A segmental assembly type variable cross-section box girder cantilever crane and hoisting method

Abstract

The present application relates to a kind of slice assembly type variable cross-section box girder cantilever crane and hoisting method, crane includes support system, walking system and hoisting system;Walking system includes two tracks beams anchored in the beam surface two sides, the support system includes two diamond truss pieces, the lower longitudinal beam of two truss pieces is temporarily anchored on track beam, hoisting system includes two mobile cross beams, two mobile cross beams are supported on the upper longitudinal beam of two support pieces and can slide along the upper longitudinal beam, two mobile cross beams are respectively equipped with two winches that can slide along mobile cross beam.By hoisting system hoisting the each board unit of box girder section and splicing into complete section, after one section hoisting is completed, support system moves forward and hoists next section.The crane structure of the present application is simple, small in size, light in weight, and has good applicability for slice assembly type box girder section assembly.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology and relates to the construction of variable cross-section box girders using the segmental prefabrication and cantilever method. Specifically, it relates to a segmented prefabrication variable cross-section box girder cantilever crane and hoisting method. Background Technology

[0002] Construction methods for variable cross-section box girders generally include cast-in-place casting with scaffolding, cantilever casting with hanging baskets, and segmental precasting and cantilever assembly. Among these, the segmental cantilever assembly method involves precasting segments and then assembling the precast concrete beam segments cantilevered towards the mid-span in a balanced manner, applying prestress to each segment. This method has become increasingly widely used due to its advantages such as shorter construction period and higher quality. Segments are often precast using the short-line method, where one segment is used as an end formwork to match the precast of the next segment. Because segments need to be repeatedly moved, and each segment is still relatively large in volume and weight, large equipment is required for relocation, storage, transportation, and lifting. This results in a large number of equipment sets being used, a long construction period, and low efficiency and high cost due to the need for measurement, positioning, and fine-tuning after each segment relocation and matching with the next segment.

[0003] Patent application CN202211297038.0 proposes a segmented prefabricated variable cross-section box girder structure and construction method. Each segment is further decomposed into multiple plate units such as top plate, bottom plate, and web plate, and these plate units are prefabricated and installed segment by segment to reduce the difficulty of prefabrication, storage, transportation, and hoisting, thereby lowering construction costs. However, currently, during segmented hoisting, due to the lack of dedicated hoisting equipment, traditional bridge deck cranes are still commonly used. These traditional bridge deck cranes are large lifting equipment, lacking flexibility during segmented hoisting, affecting construction efficiency. Moreover, due to their heavy weight, as the cantilever of the girder extends during construction, the excessive self-weight load of the bridge deck crane can cause the cantilever to deflect, affecting the structure and alignment of the girder. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a suspended hoist and hoisting method for segmented prefabricated variable cross-section box girders, so as to reduce the hoisting construction cost of segmented prefabricated variable cross-section box girders and improve construction efficiency.

[0005] The present invention provides a segmented assembly type variable cross-section box girder suspension hoist, characterized in that it includes a support system, a traveling system and a lifting system;

[0006] The support system includes two parallel diamond-shaped truss sections. Each truss section includes a horizontally arranged upper longitudinal beam and a lower longitudinal beam. Diagonal braces are connected between the rear ends of the upper and lower longitudinal beams and between the front ends of the upper and lower longitudinal beams, respectively. Vertical braces are connected between the rear ends of the upper longitudinal beam and the front ends of the lower longitudinal beam. Fixed crossbeams are connected between the upper and lower longitudinal beams of the two truss sections.

[0007] The walking system includes two track beams arranged along the bridge direction on both sides of the bridge deck, each track beam being anchored to a pre-embedded bolt on the bridge deck; the lower longitudinal beams of the two truss sections are supported on the two track beams along the bridge direction and temporarily anchored to the track beams; a support walking traction device is provided between each lower longitudinal beam and the track beam.

