Steel-concrete combined y-shaped structure with inclined legs and construction method

Abstract

The application provides a steel-concrete combined Y-shaped inclined leg structure and a construction method, relates to the technical field of bridge engineering design and construction, and comprises a steel-concrete combined Y-shaped inclined leg structure and a staged construction support system. The steel-concrete combined Y-shaped inclined leg structure comprises a concrete Y-shaped pier, a steel inclined leg and a steel box girder, and steel-concrete combined sections are arranged at the inclined positions on the two sides of the concrete Y-shaped pier. In the design process, the main girder in the Y-shaped inclined leg rigid frame bridge is designed as a steel box girder, and the inclined leg structure is designed as a steel box inclined leg. Compared with the traditional concrete Y-shaped rigid frame bridge, the self weight is lighter, the stress on the root of the inclined leg is more favorable, the excellent mechanical properties of the steel material make the steel inclined leg better resist the load transmitted by the upper structure and the secondary internal force generated by the statically indeterminate system, the Y-shaped pier is poured with high-grade concrete, the compressive resistance of the concrete is fully utilized to resist the longitudinal thrust transmitted by the inclined leg, and the performance advantages of the respective components are fully utilized.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering design and construction technology, and in particular to a steel-concrete composite Y-shaped inclined leg structure and its construction method. Background Technology

[0002] With the increasing development of society, the demand for aesthetic appeal of bridges in municipal engineering projects is growing. Y-shaped inclined leg rigid frame bridges, with their unique shape and statically indeterminate structural system, have significant advantages in reducing the main span, lowering the beam height at the pier top section, and improving the stress distribution at the pier bottom section. They have appeared frequently in bridge construction projects across the country in recent years.

[0003] Traditional Y-shaped inclined-leg rigid frame bridge joints primarily utilize cast-in-place concrete. Compared to steel structures, concrete structures have a higher proportion of dead load. The Y-shaped inclined-leg joints bear a significant load transferred from the superstructure. Furthermore, the stress superposition of secondary internal forces generated by the statically indeterminate system results in a greater combined tensile stress that the structure must resist than that of a conventional bridge substructure. Relying solely on reinforced concrete for this purpose is neither economical nor practical. In some cases, additional prestressed steel strands may be necessary to ensure compressive stress reserves in the inclined legs, mitigate crack development, and ensure durability. Additionally, the shape of the Y-shaped inclined-leg joints makes traditional construction methods cumbersome. It requires first pouring the lower inclined-leg concrete and then the upper concrete box girder to form a unified structure. This typically involves full-span scaffolding or multi-point steel pipe column scaffolding systems. Before structural system conversion, both upper and lower scaffolding systems must be kept stably bearing load simultaneously, making on-site construction complex and severely limiting the work area. For bridges constructed over water, large-scale river diversion is also required, leading to excessive costs and time commitments.

[0004] Publication No. CN109537470A discloses a Y-shaped construction support structure with real-time adjustable inclined leg stress, and a cast-in-place inclined leg rigid frame and its support construction technology. Construction is carried out by setting up a large number of steel pipe columns and erecting upper and lower layers of full-span Bailey bridge supports. Temporary inclined tension structures are set at the pier locations, and the inclined leg stress is appropriately adjusted through temporary cables to improve the stress level of the large-angle Y-shaped concrete inclined legs. The complex and cumbersome arrangement of the temporary support system and the impact of segmented concrete pouring lead to a significant increase in construction costs and construction period. In water-related areas, large-scale river channel diversion and the construction of temporary trestle bridges are also required, further increasing costs and time, necessitating improvements. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems mentioned in the background section.

