A construction method for a dual-purpose (road and rail) cable-stayed suspension bridge and the bridge itself.

Abstract

This application relates to a construction method and bridge for a dual-purpose (road and rail) cable-stayed suspension bridge, belonging to the field of bridge engineering technology. The method includes: dividing the overall control parameters of the cable structure into first-phase cable structure parameters and second-phase cable structure parameters based on the first-phase and second-phase operational loads; constructing the towers and stiffening girders in one go based on the main structure design parameters, and simultaneously installing the first-phase cable anchorage components and reserving second-phase cable anchorage positions; installing the first-phase cable structure using the first-phase cable anchorage components based on the first-phase cable structure parameters; and installing the second-phase cable structure using the reserved second-phase cable anchorage positions based on the second-phase cable structure parameters during or after the first-phase operation. By dividing the overall control parameters of the cable structure based on the phased operational load requirements and simultaneously installing the first-phase cable anchorage components and reserving second-phase cable anchorage positions during the construction of the towers and stiffening girders, dynamic matching of the cable structure cross-section with the actual load requirements is achieved.

Description

Technical Field

[0001] This application relates to the field of bridge engineering technology, and in particular to a construction method and a bridge for both road and rail cable-stayed suspension bridges. Background Technology

[0002] The cable-stayed bridge system combines the structural systems of cable-stayed bridges and suspension bridges. It has the advantages of strong span capacity and high structural rigidity, and is particularly suitable for long-span road-rail bridges.

[0003] Traditionally, cable-stayed suspension bridges for both road and rail use are typically constructed in a single phase. However, the functional planning of highways and railways may not be at the same stage. For example, highway traffic demand might be urgent, while railway development might still be in its early research stages. Constructing the highway bridge first and then the railway bridge, resulting in two separate bridges, would increase investment. Therefore, in current engineering projects, when encountering similar situations, they are all constructed as dual-purpose (road and rail) bridges. This means that the entire cable structure, including all main cables and all stay cables, is installed in the first phase of bridge construction according to the final load-bearing design for both road and rail use.

[0004] If all cable structures are installed in one go to meet the final dual-purpose road-rail load requirements, a significant amount of cable structure investment will be idle during the first phase of highway operation, significantly increasing the initial investment pressure of the project. Secondly, the load differences between the first phase of highway operation and the second phase of dual-purpose road-rail operation are significant. If all cable structures are built at once, the cable tension levels of the main cables and stay cables will be low during the lower-load highway phase, making it difficult to fully utilize the stiffness advantage of the suspension system. Insufficient tension in the stay cables, resulting in a long-term low-stress state, will negatively impact cable durability. Furthermore, under traditional one-time construction methods, if the second phase requires increased railway load, large-scale modifications or reconstruction of the existing cable structures are often necessary. This not only presents significant construction difficulties but also severely disrupts traffic on the already operational highway, making phased construction less feasible. Summary of the Invention

[0005] This application provides a method for constructing a cable-stayed suspension bridge for both road and rail use, as well as the bridge itself, to solve the technical problems in related technologies, such as the large investment pressure in the first phase, the long-term low stress of the cable structure affecting its durability, and the high construction difficulty and traffic disruption when adding cable structures in the second phase, due to the mismatch between the cable structure configuration and the phased construction requirements.

[0006] Firstly, a method for constructing a dual-purpose (road and rail) cable-stayed suspension bridge is provided, comprising: determining the first-phase and second-phase operational loads of the bridge based on its operational load requirements; determining the main structure design parameters and overall control parameters of the cable structure based on the bridge's final operational state; dividing the overall control parameters of the cable structure into first-phase cable structure parameters and second-phase cable structure parameters based on the first-phase and second-phase operational loads; constructing the towers and stiffening girders in one go based on the main structure design parameters, and simultaneously installing the first-phase cable anchorage components and reserving second-phase cable anchorage positions; and installing the first-phase cable structure using the first-phase cable anchorage components based on the first-phase cable structure parameters. During or after the first phase of operation, the second phase cable structure will be installed using the reserved second phase cable anchorage positions, based on the parameters of the second phase cable structure.

[0007] In some embodiments, the overall control parameters of the cable structure include the total cross-sectional area, total initial tension, and total stress-free length of the main cable, suspenders, and stay cables.