[0008] The lifting system includes two movable crossbeams, each equipped with two winches; each movable crossbeam is supported at both ends on the upper longitudinal beams of two truss sections, and each movable crossbeam has longitudinal pulleys at its bottom that slide along the upper longitudinal beams; each winch is fixedly mounted on a transverse trolley, the bottom of which has transverse pulleys that slide along the movable crossbeams.

[0009] Furthermore, in the aforementioned segmented prefabricated variable cross-section box girder suspension hoist, each truss segment has upwardly protruding limiting plates welded to both ends of the longitudinal beams and both ends of each movable crossbeam.

[0010] Furthermore, in the aforementioned segmented prefabricated variable cross-section box girder suspension hoist, a pad beam is fixedly installed at the bottom of both ends of the lower longitudinal beam of each truss segment. The pad beam is supported on the track beam, and a sliding plate is welded to the bottom of the pad beam.

[0011] Furthermore, in the aforementioned segmented prefabricated variable cross-section box girder suspension hoist, the support walking traction system includes a traction cylinder. The traction cylinder is inclined, with one end of the traction cylinder connected to the front end of the track beam via a pin, and the other end connected to the bottom of the lower longitudinal beam via a pin.

[0012] Furthermore, in the aforementioned segmented assembly variable cross-section box girder suspension hoist, the bottom of the lower longitudinal beam is provided with multiple connecting plates along the longitudinal direction, and the piston end of the traction cylinder is connected to one of the connecting plates by a pin.

[0013] This invention provides a method for hoisting a segmented prefabricated variable cross-section box girder, employing the aforementioned segmented prefabricated variable cross-section box girder suspension hoist, characterized by comprising the following steps:

[0014] (1) The bottom plate, two web plates and top plate of the variable cross-section box girder 0# block are lifted in sequence by a truck crane, and the steel bars between the plate units are connected to complete the installation of 0# block. Then, a cantilever crane is installed on the top surface of both ends of 0# block, and the subsequent beam segments are installed symmetrically from both ends of 0# block using the two cantilever cranes.

[0015] (2) Transport each plate unit of the variable cross-section box girder No. 1 to the bridge site, move the lifting system of the suspension crane into position, symmetrically lift the web plate units of the two No. 1 blocks to the design installation position, connect them with the web plate of No. 0 block using steel bars, and then thread longitudinal prestressing tendons between the web plates of No. 1 blocks and perform initial tensioning.

[0016] (3) The lifting system is moved into position in the longitudinal and transverse directions. The No. 1 top plate unit is symmetrically lifted using a rotating lifting device. First, the top plate unit is vertically lifted from between the two web plates to above the web plate unit. The top plate is rotated to the installation angle using a rotating lifting device. The two ends of the top plate are supported on the two web plates and connected to the No. 1 web plate unit with steel bars.

[0017] (4) Readjust the position of the suspended hoist lifting system, symmetrically hoist the No. 1 bottom plate unit, and connect it with the No. 1 web plate unit using steel reinforcement;

[0018] (5) The longitudinal prestress of block 1 is tensioned a second time to complete the assembly of block 1;

[0019] (6) Extend the track beam to the top surface of block 1, release the temporary anchorage between the lower longitudinal beam and the track beam, move the support system forward to block 1 through the support walking traction device, and then re-anchor the lower longitudinal beam and the track beam; install the subsequent blocks in sequence according to the methods of (2) to (5) until the closure is completed.

[0020] Compared with traditional bridge deck cranes, the suspended assembly crane of this invention has a simple structure, small size, light weight, and low manufacturing and operating costs. Its lifting system can flexibly adjust the position of the winch, making it suitable for segmented assembled box girder segments and significantly improving the segment erection efficiency. Due to the crane's light weight, when using this suspended assembly crane to suspend and assemble box girder segments, the installation on the beam surface will not cause the beam cantilever to deflect, ensuring the stability of the beam structure. Attached Figure Description

[0021] Figure 1 This is a side view of the crane structure of the present invention;

[0022] Figure 2 This is a three-dimensional structural diagram of the crane's support system;

[0023] Figure 3 This is a schematic diagram showing the state of the box girder web being lifted by a crane;

[0024] Figure 4 This is a schematic diagram showing the state of the top slab of the hoisted box girder;

[0025] Figure 5 This is a schematic diagram showing the state of the roof slab when it is hoisted into place.

