Installation method and system of double-tower double-span suspension stiffened beam with overhanging span suspension cable bridge steel box girder

Abstract

The application discloses a method and system for installing a double-tower double-span suspension stiffening beam with an overhanging span suspension cable bridge steel box beam, and the method comprises the following steps: S1, installing hoisting equipment and a beam storage support (including a pier-side beam storage support and a tower area beam storage support); S2, hoisting the steel box beam asymmetrically to both sides with the main tower as the center, and actively pushing the main cable saddle in stages; S3, adjusting the linear shape, welding the girth weld and removing the temporary structure after the hoisting is completed. Wherein, part of the steel box beam in the overhanging span area of the side span is temporarily stored at a low position on the pier-side beam storage support, and is lifted and positioned after the beam segment on the main span side is installed to a predetermined number. The application adopts an asymmetric hoisting sequence with the main tower as the center, cooperates with the main cable saddle pushing operation in stages, can dynamically balance the construction load difference between the main span and the side span, thereby accurately controlling the stress and deflection of the main tower, and ensures the structural safety in the whole construction process.

Description

Technical Field

[0001] This invention relates to the field of public bridge construction technology, specifically to a method and system for installing steel box girders in a double-tower, double-span suspension stiffened girder suspension bridge with outward-extending spans. Background Technology

[0002] A suspension bridge is a long-span bridge type with the main cable as the primary load-bearing structure. The traditional installation of steel box girders for three-span suspension bridges usually adopts a construction process of symmetrical hoisting from the mid-span towards the towers, or symmetrical hoisting from both towers towards the mid-span. This type of process has a clear understanding of the stress on symmetrical structures and is technically mature.

[0003] However, for special suspension bridge systems like the Rushankou Bridge, which features a double-tower, double-span suspension stiffening girder with extended side spans, the structural stress is fundamentally different from that of traditional three-span suspension bridges. This bridge type lacks a traditional mid-span, forming two independent main spans with extended side spans, making it a fully floating system. If the traditional symmetrical hoisting method were used, the main towers would be under severe unbalanced stress for an extended period during the long beam installation process, leading to a continuous accumulation of tower bending moments and lateral misalignment, easily exceeding design safety limits and posing a serious threat to the structural safety of the main towers. Simultaneously, the enormous construction internal forces also make controlling the bridge's alignment extremely difficult.

[0004] Therefore, for this special type of bridge, there is an urgent need for an innovative method for installing steel box girders to proactively and controllably manage the stress on the main tower and the structural alignment during construction, thereby ensuring construction safety and the quality of the completed bridge. Summary of the Invention

[0005] To overcome the shortcomings of existing symmetrical hoisting techniques that are unsuitable for double-tower, double-span suspension bridges with overhangs, this invention provides a method and system for installing steel box girders in double-tower, double-span suspension stiffener suspension bridges with overhangs. This solution optimizes the hoisting sequence and the timing of the main cable saddle push, achieving precise control over the stress and misalignment of the main towers and ensuring the bridge's alignment meets standards upon completion.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for installing a steel box girder of a double-tower, double-span suspension stiffened girder with an overhanging span, comprising the following steps: S1. Install hoisting equipment and beam storage supports for temporary storage of steel box girders, the beam storage supports including pier-side beam storage supports and tower area beam storage supports; S2. Install the steel box girder in sections according to the preset hoisting sequence that expands asymmetrically to both sides with the main tower as the center; during the installation process, actively push the main cable saddle towards the mid-span direction in stages according to the stress state of the main tower. S3. After all the steel box girders are hoisted into place, the alignment is adjusted, the circumferential welds of the steel box girders are welded, and the temporary structures are dismantled. In step S2, at least part of the steel box girder located in the extended area of ​​the side span is temporarily stored at a low position on the beam storage support next to the pier after hoisting. After the main span side beam segments adjacent to it are installed to a predetermined number, it is then lifted to the design elevation and connected to the hoisting cables.

[0008] Furthermore, the hoisting sequence that expands asymmetrically from the main tower to both sides is as follows: First, the initial stable beam segment group around the two main towers is installed and connected. This initial stable beam segment group includes at least the beam segments adjacent to the main towers on both sides. Then, based on this, subsequent beam segments are installed alternately in the direction of the main span mid-span and the direction of the side span extension.

[0009] Furthermore, after the initial stable beam segment assembly is installed, the first main cable saddle push is performed; subsequent main cable saddle pushes are triggered when the accumulated unbalanced load between the main span and the side spans reaches a preset threshold. The preset threshold is determined by calculation based on the allowable stress and offset value of the main tower.

