Height adjustable bracket device and steel box girder installation method

Abstract

This application discloses a height-adjustable bracket device and a method for installing steel box girders. The device includes a pair of symmetrically arranged bracket mechanisms, each bracket mechanism including a pair of sub-bracket mechanisms, which are respectively set on parallel transport tracks. Each sub-bracket mechanism includes: a fixed support section, the upper end of which is fixedly connected to the lower pressure plate and the lower end of which is hinged to the first tensioning box; a movable support section, the upper end of which is hinged to the lower pressure plate and the lower end of which is hinged to the second tensioning box; a support platform, including a lower pressure plate, an upper pressure plate, and a universal ball joint installed between them; and a first tensioning box and a second tensioning box, which are connected by prestressed steel strands. This application eliminates the crossbeams of conventional gantry cranes, simplifies the gantry crane structure, reduces the self-weight of the gantry crane, improves the stability of the steel box girder transfer and lifting, and also enhances the turnover efficiency and utilization efficiency of the gantry crane.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, specifically, it relates to a height-adjustable bracket device and a method for installing steel box girders. Background Technology

[0002] The erection of large steel box girders is a key and challenging aspect of the construction process, requiring high-quality completion while ensuring construction safety. The gantry crane, currently the most crucial construction equipment in steel box girder construction, directly impacts the safety of numerous bridge projects. Gantry cranes for large steel box girder erection consist of crossbeams and side supports. Currently, for wide-span steel box girder structures with multiple compartments (e.g., a single box with three compartments), the width is significant. For gantry crane construction, the crossbeams themselves bear considerable weight, and the large width of the girder further increases the load. Moreover, the gantry crane uses a lifting and moving method for the steel box girder, inevitably leading to potential swaying below. This weakens the gantry crane's lateral stability, especially during movement, where significant deformation occurs, posing a high operational risk.

[0003] Furthermore, there are currently no specific design specifications for temporary construction structures in the design and calculation of gantry cranes. Construction units typically rely on past engineering experience in their designs, and during verification calculations, they often fail to consider the issue of lateral stability, instead relying on experience to add various transverse bracing methods to prevent gantry crane instability. Most gantry crane analyses for engineering examples are similarly flawed, completely neglecting lateral stability issues and the impact of lateral connection structures on lateral stability.

[0004] Therefore, the current method of using gantry cranes to lift and move steel box girders is limited by various factors such as height, lifting accuracy, and the load-bearing capacity of the outriggers when transporting heavy steel box girders. If lifting a large steel box girder, it is necessary to divide it into several smaller segments. Furthermore, the number of lifting operations is high, resulting in wasted time. Therefore, it is necessary to study a solution capable of handling the moving and installation of heavy steel box girders. Summary of the Invention

[0005] This application controls the height of the support frame by adding tension steel strands, which changes the previous gantry structure and changes the steel box girder from hoisting to lifting and transporting, thus solving the problem of lateral instability of the gantry frame caused by high-altitude hoisting of steel box girders.

[0006] The above objective can be achieved through the following technical solutions:

[0007] A height-adjustable bracket device includes a pair of symmetrically arranged bracket mechanisms, each bracket mechanism including a pair of sub-bracket mechanisms, the pair of sub-bracket mechanisms being respectively mounted on parallel transport tracks, each sub-bracket mechanism including:

[0008] The fixed support section is fixedly connected to the lower pressure plate at its upper end and hinged to the first tension box at its lower end.

[0009] The movable support section is hinged at the upper end to the lower pressure plate and at the lower end to the second tension box.

[0010] The support platform includes a lower bearing plate, an upper bearing plate, and a universal ball joint installed between them;

[0011] The first and second pull boxes are connected by prestressed steel strands.

[0012] Optionally, the first box is installed on the first vehicle, and the second box is installed on the second vehicle.

[0013] Optionally, the support platform can be raised and lowered as the angle between the fixed support section and the movable support section changes.

[0014] Optionally, the support platforms of a pair of sub-bracket mechanisms have a gap, which is wider than the width of the pier.