[0006] This invention adopts the following technical solution: a steel-concrete composite Y-shaped inclined leg structure, comprising a steel-concrete composite Y-shaped inclined leg structure and a phased construction support system. The steel-concrete composite Y-shaped inclined leg structure includes a concrete Y-shaped pier, steel inclined legs, and a steel box girder. Steel-concrete composite sections are provided at the inclined positions on both sides of the concrete Y-shaped pier. Each steel-concrete composite section includes a steel box girder and shear connection components. The steel box girder of the steel-concrete composite section contains a pressure-bearing anchorage system. This pressure-bearing anchorage system consists of cable guides, anchor plates, low-retraction prestressed steel strand tensioning end anchorages, force transmission diaphragms, and low-retraction prestressed steel strand anchorage end anchorages. The low-retraction prestressed steel strand tensioning end anchor is fixedly connected to the anchor plate, and a pressure plate is fixedly installed at one end of the force transmission diaphragm. The phased construction support system includes a Y-shaped pier support system, a Y-shaped pier precast steel formwork, a lower layer steel pipe support column of the Y-shaped steel-concrete joint, a transverse connection system of the lower layer steel pipe support column of the Y-shaped steel-concrete joint, an upper layer steel pipe support column of the Y-shaped steel-concrete joint, a longitudinal and transverse connection system of the upper layer steel pipe support column of the Y-shaped steel-concrete joint, a transverse load-bearing distribution beam, a Y-shaped inclined leg steel pipe support column, a transverse connection system of the Y-shaped inclined leg steel pipe support column, a steel box girder steel pipe support column, a transverse connection system of the steel box girder steel pipe support column, and a steel beam support load-bearing distribution beam.

[0007] Preferably, the steel box girder of the steel-concrete composite section is equipped with steel inclined leg partitions, and low-retraction prestressed steel strands and corrugated pipes are installed on both sides of the concrete Y-shaped pier at the positions of the steel box girder of the steel-concrete composite section. Here, the steel inclined leg partitions can ensure the overall stability of the steel box girder, and at the same time, the steel strands are arranged in a partially staggered manner in the transverse direction of the bridge during the structural design to ensure that there is still a clear space of not less than 30mm when the steel strands and corrugated pipes intersect, thus ensuring the compactness of the concrete pouring.

[0008] Preferably, a decorative panel is fixedly installed on the outer surface of the steel box of the steel-concrete composite section. Here, the decorative panel can achieve a smooth transition of the landscape curve between the concrete Y-shaped pier and the steel inclined leg.

[0009] Preferably, the interior of the concrete Y-shaped pier is equipped with a perforated plate shear connector, which consists of a perforated plate and reinforcing bars. The perforated plate is fixedly connected to the bearing plate by full penetration welding, and the reinforcing bars pass through the perforated plate, forming a fixed connection after concrete pouring. The perforated plate shear connector achieves an effective connection between the steel structure and the concrete, ensuring the stability of the steel-concrete connection.

[0010] Preferably, the shear connector perforated plate has evenly spaced connecting holes inside, and the shear connector reinforcing bars are disposed inside the connecting holes. Here, the connecting holes facilitate the connection and installation between the shear connector reinforcing bars and the shear connector perforated plate.

[0011] Preferably, the concrete Y-shaped pier is integrally cast using high-grade C60 concrete. Here, C60 concrete ensures that the concrete Y-shaped pier has sufficient strength and stress reserve under complex stress conditions, while fully utilizing the excellent compressive strength of concrete structures.

[0012] Preferably, a hydraulic support device is fixedly installed above the transverse connection system of the lower steel pipe support column of the Y-shaped steel-concrete joint, and the output end of the hydraulic support device is fixedly connected to the steel inclined leg. Here, the hydraulic support device can locally pre-jacket the steel inclined leg, reduce the negative bending moment at the main beam support point, improve the structural stress, and adjust the structural alignment.

[0013] Preferably, a sand cylinder is fixedly installed at the top of the steel pipe support column of the steel box girder, and the transverse load-bearing distribution beam and the steel beam support load-bearing distribution beam are fixedly installed on the top of the sand cylinder. Here, the transverse load-bearing distribution beam and the steel beam support load-bearing distribution beam system built on the sand cylinder can support the segmental assembly operation of the superstructure steel box girder.

[0014] Preferably, connecting flanges are installed at the connection points of the upper and lower steel pipe support columns of the Y-shaped steel-concrete joint. These connecting flanges enable rapid connection and installation between the structures.

[0015] The construction method for a steel-concrete composite Y-shaped inclined leg structure includes the following steps:

[0016] S1: In the first phase, the construction of the substructure of the Y-shaped bridge pier, including the foundation and pile foundation, is completed. Simultaneously, steel pipe columns are driven into place, and the construction of the lower layer steel pipe support columns, the transverse connection system of the lower layer steel pipe support columns, the Y-shaped inclined leg steel pipe support columns, and the transverse connection system of the Y-shaped inclined leg steel pipe support columns are completed using pre-embedded anchors in the foundation. Pre-stressing is carried out according to the load-bearing standard of the double-layer support system. The reinforcement binding of the Y-shaped pier is completed at the top of the foundation. The positioning of the steel-concrete composite section and the fixing of the precast steel formwork for the Y-shaped bridge pier are completed using steel formwork, tie rods, the Y-shaped bridge pier support system, and necessary stiffening frames.

