Hollow sandwich steel pipe uhcp arch bridge and construction method thereof

Abstract

The application relates to a hollow sandwich steel pipe UHPC arch bridge and a construction method thereof. A main arch chord rod section comprises an outer steel pipe and an inner steel pipe arranged in the outer steel pipe, a ring-shaped sandwich layer with a size of 40mm-80mm is formed between the outer steel pipe and the inner steel pipe, a plurality of limiting blocks are arranged in the ring-shaped sandwich layer, and coaxial positioning of the inner steel pipe and the outer steel pipe is realized. Micro-expansion UHPC is used to fill the ring-shaped sandwich layer, and a high section hollow rate of 0.85-0.95 is adopted, so that the structural self weight is reduced under the premise of guaranteeing the structural bearing capacity and the rigidity. The anchoring space in the inner flange is communicated with the ring-shaped sandwich layer and filled with micro-expansion UHPC, so that the connecting joint and the main arch chord rod section form a continuous stress whole, and the outer steel pipe transmits the axial tension through welding connection with the joint pipe. In the construction, the inner flange and the main arch chord rod section are prefabricated together, and there is no need to pour in the construction site, and there is no need to set a wet joint for the section connection.

Description

Technical Field

[0001] This application relates to the field of arch bridge construction technology, and in particular to hollow hollow steel tube (UHPC) arch bridges and their construction methods. Background Technology

[0002] Steel-concrete composite arch bridges, with their advantages of rational stress distribution and high load-bearing capacity, have been widely used in bridge engineering for highways and railways. Traditional steel-concrete composite arch bridge construction relies on first erecting and closing the main arch's hollow steel pipes, then pumping concrete into the pipes on-site. This process is complex, time-consuming, and suffers from poor quality control of the concrete pouring, with common problems such as localized voids and debonding from the steel pipe walls. Furthermore, this method involves a large amount of high-altitude work, posing significant safety risks and making it unsuitable for the current trend of rapid, prefabricated bridge construction. In terms of structural stress, during the hollow steel pipe erection phase, the steel pipe components must bear their own weight and the wet weight load of the subsequently poured concrete. As the arch span increases, the steel pipe wall thickness also increases, not only increasing steel consumption and component processing difficulty but also limiting the development of structures with larger spans.

[0003] In related technologies, hollow-core steel-concrete composite structures have emerged, such as the steel-concrete composite truss bridge with built-in transverse connection structure described in Chinese patent CN219671058U. The hollow interlayer is filled with ordinary concrete, and many connecting components such as U-shaped connectors, studs and connecting cables need to be installed in the hollow interlayer. The overall structure is complex, the construction is cumbersome and difficult, and the force transmission path at the nodes is unclear. It is not suitable for use in large-span steel-concrete arch bridge structures.

[0004] Regarding the connection technology of arch rib segments, the hollow steel pipe arch rib segments of ordinary steel-concrete composite arch bridges mostly adopt the internal flange bolt connection method. For example, Chinese patent CN222771296U describes an arch rib installation and docking structure for a large-span steel-concrete composite arch bridge. It optimizes the alignment and docking efficiency of the arch ribs by setting a sleeve structure, but it does not change the fact that the internal flange is a temporary connection structure. This type of connection is only used as a temporary construction structure. It is necessary to ensure that the concrete can pass smoothly during pumping to form continuous concrete inside the pipe. After the concrete has cured and gained strength, the connection structure no longer bears the main load-bearing function. The material utilization rate is low, and the overall stress performance of the joint is not fully utilized.

[0005] In summary, existing steel-concrete composite arch bridges and related improved structures still suffer from technical defects such as low degree of prefabrication during construction, high safety risks, complex hollow sandwich structure, and limited stress performance of connection nodes. There is an urgent need to propose a new arch bridge structure to solve the above problems. Summary of the Invention

[0006] Therefore, it is necessary to provide a hollow steel tube UHPC arch bridge and its construction method to address the above problems.

[0007] A hollow-core steel tube UHPC arch bridge is disclosed. The UHPC arch bridge includes a main arch chord segment, an inner flange, and a joint pipe. The main arch chord segment includes an outer steel pipe and an inner steel pipe disposed within the outer steel pipe, forming an annular sandwich. Multiple limiting blocks are spaced around the axis of the inner steel pipe within the annular sandwich to ensure that the inner and outer steel pipes are coaxial. The annular sandwich is filled with micro-expansion UHPC concrete, and the thickness of the annular sandwich is 40mm–80mm. The cross-section of the main arch chord segment is hollow. The heart rate is 0.85–0.95. The end of the main arch chord segment is provided with the inner flange, and an anchoring space is formed within the inner flange. The anchoring space communicates with the annular interlayer of the main arch chord segment, and the anchoring space is filled with micro-expansion UHPC concrete consistent with the annular interlayer. A connection area is formed at the end of the inner flange outside the anchoring space, and the connection areas of the two main arch chord segments are connected by bolts. The joint pipe is sleeved outside the inner flange, and both ends of the joint pipe are respectively connected to the outer steel pipes of the two main arch chord segments.

[0008] In one embodiment, the inner flange includes an end plate, a first cover plate, a connecting plate, and a second cover plate. The second cover plate is disposed on the inner wall of one end of the inner steel pipe. The end plate and the second cover plate are spaced apart and opposite to each other and located outside the outer steel pipe. One end of the first cover plate is connected to the inner wall of one end of the outer steel pipe, and the other end is connected to the end plate, so that the first cover plate, the end plate, and the second cover plate form an anchoring space. One end of the connecting plate abuts against the end face of the inner steel pipe, and the other end abuts against the end plate. The first cover plate and the joint pipe support form a connecting space. When the end plates of the inner flanges of the two main arch chord segments are connected, the outer ring of the end plate is the bolt connection area located within the connecting space, and the connecting areas of the two end plates are connected by bolts.

