bearing capacity requirements, while reducing material consumption and carbon emissions.

[0024] The core of the prefabricated steel-concrete composite support structure consists of an outer steel pipe 1 and an inner steel pipe 2, which are concentrically fixed to form an annular cavity. The outer steel pipe 1 has a larger diameter than the inner steel pipe 2, and their axes coincide to form a double-layer tubular structure. Ultra-high performance concrete 3 is poured into the annular cavity. The ultra-high performance concrete 3 can be of C80 or higher strength, and the compaction must be ensured during pouring to avoid internal voids. After the ultra-high performance concrete 3 has cured, it forms a composite load-bearing body with the outer steel pipe 1 and the inner steel pipe 2, fully utilizing the combined advantages of the tensile strength of steel and the compressive strength of concrete.

[0025] Inner ring plate 4 and outer ring plate 5 are welded to both ends of the outer steel pipe 1 and inner steel pipe 2, respectively. The inner ring plate 4 is fixed to the end of the outer steel pipe 1, and the outer ring plate 5 is welded to the ends of both the outer steel pipe 1 and inner steel pipe 2, forming a double-ring plate structure. Bolt holes 15 are provided on the ring plates, and adjacent support sections are mechanically connected by high-strength bolts 6 penetrating the bolt holes of the inner ring plate 4 and outer ring plate 5. This connection method ensures the strength of the joint and facilitates rapid on-site assembly.

[0026] The joint square steel plate 10 is connected to the outer ring plate 5 at the end of the support section by high-strength bolts 6, and its surface is provided with regularly arranged joint steel bar weld points 16. The two ends of the U-shaped joint steel bar 11 are fixed at the weld point positions to form a continuous closed steel bar skeleton. The ends of the pre-embedded steel bars 9 inside the cast-in-place concrete beam 14 are equipped with steel bar connectors 8 to achieve a reliable connection with the free ends of the U-shaped joint steel bars 11.

[0027] The three-dimensional arrangement of the U-shaped joint reinforcement 11 can form a three-dimensional constraint on the cast-in-place concrete joint. Its curved section penetrates into the core area of ​​the concrete and overlaps with the longitudinally distributed pre-embedded reinforcement to form a spatial grid skeleton. This structure significantly improves the stress performance of the cast-in-place concrete joint 12.

[0028] The overall structure enhances bending stiffness through the synergistic load-bearing capacity of inner and outer steel pipes, while ultra-high performance concrete effectively suppresses local buckling of the steel pipes. The ring plate connection system enables modular and rapid assembly. This construction, while ensuring structural strength, allows for component reuse through a detachable design, significantly reducing material consumption and construction time.

[0029] In some embodiments, circumferential stiffening ribs 7 are welded between the inner ring plate 4 and the outer ring plate 5. The stiffening ribs 7 are evenly distributed along the circumference of the ring plate. The circumferential stiffening ribs 7 primarily bear the shear force transmission in the node area, diffusing the localized stress generated by the bolted connection to the entire ring plate area. This reinforced structure effectively improves the bending stiffness of the node area and prevents plastic deformation of the ring plate under repeated loading. The connection between the stiffening ribs 7 and the inner and outer steel pipes forms a continuous force transmission path, avoiding stress concentration that could lead to weld cracking. During on-site installation, the raised contours of the stiffening ribs 7 can also serve as alignment marks, assisting construction personnel in quickly calibrating the axis of the support section.

[0030] It is composed of inner ring plate 4, outer ring plate 5, high-strength bolts 6 and stiffening ribs 7. Figure 6The flange shown has adjustable parameters including the number of bolts, bolt diameter, distance from the outer wall of the outer steel pipe to the bolt center, and bolt type. Calculations revealed that the bolt diameter has the most significant impact on the bending capacity verification index, followed by the bolt type, then the number of bolts and the distance from the outer wall of the outer steel pipe to the bolt center. These parameters are adjusted sequentially in descending order of their impact on the bending capacity verification index, and the flange's load-bearing capacity is assessed to determine if it meets the requirements. Finally, the size of the connecting flange is determined.