[0008] In some embodiments, based on the Phase I and Phase II operating loads, the overall control parameters of the cable structure are divided into Phase I cable structure parameters and Phase II cable structure parameters. Specifically, this includes: obtaining the Phase I load combination value based on the Phase I dead load and highway live load; obtaining the Phase II load combination value based on the Phase II dead load, highway live load, and railway live load; dividing the total cross-sectional area of ​​the cable structure into Phase I and Phase II cross-sectional areas based on the ratio of the Phase I load combination value to the Phase II load combination value; obtaining the stress-free length of the inner main cable and the initial tension of the inner suspenders and inner stay cables based on the Phase I cable structure cross-sectional area; and obtaining the stress-free length of the outer main cable and the initial tension of the outer suspenders and outer stay cables based on the Phase II cable structure cross-sectional area.

[0009] In some embodiments, the first-phase dead load includes the self-weight of the highway bridge deck and highway ancillary facilities, and the second-phase dead load includes the first-phase dead load and the self-weight of the railway bridge deck and railway ancillary facilities.

[0010] In some embodiments, the simultaneous installation of the first-stage cable anchoring components and the reservation of the second-stage cable anchoring positions specifically includes: installing the inner main cable saddle on the cable tower and reserving the installation position of the outer main cable saddle; installing the inner stay cable anchoring components and the inner suspension cable anchoring components on the stiffening beam and reserving the outer stay cable anchoring position.

[0011] In some embodiments, the method further includes: sealing the outer main cable saddle installation position and the outer stay cable anchorage position.

[0012] In some embodiments, the first-phase cable structure is installed using first-phase cable anchoring components based on the parameters of the first-phase cable structure. Specifically, this includes: erecting the inner main cable through the inner main cable saddle; installing the inner suspenders using the inner suspender anchoring components to connect the inner main cable to the stiffening beam; installing and tensioning the inner stay cables using the inner stay cable anchoring components; and adjusting the cable tension of the inner main cable, inner suspenders, and inner stay cables according to the parameters of the first-phase cable structure.

[0013] In some embodiments, based on the parameters of the second-phase cable structure, the second-phase cable structure is installed using the reserved second-phase cable anchorage positions. Specifically, this includes: opening the installation position of the outer main cable saddle and installing the outer main cable saddle; opening the anchorage position of the outer stay cable and installing the anchorage component of the outer stay cable. The outer main cable is erected using the outer main cable saddle; the outer suspenders are installed to connect the outer main cable to the stiffening beam; the outer stay cables are installed and tensioned using the outer stay cable anchoring components; and the cable tension of the outer main cable, outer suspenders, and outer stay cables is adjusted according to the parameters of the second-phase cable structure.

[0014] In some embodiments, the stiffening girder adopts a double-layer steel truss cross-section structure, wherein the upper bridge deck is used for highway traffic and the lower bridge deck is used for railway traffic.

[0015] Secondly, a dual-purpose (road and rail) cable-stayed suspension bridge is provided, which is constructed using the construction method for a dual-purpose (road and rail) cable-stayed suspension bridge as described in any one of the first aspects.

[0016] The beneficial effects of the technical solution provided in this application include: This application provides a construction method for a dual-purpose (railway and highway) cable-stayed suspension bridge, which adopts the construction principle of building the tower and stiffening girder in one phase and configuring the cable structure in stages. By decomposing the overall control parameters of the cable structure based on the phased operation load requirements, and simultaneously installing the first-phase cable anchorage components and reserving the second-phase cable anchorage positions during the construction of the tower and stiffening girder, dynamic matching between the cable structure cross-section and the actual load requirements is achieved. This significantly reduces the investment pressure of the first phase, avoids the cable structure from being affected by long-term low stress affecting durability, and eliminates the need for large-scale dismantling and modification of the tower and stiffening girder when adding cable structures in the second phase. The installation of the second-phase cable structure can be completed during or after the operation of the first phase, achieving system conversion without affecting the traffic of the first phase operation, and greatly simplifying the construction difficulty of the second phase. Attached Figure Description

[0017] 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.