[0026] Figure 6 This is a schematic diagram showing the state of the web of the hoisted box girder;

[0027] Figure 7 This is a schematic diagram showing the state of a box girder segment after it has been cantilevered and assembled.

[0028] Figure 8 This is a schematic diagram showing the state of the crane moving forward to suspend and assemble the next box girder segment. Detailed Implementation

[0029] like Figure 1 , Figure 2 As shown, the segmented assembly variable cross-section box girder suspension hoist of the present invention includes a support system, a traveling system, and a lifting system;

[0030] The support system includes two parallel diamond-shaped truss sections. Each truss section includes a horizontally arranged upper longitudinal beam 1 and a lower longitudinal beam 2. Diagonal bracing rods 3 are connected between the rear ends of the upper and lower longitudinal beams and between the front ends of the upper and lower longitudinal beams, respectively. Vertical bracing rods 4 are connected between the rear ends of the upper longitudinal beam and the front ends of the lower longitudinal beam. Fixed crossbeams 5 are connected between the upper and lower longitudinal beams of the two truss sections, connecting the two truss sections into one unit.

[0031] The traveling system includes two track beams 6 arranged along the bridge deck on both sides, each track beam 6 being anchored to pre-embedded bolts on the bridge deck; the lower longitudinal beams 2 of the two truss sections are respectively supported on the two track beams 6 along the bridge deck and temporarily anchored to the track beams; a support traveling traction device 7 is provided between each lower longitudinal beam and the track beam. The support traveling traction device 7 can pull the support system to slide along the track beam.

[0032] The lifting system includes two movable crossbeams 8, each with two winches 9; each movable crossbeam 8 is supported at both ends on the upper longitudinal beams 1 of the two truss sections, and each movable crossbeam 8 has longitudinal pulleys 10 at its bottom ends that slide along the upper longitudinal beams; each winch 9 is fixedly mounted on a transverse trolley 11, and the bottom of the transverse trolley 11 has transverse pulleys 12 that slide along the movable crossbeams.

[0033] The aforementioned segmented, modular variable cross-section box girder suspension hoist allows for flexible adjustment of the winch's longitudinal and lateral positions by means of a moving crossbeam that can move longitudinally along the upper longitudinal beam via longitudinal pulleys, and a transverse trolley that can move longitudinally along the moving crossbeam via transverse pulleys. This adapts to the lifting of different plate units of the box girder. To achieve automatic movement of the moving crossbeam and transverse trolley, motors are installed on the crossbeam and transverse trolley respectively to drive the longitudinal and transverse pulleys.

[0034] In specific implementation of the present invention, in order to prevent the moving crossbeam from falling off the upper longitudinal beam when it moves, and to prevent the transverse trolley from falling off the moving crossbeam when it moves, upward protruding limiting plates 13 can be welded to both ends of the longitudinal beam on each truss piece and both ends of each moving crossbeam.

[0035] In a specific implementation of the present invention, in order to facilitate the installation of the support walking traction device, a pad beam 14 is fixedly installed at the bottom of both ends of the lower longitudinal beam 2 of each truss segment. The pad beam 14 is supported on the track beam 6, so that a moving gap is formed between the lower longitudinal beam 2 and the track beam 6. The support walking traction device can be set in the gap between the lower longitudinal beam and the track beam. In order to make it easy for the pad beam and the track beam to slide relative to each other, a sliding plate is welded to the bottom of the pad beam 14.

[0036] In a specific implementation of the present invention, the support walking traction device 7 may be a traction cylinder. The traction cylinder is inclined, and the base of the traction cylinder is connected to the front end of the track beam by a pin. One end of the traction cylinder is connected to the front end of the track beam by a pin, and the other end is connected to the bottom of the lower longitudinal beam by a pin.