[0017] S2: In the second stage, pour concrete Y-shaped piers. After the C60 concrete strength and modulus of elasticity reach 100%, the low-retraction prestressed steel strands are tensioned through a secondary tensioning process. At the same time, the steel strands are anchored to the anchor plate through the anchor at the tensioning end of the low-retraction prestressed steel strands, thus completing the construction process of the steel-concrete composite section.

[0018] The steel inclined leg Y-shaped bridge pier support system and Y-shaped bridge pier prefabricated steel formwork were dismantled. At the same time, the prefabricated steel inclined leg segments were transported to the site. One end was hoisted, positioned and spliced ​​with the steel box of the steel-concrete composite section. The other end was temporarily supported by a hydraulic support device connected to the horizontal connection of the Y-shaped inclined leg steel pipe support column. After the weld was connected, the basic shape of the Y-shaped inclined leg was presented.

[0019] S3: In the third stage, the upper steel pipe support columns of the Y-shaped steel-concrete joint and the longitudinal and transverse connection system of the upper steel pipe support columns of the Y-shaped steel-concrete joint are built by connecting flanges. At the same time, the steel pipe support columns of the steel box girder and the transverse connection system of the steel box girder steel pipe support columns for the construction of the steel box girder are erected. Then, sand cylinders are set on the top of the steel pipe support columns of the steel box girder, and transverse load-bearing distribution beams and steel beam support load-bearing distribution beam systems are built on the sand cylinders to support the segmental assembly of the upper structure steel box girder.

[0020] Before the Y-shaped steel box girder is joined to form a whole, the steel inclined leg is partially pre-jacked by a hydraulic support device set on the support system to reduce the negative bending moment at the support point of the main beam, improve the structural stress, and adjust the structural alignment. After the main beam of the whole bridge is welded together, the pre-jacking force of the hydraulic support device is released in sequence, and the temporary support sand cylinder is released. By applying the support point pre-jacking method, the tensile stress level of the top edge of the steel box girder at the top of the inclined leg can be effectively improved.

[0021] S4: In the fourth stage, after the main structure of the steel-concrete composite Y-shaped rigid frame bridge is completed, decorative panels are installed, the construction support system is dismantled, and the construction of ancillary and supporting facilities begins.

[0022] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0023] 1. In this invention, during the design process, the main beam of the Y-shaped inclined leg rigid frame bridge is designed as a steel box girder and the inclined leg structure is designed as a steel box inclined leg. Compared with the traditional concrete Y-shaped bridge, it is lighter in weight and more favorable for the stress at the root of the inclined leg. At the same time, the excellent mechanical properties of steel enable the steel inclined leg to better resist the load transmitted by the superstructure and the secondary internal forces generated by the statically indeterminate system of the structure. The Y-shaped pier is made of high-grade concrete, which makes full use of the economical and stable compressive strength of concrete to resist the longitudinal thrust transmitted by the inclined leg. The steel-concrete combination realizes the combination of the two materials and gives full play to their respective performance advantages.

[0024] 2. In this invention, steel-concrete composite sections are set at appropriate locations on the two Y-shaped oblique branches. By using shear connectors and low-retraction prestressed steel strands, reliable connection of the steel-concrete joints at the Y-shaped nodes is ensured while sufficient compressive stress redundancy is reserved. Furthermore, the relatively high location of the steel-concrete composite sections avoids direct contact between the steel structure and the water body, enhancing structural durability. Simultaneously, the oblique legs and main beams utilize prefabricated steel structures. Through reasonable segment division and a phased double-layer support construction method, on-site construction steps and on-site support are significantly reduced, shortening the construction period. Attached Figure Description

[0025] Figure 1 This is a general layout diagram of a steel-concrete composite Y-shaped inclined leg rigid frame bridge;

[0026] Figure 2 This is the overall layout diagram of the steel-concrete composite Y-shaped inclined leg structure;

[0027] Figure 3 This is a sectional view of a steel-concrete composite Y-shaped inclined leg structure.