[0018] Figure 1This is a schematic diagram of the overall steps of the construction method provided in the embodiments of this application; Figure 2 A detailed flowchart illustrating steps S3 is provided for embodiments of this application. Figure 3 A detailed flowchart illustrating steps S5 is provided for embodiments of this application. Figure 4 A detailed flowchart illustrating steps S6 is provided for embodiments of this application; Figure 5 This application provides an overall schematic diagram illustrating the construction of the first phase of operation. Figure 6 A partial schematic diagram provided for illustrating the construction of the first phase of operation, as part of an embodiment of this application; Figure 7 This application provides an overall schematic diagram illustrating the second phase of operation and construction. Figure 8 A partial schematic diagram provided for illustrating the second phase of operation and construction in an embodiment of this application; Figure 9 This is a schematic diagram provided for illustrating the inner main cable saddle and the outer main cable saddle in an embodiment of this application.

[0019] In the diagram: 1. Tower; 2. Stiffening girder; 20. Diagonal member; 21. Vertical member; 30. Inner main cable saddle; 300. Inner anchorage; 31. Inner stay cable anchorage component; 32. Inner suspender cable anchorage component; 40. Outer main cable saddle; 400. Outer anchorage; 41. Outer stay cable anchorage component; 42. Outer suspender cable anchorage component; 5. Main cable; 50. Inner main cable; 51. Outer main cable; 6. Suspension cable; 60. Inner suspender cable; 61. Outer suspender cable; 7. Stay cable; 70. Inner stay cable; 71. Outer stay cable; 8. Highway bridge deck; 9. Railway bridge deck. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] This application provides a method for constructing a cable-stayed suspension bridge for both road and rail use, as well as the bridge itself. It can solve the technical problems in related technologies, such as the large investment pressure in the first phase, the long-term low stress of the cable structure affecting its durability, and the high construction difficulty and traffic disruption when adding cable structures in the second phase, caused by the mismatch between the cable structure configuration and the phased construction requirements.

[0022] Reference Figure 1-9 A method for constructing a dual-purpose (road and rail) cable-stayed suspension bridge, comprising: S1: Based on the bridge's operational load requirements, the first-phase and second-phase operational loads of the bridge are determined. In this application, the first-phase operation corresponds to the highway traffic state, and its load requirement corresponds to highway load; the second-phase operation is a dual-purpose road-rail traffic state, and its load requirement corresponds to dual-purpose road-rail load. The evolution logic of initially bearing only highway loads and later needing to bear dual-purpose road-rail loads is clearly defined, thus dividing the continuous construction process into two stages with clearly defined load boundaries. This achieves dynamic matching between structural configuration and the actual load requirements of each stage, laying a design foundation that balances engineering economy and structural safety.

[0023] S2: Once the first-phase and second-phase operation loads of the bridge are determined, the design parameters of the main structure and the overall control parameters of the cable structure are determined based on the final operation state of the bridge.

[0024] The main structure in this application includes a tower 1 and a stiffening girder 2. The cable structure includes main cables 5 and stay cables 7. The main cables 5 include an inner main cable 50 and an outer main cable 51, and the stay cables 7 include an inner stay cable 70 and an outer stay cable 71. Therefore, the overall control parameters of the cable structure include the total cross-sectional area, total initial tension, and total stress-free length of the main cables 5, suspenders 6, and stay cables 7.

[0025] Specifically, an equivalent calculation model of the entire bridge's stress under the condition of railway operation was established, which was then simplified into a model of double main cables 5 and double cable stays 7 for structural analysis. The overall stress state under railway operation was used as the design benchmark to determine structural control parameters such as the total cross-sectional area of ​​the main cables 5 and cable stays 7, the total initial tension of the cable stays 7, and the total stress-free length of the main cables 5.

[0026] This application uses the final dual-use (road and rail) operational state of the bridge as the design benchmark, simultaneously determining the overall control parameters of the main structure and the cable structure. Specifically, for the cable structure, an equivalent calculation model of the entire bridge's stress on the four main cables (5) and four stay cables (7) is established and simplified into a model with two main cables (5) and two stay cables (7) for structural analysis. This determines the overall control parameters such as the total cross-sectional area, total initial tension, and total stress-free length of the main cables (5) and stay cables (7). This ensures that the bridge can meet the most demanding load requirements during its final operational phase, guaranteeing the structure's safety and stability throughout its entire life cycle. Furthermore, the simplified equivalent model reduces the design and calculation complexity of the complex multi-cable system.

[0027] S3: Based on the Phase I and Phase II operational loads, the overall control parameters of the cable structure are divided into Phase I cable structure parameters and Phase II cable structure parameters. This step, dividing the overall control parameters of the cable structure into Phase I and Phase II cable structure parameters, specifically includes: S30: Based on the first-phase dead load and highway live load, obtain the first-phase load combination value; the first-phase dead load includes the self-weight of the highway bridge deck 8 and highway ancillary facilities, and the first-phase load combination value is the sum of the first-phase dead load and highway live load.