[0010] Furthermore, during the installation process extending towards the side span, for multiple consecutive extended span beam segments located within the side span extension area and within twice the beam segment length of the nearest transition pier, a process of first temporarily storing them as a whole and then lifting them in a concentrated manner is adopted.

[0011] Furthermore, the method also includes: performing final closure in the mid-span area of ​​the main span, and tensioning the limiting cables before closure to precisely adjust and lock the overall bridge alignment.

[0012] Furthermore, the slings include permanent slings, temporary slings, and limiting slings; after the circumferential weld of the steel box girder is completed in step S3, all temporary slings are removed.

[0013] Secondly, the present invention provides a steel box girder installation system for implementing the above-described method, comprising: Lifting equipment is used for lifting and transporting steel box girders; The beam storage supports include pier-side beam storage supports set next to the piers and tower area beam storage supports set on the main tower foundation or tower bottom crossbeam, for temporary low-level storage of steel box girders. The main cable saddle is used to support the main cable and transfer the load to the main tower. The main cable saddle pushing device is connected to the main cable saddle drive and is used to drive the main cable saddle to move relative to the top of the main tower towards the mid-span direction in stages during construction. The suspension system includes permanent suspension cables, temporary suspension cables, and limiting suspension cables. The upper end of the temporary suspension cable is detachably connected to the main cable, and the lower end is used for temporary connection to the steel box girder before the circumferential weld of the steel box girder is welded. The limiting suspension cable is configured to allow for tension adjustment before the entire bridge is closed, so as to make final adjustments to the main cable alignment and the steel box girder elevation.

[0014] Thirdly, the present invention provides a double-tower, double-span suspension stiffening girder suspension bridge with outward spans constructed using the above method.

[0015] Compared with the prior art, the present invention has the following significant advantages: 1. This invention adopts an asymmetrical hoisting sequence centered on the main tower, combined with phased main cable saddle jacking operations, which can dynamically balance the construction load differences between the main span and the side spans, thereby accurately controlling the stress and displacement of the main tower and ensuring the structural safety of the entire construction process.

[0016] 2. The present invention adopts the process of "temporarily storing in a low position first and then lifting in a centralized manner" for the side span overhang beam segment, which not only reduces the early adverse effects of overhang span construction on the main tower stress, but also realizes the optimized scheduling and continuous operation of large hoisting equipment, significantly improving construction efficiency.

[0017] 3. By tensioning the limiting suspenders before the entire bridge is joined, the final precise adjustment and locking of the main cable alignment and beam segment elevation were achieved, effectively ensuring that the completed bridge alignment fully meets the design requirements.

[0018] 4. The installation system and its accompanying method of the present invention have clearly defined functions and work together seamlessly. This system provides reliable hardware support for the smooth implementation of the method.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0020] To more clearly illustrate the solutions in this invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure during the hoisting and assembly of the steel box girder in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of the steel box girder after hoisting in an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the bridged state in an embodiment of the present invention.

[0024] Figure 4 This is a diagram showing the segmentation and hoisting sequence of the steel box girder of the double-tower, double-span suspension stiffened girder suspension bridge with outward extension spans as described in this invention.

[0025] Explanation of reference numerals in the attached figures: 1. Lifting equipment; 2. Beam storage support; 21. Beam storage support beside pier; 22. Beam storage support in tower area; 3. Main cable saddle; 4. Lifting cable; 41. Permanent lifting cable; 42. Temporary lifting cable; 43. Limiting lifting cable; 5. Steel box girder; 6. Main cable; 7. Main tower; 8. Transition pier. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 This embodiment provides a method for installing the steel box girder of a double-tower, double-span suspension bridge with a stiffened girder and cantilever span, referring to... Figures 1-3 This includes the following steps: S1. Construction Preparation like Figure 1 As shown, hoisting equipment 1 and a beam storage bracket 2 for temporary storage of the steel box girders are installed. (Refer to...) Figure 2 The beam storage support 2 includes a pier-side beam storage support 21 and a tower area beam storage support 22. The hoisting equipment 1 must meet the lifting weight and hoisting radius requirements of the steel box girder 5. The beam storage support 2 must undergo load-bearing capacity calculations to ensure the stability of the temporarily stored steel box girder.

