A method for constructing a deck gantry crane

Abstract

The application discloses a bridge floor gantry crane construction method, comprising the following steps: S1: constructing a beam lifting station area, using a truck crane to install I-beams on the bridge floor, and the I-beams are respectively located on the left and right sides of the main line bridge; S2: arranging an installation site, replacing and filling brick slag in the uncured area of the site, laying prefabricated concrete slabs, pouring the track foundation of the left side of the main line bridge first to serve as the track foundation elevation, and then pouring the track foundation of the right side to make the two sides in the same plane; S3: laying a crane track, using pressing plates to fix the two sides of the track, and using a concrete enlarged foundation as a temporary anchor point; S4: firstly, assembling leg and main beam components, then assembling the leg on the bridge floor, installing the main beam and a trolley, and finally installing electrical auxiliary devices and safety protection devices; compared with a traditional construction method, most of the assembling work is installed on the ground, the leg and the main beam components are integrally hoisted, the installation efficiency is improved, and the hoisting pressure is relieved.

Description

Technical Field

[0001] This invention relates to the field of gantry crane technology, and more particularly to a construction method for a bridge gantry crane. Background Technology

[0002] Gantry cranes, also known as portal cranes, are common equipment in bridge construction. They provide lifting and transport functions by installing two outriggers within tracks laid on the bridge deck. They are characterized by high site utilization, a large operating range, wide adaptability, and strong versatility. A gantry crane consists of a main beam, outriggers, a trolley traveling mechanism, a hoisting trolley, and electrical auxiliary structures. In bridge construction, the two outriggers are erected on the left and right spans respectively, the main beam is supported above the outriggers, and the hoisting trolley is installed on top of the main beam, thus facilitating the installation of the gantry crane. Currently, the construction methods for most gantry cranes are relatively complex, resulting in a large workload for lifting and transportation, low construction efficiency, increased labor time costs, and delays in the overall bridge construction period. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a construction method for bridge gantry cranes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for constructing a bridge-mounted gantry crane, characterized by the following steps:

[0006] S1: Construct the beam lifting station area, and use a truck crane to install I-beams on the bridge deck. The I-beams are located on the left and right sides of the main bridge to support the outriggers on both sides of the gantry crane.

[0007] S2: Arrange the installation site, replace the uncured areas with brick slag, lay precast concrete slabs, first pour the track foundation of the left side of the main bridge as the track foundation elevation, and then pour the track foundation of the right side so that both sides are on the same plane.

[0008] S3; Lay crane rails, fix the rails on both sides with pressure plates, use concrete enlarged foundations as temporary anchor points, and use truck cranes to lift the enlarged foundations to the designated position on the bridge deck in advance.

[0009] S4; First, assemble the outriggers and main beam components, then erect the outriggers on the bridge deck, install the main beam and trolley, and finally install the electrical auxiliary devices and safety protection devices.

[0010] S5: After the gantry crane is installed, conduct no-load test, load test, and dynamic load test.

[0011] Preferably, the replacement of uncured areas of the site with brick slag in step S2 specifically includes:

[0012] The work area was filled and compacted with brick debris. Soft soil, drill cuttings pits, mud pits and other locations were replaced as required. To ensure that the bearing capacity and flatness of the foundation meet the requirements for the outriggers to walk, a 50cm layer of brick debris was laid for site treatment. The paved site was then repeatedly compacted.

[0013] Preferably, laying the crane track in step S3 specifically includes:

[0014] The longitudinal slope of the bridge deck meets the climbing capacity of the gantry crane, and the steel rails are laid directly on the bridge deck. The transverse slope of the bridge deck is offset in both directions, and the bridge deck is finely adjusted using rubber pads or steel plates according to the track elevation. The transverse slope of the bridge deck is offset in one direction. To level the transverse slope of the bridge deck in one direction, the track position is first roughened, and then threaded steel bars are arranged at equal intervals according to the 5cm protective layer. After that, wooden formwork is installed, and the boom is extended from the lifting station onto the bridge deck using a boom pump. Concrete is poured to form the track foundation. The track foundation and the crane track are kept straight and do not follow the slope of the bridge deck.