[0028] Figure 4 This is a cross-sectional diagram of the steel-concrete composite section;

[0029] Figure 5 This is the overall layout diagram of the construction support system for the steel-concrete composite Y-shaped inclined leg structure;

[0030] Figure 6 This is the elevation layout diagram of the support system for the first phase of construction.

[0031] Figure 7 For the corresponding Figure 6 Cross-sectional layout diagram of the support system at the pier location in the first phase of construction;

[0032] Figure 8 This is the elevation layout diagram of the support system for the second phase of construction.

[0033] Figure 9 For the corresponding Figure 8 Cross-sectional layout diagram of the support system at the location of the steel-concrete composite section in the second stage of construction;

[0034] Figure 10 This is the elevation layout diagram of the support system for the third phase of construction;

[0035] Figure 11 For the corresponding Figure 10 Cross-sectional layout diagram of the support system at the pier location in the third stage of construction;

[0036] Figure 12 For the corresponding Figure 10 Cross-sectional layout diagram of the support system at the top of the steel inclined leg in the third stage of construction;

[0037] Figure 13 This is the facade layout diagram after the removal of the Y-shaped inclined leg structure support for the fourth stage steel-concrete composite structure.

[0038] Legend:

[0039] 1. Concrete Y-shaped pier; 2. Steel box girder of the steel-concrete composite section; 3. Steel inclined leg diaphragm; 4. Bearing plate; 5. Cable guide; 6. Anchor plate; 7. Anchorage at the tensioning end of low-retraction prestressed steel strands; 8. Force transmission diaphragm; 9. Low-retraction prestressed steel strands and corrugated pipes; 10. Anchorage at the anchoring end of low-retraction prestressed steel strands; 11. Perforated plate of shear connector; 12. Reinforcing steel of shear connector; 13. Decorative panel; 14. Steel inclined leg; 15. Steel box girder; 16. Y-shaped pier support system; 17. Precast steel formwork for Y-shaped pier; 18. Y-shaped steel-concrete joint. 19. Lower steel pipe support column; 20. Lateral connection system of lower steel pipe support column of Y-structure steel-concrete joint; 21. Hydraulic support device; 22. Connecting flange; 23. Upper steel pipe support column of Y-structure steel-concrete joint; 24. Longitudinal and transverse connection system of upper steel pipe support column of Y-structure steel-concrete joint; 25. Sand cylinder; 26. Lateral load-bearing distribution beam; 27. Y-structure inclined leg steel pipe support column; 28. Lateral connection system of Y-structure inclined leg steel pipe support column; 29. ​​Steel box girder steel pipe support column; 30. Steel beam support load-bearing distribution beam. Detailed Implementation

[0040] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0041] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0042] Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional in this technical field.

[0043] Example 1

[0044] Please see Figure 1-13This invention provides a technical solution comprising a steel-concrete composite Y-shaped inclined leg structure and a phased construction support system. The steel-concrete composite Y-shaped inclined leg structure includes a concrete Y-shaped pier 1, steel inclined legs 14, and a steel box girder 15. Steel-concrete composite sections are provided at the inclined positions on both sides of the concrete Y-shaped pier 1. Each steel-concrete composite section includes a steel box 2. The steel box 2 contains a steel-concrete composite section pressure-bearing anchorage system, which consists of a cable guide 5, an anchor plate 6, a low-retraction prestressed steel strand tensioning end anchor 7, a force transmission diaphragm 8, and a low-retraction prestressed steel strand anchoring end anchor 10. The low-retraction prestressed steel strand tensioning end anchor 7 and the anchor plate 6... The fixed connection is provided, with a bearing plate 4 fixedly installed at one end of the force transmission diaphragm 8. The phased construction support system consists of the Y-shaped pier support system 16, the Y-shaped pier precast steel formwork 17, the lower layer steel pipe support column of the Y-shaped steel-concrete node 18, the transverse connection system of the lower layer steel pipe support column of the Y-shaped steel-concrete node 19, the upper layer steel pipe support column of the Y-shaped steel-concrete node 22, the longitudinal and transverse connection system of the upper layer steel pipe support column of the Y-shaped steel-concrete node 23, the transverse load-bearing distribution beam 25, the Y-shaped inclined leg steel pipe support column 26, the transverse connection system of the Y-shaped inclined leg steel pipe support column 27, the steel box girder steel pipe support column 28, the transverse connection system of the steel box girder steel pipe support column 29, and the steel beam support load-bearing distribution beam 30.