[0028] S2. Segmented hoisting of steel box girder and saddle-pushing of main cable. Reference Figure 1 Following a pre-set hoisting sequence that expands asymmetrically to both sides from the main tower 7 as the center, the steel box girder 5 was installed in sections. During the installation process, based on the stress state of the main tower 7, the main cable saddle 3 was actively pushed towards the mid-span in stages.

[0029] The specific hoisting sequence is as follows: First, complete the installation and connection of the initial stable beam segment group surrounding the two main towers 7. This initial stable beam segment group includes at least the beam segments adjacent to the two sides of the main tower. Then, based on this, alternately extend the installation of subsequent beam segments towards the mid-span direction of the main span and the outward extension direction of the side spans.

[0030] After the initial stable beam segment assembly is installed, the first main cable saddle jacking operation is performed. Subsequent main cable saddle jacking operations are triggered when the accumulated unbalanced load between the main span and the side spans reaches a preset threshold.

[0031] At least part of the steel box girder 5 located in the extended area of ​​the side span is temporarily stored at a low position on the beam storage support 21 next to the pier after hoisting. After the adjacent main span side beam segments are installed to the predetermined number, they are then lifted to the design elevation and connected to the lifting cables 4.

[0032] When extending the installation towards the side span, for multiple consecutive extended span beam segments adjacent to transition pier 8, the process of first temporarily storing them as a whole and then lifting them to the design elevation is adopted.

[0033] S3. Linear fine-tuning and Helong The steel box girder is finally joined in the mid-span area of ​​the main span. Before joining, the limiting suspension cable 43 is tensioned to apply a preset tension, thereby making final adjustments to the main cable alignment and beam segment elevation, and locking the overall bridge alignment.

[0034] S4 Welding and Temporary Structure Removal After all steel box girders 5 are hoisted into place and their alignment adjusted, the circumferential welds of the steel box girders are then performed. The lifting cables 4 include permanent lifting cables 41, temporary lifting cables 42, and limiting lifting cables 43. After the circumferential welds are completed, all temporary lifting cables 42 are removed, such as... Figure 3 As shown, the steel box girder installation is complete.

[0035] By employing an asymmetrical hoisting sequence centered on the main tower, coupled with phased main cable saddle pushing operations, the load differences between the main span and the side spans can be effectively balanced. This operation allows for precise control of the stress and displacement of the main tower, ensuring structural safety during construction.

[0036] Example 2 This embodiment provides a steel box girder installation system for a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans, referring to... Figure 1 The system includes hoisting equipment 1, beam storage support 2, main cable saddle 3, main cable bearing 6, main cable saddle jacking device, and sling system. Hoisting equipment 1 is used for lifting and transferring the steel box girder 5. In specific applications, hoisting equipment 1 can be, for example, a cable-mounted crane, with a rated lifting capacity matching the hoisting requirements of the steel box girder 5. The beam storage support 2 includes a pier-side beam storage support 21 located beside the pier and a tower area beam storage support 22 located on the main tower 7's abutment or tower base crossbeam, used for temporarily storing the steel box girder 5 at a low position during construction. The main cable saddle 3 carries the main cable 6 and transfers the load to the main tower 7; the main cable saddle jacking device is driven by the main cable saddle 3 and is used to drive the main cable saddle 3 to move relative to the top of the main tower 7 towards the mid-span direction in stages during construction. (Refer to...) Figure 2The suspension system includes a permanent suspension cable 41, a temporary suspension cable 42, and a limiting suspension cable 43. The permanent suspension cable 41 is used to suspend the steel box girder 5 and transfer the load for a long period after the bridge is completed. The upper end of the temporary suspension cable 42 is detachably connected to the main cable 6, and the lower end is used to temporarily connect to the steel box girder 5 before the circumferential weld of the steel box girder is welded. The limiting suspension cable 43 is configured to adjust the tension before the entire bridge is closed, so as to make final adjustments to the main cable alignment and the steel box girder elevation.

[0037] The system is used to implement the installation method in Example 1, and can accurately complete the processes of hoisting, temporary storage, main cable saddle pushing and alignment adjustment of steel box girders, ensuring the smooth installation of steel box girders for this type of suspension bridge.

[0038] Example 3 This embodiment relates to a method for installing steel box girders in a double-tower, double-span suspension bridge with stiffened girder and overhanging spans, applied to the main bridge construction of the Rushankou Bridge project. The bridge has two main towers 7, with main cables 6 spanning the towers 7 and connected to the stiffened steel box girder 5 below via suspenders 4. The end spans are supported by transition piers 8. The construction system mainly includes hoisting equipment 1 such as a bridge deck crane, girder storage supports 2, main cable saddles 3 and their jacking devices, and a suspender system composed of permanent suspenders 41, temporary suspenders 42, and limiting suspenders 43.