[0028] S31: Based on the second-phase dead load, highway live load, and railway live load, obtain the second-phase load combination value; the second-phase dead load includes the first-phase dead load and the self-weight of the railway bridge deck 9 and railway ancillary facilities, and the second-phase load combination value is the sum of the second-phase dead load, highway live load, and railway live load.

[0029] S32: Based on the ratio of the first-stage load combination value to the second-stage load combination value, the total cross-sectional area of ​​the cable structure is divided into the cross-sectional area of ​​the first-stage cable structure and the cross-sectional area of ​​the second-stage cable structure.

[0030] S33: Based on the cross-sectional area of ​​the first-phase cable structure, obtain the stress-free length of the inner main cable 50 and the initial tension of the inner suspender cable 60 and the inner stay cable 70.

[0031] S34: Based on the cross-sectional area of ​​the second-phase cable structure, obtain the stress-free length of the outer main cable 51 and the initial tension of the outer suspension cable 61 and the outer stay cable 71.

[0032] In this application, the first-phase cable structure and the second-phase cable structure are divided into first-phase construction and second-phase construction based on the division results. Based on the determined main structure design parameters and overall control parameters of the cable structure, an accurate total basis and control target are provided for the precise breakdown of the overall parameters into the parameters of the first-phase and second-phase cable structures in the process, avoiding the risk that the final structure may be insufficient in bearing capacity due to phased construction.

[0033] By precisely quantifying the stress boundaries at different operational stages, the load combination values ​​for the first phase, which only include the dead load and live load of the highway bridge deck 8, and the load combination values ​​for the second phase, which include the dead load and live load of the railway bridge deck 9, were calculated. This clarified the differences in the total load that the structure needs to bear at each stage. Secondly, using the mechanical principles of cable structure bearing capacity and cross-sectional area, the total cross-sectional area of ​​the cable structure was precisely divided according to the ratio of the first and second phase load combination values ​​to determine the specific cable material usage required for each phase. This step is the core of achieving phased configuration. Finally, based on the determined cross-sectional area for each phase, and combined with the nonlinear mechanical models of suspension bridges and cable-stayed bridges, key construction control indicators such as the stress-free length and initial tension of the main cable 5 for each phase were derived in reverse. This entire process achieved a step-by-step transformation from "load requirements" to "structural geometric parameters" and then to "construction control indicators," ensuring that the cable structure installed in the first phase only met the load requirements of the current phase and was subjected to moderate stress, thus avoiding material waste. Meanwhile, the cable structure added in the second phase just made up for the remaining bearing capacity, so that the cable stress level of the entire bridge at different operating stages was within the design controllable range, ensuring the unity of safety, stress rationality and engineering economy during the structural system transformation process.

[0034] S4: Based on the main structural design parameters, the cable tower 1 and stiffening girder 2 are constructed in one go, and the first-phase cable anchorage components are installed simultaneously, with reserved positions for the second-phase cable anchorage. The stiffening girder 2 adopts a double-layer steel truss cross-section structure, with the upper deck used for highway traffic and the lower deck for railway traffic. The upper and lower decks are connected by diagonal braces 20 and vertical braces 21. Alternatively, a separate layout for highway and railway traffic may be adopted in another embodiment.

[0035] In addition, the installation of the first-phase cable anchoring components and the reservation of second-phase cable anchoring positions are carried out simultaneously. Specifically, this includes: installing an inner main cable saddle 30 on the upper crossbeam of the cable tower 1 to support the inner main cable 50, and reserving a position for the installation of the outer main cable saddle 40; and installing an inner stay cable anchoring component 31 and an inner suspension cable anchoring component 32 on the stiffening beam 2, and reserving a position for the anchoring of the outer stay cable 71. Furthermore, the method also involves sealing the installation positions of the outer main cable saddle 40 and the anchoring positions of the outer stay cable 71. The sealing treatment includes, but is not limited to, pre-embedding steel plates at corresponding positions in the main structure, leaving openings, or performing local reinforcement to form concealed and reactivatable reserved interfaces.