[0015] Preferably, assembling the outriggers in step S4 specifically includes:

[0016] Determine the outrigger assembly positioning points on the site. Position the truck crane at a suitable location on the ground and assemble the outriggers first. Then, assemble the traveling trolley, upper connecting beam, and lower connecting beam in sequence. After leveling the four corner points with a level, assemble the outrigger connecting frame. Finally, install the outrigger ladder, back cage, and fall arrestor.

[0017] Preferably, the assembly of the main beam components in step S4 specifically includes:

[0018] Depending on site requirements, the assembly can be carried out on the ground or assembled into segments and then hoisted to the bridge deck for assembly; the area outside the connecting beam under the outriggers can be selected as the main beam assembly location, avoiding the outrigger installation location; the individual segment numbers of the main beams can be identified, and the main beams can be assembled segment by segment, and finally the guardrails, walkways, stop plates and other accessories can be assembled.

[0019] Preferably, assembling the outriggers in step S4 specifically includes:

[0020] The outriggers are hoisted using a truck crane, with both outriggers pre-connected to the top. A plumb line is set during outrigger installation, extending to the lower crossbeam, for observing verticality after erection. Guy ropes are reliably fixed to their respective ground anchors. The hand-operated hoist is adjusted to ensure the main outrigger is vertical. The guy ropes on both sides should be pre-tightened synchronously as much as possible. The plumb line, pre-suspended from the midpoint of the outrigger's top, is used to ensure the outrigger is vertical. The verticality and straightness of the outrigger are adjusted. After the hand-operated hoist is engaged, the crane is slightly loosened to observe the outrigger's stability. Only after confirming everything is correct can the hook be completely released. Channel steel is installed horizontally under the outrigger to secure it.

[0021] Preferably, the installation of the main beam and the trolley in step S4 specifically includes:

[0022] The lifting points at both ends of the main beam are connected by slings. Two truck cranes are used to lift the beam simultaneously. The beam is first suspended for 3 minutes for observation. Once stable, it can be lifted synchronously. When the lower surface of the main beam is about 1 meter above the top of the outriggers, the lifting is stopped. After observing that the main beam is no longer swaying, both truck cranes swing their booms towards the outriggers until they are directly above the outriggers. After the main beam is stable and no longer swaying, it is slowly lowered. When the load sensor shows that it has contacted the outriggers, it is lifted a little more. The main beam is guided to be accurately aligned with the outriggers using a crowbar. The alignment is assisted by fine-tuning the hand chain hoist. The bolts are tightened one by one. The same steps are repeated for the other main beam and the lifting trolley. After completion, all guy ropes are removed.

[0023] Preferably, the load test is performed in step S5, specifically including:

[0024] Based on the weight of the I-beam, load the gantry crane, trolley traveling mechanism, and hoisting mechanism with 80% of the rated lifting capacity, performing each movement in all directions at least three times. First, stop the unloaded trolley at its limit position and take the midpoint of the main beam span as the deflection measurement reference point, measuring the elevation of this reference point under unloaded conditions. Then, stop the trolley hoisting mechanism in the middle of the main beam span and load it with the rated lifting capacity, with the load 100mm to 200mm off the ground, maintaining this position for 10 minutes. Measure the downward deflection value of the reference point, then unload the load. Divide the downward deflection value of the main beam reference point by the span of the gantry crane to obtain the static rigidity of the gantry crane span.

[0025] The present invention has the following beneficial effects:

[0026] The bridge gantry crane construction method provided by this invention, compared with traditional construction methods, involves carrying out most of the assembly work on the ground, and hoisting the outriggers and main beam components as a whole, thereby improving installation efficiency and reducing hoisting pressure. Simultaneously, by arranging the installation site and adjusting the bridge deck cross slope, the straightness of the crane track is ensured, and devices such as plumb lines, guy ropes, and hand-operated hoists are used to ensure the verticality of the outriggers, effectively improving the overall installation accuracy. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the mainline bridge described in this invention.