[0045] On the one hand, during the design process, the main beam of the Y-shaped inclined leg rigid frame bridge is designed as a steel box girder 15, and the inclined leg structure is designed as a steel box inclined leg. Compared with the traditional concrete Y-shaped frame bridge, it is lighter in weight and more favorable for the stress at the root of the inclined leg. At the same time, the excellent mechanical properties of steel enable the steel inclined leg 14 to better resist the load transmitted by the superstructure and the secondary internal forces generated by the statically indeterminate system of the structure. The Y-shaped pier is made of high-grade concrete, which makes full use of the economical and stable compressive strength of concrete to resist the longitudinal thrust transmitted by the inclined leg. The steel-concrete combination realizes the combination of the two materials and gives full play to their respective performance advantages.

[0046] On the other hand, steel-concrete composite sections are set at appropriate locations on the two Y-shaped diagonal branches. By using shear connectors and low-retraction prestressed steel strands, reliable connection between the steel-concrete joints of the Y-shaped structure is ensured while sufficient compressive stress redundancy is reserved. Furthermore, the relatively high location of the steel-concrete composite sections avoids direct contact between the steel structure and the water body, enhancing structural durability. Simultaneously, the diagonal legs and main beams utilize prefabricated steel structures. Through reasonable segment division and a phased double-layer support construction method, on-site construction steps and scaffolding are significantly reduced, shortening the construction period.

[0047] The steel box 2 of the steel-concrete composite section is equipped with steel inclined leg partitions 3. Low-retraction prestressed steel strands and corrugated pipes 9 are installed on both sides of the concrete Y-shaped pier 1 at the positions of the steel box 2 of the steel-concrete composite section. The steel inclined leg partitions 3 can ensure the overall stability of the steel box. At the same time, the steel strands are arranged in a local staggered manner in the transverse direction during the structural design to ensure that there is still a clear space of not less than 30mm when the steel strands and corrugated pipes are intersected, so as to ensure the compactness of the concrete pouring. The outer surface of the steel box 2 of the steel-concrete composite section is fixedly installed with decorative panels 13. The decorative panels 13 can realize the smooth transition of the landscape curve between the concrete Y-shaped pier 1 and the steel inclined leg 14.

[0048] The concrete Y-shaped pier 1 is internally equipped with a perforated plate shear connector. This connector consists of a perforated plate 11 and shear connector reinforcing bars 12. The perforated plate 11 is fixedly connected to the bearing plate 4 via full penetration welding. The reinforcing bars 12 pass through the perforated plate 11, forming a fixed connection after concrete pouring. The perforated plate shear connector effectively connects the steel structure and concrete, ensuring the stability of the steel-concrete connection. The perforated plate 11 has evenly spaced connection holes, and the reinforcing bars 12 are positioned inside these holes, facilitating the connection and installation between the reinforcing bars 12 and the perforated plate 11.

[0049] The concrete Y-shaped pier 1 is integrally cast using high-grade C60 concrete. C60 concrete ensures sufficient strength and stress reserve for the Y-shaped pier 1 under complex stress conditions, while fully utilizing the excellent compressive strength of the concrete structure. A hydraulic support device 20 is fixedly installed above the transverse connection system 19 of the lower layer steel pipe support column of the Y-shaped steel-concrete joint. The output end of the hydraulic support device 20 is fixedly connected to the steel inclined leg 14. The hydraulic support device 20 can perform local pre-jacking of the steel inclined leg 14, reducing the negative bending moment at the main beam support point, improving structural stress, and adjusting… The structural alignment features a sand cylinder 24 fixedly installed at the top of the steel box girder steel pipe support column 28. The transverse load-bearing distribution beam 25 and the steel beam support load-bearing distribution beam 30 are fixedly installed on the top of the sand cylinder 24. The transverse load-bearing distribution beam 25 and the steel beam support load-bearing distribution beam 30 system are built on the sand cylinder 24, which can support the segmental assembly of the upper structure steel box girder 15. Connecting flanges 21 are installed at the connection points of the upper steel pipe support column 22 and the lower steel pipe support column 18 of the Y-shaped steel-concrete joint. The connecting flanges 21 can realize the rapid connection and installation between structures.