[0036] Firstly, taking advantage of the requirement to maintain the overall continuity of the main load-bearing framework, the main structure of the cable tower 1 and stiffening beam 2 was completed in one go during the first phase of construction. This avoids the structural joint weakness caused by phased pouring and ensures the overall rigidity and durability of the main structure. For the first-phase cable structure, the main cable saddles and anchoring components were directly installed to form a complete force transmission path. For the second-phase cable structure, steel plates were pre-embedded, holes were left, or local reinforcements were carried out at corresponding locations in the main structure to form concealed and reactivatable pre-reserved interfaces. On the one hand, this avoids secondary operations such as drilling, welding, and reinforcement of existing concrete or steel structures during the second-phase construction, eliminating the risk of damage to the integrity of the main structure during later modifications and ensuring the reliability of the anchoring system. On the other hand, it greatly simplifies the second-phase construction process. When adding the cable structure, there is no need for large-scale traffic closures or interruptions to the operation of the first phase, significantly reducing interference with existing road traffic and achieving compatibility between the expansion project and the existing operational status.

[0037] S5: Based on the parameters of the first-phase cable structure, the first-phase cable structure is installed using the first-phase cable anchoring components, specifically including: S50: After the cable tower 1 and stiffening beam 2 are built in one go according to the final dual-purpose road and rail design, the inner main cable 50 is first erected using the inner main cable saddle 30, and the inner main cable 50 is fixed to the inner anchor 300; S51: Then the inner suspender cable 60 is installed using the inner suspender cable anchoring component 32 to connect the inner main cable 50 to the stiffening beam 2; S52: The inner stay cable 70 is installed and tensioned using the inner stay cable anchoring component 31; S53: Finally, the cable tension of the inner main cable 50, inner suspender cable 60 and inner stay cable 70 is adjusted according to the parameters of the first-phase cable structure. During the first phase of construction, the anchoring components of the inner stay cable 70 and the second-phase cable corresponding to the outer stay cable 71 were directly installed and used. The anchoring positions of the outer stay cable 71 and the second-phase cable were sealed with pre-embedded steel plates or left with empty holes as reserved positions for tensioning the outer stay cable 71.

[0038] During the first phase of construction, in accordance with highway load-bearing design requirements, only the inner main cables 50 are installed and connected to the stiffening girder 2 via inner suspenders 60, while the inner stay cables 70 are tensioned. At this stage, the cable structure cross-section includes the cable surfaces of two inner main cables 50 and two inner stay cables 70, forming a simplified cable-stayed-suspension cooperative system. During this phase, only the highway bridge deck 8 is laid on the stiffening girder 2, and the traffic load is the load of highway vehicles. The cable tension of the inner main cables 50 and inner stay cables 70 is designed and adjusted according to highway load requirements, which can meet the strength, stiffness, and stability requirements of the first phase of operation.

[0039] S6: During or after the first phase of operation, based on the parameters of the second phase cable structure, install the second phase cable structure using the reserved second phase cable anchorage positions. Specifically, this includes: S60: Open the installation position of the outer main cable saddle 40 and install the outer main cable saddle 40; S61: Open the anchorage position of the outer stay cable 71 and install the outer stay cable anchorage component 41; S62: Then use the outer main cable saddle 40 to erect the outer main cable 51; S63: Install the outer suspender 61 to connect the outer main cable 51 to the stiffening beam 2. The outer suspender 61 is connected through the pre-installed outer suspender anchorage component 42; S64: Use the outer stay cable anchorage component 41 to install and tension the outer stay cable 71; S65: Finally, adjust the cable tension of the outer main cable 51, outer suspender 61, and outer stay cable 71 according to the parameters of the second phase cable structure.

[0040] Once the railway construction conditions are met, the second phase of construction will commence. While maintaining the unchanged stress state of the inner main cable 50 and inner stay cable 70, precise cable force control will ensure that the stress changes of the inner main cable 50 and inner stay cable 70 are kept within allowable limits during the process of adding the outer main cable 51 and tensioning the outer stay cable 71, thus maintaining a stable alignment and stress state of the stiffening girder. The outer main cable saddle 40 will be installed, and the outer main cable 51 will be gradually added. The outer main cable 51 will be fixed to the outer anchorage 400 and connected to the stiffening girder 2 via the outer suspender cable 61. Simultaneously, the outer suspender cable 61 will be opened, the outer stay cable 71 will be installed and tensioned, and the lower end of the outer stay cable 71 will be anchored on the stiffening girder 2. After the completion of the second phase of construction, the cable structure cross-section will expand to four main cables 5 and four stay cables 7. At this point, the railway bridge deck 9 and related ancillary structures will be laid underneath, and the entire bridge will be designed for dual-purpose road and rail load-bearing operation.

