Hybrid girder partial cable-stayed bridge steel box girder hoisting low stress closure method

Abstract

The application discloses a low-stress closure method for hoisting a steel box girder of a hybrid girder partial cable-stayed bridge. The method comprises the following steps: installing an external prestressing tendon at a two-closure end or outside of a steel box girder to be closed; making the external prestressing tendon penetrate through the steel box girder; and applying force to the steel box girder by the external prestressing tendon until the steel box girder reaches a predetermined degree. By setting the external prestressing tendon used temporarily in construction, the external prestressing tendon penetrates through the steel box girder hoisted as a whole, and vertical force is applied to the steel box girder by tensioning the external prestressing tendon, so that the stress of the steel box girder is improved, the end corner of the steel box girder at a closure opening is adjusted, and the closure construction is facilitated.

Description

Technical Field

[0001] This application relates to the technical field of cable-stayed bridge construction, and in particular to a low-stress closure method for hoisting steel box girders in a hybrid beam cable-stayed bridge. Background Technology

[0002] The hybrid beam partially cable-stayed bridge is a new type of composite structure bridge. The use of a steel box girder section in the middle of the main span can significantly reduce the self-weight of the main girder and increase the applicable span of the partially cable-stayed bridge.

[0003] The existing construction method for steel box girders involves transporting the entire steel box girder segment to the water area under the bridge, then using a bridge deck crane or floating crane to lift it as a whole, and finally bolting the steel box girder together on site after it is in place.

[0004] For large-span steel box girders, they are in a simply supported state during hoisting and form a continuous structure after assembly. The stress state before and after the construction system conversion is significant. Direct welding and closure in the simply supported state results in the permanent existence of stress in the structure. During the operation phase, the stress of the steel box girder is excessive under the action of secondary dead loads, live loads, and additional loads, often requiring an increase in section height or steel plate thickness, leading to uneconomical structural design. In addition, the end rotation angle of the simply supported steel box girder is large during closure and cannot be effectively adjusted, making on-site welding or fitting welding difficult. Summary of the Invention

[0005] In view of this, this application provides a low-stress closure method for the hoisting of steel box girders in a hybrid beam cable-stayed bridge. This method can apply vertical force to the mid-span of the steel box girder, improve the stress of the steel box girder, and adjust the end rotation angle of the closure joint steel box girder, thus facilitating the closure construction.

[0006] This application provides a low-stress closure method for the hoisting of steel box girders in a hybrid beam cable-stayed bridge, including:

[0007] External prestressing tendons are installed at the second closure end or on the outside of the steel box girder in the area to be closed;

[0008] The external prestressed tendons are made to penetrate the steel box girder;

[0009] External prestressing tendons are applied to the steel box girder until the steel box girder reaches the predetermined degree.

[0010] Optionally, external prestressing tendons are installed, specifically:

[0011] External prestressing anchorage ends for fixing external prestressing tendons are set at designated locations on the concrete beam segments of the hybrid beam cable-stayed bridge.

[0012] Optionally, the installation of external prestressing tendons also includes:

[0013] A deflector is installed at a designated location on the concrete beam segment of the hybrid beam section of the cable-stayed bridge for winding external prestressing tendons.

[0014] Optionally, before the external prestressing tendons pass through the steel box girder and after installing the external prestressing tendons at the second closure end or outside the closure area of ​​the steel box girder, the method further includes:

[0015] After the steel box girder is hoisted to the closing position, the two ends of the steel box girder are temporarily hinged to the closing end.

[0016] Optionally, before the external prestressing tendons pass through the steel box girder and after installing the external prestressing tendons at the second closure end or outside the closure area of ​​the steel box girder, the method further includes:

[0017] Install steering gears on the steel box girder.

[0018] Optionally, the steering gear is installed in the lower middle part of the steel box girder.

[0019] Optionally, after tensioning the steel box girder with external prestressing tendons, the following may also be included:

[0020] After the tension of the external prestressing tendons is released, it is determined whether they should be used as permanent external tendons based on the main bridge displacement and stress monitoring during the operation period.

[0021] Optionally, the predetermined degree includes the stress being reduced to a predetermined value, and / or the steel box girder being in a predetermined closing posture.