[0015] Optionally, the universal ball joint includes a fixed base, a ball, and a connecting rod. The fixed base is fixedly connected to the upper end of the lower pressure plate, the ball is disposed in the fixed base, and the connecting rod is fixedly connected to the ball. The connecting rod is connected to the upper pressure plate.

[0016] Optionally, the prestressed steel strands are tensioned and released using jacks and tool anchors.

[0017] This application also provides a method for installing a steel box girder, which uses the aforementioned height-adjustable bracket device to move the steel box girder and adjust its height, including the following steps:

[0018] Step S1: The steel box girder is placed on the bracket device by the gantry crane at the main bridge end, so that the two ends of the steel box girder are respectively placed on the upper bearing plates of a pair of bracket mechanisms. The bracket device and the steel box girder on it are transported by the first vehicle and the second vehicle along the transport tracks laid on both sides of the bridge pier layout line.

[0019] Step S2: Use a satellite positioning system to track the coordinates of the four corners of the steel box girder and confirm the position corresponding to the bridge pier;

[0020] Step S3: After the steel box girder is transported to the designated location coordinates, the steel strands are released to reduce the height of the support platform, allowing the steel box girder to be erected on the bridge pier.

[0021] Step S5: Control the release of the steel strands to further reduce the height of the support platform and separate the bracket device from the steel box girder;

[0022] Step S6: The bracket mechanism returns to the starting bridgehead, and by tensioning the steel strands, the support platform reaches the next target height to begin the transportation of the next segment of the steel box girder.

[0023] Step S7, repeat steps S1 to S6.

[0024] Optionally, step S4 is also included, which uses the correlation between the elongation of the steel strand and the height of the support platform to perform height tracking and adjustment of the steel box girder using a two-dimensional fuzzy controller. The two-dimensional fuzzy controller uses the deviation between the real-time elongation of the steel strand and the specified elongation, as well as the change of the deviation, as input variables to track and adjust until the specified elongation is reached, so that the steel box girder reaches the specified height position.

[0025] Optionally, in step S2, the lifting point of the gantry crane is determined by using the CAD solid model of the steel box girder to determine the position of the center of gravity of the steel box girder, and selecting the intersection of the vertical line of the center of gravity and the top surface of the CAD solid model of the steel box girder as the lifting point of the resultant force.

[0026] Optionally, during the process of raising the bracket by tensioning the steel strand, the cable force can be measured by pressure sensor method or vibration frequency method, thereby establishing the relationship between the elongation of the steel strand and the height of the bracket.

[0027] Compared with the prior art, this application has the following advantages:

[0028] (1) The crossbeams of the previous gantry frame were eliminated, which simplified the structure of the gantry frame, reduced the self-weight of the gantry frame, improved the stability of the steel box girder transfer and lifting, and also enhanced the turnover efficiency and utilization efficiency of the gantry frame.

[0029] (2) The prestressed tensioning process is adopted to achieve rapid, simple and precise adjustment of the bracket height.

[0030] (3) Using a support method to move the crossbeam provides greater stability compared to hoisting.

[0031] (4) Without the constraint of the crossbeam, the fixed support section and the movable support section can move relatively flexibly and freely. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the height-adjustable bracket device of this invention being lowered in an embodiment.

[0033] Figure 2 This is a schematic diagram of a sub-bracket mechanism according to an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the fixed support section according to an embodiment of the present invention.

[0035] Figure 4This is a schematic diagram of the active support segment according to an embodiment of the present invention.

[0036] Figure 5 This is a schematic diagram of the tensioning box according to an embodiment of the present invention.

[0037] Figure 6 This is a schematic diagram of a pair of sub-bracket mechanisms according to an embodiment of the present invention.

[0038] Figure 7 This is a schematic diagram of a bracket device for transporting steel box girders according to an embodiment of the present invention. Detailed Implementation

[0039] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0040] The height-adjustable bracket device of this embodiment is used to support the installation of large steel box girders and can be applied in the installation of various large components such as bridges, buildings, and ships. The following is in conjunction with... Figure 1 , Figure 2 To illustrate the height-adjustable bracket device.