[0028] Figure 2 This is a structural schematic diagram of the gantry crane described in this invention.

[0029] Figure 3 This is a schematic diagram of the track foundation described in this invention.

[0030] Figure 4 This is a schematic diagram of the assembled support legs according to the present invention.

[0031] Figure 5 This is a schematic diagram of the state for conducting the load test as described in this invention.

[0032] Figure 6 This is a schematic diagram illustrating the state of typhoon prevention measures as described in this invention.

[0033] Attached diagram descriptions: 1. Main bridge; 2. I-beam; 3. Track foundation; 4. Crane rail; 5. Pressure plate; 6. Concrete spread foundation; 7. Outrigger; 8. Guy rope; 9. Hand chain hoist; 10. Channel steel; 11. Main beam; 12. Trolley; 13. Anchor bolts. Detailed Implementation

[0034] 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, and 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.

[0035] Reference Figures 1 to 6 One embodiment provided by the present invention:

[0036] A construction method for a bridge-mounted gantry crane includes the following steps:

[0037] S1: Construct the beam lifting station area, and use a truck crane to install I-beams 2 on the bridge deck. The I-beams 2 are located on the left and right sides of the main bridge 1, respectively, to support the two outriggers 7 of the gantry crane.

[0038] S2: Arrange the installation site, replace the uncured area with brick slag, lay precast concrete slabs, first pour the track foundation 3 of the left side of the main bridge 1 as the elevation of track foundation 3, and then pour the track foundation 3 of the right side so that both sides are on the same plane.

[0039] S3; Lay crane rails 4, fix the rails on both sides with pressure plates 5, use concrete enlarged foundations 6 as temporary anchor points, and use truck cranes to lift the enlarged foundations to the designated position on the bridge deck in advance.

[0040] S4; First, assemble the outrigger 7 and main beam components, then assemble the outrigger 7 on the bridge deck, install the main beam 11 and trolley 12, and finally install electrical auxiliary devices and safety protection devices.

[0041] S5: After the gantry crane is installed, conduct no-load test, load test, and dynamic load test.

[0042] The bridge gantry crane construction method provided by this invention, compared with traditional construction methods, allows most of the assembly work to be carried out on the ground, with the outriggers 7 and main beam components being hoisted as a whole, improving installation efficiency and reducing hoisting pressure. Simultaneously, by arranging the installation site and adjusting the bridge deck cross slope, the straightness of the crane track 4 is ensured, and devices such as plumb lines, guy ropes 8, and hand-operated hoists 9 are used to ensure the verticality of the outriggers 7, effectively improving the overall installation accuracy.

[0043] In this embodiment, preferably, step S1 involves using a truck crane to install the I-beam 2 on the bridge deck, specifically including:

[0044] For the I-beam 2 of the main bridge 1, two truck cranes were used to lift it in two stages. After the truck crane lifted the I-beam 2, it was adjusted horizontally once to ensure that the beam could be lifted vertically above the bridge deck. After the I-beam 2 was lifted vertically above the bridge deck, it was adjusted horizontally a second time and then moved laterally into place before being lowered.

[0045] In this embodiment, preferably, the replacement of uncured areas of the site with brick slag in step S2 specifically includes:

[0046] The work area was filled and compacted with brick debris. Soft soil, drill cuttings pits, mud pits and other locations were replaced as required. To ensure that the bearing capacity and flatness of the foundation meet the requirements for the outriggers to move, a 50cm layer of brick debris was laid for site treatment. The paved site was then repeatedly compacted.