[0009] In one embodiment, the sides of the connecting plate are, in sequence, a first side, a second side, a third side, a fourth side, and a fifth side. The first side abuts against the end face of the inner steel pipe, the adjacent second side is connected to the inner wall of the outer steel pipe, the third side is connected to the inner wall of the first cover plate, the fourth side is connected to the inner wall of the end plate, and the fifth side is located within the anchoring space. There are multiple connecting plates, and the multiple connecting plates are spaced apart around the axis of the outer steel pipe on the inner wall of the first cover plate.

[0010] In one embodiment, the outer diameter of the outer steel pipe is 800mm~1800mm, the wall thickness of the outer steel pipe is 10mm~30mm, and the wall thickness of the inner steel pipe is 8mm~22mm; the annular interlayer is filled with micro-expansion UHPC concrete of UHPC120 to UHPC180; and the volume content of steel fibers in the micro-expansion UHPC concrete is 1%.

[0011] In one embodiment, the main arch chord segment includes at least two straight sleeves. Each straight sleeve includes an outer steel pipe and an inner steel pipe disposed inside the outer steel pipe. At least two limiting blocks are provided in the annular interlayer at one end of the inner and outer steel pipes. Each limiting block is spaced apart around the axis of the inner steel pipe, and the thickness of the limiting block is the same as the thickness of the annular interlayer. The inner steel pipes of two adjacent straight sleeves are welded together, and the outer steel pipes are welded together. Adjacent straight sleeves are connected to the end of a straight sleeve where the limiting blocks are provided.

[0012] In one embodiment, the hollow sandwich steel tube UHPC arch bridge also includes vertical web members and diagonal web members. The vertical web members and diagonal web members are provided between the upper chord and the lower chord formed by splicing the main arch chord segments. A stiffening ring plate is provided on the inner wall of the inner steel tube at the intersection of the center line of the vertical web members and the center line of the main arch chord segment.

[0013] In one embodiment, the hollow sandwich steel tube UHPC arch bridge also includes an arch abutment and chord embedded steel pipe sections. The chord embedded steel pipe sections are welded to the outer steel pipe of the main arch chord segment located at the arch abutment. The connection positions of the chord embedded steel pipe sections and the main arch chord segment are all located within the arch abutment. A capping steel plate is installed inside the inner steel pipe of the main arch chord segment near the arch abutment. Concrete is poured into the chord embedded steel pipe sections and the inner steel pipe below the capping steel plate.

[0014] A construction method for a hollow hollow steel tube UHPC arch bridge, applied to the aforementioned hollow hollow steel tube UHPC arch bridge, the construction method comprising: The outer steel pipe is sleeved on the inner steel pipe to form the main arch chord segment. Micro-expansion UHPC concrete is poured into the annular interlayer between the inner and outer steel pipes to complete the prefabrication of each main arch chord segment. Pre-embed steel pipes for the chord section in the arch seat, and weld the main arch chord segment located at the arch seat to the pre-embedded steel pipes to form the arch foot, and then inject concrete into the arch foot. The other main arch chord segments are hoisted into place according to the design position. After the adjacent two main arch chord segments are connected by inner flange bolts, they are welded together by joint pipes to form a hollow sandwich steel pipe UHPC arch bridge.

[0015] In one embodiment, the outer steel pipe is sleeved on the inner steel pipe to form the main arch chord segment, including: In the factory, steel plates are rolled and welded to form inner and outer steel pipes. The outer steel pipe is then placed on the inner steel pipe and vertically on a support so that the outer and inner steel pipes are coaxial. At least two limiting blocks are then set in the annular interlayer at one end of the outer and inner steel pipes to form a straight sleeve. Weld the adjacent inner steel pipes to the inner steel pipes of the completed straight sleeve, then insert the outer steel pipe into the adjacent inner steel pipe, and set a limiting block in the annular interlayer at the end of the inner steel pipe and the outer steel pipe away from the completed straight sleeve, then weld the outer steel pipe to the outer steel pipe of the completed straight sleeve; cyclically connect the inner steel pipe and the outer steel pipe until the processing of the main arch chord segment is completed.

[0016] In one embodiment, a pre-embedded steel pipe section of the chord is pre-embedded within the arch abutment, and the main arch chord segment located at the arch abutment is welded to the pre-embedded steel pipe section of the chord to form the arch foot. Concrete is then injected into the arch foot, including: Pre-embed steel pipes for the chord members within the arch abutment; The outer steel pipe of the main arch chord segment located at the arch abutment is welded to the pre-embedded steel pipe of the chord segment through a closure joint to form the arch foot. A cover plate is installed inside the inner steel pipe of the main arch chord segment near the arch seat; Concrete is injected into the inner steel pipe below the pre-embedded section of the chord and the capping steel plate; Concrete for sealing the arch is poured on the arch abutment so that the connection between the main arch chord segment and the pre-embedded steel pipe of the chord is located inside the concrete for sealing the arch, and the cover steel plate is located outside the concrete for sealing the arch.

[0017] Compared with existing technologies, the above-mentioned hollow steel tube UHPC arch bridge and its construction method have at least the following advantages: By setting multiple limiting blocks spaced at intervals around the axis of the inner steel pipe within the annular interlayer, coaxial positioning of the inner and outer steel pipes can be achieved, eliminating the need for complex connecting components, simplifying the internal structure and prefabrication process, and reducing processing difficulty and cost. Using micro-expansion UHPC concrete to fill the annular interlayer between the inner and outer steel pipes, combined with a high cross-sectional void ratio of 0.85–0.95, significantly reduces the structure's self-weight and foundation load while ensuring structural bearing capacity and stiffness. The annular interlayer thickness design of 40mm–80mm is adapted to the material pouring characteristics of UHPC, ensuring dense and uniform concrete pouring within the interlayer and guaranteeing construction quality.