[0050] The construction method for a steel-concrete composite Y-shaped inclined leg structure includes the following steps:

[0051] S1: In the first stage, the construction of the substructure of the Y-shaped bridge pier, including the abutment and pile foundation, is completed. Simultaneously, steel pipe columns are driven into place, and anchors are pre-embedded in the abutment to complete the construction of the lower layer steel pipe support column 18, the transverse connection system 19, the inclined leg steel pipe support column 26, and the transverse connection system 27 of the Y-shaped steel-concrete joint. Pre-stressing is carried out according to the load-bearing standard of the double-layer support. The reinforcement binding of the Y-shaped pier is completed at the top of the abutment. Steel formwork is used to tie anchor rods, the Y-shaped bridge pier support system 16, and necessary stiffening frames to complete the positioning of the steel-concrete joint section and the fixing of the precast steel formwork 17 for the Y-shaped bridge pier.

[0052] S2: In the second stage, the concrete Y-shaped pier 1 is poured. After the C60 concrete strength and modulus of elasticity reach 100%, the low-retraction prestressed steel strand 9 is tensioned through a secondary tensioning process. At the same time, the steel strand is anchored to the anchor plate 6 through the low-retraction prestressed steel strand tensioning end anchor 7, thus completing the construction process of the steel-concrete composite section.

[0053] The steel inclined leg 14Y-shaped bridge pier support system 16 and Y-shaped bridge pier precast steel formwork 17 were dismantled. At the same time, the precast steel inclined leg 14 segments were transported to the site. One end was hoisted, positioned and spliced ​​with the steel box 2 of the steel-concrete composite section. The other end was temporarily supported by the hydraulic support device 20 on the transverse connection system 27 of the Y-shaped inclined leg steel pipe support column. After the weld was connected, the basic shape of the Y-shaped inclined leg was presented.

[0054] S3: In the third stage, the upper steel pipe support column 22 of the Y-shaped steel-concrete joint and the longitudinal and transverse connection system 23 of the upper steel pipe support column of the Y-shaped steel-concrete joint are built by connecting flange 21. At the same time, the steel pipe support column 28 of the steel box girder and the transverse connection system 29 of the steel box girder steel pipe support column are erected for the construction of steel box girder 15. Then, a sand cylinder 24 is set on the top of the steel pipe support column 28 of the steel box girder. A transverse load-bearing distribution beam 25 and a steel beam support load-bearing distribution beam 30 system are built on the sand cylinder 24 to support the segmental assembly operation of the upper structure steel box girder 15.

[0055] Before the Y-shaped steel box girder 15 is joined to form a whole, the steel inclined leg 14 is partially pre-jacked by the hydraulic support device 20 set on the support system to reduce the negative bending moment at the support point of the main beam, improve the structural stress, and adjust the structural alignment. After the main beam is welded and joined together, the pre-jacking force of the hydraulic support device 20 is released in sequence, and the temporary support sand cylinder 24 is released. By applying the support point pre-jacking method, the tensile stress level at the top edge of the steel box girder 15 at the top of the inclined leg can be effectively improved.

[0056] S4: In the fourth stage, after the main structure of the steel-concrete composite Y-shaped rigid frame bridge is completed, decorative panels 13 are installed, the construction support system is dismantled, and the construction of ancillary and supporting facilities begins.