[0022] The above-described method for low-stress closure of a hybrid beam cable-stayed bridge steel box girder involves setting up temporary external prestressing tendons for construction. These tendons pass through the hoisted steel box girder and, by tensioning them, apply vertical force to the mid-span of the steel box girder. This improves the stress in the steel box girder and adjusts the rotation angle at the end of the closure joint, facilitating the closure construction. Attached Figure Description

[0023] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the hoisting and closure of the steel box girder of the hybrid beam cable-stayed bridge provided in the embodiments of this application. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and 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.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] Before introducing the technical solution of this application, it is necessary to explain the background of the invention.

[0030] It is common practice in related technologies that the construction method for steel box girders involves transporting the entire steel box girder segment to the water area under the bridge, then using a bridge deck crane or floating crane to lift it as a whole, and finally bolting the steel box girder together on site after it is in place.

[0031] However, for large-span steel box girders, they are in a simply supported state during hoisting and form a continuous structure after assembly. The stress state before and after the construction system conversion is significant. Directly welding and assembling in the simply supported state results in the permanent existence of stress in the structure. During the operation phase, the stress on the steel box girder is excessive under the action of secondary dead loads, live loads, and additional loads, often requiring an increase in section height or steel plate thickness, leading to uneconomical structural design. In addition, the end rotation angle of the simply supported steel box girder is large during assembly and cannot be effectively adjusted, making on-site welding and cutting difficult.

[0032] Based on the above analysis, the inventors have discovered that the following key aspects require breakthroughs in solving the aforementioned problems:

[0033] (1) When steel box girders are hoisted using bridge deck cranes, the stress in the simply supported state must meet the requirements of the specifications;

[0034] (2) Before hoisting and locking the steel box girder, reliable methods should be used to reduce the stress in the steel box girder, adjust the overall alignment and closing angle of the steel box girder, and then complete the system conversion. This can significantly reduce the stress in the steel box girder during the bridge completion stage, thereby optimizing the section height or the thickness of the steel box girder plate.

[0035] (3) While adjusting the stress state of the steel box girder before closure, its end rotation angle is also adjusted to facilitate closure control and on-site welding closure.

[0036] Based on the aforementioned breakthroughs, the inventors have proposed a low-stress closure method for the steel box girder hoisting of a hybrid beam cable-stayed bridge. This method involves setting up temporary external prestressing tendons that pass through the hoisted steel box girder. By tensioning these external prestressing tendons, a vertical force is applied to the mid-span of the steel box girder, improving its stress and adjusting the rotation angle at the closure joint, thus facilitating the closure construction. This invention is thus established.

[0037] refer to Figure 1 This application provides a low-stress closure method for hoisting steel box girders of a hybrid beam cable-stayed bridge, comprising:

[0038] External prestressing tendons are installed at the second closure end or on the outside of the steel box girder in the area to be closed;

[0039] The aforementioned external prestressed tendons are made to penetrate the aforementioned steel box girder;

[0040] External prestressing tendons are applied to the steel box girder until the steel box girder reaches the predetermined degree.

[0041] As a concrete example, the installation of external prestressed tendons is as follows:

[0042] External prestressing anchorage ends for fixing external prestressing tendons are set at designated locations on the concrete beam segments of the hybrid beam cable-stayed bridge.

[0043] Therefore, the external prestressed tendons can be well fixed through the external prestressed anchoring end.

[0044] As for the specific structure of the anchorage at the external prestressed anchorage end, an anchorage device widely used in the construction field can be adopted.

[0045] As a concrete example of demonstration, the installation of external prestressed tendons also includes:

[0046] A deflector is installed at a designated location on the concrete beam segment of the hybrid beam section of the cable-stayed bridge for winding external prestressing tendons.

[0047] In this way, the non-anchored positions of the external prestressing tendons are supported by the steering mechanism, preventing the external prestressing tendons from becoming partially entangled in other positions of the concrete beam segment, which would hinder the subsequent tensioning of the steel box girder.

[0048] As a specific example, before the aforementioned external prestressing tendons penetrate the aforementioned steel box girder, and after the external prestressing tendons are installed at the second closure end or outside of the steel box girder's closure area, the method further includes:

[0049] After the steel box girder is hoisted to the closing position, the two ends of the steel box girder are temporarily hinged to the aforementioned closing end.