[0018] The anchoring space inside the inner flange is connected to the annular interlayer and filled with micro-expansion UHPC concrete of the same material, making the connection node and the main arch chord segment a continuous load-bearing unit. The inner flange transmits most of the axial pressure through bolts, while the outer steel pipe transmits most of the axial tensile force through welding to the joint pipe. This achieves reliable force transmission between segments and overall coordinated work, changing the traditional attribute of flanges as only temporary construction structures. Furthermore, the inner flange is prefabricated together with the main arch chord segment during construction, eliminating the need for on-site grouting. Wet joints are not required between the main arch chord segments, and the inner flange can be made of a solid steel plate without holes, ensuring continuous and reliable force transmission.

[0019] The aforementioned hollow-core steel pipe UHPC arch bridge employs a hollow-core main arch chord segment design, significantly reducing the structure's self-weight while ensuring dense and uniform concrete pouring within the interlayer, thus guaranteeing construction quality. Segment connections are quickly achieved via bolts on the outer side of the inner flange, with externally fitted joint pipes providing sealing protection. This design balances the load-bearing capacity and durability of the joints, avoiding the stress concentration and weak load-bearing issues of traditional connection joints. Furthermore, no on-site die-casting concrete is required, effectively improving construction efficiency. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the various components are shown in the drawings only as examples and not necessarily to actual scale.

[0023] Figure 1 This is a schematic diagram of a hollow steel tube UHPC arch bridge.

[0024] Figure 2 for Figure 1 A magnified view of a portion of the main arch.

[0025] Figure 3 for Figure 2 The cross-sectional view of the main arch along line AA is shown.

[0026] Figure 4 Sectional view of the main arch chord segment Figure 1 .

[0027] Figure 5 Sectional view of the main arch chord segment Figure 2 .

[0028] Figure 6 Partial sectional view of the main arch chord segment, inner flange, and joint pipe.

[0029] Figure 7 for Figure 6 The cross-sectional view of the main arch chord segment and inner flange along line CC is shown.

[0030] Figure 8 This is a structural diagram of the arch base and arch foot.

[0031] Explanation of reference numerals in the attached figures: 10. Hollow Core Steel Pipe UHPC Arch Bridge; 100. Main Arch Chord Segment; 102. Straight Sleeve; 104. Upper Chord; 106. Lower Chord; 110. Outer Steel Pipe; 120. Inner Steel Pipe; 130. Annular Sandwich; 140. Limiting Block; 150. Stiffening Circular Plate; 200. Vertical Web Member; 300. Diagonal Web Member; 400. Inner Flange; 410. Anchorage Space; 420. End Plate; 430. First Cover Plate; 440. Connecting Plate; 450. Second Cover Plate; 460. Connecting Space; 500. Joint Pipe; 600. Arch Seat; 610. Chord Embedded Section Steel Pipe; 620. Detailed Implementation

[0032] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0033] See Figures 1 to 4In one embodiment of this application, a hollow steel tube UHPC arch bridge 10 is provided. The hollow steel tube UHPC arch bridge 10 includes a main arch chord segment 100. The main arch chord segment 100 includes an outer steel tube 110 and an inner steel tube 120 disposed inside the outer steel tube 110. An annular sandwich 130 is formed between the outer steel tube 110 and the inner steel tube 120. A plurality of limiting blocks 140 are provided in the annular sandwich 130 at intervals around the axis of the inner steel tube 120 so that the inner steel tube 120 and the outer steel tube 110 are coaxially arranged. The annular sandwich 130 is filled with micro-expansion UHPC concrete, and the thickness of the annular sandwich 130 is 40mm to 80mm. The cross-sectional hollowness of the main arch chord segment 100 is 0.85 to 0.95. The cross-sectional hollowness ratio is the ratio of the outer diameter of the inner steel pipe 120 to the inner diameter of the outer steel pipe 110, or the ratio of the area of ​​the outer diameter of the inner steel pipe 120 to the area of ​​the inner diameter of the outer steel pipe 110. The thickness of the annular interlayer 130 refers to the radial width, that is, the distance from the inner wall of the outer steel pipe 110 to the outer wall of the inner steel pipe 120.

[0034] By setting multiple limiting blocks 140 spaced around the axis of the inner steel pipe 120 within the annular interlayer 130, coaxial positioning of the inner steel pipe 120 and the outer steel pipe 110 can be achieved without complex connecting components, simplifying the internal structure and prefabrication construction process. The annular interlayer 130 between the inner and outer steel pipes 120 is filled with micro-expansion UHPC concrete, coupled with a high cross-sectional void ratio of 0.85–0.95, significantly reducing the structural self-weight and foundation load while ensuring structural bearing capacity and stiffness. The 40mm–80mm thickness of the annular interlayer 130 is designed to match the material pouring characteristics of UHPC, ensuring dense and uniform concrete pouring within the interlayer. This meets the structural stress requirements while also considering the fluidity of UHPC during injection and the control requirements of the self-weight of the fully prefabricated segments, ensuring construction quality. The main arch chord segment 100 of this application can be used in large-span steel-concrete composite arch bridges. Instead of relying on on-site casting of concrete inside the pipe, it adopts an installation method of assembling the entire prefabricated main arch chord segment 100. This improves material strength and reduces structural weight without significantly increasing steel consumption, utilizing ultra-high performance concrete (UHPC) combined with a high void ratio design to form a lightweight and high-strength component.