[0041] The height-adjustable bracket device includes a pair of symmetrically arranged bracket mechanisms 100, which can be symmetrically arranged at both ends of the large steel box girder 200 to support the large steel box girder.

[0042] Each bracket mechanism 100 includes a pair of sub-bracket mechanisms, which are respectively arranged on parallel transport tracks, i.e., one sub-bracket mechanism is arranged on the left transport track and the other sub-bracket mechanism is arranged on the right transport track. The transport tracks are arranged on both sides of the bridge pier layout. Each sub-bracket mechanism includes a fixed support section 1, a movable support section 2, a support platform 5, a first tensioning box 3, and a second tensioning box 4. The support platform 5 consists of a lower pressure plate 51, an upper pressure plate 52, and an adjustable universal ball joint 53. Both the upper and lower pressure plates are made of steel. The lower pressure plate 51 is used to connect with the fixed support section 1 and the movable support section 2.

[0043] The fixed support section 1 and the movable support section 2 can be made of steel pipes or welded steel frames, for example, both can be inverted A-shaped frames. The fixed support section 1 and the movable support section 2 can be vertically or inclined. The upper end of the fixed support section 1 is fixedly connected to the lower end of the lower pressure plate 51, for example, by welding or bolting. The lower end of the fixed support section 1 is hinged to the first tension box 3. Therefore, the fixed support section 1 can restrict the movement of the support platform 5 in any direction and also restrict the rotation at the connection constraint between the fixed support section 1 and the lower pressure plate 51, mainly serving a supporting function. The upper end of the movable support section 2 is hinged to the lower end of the lower pressure plate 51, and the lower end is hinged to the second tension box 4. The upper end face of the upper pressure plate 52 is supported on one end of the steel box girder 200. Specifically, in one bracket mechanism 100, the upper bearing plate 52 of one sub-bracket mechanism is supported on the left side of one end of the steel box girder 200, and the upper bearing plate 52 of the other sub-bracket mechanism is supported on the right side of the same end of the steel box girder 200; in another bracket mechanism 100, the upper bearing plate 52 of one sub-bracket mechanism is supported on the left side of the other end of the steel box girder 200, and the upper bearing plate 52 of the other sub-bracket mechanism is supported on the right side of the other end of the steel box girder 200. Furthermore, as... Figure 6 As shown, there is a certain gap between the upper support platforms 5 of the pair of sub-bracket mechanisms. The gap should be wider than the width of the pier so that even if the height of the support platforms 5 of the pair of sub-bracket mechanisms is reduced to below the height of the pier, the support platforms will not interfere with the pier during the movement along the transport track.

[0044] The upper bearing plate 52 is used to support the lower end of the steel box girder 200. A universal ball joint 53 is installed between the upper bearing plate 52 and the lower bearing plate 51, which can be adjusted in any direction. Furthermore, the horizontal direction and overall balance of the steel box girder 200 above the support platform 5 can be observed in real time through monitoring and measurement to prevent tipping.

[0045] The first tension box 3 and the second tension box 4 have the same structure and are connected by prestressed steel strands. The first tension box 3 is mounted on the first vehicle 31, and the second tension box 4 is mounted on the second vehicle 41. The first vehicle 31 and the second vehicle 41 can move along a transport track along the length of the bridge. When the first vehicle 31 is stationary, the second vehicle 41 can be moved by tensioning the steel strands, thereby causing the movable support section 2 connected to the second tension box 4 to deflect. The bracket mechanism 100 can raise and lower the supported steel box girder 200 according to the angle between the fixed support section 1 and the movable support section 2.

[0046] A pair of bracket mechanisms 100 are symmetrically arranged at both ends of the steel box girder 200, with their upper bearing plates 52 respectively supporting both ends of the steel box girder 200. By simultaneously tensioning their respective steel strands 6, the movable support section 2 can be tilted at an angle, causing the universal ball joint 53 to rise and fall accordingly. However, the upper bearing plate 52 above the universal ball joint 53 will not tilt, thus allowing adjustment of the height of the steel box girder without causing it to tilt. For example, according to... Figure 1 If the steel strand 6 is tensioned in the tensioning direction, the height of the movable support section 2 will decrease, which in turn causes the upper bearing plate 52 to decrease, thus reducing the height of the steel box girder 200. However, if it is according to... Figure 1 Tensing the steel strands 6 in the opposite direction will raise the height of the movable support section 2, thereby raising the upper bearing plate 52 and increasing the height of the steel box girder 200. Therefore, the erection of the entire girder segment can be achieved by tensioning and releasing the steel strands during the erection of the bridge's steel box girder.