[0041] In this application, regardless of the arrangement scheme, as long as the design of the stiffening beam 2 reserves the anchorage position of the outer stay cable 71 and adopts the method of phased installation of the main cable 5 and tensioning of the stay cable 7, it is within the protection scope of this invention.

[0042] This application establishes overall parameters based on the final operational state and precisely divides the cable structure parameters into Phase I and Phase II parts according to the phased load requirements. From the design source, it achieves dynamic matching between the cable structure configuration and the actual load, ensuring appropriate cable force levels at each stage. Furthermore, at the construction level, it establishes a strategy of constructing Tower 1 and Stiffening Girder 2 in one go, reserving anchorage positions for Phase II. This avoids redundant construction of the main structure or large-scale dismantling and alteration later, providing a physical basis for Phase II expansion and further implementing the phased installation of the cable structure. This design, on the one hand, significantly reduces the initial investment pressure of Phase I by configuring the cable structure in stages and avoids material waste or corrosion problems caused by insufficient stress in the cable structure during low-load stages; on the other hand, the reserved anchorage positions allow for rapid implementation of Phase II expansion without interrupting Phase I operation, effectively simplifying construction procedures and reducing interference with existing traffic. Thus, while ensuring the structural safety of the bridge throughout its entire life cycle, it achieves an optimal balance between engineering economy and construction convenience.

[0043] This application also provides a dual-purpose (road and rail) cable-stayed suspension bridge, constructed using the construction method for a dual-purpose (road and rail) cable-stayed suspension bridge as described in any of the first aspects. The bridge includes a pylon 1, a stiffening girder 2, main cables 5, and stay cables 7. The main cables 5 include an inner main cable 50 and an outer main cable 51, and the stay cable 7 system includes an inner stay cable 70 and an outer stay cable 71. The pylon 1 and stiffening girder 2 are constructed in one phase during the first phase of construction, with provisions for the anchorage of the outer main cable saddle 40 and the outer stay cable 71 in the second phase. During the first phase of construction, the inner main cables 50 are installed according to highway load capacity, and the inner stay cables 70 are tensioned. During the second phase of construction, the outer main cables 51 are added according to dual-purpose (road and rail) load capacity, and the outer stay cables 71 are tensioned, ultimately forming a cable-stayed suspension system with two rows of four main cables 5 and four stay cables 7 working together to bear the load.

[0044] By configuring the cable structure cross-section in stages, only a portion of the main cable 5 and a portion of the stay cables 7 need to be installed in the first phase of the highway project. This avoids the capital occupation and idle waste caused by the one-time investment in the entire cable structure, significantly reducing the investment pressure in the first phase of the project. This is particularly significant for projects with unclear railway construction schedules.

[0045] Furthermore, in the first phase, the highway stage, the load is borne by two main cables (5) and two stay cables (7), while in the second phase, the dual-purpose road and rail stage, the load is expanded to four main cables (5) and four stay cables (7). The number and arrangement of cable structures in different operational stages are adapted to the actual load requirements. The cable force level in the first phase is moderate, and the stiffness of both the suspension and stay systems can be fully utilized. After the addition of the outer cable structure in the second phase, the four cable systems work together, resulting in a more uniform overall stress distribution. Moreover, the second phase is easier to construct. The tower (1) and stiffening beam (2) were built in the first phase and the anchoring structure for the second phase was reserved. When adding the main cables (5) and tensioning the stay cables (7) later, there is no need for large-scale dismantling and modification of the main structure. The construction process is relatively simple, with minimal interference to the traffic on the already opened highway, and the feasibility of phased construction is significantly enhanced. Finally, the resulting system of four main cables 5 and four stay cables 7 working together to bear the load can simultaneously leverage the vertical stiffness advantage of cable-stayed bridges and the large-span load-bearing advantage of suspension bridges, meeting the comprehensive requirements of dual-purpose railway and highway bridges in terms of strength, stiffness, and stability.