[0035] In one embodiment, the outer diameter of the outer steel pipe 110 is 800mm~1800mm, the wall thickness of the outer steel pipe 110 is 10mm~30mm, and the wall thickness of the inner steel pipe 120 is 8mm~22mm; micro-expansion UHPC concrete of UHPC120 to UHPC180 is poured into the annular interlayer 130; and the volumetric content of steel fibers in the micro-expansion UHPC concrete is 1% of the total volume. Preferably, micro-expansion, shrinkage-compensating, and vibration-free UHPC is used. Although the volumetric content of steel fibers in the micro-expansion UHPC concrete is reduced, the main arch chord segment 100 can meet the compressive strength requirements due to the constricting effect of the hollow interlayer steel pipe on the concrete, thus saving material costs.

[0036] In this embodiment, the outer steel pipe 110 has an outer diameter of 900 mm and a wall thickness reduced to 12 mm; the inner steel pipe 120 has an outer diameter of 776 mm and a wall thickness of 10 mm; the annular interlayer 130 has a thickness of 50 mm and is filled with UHPC120 grade ultra-high performance concrete (UHPC), whose standard value for axial compressive strength is 93 MPa, the design value is 56 MPa, and the cross-sectional void ratio is close to 0.886.

[0037] See Figure 4 and Figure 5 In one embodiment, the main arch chord segment 100 includes at least two straight sleeves 102. Each straight sleeve 102 includes an outer steel pipe 110 and an inner steel pipe 120 disposed inside the outer steel pipe 110. At least two limiting blocks 140 are provided in the annular interlayer 130 at one end of the inner steel pipe 120 and the outer steel pipe 110. Each limiting block 140 is spaced apart around the axis of the inner steel pipe 120, and the thickness of the limiting block 140 is the same as the thickness of the annular interlayer 130. The inner steel pipes 120 of two adjacent straight sleeves 102 are welded together, and the outer steel pipes 110 are welded together. The adjacent straight sleeves 102 are connected to the end of the straight sleeve 102 where the limiting blocks 140 are provided.

[0038] In this embodiment, the steel pipes in the main arch chord segment 100 are generally rolled and welded from steel plates in a factory. The rolled pipes are typically straight pipes. Therefore, the main arch chord segment 100 generally includes multiple short straight sleeves 102 that fit the curve of the main arch rib. The length of the factory-processed straight sleeves 102 is 2000mm~2500mm. In this application, the hollow sandwich steel pipe UHPC arch bridge 10 sets the length of the processed straight sleeves 102 to 2500mm. To ensure that the thickness of the annular sandwich 130 between the inner steel pipe 120 and the outer steel pipe 110 of the straight sleeve 102 is 50mm, three limiting blocks 140 are uniformly welded 25mm from the end of the steel pipe to limit and fix the lateral relative distance between the inner steel pipe 120 and the outer steel pipe 110.

[0039] The entire main arch chord segment 100 is prefabricated by dividing it into at least two standardized straight sleeve units 102, which solves the problems of high overall processing difficulty and difficulty in controlling forming accuracy of long arch rib segments. Within the annular interlayer 130 at the end of the straight sleeve 102, limiting blocks 140 are arranged at intervals around the axis of the inner steel pipe 120, with the thickness of the limiting blocks 140 being completely consistent with the thickness of the annular interlayer 130. This ensures the coaxiality of the inner and outer steel pipes 110, avoids the misalignment of the inner steel pipe 120, and ensures that the thickness of the annular interlayer 130 is uniform along the circumference and axial direction. The limiting blocks 140 also serve as internal support components between the inner steel pipe 120 and the outer steel pipe 110. During the welding of adjacent straight sleeves 102, they can effectively resist local deformation of the inner steel pipe 120 or the outer steel pipe 110 caused by welding thermal stress, control the cross-sectional shape and position accuracy during the welding process, and avoid welding defects such as out-of-roundness, dents, and misalignment. All splicing and welding operations of the straight sleeves 102 can be completed in the factory.

[0040] In this embodiment, the main arch chord of the hollow sandwich steel tube UHPC arch bridge 10 can be divided into 12 prefabricated main arch chord segments 100. Each main arch chord segment 100 is formed by splicing at least two straight sleeves 102, so as to control the load of a single main arch chord segment 100 and reduce the construction difficulty.

[0041] See Figure 2 and Figure 3 In one embodiment, the hollow steel tube UHPC arch bridge 10 further includes vertical web members 200 and diagonal web members 300. The vertical web members 200 and diagonal web members 300 are provided between the upper chord 104 and lower chord 106, which are formed by splicing the main arch chord segments 100. A stiffening ring plate 150 is provided on the inner wall of the inner steel tube 120 at the intersection of the center lines of the vertical web members 200 and the main arch chord segments 100. Specifically, the stiffening ring plate 150 has a thickness of 20 mm and a width of 356 mm. To address the complex local stress caused by concentrated forces at the suspension points, stiffening ring plates 150 are respectively provided on the inner wall of the inner steel tube 120 at the intersection of the center lines of the vertical web members 200 and the upper chord 104 and lower chord 106 to enhance local stability and prevent buckling. Meanwhile, the stiffening ring plate 150 can directly constrain the radial deformation of the inner steel pipe 120, improve the local stability bearing capacity and bending stiffness of the inner steel pipe 120, compensate for the stress deficiency of the unsupported inner wall of the hollow structure, and avoid local depression and plastic buckling failure of the inner steel pipe 120 under concentrated loads. The stiffening ring plate 150 can be welded and installed simultaneously during the factory prefabrication stage of the inner steel pipe 120.