[0037] To facilitate the connection between the traction cylinder and the bottom of the lower longitudinal beam, multiple connecting plates 15 can be installed longitudinally along the bottom of the lower longitudinal beam. The piston end of the traction cylinder is connected to one of the connecting plates via a pin. When the cylinder traction support system moves, the piston rod is first retracted, and the traction support system moves forward one stroke. Then, the connection between the cylinder and the lower longitudinal beam is released, the cylinder piston rod extends, and it reconnects to the lower longitudinal beam. The piston rod is then retracted again to move the traction support system. This cycle continues until the support system is moved to the predetermined position.

[0038] The method for hoisting segmented, prefabricated variable cross-section box girders using the aforementioned suspended hoist is as follows:

[0039] (1) First, a truck crane is used to lift the bottom plate, two web plates and top plate of the variable cross-section box girder 0# block in sequence, and the steel bars between the plate units are connected to complete the installation of 0# block. Then, a cantilever crane is installed on the top surface of both ends of 0# block 16, and the subsequent beam segments are installed symmetrically from both ends of 0# block using the two cantilever cranes.

[0040] (2) Figure 3 As shown, the plate units of the variable cross-section box girder No. 1 block are transported to the bridge site. The lifting system of the suspension hoist is adjusted to move the winch 9 longitudinally and laterally to the appropriate position. The web plate units 17 of the two No. 1 blocks are symmetrically hoisted to the design installation position and connected with the web plate of No. 0 block using steel bars. Then, longitudinal prestressing tendons are inserted between the web plates of the two No. 1 blocks and initial tensioning is performed.

[0041] (3) Figure 4 , Figure 5 As shown, the hoist is moved to the position between the two webs, and the top plate unit 18 of block 1 is symmetrically hoisted using the rotating hoist 20. First, the top plate unit 18 is vertically lifted from between the two webs to above the web unit 17. Then, the top plate is rotated to the installation angle using the rotating hoist, and the two ends of the top plate are supported on the two webs and connected to the web unit of block 1 with steel bars.

[0042] (4) Figure 6 , Figure 7 As shown, the position of the suspended hoist lifting system was readjusted, and the bottom plate unit 19 of block #1 was symmetrically hoisted and connected with the bottom of the web plate unit 17 of block #1 using steel bars;

[0043] (5) The longitudinal prestress of block 1 is tensioned a second time to complete the assembly of block 1;

[0044] (6) Figure 8 As shown, extend the track beam 6 to the top surface of block 1, release the temporary anchorage between the lower longitudinal beam and the track beam, move the support system forward to block 1 through the support walking traction device, and re-anchor the lower longitudinal beam 2 and the track beam 6; install the subsequent blocks according to the methods of (2) to (5) until the closure.

[0045] Since the width of the top plate is greater than the width of the bottom plate, in step (4) above, if the winch traction rope is lowered from both sides of the top plate to lift the bottom plate, the traction rope will scrape against both sides of the top plate. In order to facilitate the lifting of the bottom plate, vertical through holes can be set in the top plate unit at a certain distance from both sides. The distance between the two through holes is equal to the width of the bottom plate. When lifting the bottom plate unit, the winch traction rope is passed through the vertical through holes on the top plate to connect the bottom plate unit for lifting.