[0031] In some embodiments, the joint square steel plate 10 and the outer ring plate 5 are tightly connected by multiple high-strength bolts 6. This bolted connection method enables rapid assembly and disassembly. The joint square steel plate 10 can be pre-welded with U-shaped joint reinforcing bars 11 to form a standardized connection module. During disassembly, simply loosening the bolts separates the joint square steel plate 10 from the prefabricated support section, which is then retained for reuse.

[0032] In some embodiments, multiple U-shaped joint steel bars 11 connected to the steel bar connector 8 are staggered with multiple U-shaped joint steel bars 11 welded on the joint square steel plate 10 to adjust the length of the cast-in-place concrete joint 12.

[0033] In some embodiments, a cast-in-place concrete joint 12 is formed between the joint square steel plate 10 and the cast-in-place concrete beam 14. The gap between the joint square steel plate 10 and the cast-in-place concrete beam 14 is integrally connected by cast-in-place concrete. After the joint square steel plate 10 is installed and positioned, a formwork is erected on the side close to the cast-in-place concrete beam 14 to form a closed pouring space, and concrete is poured to form the cast-in-place concrete joint 12. The cast-in-place concrete joint 12 is internally configured with multiple layers of U-shaped joint steel bars 11 (the joint steel bars 11 include three types: 11-1, 11-2, and 11-3, of which 11-1 and 11-2 are U-shaped joint steel bars, 11-1 is a U-shaped steel bar connected to the steel bar connector, 11-2 is a U-shaped steel bar connected to the supporting section square steel plate, and 11-3 is a regular steel bar, only used to improve the out-of-plane bending bearing capacity). The ends of the steel bars are connected to... Figure 3 The weld points shown are connected, and their positions are set based on structural stability. Furthermore, the reinforcing steel cage includes stirrups 11-4 to enhance the shear resistance of the joints. The length of the cast-in-place section can be adjusted according to the actual width of the foundation pit by regulating the lap depth of the U-shaped joint reinforcing bars 11 on the joint square steel plate 10 and the U-shaped joint reinforcing bars 11 connected to the side reinforcing bar connectors 8 of the cast-in-place concrete beam 14. This variable length design allows the support system to adapt to different engineering conditions, avoiding the increased costs associated with customized production.

[0034] In some embodiments, the cast-in-place concrete beam 14 is reinforced with beam reinforcement 13. This reinforcement system effectively transfers the support load to the enclosure structure, and the diagonal steel mesh can distribute the load and reduce stress concentration at the joints.

[0035] In some embodiments, the cast-in-place concrete beam and the diaphragm wall form a T-beam structure. The minimum distance between the centerline of the current waist beam position of the cast-in-place concrete beam 14 and the centerlines of the upper and lower adjacent support structures is a preset multiple of the flange width of the T-beam structure. The reinforcement in the diaphragm wall is locally densified within the current waist beam width range.

[0036] Specifically, because the support structure in this embodiment does not have figure-eight braces, and the axial force on the support is extremely large, this will lead to a sharp increase in the bending moment and shear force on the chord beam. Calculations show that when the support spacing increases from 3m to 9m, the shear force of the chord beam at the support end will increase by approximately 3 times, and the bending moment by approximately 10 times. If calculated using traditional design methods, considering only the chord beam cross-section in the design section might result in an excessively large chord beam cross-section, requiring 1.8m × 2.4m, with longitudinal reinforcement of 20Φ32 + 20Φ32 and stirrup reinforcement of Φ14@150 six-legged stirrups to meet the requirements. (See [link to relevant documentation]). Figure 9 (a). In reality, the concrete wainscoting and the diaphragm wall share the load. To make the calculation conform to the actual load characteristics, the concrete wainscoting and the diaphragm wall can be designed as a T-beam structure. The minimum distance between the centerline of the current wainscoting position of the cast-in-place concrete beam 14 and the centerlines of the upper and lower adjacent support structures is taken as the flange width of the T-beam structure.