[0039] For detailed installation instructions, please refer to... Figures 1-4 This includes the following steps: S1. Construction Preparation A large-tonnage cable-stayed crane was installed within the site as hoisting equipment 1, and its commissioning and acceptance were completed. A beam storage support 21 was erected beside the transition pier 8, and a tower area beam storage support 22 was erected on the main tower 7's foundation or bottom crossbeam. Both types of supports used steel profiles. After erection, a static load test was conducted to ensure the load-bearing capacity met the requirements.

[0040] S2. Segmented hoisting of steel box girder and saddle-pushing of main cable. (1) Installation of the initial stable beam segment group and the first jacking Reference Figure 4 In the diagram, the directions marked "Weihai" and "Yantai" indicate the start and end points of the bridge; "Transition Pier" refers to the supporting structure of the side span extension; "Tower" refers to the main tower 7 of the bridge; Closure Section is the area where the steel box girder is finally connected; the numbers in the diagram (such as B1, B2...B47, etc.) correspond to the beam segment numbers of steel box girder 5; the "Cable Clamp Type" column in the table corresponds to the installation position of suspender cable 4, and "L, B, M" etc. are cable clamp classification identifiers.

[0041] Beam segments numbered B26, B27, B28, and B25 were installed sequentially to form an initial stable beam segment group, completing the temporary connection between the beam segments. Then, the main cable saddle jacking device was activated to push the main cable saddle 3 towards the mid-span, completing the first jacking operation.

[0042] (2) Alternating extension hoisting and subsequent jacking Based on the initial stable beam segment group, subsequent beam segments are hoisted alternately towards the mid-span direction of the main span and the outward extension direction of the side span. During the installation of beam segments numbered B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, B11, B12, B13, B16, B21, B20, B15, B19, B14, and B18, a portion of them are temporarily stored on the beam storage support 2 to proactively delay the impact of this portion of the load on the main tower.

[0043] The load difference between the main span and the side spans is monitored in real time. When the unbalanced load reaches a preset threshold, the main cable saddle jacking device is restarted for jacking. This preset threshold is determined comprehensively based on the real-time stress, deviation, and design safety factor of the main tower 7. The jacking device drives the main cable saddle 3 to move a certain displacement towards the mid-span, thereby adjusting the span ratio of the main cable 6, actively correcting the deviation of the main tower 7, and pulling it back to the safe range. In this embodiment, this dynamic control process involves four main cable saddle jacking operations.

[0044] (3) Concentrated lifting of the overhanging span beam segment After the adjacent beam segments on the main span side are installed to the predetermined number, the continuous multiple overhanging beam segments that are temporarily stored on the beam storage support 21 next to the pier and are within twice the beam segment length of the nearest transition pier 8 are lifted to the design elevation, connected to the adjacent beam segments, and the corresponding permanent slings 41 are installed.

[0045] S3. Linear fine-tuning and Helong When the installation on the main span side progresses to a certain stage, and the stress state of the main tower 7 allows and requires the load of the extended span to participate in the overall balance, the extended span continuous beam segments temporarily stored on the beam storage support 21 next to the pier are concentrated and lifted in batches to the design elevation and connected to the temporary slings 42. This measure can efficiently utilize hoisting resources and facilitate alignment control.

[0046] As installation progresses, the final closure point naturally appears in the mid-span area of ​​the main span. Before closure, the tensioning limit cable 43 is tensioned, and by applying precise preset tension to it, the alignment of the main cable 6 and the elevation of the steel box girder 5 are systematically fine-tuned and locked for the last time to ensure the accuracy of closure.

[0047] S4. Welding and temporary structure dismantling After the hoisting, assembly, and alignment adjustment of all steel box girders 5 were completed, all circumferential welds were performed to form a continuous whole for the entire bridge. Once the welding was completed and passed inspection, all temporary slings 42 were removed. At this point, the bridge construction was complete. Figure 3 As shown, the structure was transformed from a temporary suspension system during the construction phase into a permanent bridge system as required by the design.