[0047] As can be seen from the above structure, the height-adjustable bracket device in this embodiment omits the crossbeam of the conventional gantry, greatly reducing the weight of the gantry. Moreover, unlike gantry hoisting, this embodiment uses a bracket to support the steel box girder for transport, which significantly reduces the possibility of instability of the steel box girder during transport. It also has a height adjustment function, making it suitable for the erection and installation of large steel box girders.

[0048] This embodiment also provides a method for installing steel box girders, which uses the aforementioned bracket device to transport the steel box girders and adjust their height, including the following steps:

[0049] Step S1: The steel box girder 200 is placed on the bracket device using the gantry crane at the main bridge end. Specifically, both ends of the steel box girder 200 are placed on the upper bearing plates 52 of a pair of bracket mechanisms 100. More specifically, the upper bearing plate 52 of one sub-bracket mechanism is supported on the left side of one end of the steel box girder 200, and the upper bearing plate 52 of the other sub-bracket mechanism is supported on the right side of the same end of the steel box girder 200. In the other bracket mechanism 100, the upper bearing plate 52 of one sub-bracket mechanism is supported on the left side of the other end of the steel box girder 200, and the upper bearing plate 52 of the other sub-bracket mechanism is supported on the right side of the other end of the steel box girder 200.

[0050] like Figure 7As shown, the first vehicle 31 and the second vehicle 41 transport the support frame and the steel box girder 200 along the transport track 500. In this way, the gantry crane at the main bridgehead does not need to travel to move the entire steel box girder; instead, the movement and height adjustment of the entire steel box girder are achieved by the support frame. The lifting point of the gantry crane can be determined using the CAD solid model of the steel box girder, by determining the center of gravity position of the steel box girder, and selecting the intersection of the vertical line of the center of gravity and the top surface as the resultant force point, to ensure that the spatial angle after the steel box girder is lifted matches the theoretical angle.

[0051] Step S2: Use the BeiDou satellite positioning system to track the coordinates of the four corners of the steel box girder and confirm the position corresponding to the bridge pier.

[0052] Step S3: After the steel box girder arrives at the designated coordinates, the steel strands are released, meaning the elongation of the steel strands is increased, the angle between the fixed and movable supports widens, and the bracket lowers the steel box girder to the set height. During the tensioning process, the angle between the movable support section 2 and the vertical direction in the entire bracket device is θ, the vertical distance is a, the length of the movable support section 2 is c, and the distance of the tensioned steel strands below is b. The vertical distance of the overall structure, a, is cosθ × c. Adjusting the angle θ within the tensioning box is mainly achieved by controlling the elongation of the steel strands within the tensioning box.

[0053] Step S4 involves using a two-dimensional fuzzy controller to track and adjust the height of the steel box girder, leveraging the correlation between the elongation of the steel strand and the height of the bracket. After confirming the accurate height, the steel box girder is erected on the pier top and can be welded and assembled with the previously erected steel box girder. The two-dimensional fuzzy controller uses the deviation between the real-time elongation of the steel strand and a specified elongation, as well as the change in this deviation, as input variables to track and adjust until the specified elongation is achieved, thus ensuring the steel box girder reaches the designated height. The correlation between the elongation of the steel strand and the height of the bracket can be established by measuring the cable force using a pressure sensor method or a vibration frequency method during the tensioning of the steel strand and the raising of the bracket.

[0054] Step S5: After the steel box girder is erected and completed on the pier top, the tension box is used to release the steel strands, increasing the elongation of the steel strands and lowering the bracket, so that the support platform 5 is no longer in contact with the bottom of the steel box girder. At this point, the steel box girder has been erected on the pier.