[0042] See Figures 6 to 7In one embodiment, the hollow steel tube UHPC arch bridge 10 further includes an inner flange 400 and a joint pipe 500. The end of the main arch chord segment 100 is provided with an inner flange 400, and an anchoring space 410 is formed inside the inner flange 400. The anchoring space 410 is connected to the annular interlayer 130 of the main arch chord segment 100. The anchoring space 410 is filled with micro-expansion UHPC concrete consistent with the annular interlayer 130. The end of the inner flange 400 and outside the anchoring space 410 form a connection area. The connection areas of the two main arch chord segments 100 are connected by bolts. The joint pipe 500 is sleeved outside the inner flange 400, and the two ends of the joint pipe 500 are respectively connected to the outer steel pipes 110 of the two main arch chord segments 100.

[0043] The anchoring space 410 inside the inner flange 400 is connected to the annular interlayer 130 and filled with micro-expansion UHPC concrete of the same material, making the connection node and the main arch chord segment 100 form a continuous load-bearing whole. The inner flange 400 transmits most of the axial pressure through bolts, and the outer steel pipe 110 transmits most of the axial tensile force through welding connection with the joint pipe 500, realizing reliable force transmission between segments and overall coordinated work, changing the traditional attribute of flanges as only temporary construction structures. At the same time, the inner flange 400 and the main arch chord segment 100 are prefabricated together during construction, eliminating the need for on-site grouting. The connection between the main arch chord segments 100 does not require wet joints, and the inner flange 400 can be made of solid steel plate without holes, ensuring continuous and reliable force transmission.

[0044] Specifically, the inner flange 400 includes an end plate 420, a first cover plate 430, a connecting plate 440, and a second cover plate 450. The second cover plate 450 is disposed on the inner wall of one end of the inner steel pipe 120. The end plate 420 and the second cover plate 450 are spaced apart and opposite to each other, located outside the outer steel pipe 110. One end of the first cover plate 430 is connected to the inner wall of one end of the outer steel pipe 110, and the other end is connected to the end plate 420, so that the first cover plate 430, the end plate 420, and the second cover plate 450 form an anchoring space 410. One end of the connecting plate 440 abuts against the end face of the inner steel pipe 120, and the other end abuts against the end plate 420. A closed anchoring space 410 is formed by the first cover plate 430, the end plate 420, and the second cover plate 450. This space is directly connected to the annular interlayer 130 of the main arch chord. After the micro-expansion UHPC is injected, the inner flange 400, the inner steel pipe 120, the outer steel pipe 110, and the UHPC in the annular interlayer 130 can form a rigid anchoring whole, avoiding the problems of stress concentration and weld cracking that are prone to occur when the traditional flange relies solely on the weld for force transmission. This improves the reliability of the node anchoring and the overall load-bearing performance. A connecting plate 440 is set between the end face of the inner steel pipe 120 and the end plate 420. It can bond with the UHPC in the anchoring area to transmit force and can also serve as an internal stiffening component of the end plate 420, improving the rigidity of the end plate 420 and preventing the end plate 420 from warping and failing. All steel plate components can be welded and assembled in the factory. The UHPC in the anchoring space 410 can be synchronously grouted and cured with the annular interlayer 130, realizing the integrated prefabrication of the ends of the main arch chord segment 100.

[0045] Furthermore, the first cover plate 430 and the joint pipe 500 support and enclose a connection space 460. When the end plates 420 of the inner flanges 400 of the two main arch chord segments 100 are joined, the outer ring of the end plate 420, which is the bolt connection area, is located within the connection space 460, and the connection areas of the two end plates 420 are connected by bolts. The first cover plate 430 and the outer joint pipe 500 together enclose the connection space 460. After the two main arch chord segments 100 are joined, the bolt connection area of ​​the outer ring of the end plate 420 is completely contained within this enclosed space, isolating the bolt connection pair from the external environment and preventing direct erosion by rainwater and other corrosive media. At the same time, the joint pipe 500 makes the outer surface of the node area continuous and smooth, which can also improve the overall appearance of the structure and reduce wind load.

[0046] In one embodiment, the sides of the connecting plate 440 are, in order, a first side, a second side, a third side, a fourth side, and a fifth side. The first side abuts against the end face of the inner steel pipe 120, the adjacent second side is connected to the inner wall of the outer steel pipe 110, the third side is connected to the inner wall of the first cover plate 430, the fourth side is connected to the inner wall of the end plate 420, and the fifth side is located within the anchoring space 410. The four sides of the connecting plate 440 are rigidly connected to the end face of the inner steel pipe 120, the inner wall of the outer steel pipe 110, the inner wall of the first cover plate 430, and the inner wall of the end plate 420, respectively. This connects the core component of the inner flange 400 with the inner steel pipe 120 and outer steel pipe 110 of the main arch chord segment 100 into an integral load-bearing frame. This simultaneously constrains the out-of-plane warping of the end plate 420, the radial deformation of the first cover plate 430, and the relative misalignment of the inner steel pipe 120 and outer steel pipe 110, thereby improving the overall bending, shear, and torsional stiffness of the node. The fifth side of the connecting plate 440 extends into the anchoring space 410. After the micro-expansion UHPC is injected, this side is completely embedded in the UHPC matrix, forming an embedded anchoring effect.

[0047] In this embodiment, there are multiple connecting plates 440, which are spaced apart on the inner wall of the first cover plate 430 around the axis of the outer steel pipe 110. The multiple connecting plates 440 are evenly distributed circumferentially, which can evenly distribute the nodal load along the entire circumference. When the nodal is subjected to bending moment, the connecting plates 440 in the tension and compression zones can respectively cooperate to bear the tensile and compressive stresses, thereby improving the bending bearing capacity and stress uniformity of the nodal. At the same time, it can also maintain the unobstructed communication between the anchoring space 410 and the annular interlayer 130.