[0048] It should be noted that the construction sequence, jacking stage, and beam segment storage range described above with specific numbers are merely one specific embodiment of the technical solution of this invention, used to clearly demonstrate how to achieve the core steps defined in the claims, such as "asymmetrical expansion from the main tower to both sides," "staged jacking," and "temporary storage before lifting." The scope of protection of this invention is not limited to these specific details. Any alternative construction method based on the same inventive concept, which adaptively adjusts the hoisting sequence, jacking timing, or storage strategy to achieve the purpose of controlling the stress on the main tower and the bridge alignment, falls within the scope of protection of the claims of this invention.

Claims

1. A method for installing a steel box girder of a double-tower, double-span suspension stiffened girder with overhanging spans, characterized in that, Includes the following steps: S1. Install hoisting equipment (1) and a beam storage bracket (2) for temporary storage of steel box girders, the beam storage bracket (2) including a beam storage bracket (21) next to the pier and a beam storage bracket (22) in the tower area. S2. Install the steel box girder (5) in sections according to the preset hoisting sequence that expands asymmetrically to both sides with the main tower (7) as the center. During the installation process, according to the stress state of the main tower (7), actively push the main cable saddle (3) towards the middle span in stages. S3. After all the steel box girders (5) are hoisted into place, the alignment is adjusted, the circumferential welds of the steel box girders are welded, and the temporary structures are dismantled. In step S2, at least part of the steel box girder (5) located in the side span extension area is temporarily stored at a low position on the pier-side beam storage support (21) after hoisting. After the adjacent main span side beam segments are installed to a predetermined number, they are then lifted to the design elevation and connected to the slings (4).

2. The method for installing steel box girders of a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans according to claim 1, characterized in that, The hoisting sequence, which expands asymmetrically from the main tower to both sides, is as follows: First, the initial stable beam segment group around the two main towers (7) is installed and connected. This initial stable beam segment group includes at least the beam segments adjacent to the two sides of the main tower. Then, based on this, the subsequent beam segments are installed alternately in the direction of the main span mid-span and the direction of the side span extension.

3. The method for installing steel box girders of a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans according to claim 2, characterized in that, After the initial stable beam segment group is installed, the first main cable saddle push is performed; subsequent main cable saddle pushes are triggered when the accumulated unbalanced load between the main span and the side span reaches a preset threshold.

4. The method for installing steel box girders of a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans according to claim 1, characterized in that, When extending the installation towards the side span, for multiple consecutive extended span beam segments located within the side span extension area and within twice the beam segment length of the nearest transition pier (8), a process of first temporarily storing and then centrally lifting them is adopted.

5. The method for installing steel box girders of a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans according to claim 1, characterized in that, The method further includes: performing final closure in the mid-span area of ​​the main span, and tensioning the limiting suspenders (43) before closure to adjust and lock the overall bridge alignment.

6. The method for installing steel box girders of a double-tower, double-span suspension stiffened girder suspension bridge with overhanging spans according to claim 1, characterized in that, The slings (4) include permanent slings (41), temporary slings (42) and limiting slings (43); after the circumferential weld of the steel box girder in step S3 is completed, all temporary slings (42) are removed.

7. A steel box girder installation system for a double-tower, double-span suspension stiffened girder with overhanging span suspension bridge, used to implement the steel box girder installation method for a double-tower, double-span suspension stiffened girder with overhanging span suspension bridge as described in any one of claims 1-6, characterized in that, include: Lifting equipment (1) is used for lifting and transporting steel box girders (5); The beam storage support (2) includes the pier-side beam storage support (21) set next to the pier and the tower area beam storage support (22) set on the main tower (7) pier or the tower bottom crossbeam, for temporary low-level storage of steel box girders (5); The main cable saddle (3) is used to support the main cable (6) and transfer the load to the main tower (7). The main cable saddle pushing device is connected to the main cable saddle (3) and is used to drive the main cable saddle (3) to move relative to the top of the main tower (7) towards the middle span in stages during the construction process; The suspension system includes permanent suspension cables (41), temporary suspension cables (42) and limiting suspension cables (43). The permanent suspension cables (41) are used to suspend the steel box girder (5) for a long time after the bridge is completed and to transfer the load. The upper end of the temporary suspension cables (42) is detachably connected to the main cable (6), and the lower end is used to temporarily connect to the steel box girder (5) before the circumferential weld of the steel box girder is welded. The limiting suspension cables (43) are configured to be tension-adjusted before the bridge is fully closed, so as to make final adjustments to the main cable alignment and the steel box girder elevation.

8. A double-tower, double-span suspension bridge with a stiffened girder and an overhang, constructed using the method described in any one of claims 1-6.

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