[0050] As a specific example, before the aforementioned external prestressing tendons penetrate the aforementioned steel box girder and after installing the external prestressing tendons at the second closure end or outside of the steel box girder's closure area, the method further includes:

[0051] Install steering gears on the steel box girder.

[0052] As a specific example, the aforementioned steering gear is installed in the lower middle part of the steel box girder.

[0053] As a specific example, the process of tensioning a steel box girder with externally prestressed tendons also includes:

[0054] After the tension of the external prestressing tendons is released, it is determined whether they should be used as permanent external tendons based on the main bridge displacement and stress monitoring during the operation period.

[0055] As a specific example, the aforementioned predetermined degree includes the stress being reduced to a predetermined value, and / or the steel box girder being in a predetermined closing posture.

[0056] The closing process of this application will now be described in a common application scenario. It should be noted that this common implementation scheme should not be used as the basis for determining the essential features for understanding the technical problem claimed to be solved by this application; it is merely an example.

[0057] Refer again Figure 1 The assembly process is as follows:

[0058] S1. Install external prestressed anchorage ends and steering devices at appropriate locations on the concrete beam segments of the cable-stayed bridge in the hybrid beam section, and install steering devices near the mid-span of the steel box girder in the main span.

[0059] S2. Based on the stress of the steel box girder during the construction and completion stages, determine the stress adjustment range of the steel box girder during the system transformation process, and then determine the amount and tension of temporary external prestressing.

[0060] S3. After the mid-span steel box girder is hoisted to the closing position, the closing end is temporarily hinged, a suitable number of external tendons are passed through, and tensioned to the aforementioned determined value;

[0061] S4. Based on on-site monitoring and measured displacement of the steel box girder, fine-tune the external tension force, lock the closure end at an opportune time, and then weld the joint section to complete the closure of the steel box girder and the steel-concrete joint section.

[0062] S5. Release the tension of the external prestressed tendons and use them as permanent external tendons as appropriate, depending on the displacement and stress monitoring of the main bridge during the operation period.

[0063] Compared with related technologies, this application has the following advantages:

[0064] (1) It can optimize the stress state of the steel box girder and the connecting section of the hybrid beam cable-stayed bridge;

[0065] (2) Facilitates fine-tuning of the end angle of the steel box girder at the construction closure joint;

[0066] (3) External prestressed steel strands can also be used as permanent external strands during operation to adjust the stress and deflection of the main beam during operation.

[0067] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A low-stress closure method for hoisting steel box girders in a hybrid beam cable-stayed bridge, characterized in that, include: External prestressing tendons are installed at the second closure end or on the outside of the steel box girder in the area to be closed; The external prestressed tendons are made to penetrate the steel box girder; The external prestressing tendons apply force to the steel box girder until the steel box girder reaches the predetermined degree. The installation of external prestressing tendons specifically involves setting up external prestressing anchorage ends at designated locations on the concrete beam segments of the cable-stayed bridge in the hybrid beam section to fix the external prestressing tendons. Before the external prestressed tendons pass through the steel box girder and after the external prestressed tendons are installed at the two closure ends or outside the closure area of ​​the steel box girder, the method further includes: after the steel box girder is hoisted to the closure position, the two ends of the steel box girder are temporarily hinged to the closure ends. Before the external prestressing tendons pass through the steel box girder and after the external prestressing tendons are installed at the second closure end or outside the closure area of ​​the steel box girder, the method further includes: installing a steering device on the steel box girder; The predetermined degree includes the stress being reduced to a predetermined value, and / or the steel box girder being in a predetermined closing posture.

2. The method for low-stress closure of the steel box girder of a hybrid beam cable-stayed bridge according to claim 1, characterized in that, The installation of external prestressing tendons also includes: A deflector is installed at a designated location on the concrete beam segment of the hybrid beam section of the cable-stayed bridge for winding external prestressing tendons.

3. The method for low-stress closure of the steel box girder of a hybrid beam cable-stayed bridge according to claim 1, characterized in that, The steering gear is installed in the lower middle part of the steel box girder.

4. The method for low-stress closure of the steel box girder of a hybrid beam cable-stayed bridge according to claim 1, characterized in that, After tensioning the steel box girder with external prestressed tendons, the following steps are also included: After the tension of the external prestressing tendons is released, it is determined whether they should be used as permanent external tendons based on the main bridge displacement and stress monitoring during the operation period.

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