[0048] In this embodiment, the outer steel pipe 110 extends 100mm from the first cover plate 430, and the length difference between the inner steel pipe 120 and the outer steel pipe 110 at their ends is 300mm. The 300mm axial depth provides sufficient bonding and anchoring length for the UHPC. The 100mm extension of the outer steel pipe 110 from the first cover plate 430 provides sufficient circumferential welding lap length for the outer joint pipe 500, ensuring sufficient weld leg size and connection strength between the joint pipe 500 and the outer steel pipe 110. Specifically, the length of the joint pipe 500 is 400mm. In other embodiments, the length of the joint pipe 500 can be set according to the distance between the two outer steel pipes 110 after the two inner flanges 400 are butted together.

[0049] See Figure 1 and Figure 8In one embodiment, the hollow sandwich steel tube UHPC arch bridge 10 also includes an arch seat 600 and a chord embedded section steel pipe 610. The chord embedded section steel pipe 610 is welded to the outer steel pipe 110 of the main arch chord segment 100 located at the arch seat 600. The chord embedded section steel pipe 610 and the connection position between the chord embedded section steel pipe 610 and the main arch chord segment 100 are all located inside the arch seat 600. A cover steel plate 620 is provided in the inner steel pipe 120 of the main arch chord segment 100 near the arch seat 600. Concrete is poured into the inner steel pipe 120 below the cover steel plate 620 and the chord embedded section steel pipe 610. The steel pipe 610 of the chord pre-embedded section is welded to the outer steel pipe 110 of the main arch chord, and the entire connection section is embedded in the concrete of the arch seat 600. With the design of pouring solid concrete below the cover steel plate 620, the arch foot anchorage section is transformed from a hollow section to a solid steel pipe concrete section, which greatly improves the axial compressive strength, shear strength and local bearing capacity of the anchorage section.

[0050] The aforementioned hollow-core steel pipe UHPC arch bridge 10 employs a hollow-core main arch chord segment design of 100, significantly reducing the structure's self-weight while ensuring dense and uniform concrete pouring within the interlayer, thus guaranteeing construction quality. The inner flange 400 utilizes bolts for rapid segment connection, and an external joint pipe 500 provides sealing protection, balancing the joint's load-bearing capacity and durability, and avoiding the stress concentration and weak load-bearing issues of traditional connection joints. No die-cast concrete is required on-site, effectively improving construction efficiency.

[0051] Traditional steel-concrete composite arch bridges use fully cast-in-place concrete within the arch rib steel tubes, with a wall thickness typically between 20mm and 24mm, filled with C55 self-compacting shrinkage-compensating concrete. This paper compares the load-bearing capacity of key components and the overall structure of the hollow-core steel-concrete composite UHPC arch bridge 10 in this application, based on a finite element model and load combinations according to current specifications. Both schemes' main arch structures meet the load-bearing capacity requirements. The most unfavorable section is located at the arch foot, and its load-bearing capacity verification results are shown in Table 1.

[0052] Table 1. Design values ​​of internal forces in the upper and lower chord members of the arch rib at the most unfavorable arch foot and allowable values ​​of axial force under eccentric compression in single tubes of 106.

[0053] Analysis shows that although the axial bearing capacity of a single component of the hollow sandwich steel tube UHPC arch bridge 10 of this application is slightly lower than that of the traditional scheme, the self-weight of the main arch structure is significantly reduced by about 50%, and the internal force level of the entire bridge is reduced accordingly. In the end, the safety factor of each control section still meets the specification requirements, which verifies the feasibility and safety of the technical solution of the hollow sandwich steel tube UHPC arch bridge 10 of this application.

[0054] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing this application and for simplification, 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. Therefore, they should not be construed as limitations on this application. Furthermore, the term "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0055] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0056] See Figures 1 to 3 In one embodiment, this application also describes a construction method for a hollow steel tube UHPC arch bridge 10, applicable to the hollow steel tube UHPC arch bridge 10 in any of the above embodiments. Specifically, the construction method includes: Step S1: The outer steel pipe 110 is fitted onto the inner steel pipe 120 to form the main arch chord segment 100. Micro-expansion UHPC concrete is poured into the annular interlayer 130 between the inner steel pipe 120 and the outer steel pipe 110, completing the prefabrication of each main arch chord segment 100. Specifically, forming the main arch chord segment 100 by fitting the outer steel pipe 110 onto the inner steel pipe 120 includes: In the factory, steel plates are rolled and welded to form an inner steel pipe 120 and an outer steel pipe 110. The outer steel pipe 110 is fitted onto the inner steel pipe 120 and placed vertically on a support so that the outer steel pipe 110 and the inner steel pipe 120 are coaxial. Then, at least two limiting blocks 140 are set in the annular interlayer 130 at one end of the outer steel pipe 110 and the inner steel pipe 120 to form a straight sleeve. Weld adjacent inner steel pipes 120 to the inner steel pipes 120 of the completed straight sleeve, then insert an outer steel pipe 110 into the adjacent inner steel pipes 120, and set a limiting block 140 in the annular interlayer 130 at the end of the inner steel pipe 120 and the outer steel pipe 110 away from the completed straight sleeve, then weld the outer steel pipe 110 to the outer steel pipe 110 of the completed straight sleeve; cyclically connect the inner steel pipe 120 and the outer steel pipe 110 until the processing of the main arch chord segment 100 is completed.