[0046] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0047] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0048] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for constructing a dual-purpose (road and rail) cable-stayed suspension bridge, characterized in that, It includes: Based on the bridge's operational load requirements, the first-phase operational load and the second-phase operational load of the bridge are determined. Based on the final operational status of the bridge, determine the design parameters of the main structure and the overall control parameters of the cable structure; Based on the first-phase operation load and the second-phase operation load, the overall control parameters of the cable structure are divided into first-phase cable structure parameters and second-phase cable structure parameters; Based on the main structural design parameters, the cable tower (1) and stiffening beam (2) were constructed in one go, and the first-phase cable anchorage components and the reserved second-phase cable anchorage positions were installed simultaneously; Based on the parameters of the first-phase cable structure, the first-phase cable structure is installed using the first-phase cable anchoring components; During or after the first phase of operation, the second phase cable structure will be installed using the reserved second phase cable anchorage positions, based on the parameters of the second phase cable structure.

2. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 1, characterized in that: The overall control parameters of the cable structure include the total cross-sectional area, total initial tension, and total stress-free length of the main cable (5), suspension cable (6), and stay cable (7).

3. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 2, characterized in that: Based on the Phase I and Phase II operational loads, the overall control parameters of the cable structure are divided into Phase I cable structure parameters and Phase II cable structure parameters, specifically including: Based on the first-phase dead load and highway live load, obtain the first-phase load combination value; Based on the second-phase dead load, highway live load, and railway live load, obtain the second-phase load combination value; Based on the ratio of the first-stage load combination value to the second-stage load combination value, the total cross-sectional area of ​​the cable structure is divided into the cross-sectional area of ​​the first-stage cable structure and the cross-sectional area of ​​the second-stage cable structure. Based on the cross-sectional area of ​​the first-phase cable structure, the stress-free length of the inner main cable (50) and the initial tension of the inner suspension cable (60) and the inner stay cable (70) were obtained; Based on the cross-sectional area of ​​the second-phase cable structure, the stress-free length of the outer main cable (51) and the initial tension of the outer suspension cable (61) and the outer stay cable (71) were obtained.

4. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 3, characterized in that: The first-phase dead load includes the self-weight of the highway bridge deck (8) and highway ancillary facilities, and the second-phase dead load includes the first-phase dead load and the self-weight of the railway bridge deck (9) and railway ancillary facilities.

5. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 1, characterized in that: The simultaneous installation of the first-phase cable anchorage components and the reservation of locations for the second-phase cable anchorage specifically includes: Install the inner main cable saddle (30) on the tower (1) and reserve the installation position for the outer main cable saddle (40); Install the inner side cable anchoring component (31) and the inner side cable anchoring component (32) on the stiffening beam (2), and reserve the anchoring position for the outer side cable (71).

6. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 5, characterized in that: The method further includes: sealing the installation position of the outer main cable saddle (40) and the anchoring position of the outer stay cable (71).

7. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 5, characterized in that: Based on the parameters of the first-phase cable structure, the first-phase cable structure is installed using the first-phase cable anchoring components, specifically including: The inner main cable (50) is erected through the inner main cable saddle (30). The inner sling (60) is installed using the inner sling anchor member (32) to connect the inner main cable (50) to the stiffening beam (2); The inner stay cable (70) is installed and tensioned using the inner stay cable anchoring member (31); Adjust the cable tension of the inner main cable (50), inner suspension cable (60) and inner stay cable (70) according to the parameters of the first phase cable structure.

8. A method for constructing a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 6, characterized in that: Based on the parameters of the second-phase cable structure, the second-phase cable structure is installed using the reserved anchorage locations, specifically including: Open the outer main cable saddle (40) installation position and install the outer main cable saddle (40). Open the anchoring position of the outer stay cable (71) and install the outer stay cable anchoring component (41). Use the outer main cable saddle (40) to erect the outer main cable (51); Install the outer slings (61) to connect the outer main cable (51) to the stiffening beam (2); The outer stay cable (71) is installed and tensioned using the outer stay cable anchoring member (41); Adjust the cable tension of the outer main cable (51), outer suspension cable (61) and outer stay cable (71) according to the second phase cable structure parameters.

9. The construction method of a dual-purpose (road and rail) cable-stayed suspension bridge as described in claim 1, characterized in that: The stiffening beam (2) adopts a double-layer steel truss cross-section structure, in which the upper bridge deck is used for highway traffic and the lower bridge deck is used for railway traffic.

10. A cable-stayed suspension bridge for both road and rail use, characterized in that: The bridge is constructed using the construction method for a dual-purpose (road and rail) cable-stayed suspension bridge as described in any one of claims 1-9.

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