[0055] Step S6: Then, the first vehicle 31 and the second vehicle 41 move along the transport track 500, thereby transferring both bracket mechanisms back to the bridgehead. By tensioning the steel strands, the support platform is brought to a precise directional position at the next target height (which can be precisely locked using 3D Beidou navigation), and the transport of the next segment of the steel box girder begins. Step S7: Repeat steps S1 to S6.

[0056] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications are all within the protection scope of the claims of the present invention.

Claims

1. A height adjustable cradle device, characterized in that, It includes a pair of symmetrically arranged bracket mechanisms, each bracket mechanism comprising a pair of sub-bracket mechanisms, the sub-bracket mechanisms being respectively arranged on parallel transport tracks, each sub-bracket mechanism comprising: The fixed support section is fixedly connected to the lower pressure plate at its upper end and hinged to the first tension box at its lower end. The movable support section is hinged at the upper end to the lower pressure plate and at the lower end to the second tension box. The support platform includes a lower pressure plate, an upper pressure plate, and a universal ball joint installed between them; The first and second pull-out boxes are connected by prestressed steel strands. The prestressed steel strands are tensioned and released using jacks and tool anchors. The first container is installed on the first vehicle, and the second container is installed on the second vehicle. Transport tracks are arranged on both sides of the bridge pier layout line, and the first and second vehicles are set on the transport tracks.

2. The height adjustable cradle device of claim 1, wherein, The support platform rises and falls as the angle between the fixed support section and the movable support section changes.

3. The height adjustable cradle device of claim 1, wherein, The support platforms of a pair of bracket mechanisms are spaced apart, and the spaced apart is wider than the width of the pier.

4. The height adjustable cradle device of claim 1, wherein, The universal ball joint includes a fixed base, a ball, and a connecting rod. The fixed base is fixedly connected to the upper end of the lower pressure plate. The ball is disposed inside the fixed base, and the connecting rod is fixedly connected to the ball. The connecting rod is connected to the upper pressure plate.

5. A method of installing a steel box girder, characterized by, The method of transferring and adjusting the height of steel box girders using the height-adjustable bracket device according to any one of claims 2 to 4 includes the following steps: Step S1: The steel box girder is placed on the bracket device by the gantry crane at the main bridge end, so that the two ends of the steel box girder are respectively placed on the upper bearing plates of a pair of bracket mechanisms. The bracket device and the steel box girder on it are transported by the first vehicle and the second vehicle along the transport tracks laid on both sides of the bridge pier layout line. Step S2: Use a satellite positioning system to track the coordinates of the four corners of the steel box girder and confirm the position corresponding to the bridge pier; Step S3: After the steel box girder is transported to the designated location coordinates, the steel strands are released to reduce the height of the support platform, allowing the steel box girder to be erected on the bridge pier. Step S4: Utilizing the correlation between the elongation of the steel strand and the height of the support platform, a two-dimensional fuzzy controller is used to track and adjust the height of the steel box girder. The two-dimensional fuzzy controller uses the deviation between the real-time elongation of the steel strand and the specified elongation, as well as the change in the deviation, as input variables to track and adjust until the specified elongation is reached, so that the steel box girder reaches the specified height position. Step S5: Control the release of the steel strands to further reduce the height of the support platform and separate the bracket device from the steel box girder; Step S6: The bracket mechanism returns to the starting bridgehead, and by tensioning the steel strands, the support platform reaches the next target height to begin transporting the next segment of the steel box girder. Step S7, repeat steps S1 to S6.

6. The steel box girder installation method according to claim 5, characterized in that, In step S2, the lifting point of the gantry crane is determined by using the CAD solid model of the steel box girder to determine the position of the center of gravity of the steel box girder, and the intersection of the vertical line of the center of gravity and the top surface of the CAD solid model of the steel box girder is selected as the lifting point of the resultant force.

7. The steel box girder installation method according to claim 5, wherein During the process of raising the bracket by tensioning the steel strand, the cable force is measured by pressure sensor method or vibration frequency method, thereby establishing the relationship between the elongation of the steel strand and the height of the bracket.

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