[0057] Furthermore, micro-expansion UHPC concrete is injected into the annular interlayer 130 between the inner steel pipe 120 and the outer steel pipe 110. The micro-expansion UHPC concrete is simultaneously die-cast into the anchoring space 410 of the inner flange 400 so that the inner flange 400 and the main arch chord segment 100 form an integral load-bearing component.

[0058] Step S2: Embed the chord pre-embedded section steel pipe 610 in the arch seat 600, and weld the main arch chord segment 100 located at the arch seat 600 to the chord pre-embedded section steel pipe 610 to form the arch foot, and then inject concrete into the arch foot.

[0059] Specifically, step S2 includes: Pre-embed steel pipe 610 of chord member pre-embedded section in arch seat 600; The outer steel pipe 110 of the main arch chord segment 100 located at the arch abutment 600 is connected to the chord embedded section steel pipe 610 by welding through a closure joint to form the arch foot. A cover plate 620 is installed inside the inner steel pipe 120 of the main arch chord segment 100 near the arch seat 600; Concrete is injected into the inner steel pipe 120 below the pre-embedded section steel pipe 610 and the capping steel plate 620 of the chord member; Concrete for sealing the arch is poured on the arch seat 600 so that the connection between the main arch chord segment 100 and the chord embedded section steel pipe 610 is located inside the concrete for sealing the arch, and the cover steel plate 620 is located outside the concrete for sealing the arch.

[0060] Step S3: Hoist the other main arch chord segments 100 into place according to the design position. After the adjacent two main arch chord segments 100 are bolted together with inner flanges 400, they are welded together with joint pipes 500 to form a hollow sandwich steel pipe UHPC arch bridge 10.

[0061] By setting limiting blocks 140 at the ends of the inner steel pipe 120 and the outer steel pipe 110, the radial relative position of the inner steel pipe 120 and the outer steel pipe 110 can be limited, ensuring coaxiality and uniformity of the thickness of the annular interlayer 130. The overall welding of long segments is broken down into multi-stage, step-by-step operations, dispersing welding thermal stress and effectively avoiding problems such as the accumulation of welding deformation in long components. Simultaneously, the micro-expansion UHPC is poured in a factory environment, ensuring stable operating conditions and avoiding material performance degradation caused by insufficient on-site curing conditions. This method transfers the core processing and UHPC pouring of the main arch chord segment 100 entirely to the factory, combined with a refined segment-by-segment splicing process, achieving standardized, high-quality, and high-efficiency component production. For the construction of the arch abutment 600 and the arch foot, the steel pipe 610 of the pre-embedded chord section is first pre-embedded during the construction stage of the arch abutment 600. Subsequently, the precast arch foot segment is welded to the pre-embedded section on site. The boundary between the solid anchorage section of the arch foot and the upper hollow main body section is precisely defined by the capping steel plate 620. At the same time, the capping steel plate 620 is set outside the arch sealing concrete to keep the stiffness transition section in the design stress position and avoid stress concentration caused by abrupt change in cross-sectional stiffness. As the most critical part of the entire bridge under stress, the arch foot is constructed in this way. Through the process design of pre-embedded positioning, zoned grouting, and full-embedded protection, the construction operability and the structural performance of the completed bridge are taken into account.

[0062] On-site installation requires only hoisting and alignment, tightening of 400mm bolts on the inner flange, and welding of 500mm welded joint pipes. It eliminates the need for complex operations such as high-altitude concrete pumping and prolonged on-site curing, significantly shortening the on-site construction period and reducing labor and machinery costs. This construction method completely abandons the traditional method of erecting and closing empty steel pipes and pumping concrete into the pipes on-site, achieving fully prefabricated dry assembly of the arch ribs, resulting in a qualitative improvement in construction efficiency and safety.

[0063] Unless otherwise stated, the numerical parameters set forth in this specification and the appended claims are approximate values ​​and may vary depending on the desired properties to be obtained by attempting to obtain the subject matter disclosed herein. As used herein, values ​​or amounts of mass, weight, time, volume, concentration, or percentage mean, in some embodiments, ±20%; in some embodiments, ±10%; in some embodiments, ±5%; in some embodiments, ±1%; in some embodiments, ±0.5%; and in some embodiments, ±0.1%, as these differences are suitable for performing the methods disclosed herein.

[0064] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A hollow-core steel tube UHPC arch bridge, characterized in that, The hollow-core steel tube UHPC arch bridge includes: The main arch chord segment comprises an outer steel pipe and an inner steel pipe disposed within the outer steel pipe, forming an annular interlayer. Multiple limiting blocks are spaced apart around the axis of the inner steel pipe within the annular interlayer to ensure that the inner and outer steel pipes are coaxially aligned. The annular interlayer is filled with micro-expansion UHPC concrete, and its thickness is 40mm–80mm. The cross-sectional void ratio of the main arch chord segment is 0.85–0.

95. The inner flange and joint pipe are provided at the end of the main arch chord segment. The inner flange includes an end plate, a first cover plate, a connecting plate, and a second cover plate. The second cover plate is disposed on the inner wall of one end of the inner steel pipe. The end plate and the second cover plate are spaced apart and opposite to each other and located outside the outer steel pipe. One end of the first cover plate is connected to the inner wall of one end of the outer steel pipe, and the other end is connected to the end plate, so that the first cover plate, the end plate, and the second cover plate form an anchoring space, and the anchoring space is connected to the annular interlayer of the main arch chord segment. The anchoring space is filled with […]. The annular interlayer is made of consistent micro-expansion UHPC concrete; one end of the connecting plate abuts against the end face of the inner steel pipe, and the other end abuts against the end plate; the end of the inner flange and the anchoring space form a connection area, and the first cover plate and the joint pipe form a connection space. When the end plates of the inner flanges of the two main arch chord segments are joined, the outer ring of the end plate is a bolt connection area and is located in the connection space. The connection areas of the two end plates are connected by bolts; the joint pipe is sleeved on the inner flange, and both ends of the joint pipe are respectively connected to the outer steel pipes of the two main arch chord segments.