[0057] Working principle: In the actual construction process, it is mainly divided into four stages: In the first stage, the construction of the lower structure of the Y-shaped pier and the pile foundation is completed. Steel pipe columns are driven in, and simultaneously, the construction of the lower layer steel pipe support column 18, the transverse connection system 19, the inclined leg steel pipe support column 26, and the transverse connection system 27 of the Y-shaped steel-concrete joint are completed through pre-embedded anchors in the pier cap. Pre-stressing is carried out according to the load-bearing standard of the double-layer support. The reinforcement binding of the Y-shaped pier is completed at the top of the pier cap. The steel formwork is used to tie the anchor rods, the Y-shaped pier support system 16, and the necessary stiffening frame to complete the positioning of the steel-concrete joint section. The first stage involves fixing the precast steel formwork 17 of the Y-shaped pier; the second stage involves pouring concrete for the Y-shaped pier 1. After the C60 concrete reaches 100% strength and modulus of elasticity, the low-retraction prestressed steel strands and corrugated pipes 9 are tensioned through a secondary tensioning process. At the same time, the steel strands are anchored to the anchor plate 6 through the anchor 7 at the tensioning end of the low-retraction prestressed steel strands, completing the construction process of the steel-concrete composite section; the support system 16 of the Y-shaped pier and the precast steel formwork 17 of the Y-shaped pier are dismantled. At the same time, the precast steel leg 14 segments are transported to the site. One end is hoisted, positioned, and spliced ​​with the steel box 2 of the steel-concrete composite section, while the other end is supported by the Y-shaped pier steel pipe. The hydraulic support device 20 provides temporary support on the transverse connection system 27 of the column. After the weld connection, the basic shape of the Y-shaped inclined leg is formed. In the third stage, the upper steel pipe support column 22 of the Y-shaped steel-concrete node and the longitudinal and transverse connection system 23 of the upper steel pipe support column of the Y-shaped steel-concrete node are built through the connecting flange 21. At the same time, the steel pipe support column 28 of the steel box girder and the transverse connection system 29 of the steel pipe support column of the steel box girder are erected for the construction of the steel box girder 15. Then, a sand cylinder 24 is set on the top of the steel pipe support column 28 of the steel box girder. A transverse load-bearing distribution beam 25 and a steel beam support load-bearing distribution beam 30 system are built on the sand cylinder 24 to support the section of the upper structure steel box girder 15. The first stage involves the assembly of sections; before the Y-shaped steel box girder 15 is joined to form a whole, the hydraulic support device 20 set on the support system is used to pre-push the steel inclined leg 14 locally to reduce the negative bending moment at the support point of the main beam, improve the structural stress, and adjust the structural alignment. After the main beam of the entire bridge is welded together, the pre-push force of the hydraulic support device 20 is released in sequence, and the temporary support sand cylinder 24 is released. By applying the support point pre-push method, the tensile stress level at the top edge of the steel box girder 15 at the top of the inclined leg can be effectively improved; in the fourth stage, after the main structure of the steel-concrete composite Y-shaped rigid frame bridge is completed, the decorative panel 13 is installed, the construction support system is dismantled, and the construction of auxiliary and supporting facilities begins.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A reinforced concrete composite Y-shaped inclined leg structure, comprising a reinforced concrete composite Y-shaped inclined leg structure and a phased construction support system, characterized in that: The steel-concrete composite Y-shaped inclined leg structure includes a concrete Y-shaped pier (1), steel inclined legs (14), and a steel box girder (15). Steel-concrete composite sections are provided at the inclined positions on both sides of the concrete Y-shaped pier (1). Each steel-concrete composite section includes a steel box girder (2). The steel box girder (2) contains a steel-concrete composite section pressure-bearing anchorage system. This system consists of a cable guide (5), an anchor plate (6), a low-retraction prestressed steel strand tensioning end anchorage (7), a force transmission diaphragm (8), and a low-retraction prestressed steel strand anchorage end anchorage (10). The low-retraction prestressed steel strand tensioning end anchorage (7) is fixedly connected to the anchor plate (6). The force transmission diaphragm (8)... One end is fixedly installed with a pressure plate (4). The phased construction support system includes a Y-shaped pier support system (16), a Y-shaped pier precast steel formwork (17), a Y-shaped steel-concrete node lower layer steel pipe support column (18), a Y-shaped steel-concrete node lower layer steel pipe support column transverse connection system (19), a Y-shaped steel-concrete node upper layer steel pipe support column (22), a Y-shaped steel-concrete node upper layer steel pipe support column longitudinal and transverse connection system (23), a transverse load-bearing distribution beam (25), a Y-shaped inclined leg steel pipe support column (26), a Y-shaped inclined leg steel pipe support column transverse connection system (27), a steel box girder steel pipe support column (28), a steel box girder steel pipe support column transverse connection system (29), and a steel beam support load-bearing distribution beam (30). The steel box (2) of the steel-concrete composite section is equipped with steel inclined leg partition (3), and low shrinkage prestressed steel strands and corrugated pipes (9) are installed on both sides of the concrete Y-shaped pier (1) at the position of the steel box (2) of the steel-concrete composite section. The concrete Y-shaped pier (1) is provided with an open plate shear connector inside. The open plate shear connector consists of an open plate (11) and a reinforcing bar (12). The open plate (11) and the bearing plate (4) are fixedly connected by full penetration welding. The reinforcing bar (12) passes through the open plate (11) and forms a fixed connection after the concrete is poured.

2. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: A decorative panel (13) is fixedly installed on the outer surface of the steel box (2) of the steel-concrete composite section.

3. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: The shear connector perforated plate (11) has uniformly opened connecting holes inside, and the shear connector reinforcing bar (12) is placed inside the connecting holes.

4. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: The concrete Y-shaped pier (1) is integrally cast using high-grade C60 concrete.

5. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: A hydraulic support device (20) is fixedly installed above the transverse connection system (19) of the lower layer steel pipe support column of the Y-structure steel-concrete node, and the output end of the hydraulic support device (20) is fixedly connected to the steel inclined leg (14).

6. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: A sand cylinder (24) is fixedly installed at the top of the steel pipe support column (28) of the steel box girder, and the transverse load-bearing distribution beam (25) and the load-bearing distribution beam (30) of the steel beam support are fixedly installed at the top of the sand cylinder (24).

7. The steel-concrete composite Y-shaped inclined leg structure according to claim 1, characterized in that: A connecting flange (21) is installed at the connection between the upper steel pipe support column (22) and the lower steel pipe support column (18) of the Y-structure steel-concrete node.

8. The construction method of the steel-concrete composite Y-shaped inclined leg structure as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: In the first stage, the construction of the lower structure of the Y-shaped bridge pier and the pile foundation is completed. The steel pipe columns are driven and the lower layer steel pipe support column (18), the transverse connection system (19), the inclined leg steel pipe support column (26), and the transverse connection system (27) of the Y-shaped steel-concrete joint are completed through the pre-embedded anchors in the pier. The pre-stressing is carried out according to the bearing standard of the double-layer support. The Y-shaped pier reinforcement binding operation is completed at the top of the pier. The steel formwork is used to tie the anchor rod, the Y-shaped bridge pier support system (16), and the stiffening frame to complete the positioning of the steel-concrete joint section and the fixing of the Y-shaped bridge pier prefabricated steel formwork (17). S2: In the second stage, pour concrete Y-shaped pier (1). After the C60 concrete strength and elastic modulus reach 100%, the low-retraction prestressed steel strand (9) is tensioned through a secondary tensioning process. At the same time, the steel strand is anchored to the anchor plate (6) through the low-retraction prestressed steel strand tensioning end anchor (7) to complete the construction process of the steel-concrete composite section. The steel inclined leg Y-shaped bridge pier support system (16) and Y-shaped bridge pier prefabricated steel template (17) were dismantled. At the same time, the steel inclined leg (14) segments prefabricated in the factory were transported to the site. One end was hoisted, positioned and spliced ​​with the steel box (2) of the steel-concrete composite section. The other end was temporarily supported by the hydraulic support device (20) on the transverse connection system (27) of the Y-shaped inclined leg steel pipe support column. After the weld was connected, the basic shape of the Y-shaped inclined leg was presented. S3: In the third stage, the upper steel pipe support column (22) of the Y-structure steel-concrete node and the longitudinal and transverse connection system (23) of the upper steel pipe support column of the Y-structure steel-concrete node are built by connecting flange (21). At the same time, the steel pipe support column (28) of the steel box girder (15) and the transverse connection system (29) of the steel pipe support column of the steel box girder are erected. Then, a sand cylinder (24) is set on the top of the steel pipe support column (28). A transverse load-bearing distribution beam (25) and a steel beam support load-bearing distribution beam (30) are built on the sand cylinder (24) to support the segmental assembly operation of the upper structure steel box girder (15). Before the Y-shaped steel box girder (15) is joined to form a whole, the steel inclined leg (14) is partially pre-jacked by the hydraulic support device (20) set on the support system to reduce the negative bending moment at the support point of the main beam, improve the structural stress, and adjust the structural alignment. After the main beam is fully welded and joined, the pre-jacking force of the hydraulic support device (20) is released in sequence, and the temporary support sand cylinder (24) is released. By applying the support point pre-jacking method, the tensile stress level of the top edge of the steel box girder (15) at the top of the inclined leg can be effectively improved. S4: In the fourth stage, after the main structure of the steel-concrete composite Y-shaped rigid frame bridge is completed, decorative panels (13) are installed, the construction support system is dismantled, and the construction of ancillary and supporting facilities begins.

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