Claims

1. A method for hoisting a segmented, prefabricated variable cross-section box girder, characterized in that, A suspended crane is used, which includes a support system, a traveling system, and a lifting system; The support system includes two parallel diamond-shaped truss sections. Each truss section includes a horizontally arranged upper longitudinal beam and a lower longitudinal beam. Diagonal braces are connected between the rear ends of the upper and lower longitudinal beams and between the front ends of the upper and lower longitudinal beams, respectively. Vertical braces are connected between the rear ends of the upper longitudinal beam and the front ends of the lower longitudinal beam. Fixed crossbeams are connected between the upper and lower longitudinal beams of the two truss sections. The walking system includes two track beams arranged along the bridge direction on both sides of the bridge deck, each track beam being anchored to a pre-embedded bolt on the bridge deck; the lower longitudinal beams of the two truss sections are supported on the two track beams along the bridge direction and temporarily anchored to the track beams; a support walking traction device is provided between each lower longitudinal beam and the track beam. The lifting system includes two movable crossbeams, each equipped with two winches; each movable crossbeam is supported at both ends on the upper longitudinal beams of two truss sections, and each movable crossbeam has longitudinal pulleys at its bottom ends that slide along the upper longitudinal beams; each winch is fixedly mounted on a transverse trolley, the bottom of which has transverse pulleys that slide along the movable crossbeams. The hoisting method includes the following steps: (1) The bottom plate, two web plates and top plate of the variable cross section box girder 0# block are lifted in sequence by a truck crane, and the steel bars between the plate units are connected to complete the installation of 0# block. Then, a cantilever crane is installed on the top surface of both ends of 0# block, and the subsequent beam segments are installed symmetrically from both ends of 0# block using the two cantilever cranes. (2) Transport each plate unit of the No. 1 block of the variable cross-section box girder to the bridge site, move the lifting system of the suspension crane into position, symmetrically lift the web plate units of the two No. 1 blocks to the design installation position, and connect them with the web plate of the No. 0 block using steel bars. Then, insert longitudinal prestressing tendons between the web plates of the No. 1 blocks and perform initial tensioning. (3) The lifting system is moved into position in the longitudinal and transverse directions. The No. 1 top plate unit is symmetrically lifted using a rotating lifting device. First, the top plate unit is vertically lifted from between the two web plates to above the web plate unit. The top plate is rotated to the installation angle using a rotating lifting device. The two ends of the top plate are supported on the two web plates and connected to the No. 1 web plate unit with steel bars. (4) Readjust the position of the suspended hoist lifting system, symmetrically hoist the No. 1 bottom plate unit, and connect it with the No. 1 web plate unit with steel bars; set vertical through holes at a certain distance from both sides on the top plate unit in advance, and the distance between the two through holes is equal to the width of the bottom plate. When hoisting the bottom plate unit, pass the traction rope of the winch through the vertical through hole on the top plate and connect it with the bottom plate unit for hoisting. (5) The longitudinal prestress of block 1 is tensioned a second time to complete the assembly of block 1; (6) Extend the track beam to the top surface of block 1, release the temporary anchorage between the lower longitudinal beam and the track beam, move the support system forward to block 1 through the support walking traction device, and then re-anchor the lower longitudinal beam and the track beam; install the subsequent blocks in sequence according to the method from step (2) to step (5) until the closure.

2. The method for hoisting segmented prefabricated variable cross-section box girders according to claim 1, characterized in that: Each truss segment of the suspended hoist has upwardly protruding limiting plates welded to both ends of its longitudinal beams and both ends of its movable crossbeams.

3. The method for hoisting segmented prefabricated variable cross-section box girders according to claim 1, characterized in that: Each truss segment of the suspended hoist has a pad beam fixedly installed at both ends of the lower longitudinal beam. The pad beam is supported on the track beam, and a sliding plate is welded to the bottom of the pad beam.

4. The method for hoisting segmented prefabricated variable cross-section box girders according to claim 3, characterized in that: The support walking traction device of the suspended crane includes a traction cylinder. The traction cylinder is inclined, with one end of the traction cylinder connected to the front end of the track beam by a pin, and the other end connected to the bottom of the lower longitudinal beam by a pin.

5. The method for hoisting segmented prefabricated variable cross-section box girders according to claim 4, characterized in that: The bottom of the lower longitudinal beam of the suspended hoist is provided with multiple connecting plates along the longitudinal direction, and the piston end of the traction cylinder is connected to one of the connecting plates by a pin.

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