2. The hollow-core steel tube UHPC arch bridge according to claim 1, characterized in that, The sides of the connecting plate are, in sequence, a first side, a second side, a third side, a fourth side, and a fifth side. The first side abuts against the end face of the inner steel pipe, the adjacent second side is connected to the inner wall of the outer steel pipe, the third side is connected to the inner wall of the first cover plate, the fourth side is connected to the inner wall of the end plate, and the fifth side is located within the anchoring space. There are multiple connecting plates, which are spaced apart around the axis of the outer steel pipe on the inner wall of the first cover plate.

3. The hollow-core steel tube UHPC arch bridge according to claim 1 or 2, characterized in that, The outer steel pipe has an outer diameter of 800mm to 1800mm and a wall thickness of 10mm to 30mm. The inner steel pipe has a wall thickness of 8mm to 22mm. The annular interlayer is filled with micro-expansion UHPC concrete of UHPC120 to UHPC180. The volume fraction of steel fibers in the micro-expansion UHPC concrete is 1%.

4. The hollow-core steel tube UHPC arch bridge according to claim 1 or 2, characterized in that, The main arch chord segment includes at least two straight sleeves. Each straight sleeve includes an outer steel pipe and an inner steel pipe disposed inside the outer steel pipe. At least two limiting blocks are provided in the annular interlayer at one end of the inner and outer steel pipes. Each limiting block is spaced apart around the axis of the inner steel pipe, and the thickness of the limiting block is the same as the thickness of the annular interlayer. The inner steel pipes of two adjacent straight sleeves are welded together, and the outer steel pipes are welded together. Adjacent straight sleeves are connected to the end of a straight sleeve where the limiting blocks are provided.

5. The hollow-core steel tube UHPC arch bridge according to claim 1 or 2, characterized in that, It also includes vertical web members and diagonal web members. The vertical web members and diagonal web members are provided between the upper chord and the lower chord formed by splicing the main arch chord segments. A stiffening ring plate is provided on the inner wall of the inner steel pipe at the intersection of the center line of the vertical web member and the center line of the main arch chord segment.

6. The hollow sandwich steel tube UHPC arch bridge according to claim 1 or 2, characterized in that, It also includes an arch seat and a pre-embedded steel pipe section for the chord members. The pre-embedded steel pipe section for the chord members is welded to the outer steel pipe of the main arch chord member segment located at the arch seat. The pre-embedded steel pipe section for the chord members and the connection points between the pre-embedded steel pipe section for the chord members and the main arch chord member segment are all located within the arch seat. A capping steel plate is installed inside the inner steel pipe of the main arch chord member segment near the arch seat. Concrete is poured into the pre-embedded steel pipe section for the chord members and the inner steel pipe below the capping steel plate.

7. A construction method for a hollow hollow steel tube UHPC arch bridge, applicable to the hollow hollow steel tube UHPC arch bridge according to any one of claims 1-6, characterized in that, The construction method includes: The outer steel pipe is sleeved on the inner steel pipe to form the main arch chord segment. Micro-expansion UHPC concrete is poured into the annular interlayer between the inner and outer steel pipes to complete the prefabrication of each main arch chord segment. Pre-embed steel pipes for the chord section in the arch seat, and weld the main arch chord segment located at the arch seat to the pre-embedded steel pipes to form the arch foot, and then inject concrete into the arch foot. The other main arch chord segments are hoisted into place according to the design position. After the adjacent two main arch chord segments are connected by inner flange bolts, they are welded together by joint pipes to form a hollow sandwich steel pipe UHPC arch bridge.

8. The construction method of the hollow sandwich steel tube UHPC arch bridge according to claim 7, characterized in that, The outer steel pipe is fitted onto the inner steel pipe to form the main arch chord segment, including: In the factory, steel plates are rolled and welded to form inner and outer steel pipes. The outer steel pipe is then placed on the inner steel pipe and vertically on a support so that the outer and inner steel pipes are coaxial. At least two limiting blocks are then set in the annular interlayer at one end of the outer and inner steel pipes to form a straight sleeve. Weld the adjacent inner steel pipes to the inner steel pipes of the completed straight sleeve, then insert the outer steel pipe into the adjacent inner steel pipe, and set a limiting block in the annular interlayer at the end of the inner steel pipe and the outer steel pipe away from the completed straight sleeve, then weld the outer steel pipe to the outer steel pipe of the completed straight sleeve; cyclically connect the inner steel pipe and the outer steel pipe until the processing of the main arch chord segment is completed.

9. The construction method of the hollow sandwich steel tube UHPC arch bridge according to claim 7, characterized in that, Pre-embedded steel pipes for the chord members within the arch abutment, and weld the main arch chord segments located at the arch abutment to the pre-embedded steel pipes to form the arch foot. Concrete is then poured into the arch foot, including: Pre-embed steel pipes for the chord members within the arch abutment; The outer steel pipe of the main arch chord segment located at the arch abutment is welded to the pre-embedded steel pipe of the chord segment through a closure joint to form the arch foot. A cover plate is installed inside the inner steel pipe of the main arch chord segment near the arch seat; Concrete is injected into the inner steel pipe below the pre-embedded section of the chord and the capping steel plate; Concrete for sealing the arch is poured on the arch abutment so that the connection between the main arch chord segment and the pre-embedded steel pipe of the chord is located inside the concrete for sealing the arch, and the cover steel plate is located outside the concrete for sealing the arch.

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