[0037] Calculations show that, with a 1.4m × 1.8m cross-section for the lintel beam, the final selection is to locally densify the reinforcement of the diaphragm wall within the width of the lintel beam. This results in longitudinal reinforcement of 20Φ32 + 16Φ28 in the densified zone, while the stirrup reinforcement remains Φ14@150 with six legs, which meets the requirements. (See [reference needed]). Figure 9 (b) This design method can significantly reduce the cross-sectional dimensions of the chord beams and also reduce the longitudinal reinforcement area, thereby further reducing building material consumption and meeting the requirements of green building and circular economy development.

[0038] This invention also proposes a design and construction method for a prefabricated assembled steel-concrete composite support structure, used to realize the aforementioned prefabricated assembled steel-concrete composite support structure. Figure 10 This is a design flowchart of a prefabricated assembled steel-concrete composite support structure provided by an embodiment of the present invention; Figure 11 This is a schematic diagram illustrating the design and construction process of a prefabricated assembled steel-concrete composite support structure according to an embodiment of the present invention. (See attached diagram.) Figure 10-11 It includes the following steps: S1. First, design the initial support structure scheme according to the traditional method, and select the precast support model according to the support bearing capacity requirements of the calculation sheet. Replace the traditional concrete support in the initial support structure scheme with precast support to obtain the optimized support structure scheme. S2. Perform flange bearing capacity verification and cast-in-place concrete beam bearing capacity verification on the optimized support structure scheme. S3. If the requirements are met, output the final solution and execute the construction process of the prefabricated steel-concrete composite support structure according to the final solution; otherwise, optimize the T-beam structure design of the waist beam of the cast-in-place concrete beam, adjust the cross-sectional dimensions of the cast-in-place concrete beam and increase the reinforcement in a specific area within the diaphragm wall, adjust the bolt diameter, bolt type, number of bolts and flange size of the connecting flange in sequence, and re-execute S2-S3 until the flange bearing capacity verification and the cast-in-place concrete beam bearing capacity verification meet the requirements, and output the final solution. The construction process for the prefabricated steel-concrete composite support structure, implemented according to the final plan, includes the following sub-steps: S31. After concentrically fixing the outer steel pipe 1 and the inner steel pipe 2, pour ultra-high performance concrete 3 into the formed annular cavity, weld the inner ring plate 4 and the outer ring plate 5 with bolt holes 15 to both ends of the outer steel pipe 1 and the inner steel pipe 2, and weld the stiffening rib 7 between the inner ring plate 4 and the outer ring plate 5 to obtain the prefabricated support section. S32. Hoist the prefabricated support section to the working face of the foundation pit; S33. The outer ring plate 5 and inner ring plate 4 of the adjacent support section are aligned and connected by high-strength bolts 6. S34. The square steel plate 10 with U-shaped joint steel bars 11 welded on it is connected to the outer ring plate 5 by high-strength bolts 6. S35. The multiple U-shaped joint steel bars 11 connected to the steel bar connector 8 are staggered and overlapped with the multiple U-shaped joint steel bars 11 welded on the joint square steel plate 10. S36. Ultra-high performance concrete 3 is poured into the gap between the joint square steel plate 10 and the cast-in-place concrete beam 14 to form a cast-in-place concrete joint 12.

[0039] like Figure 11 As shown in (a), in Figure 11 In (a), embedded steel bars 9 and steel bar connectors 8 are installed in the concrete body of the cast-in-place concrete beam 14. The steel bar connectors 8 are connected to the ends of several U-shaped joint steel bars 11. At this time, the embedded steel bar system is in a state of waiting to be connected, providing a reliable anchoring foundation for subsequent assembly processes.

[0040] Figure 11(b) Standardized connection end face of prefabricated support section. The surface of the joint square steel plate 10 is arranged with welded U-shaped joint steel bars 11. The prefabricated module pre-completes the positioning welding of the U-shaped joint steel bars 11 to ensure the accuracy of the connector alignment during on-site assembly.

[0041] Figure 11 (c) is the process of interactive anchoring between the precast support section and the cast-in-place concrete beam 14. The U-shaped ends of the U-shaped joint steel bars 11 of the precast support section are staggered with the U-shaped ends of the U-shaped joint steel bars 11 on the side of the cast-in-place concrete beam 14.

[0042] Figure 11 (d) To form a cast-in-place concrete joint 12, ultra-high performance concrete is poured into the gap between the joint steel plate 10 and the cast-in-place concrete beam 14. The cast-in-place concrete joint 12 completely fills the gap between the precast section and the cast-in-place concrete beam 14, and the ultra-high performance concrete encapsulates all exposed steel bar joints, completing the construction process of the foundation pit support. After the ultra-high performance concrete hardens, the bent and straight sections of the U-shaped steel bars bear the bending moment and shear force respectively, and the entire support system forms a complete load transfer path. By using ultra-high performance concrete to replace traditional concrete, the high strength and early strength characteristics of ultra-high performance concrete achieve the strength requirements of replacing traditional concrete supports and significantly shorten the construction period.

[0043] This invention, by employing a composite structure of concentric double steel pipes and filled concrete, fully leverages the advantages of the annular cross-section in terms of stress, maximizing the compressive and bending bearing capacity of the components. This structural form not only improves overall stability but also enhances adaptability under complex loads. The concentric double steel pipe composite support consists of a series of standardized, mass-produced prefabricated components. The appropriate support segment can be flexibly selected based on the bearing capacity requirements derived from engineering calculations, thus achieving precise matching of engineering needs, effectively reducing material waste and carbon emissions, and conforming to the concept of green and low-carbon construction. Through the inner and outer ring plate bolt connection technology, the prefabricated support segments achieve rapid assembly and disassembly. The flexible connection method using U-shaped joint steel bars and steel bar connectors, through the synergistic effect of welded nodes and cast-in-place joints, enhances the shear resistance and dimensional adaptability of the joint area, and also improves its overall bearing capacity and dimensional adaptability, ensuring the reliability and safety of the structural connection. The adjustable cast-in-place concrete joint design, based on the staggered lap joint principle of embedded steel bars and joint steel bars, effectively compensates for dimensional deviations during foundation pit construction. Once construction is complete, the precast support section can be removed intact by dismantling the concrete joint, reducing the amount of concrete poured on-site, significantly shortening the construction cycle, improving construction efficiency, achieving reusability, reducing building material consumption, and meeting the requirements of green construction and circular economy development. Furthermore, compared to traditional construction methods, this invention does not require prestressing, offering advantages in construction process and a simpler construction method.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A prefabricated assembled steel-concrete composite support structure, characterized in that, include: An outer steel pipe (1) and an inner steel pipe (2) are provided, and an annular cavity is formed between the outer steel pipe (1) and the inner steel pipe (2), and the annular cavity is filled with ultra-high performance concrete (3). Inner ring plate (4) and outer ring plate (5) are welded to both ends of the outer steel pipe (1) and the inner steel pipe (2). The outer ring plate (5) is simultaneously welded to the ends of the outer steel pipe (1) and the inner steel pipe (2). The inner ring plate (4) is welded to the outer wall of the outer steel pipe (1). Bolt holes (15) are provided on the inner ring plate (4) and the outer ring plate (5). The inner ring plate (4) and the outer ring plate (5) are connected by high-strength bolts (6). The outer ring plate (5) at one end of the outer steel pipe (1) and the inner steel pipe (2) connected to the cast-in-place concrete beam (14) is also connected to a joint square steel plate (10); The joint square steel plate (10) is welded with multiple U-shaped joint steel bars (11). The two ends of the U-shaped joint steel bars (11) are welding points, which are used to weld and fix them to the joint steel bar welding points (16) on the joint square steel plate (10). The embedded steel bars (9) are set in the cast-in-place concrete beam (14), and the ends of the embedded steel bars (9) are provided with steel bar connectors (8). The steel bar connectors (8) are connected to the two ends of multiple U-shaped joint steel bars (11).

2. The prefabricated assembled steel-concrete composite support structure according to claim 1, characterized in that, The outer steel pipe (1) and the inner steel pipe (2) are concentric circular steel pipes of different diameters.

3. The prefabricated assembled steel-concrete composite support structure according to claim 2, characterized in that, The outer steel pipe (1) and the inner steel pipe (2) are combinations of various types of round steel pipes. The appropriate type of round steel pipe combination of the outer steel pipe (1) and the inner steel pipe (2) is selected according to the support bearing capacity requirements.

4. The prefabricated assembled steel-concrete composite support structure according to claim 1, characterized in that, A circumferential stiffening rib (7) is welded between the inner ring plate (4) and the outer ring plate (5).

5. A prefabricated assembled steel-concrete composite support structure according to claim 1, characterized in that, The joint square steel plate (10) and the outer ring plate (5) are tightly connected by multiple high-strength bolts (6).

6. The prefabricated assembled steel-concrete composite support structure according to claim 1, characterized in that, The joint square steel plate (10) forms a cast-in-place concrete joint (12) with the cast-in-place concrete beam (14).

7. A prefabricated assembled steel-concrete composite support structure according to claim 6, characterized in that, Multiple U-shaped joint steel bars (11) connected to the steel bar connector (8) are staggered with multiple U-shaped joint steel bars (11) welded on the joint square steel plate (10) to adjust the length of the cast-in-place concrete joint (12).

8. A prefabricated assembled steel-concrete composite support structure according to claim 6, characterized in that, The cast-in-place concrete beam (14) and the diaphragm wall form a T-beam structure. The minimum distance between the centerline of the current waist beam position of the cast-in-place concrete beam (14) and the centerlines of the upper and lower adjacent support structures is taken as the flange width of the T-beam structure. The reinforcement in the diaphragm wall is locally densified within the current waist beam width range.

9. A design and construction method for a prefabricated assembled steel-concrete composite support structure, used to implement the prefabricated assembled steel-concrete composite support structure as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. First, design the initial support structure scheme according to the traditional method, and select the precast support model according to the support bearing capacity requirements of the calculation sheet. Replace the traditional concrete support in the initial support structure scheme with precast support to obtain the optimized support structure scheme. S2. Perform flange bearing capacity verification and cast-in-place concrete beam bearing capacity verification on the optimized support structure scheme. S3. If the verification results meet the requirements, output the final scheme and execute the construction process of the prefabricated steel-concrete composite support structure according to the final scheme; otherwise, optimize the T-beam structure design of the waist beam of the cast-in-place concrete beam (14), adjust the cross-sectional size of the cast-in-place concrete beam (14) and densify the reinforcement in the preset area of ​​the diaphragm wall, adjust the bolt diameter, bolt type, number of bolts and flange size of the connecting flange in sequence, and re-execute S2-S3 until the flange bearing capacity verification and the cast-in-place concrete beam bearing capacity verification meet the requirements, and output the final scheme.

10. The design and construction method of a prefabricated assembled steel-concrete composite support structure according to claim 9, wherein step S3, the construction process of the prefabricated assembled steel-concrete composite support structure according to the final scheme includes: S31. After concentrically fixing the outer steel pipe (1) and the inner steel pipe (2), pour ultra-high performance concrete (3) into the formed annular cavity, weld the inner ring plate (4) and the outer ring plate (5) with bolt holes (15) at both ends of the outer steel pipe (1) and the inner steel pipe (2), and weld the stiffening rib (7) between the inner ring plate (4) and the outer ring plate (5) to obtain the prefabricated support section; S32. Hoist the prefabricated support section to the working face of the foundation pit; S33. The outer ring plate (5) of the adjacent support section is aligned and connected with the inner ring plate (4) by high-strength bolts (6); S34. The joint square steel plate (10) with U-shaped joint steel bars (11) welded on it is connected to the outer ring plate (5) by the high-strength bolts (6); S35. The multiple U-shaped joint steel bars (11) connected to the steel bar connector (8) are staggered and overlapped with the multiple U-shaped joint steel bars (11) welded on the joint square steel plate (10). S36. Ultra-high performance concrete (3) is poured into the gap between the joint square steel plate (10) and the cast-in-place concrete beam (14) to form a cast-in-place concrete joint (12).

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