[0047] In this embodiment, preferably, laying the crane track 4 in step S3 specifically includes:

[0048] The longitudinal slope of the bridge deck meets the climbing capacity of the gantry crane, and the steel rails are laid directly on the bridge deck. The transverse slope of the bridge deck is bidirectionally offset, and the rubber pads or steel plates are used for fine adjustment according to the track elevation. The transverse slope of the bridge deck is unidirectionally offset. To level the unidirectional transverse slope of the bridge deck, the track position is first roughened, and then the threaded steel bars are arranged at equal intervals according to the 5cm protective layer. After that, the wooden formwork is installed, and the boom is extended from the lifting station onto the bridge deck using a boom pump. Concrete is poured to form the track foundation 3. The track foundation 3 and the crane track 4 are ensured to be straight and do not follow the slope of the bridge deck.

[0049] In this embodiment, preferably, the assembly of the support leg 7 in step S4 specifically includes:

[0050] Determine the assembly positioning point for outrigger 7 on the site. Position the truck crane at a suitable location on the ground and assemble outrigger 7 first. Then, assemble the traveling trolley, upper connecting beam, and lower connecting beam in sequence. After leveling the four corner points with a level, assemble the outrigger connecting frame. Finally, install the outrigger ladder, back cage, and fall arrestor.

[0051] Precautions: After the main members and upper and lower connecting beams are assembled, they must be checked and leveled to avoid twisting during subsequent assembly. Members must be assembled according to their joint numbers to avoid forced connections that could cause twisting. After assembly, check the tightness of bolts, pins, cotter pins, and other connecting parts.

[0052] In this embodiment, preferably, the assembly of the main beam components in step S4 specifically includes:

[0053] Depending on the site requirements, the assembly can be carried out on the ground or assembled into segments and then hoisted to the bridge deck for assembly; the area outside the connecting beam under the outrigger 7 is selected as the assembly location for the main beam 11, avoiding the installation location of the outrigger 7; the single-section number of the main beam 11 is identified, and the main beam 11 is assembled section by section, and finally the guardrail walkway, stop plate and other accessories are assembled.

[0054] Precautions: Ensure that the main beam's 11-span span, pre-camber, lateral bend, and track joint misalignment are within allowable limits. Assemble components according to joint numbers to avoid forced connections that could cause twisting. Main beam joint pin connections must be secure, and cotter pins must be correctly installed. Walkway railings must be securely connected, and the walkways must show no obvious deformation. Due to the central divider on both sides of the bridge deck, assembly personnel must use the crosswalk access and are prohibited from walking through the middle of the gantry crane trusses.

[0055] In this embodiment, preferably, the assembly of the support leg 7 in step S4 specifically includes:

[0056] The outrigger 7 is hoisted using a truck crane, with both outriggers 7 pre-connected to the top. A plumb line is set during outrigger 7 installation, extending to the lower crossbeam, for observing verticality after erection. Guy ropes 8 are reliably fixed to their respective ground anchors. The hand-operated hoist 9 is adjusted to ensure the main outrigger 7 is vertical. The pre-tensioning of both guy ropes 8 should be synchronized as much as possible. The plumb line, pre-suspended from the midpoint of the top of the outrigger 7, is used to ensure the outrigger 7 is vertical. The verticality and straightness of the outrigger 7 are adjusted. After the hand-operated hoist 9 is pulled, the crane is slightly loosened to observe the stability of the outrigger 7. Only after confirming everything is correct can the hook be completely released. Channel steel 10 is installed on the lower crossbeam to secure the outrigger 7.

[0057] Precautions: When using the crane, avoid touching the pre-laid guy ropes 8. The lifting process requires unified command and close coordination. Take care to prevent the guy ropes 8 and hemp ropes from snagging on other components. During the lifting process, the operator should constantly monitor the load and torque status and anticipate potential problems. Unhooking is only permitted after all securing measures are in place.

[0058] In this embodiment, preferably, the installation of the main beam 11 and the trolley 12 in step S4 specifically includes:

[0059] The lifting points at both ends of the main beam 11 are connected by slings. Two truck cranes are used to lift it simultaneously. The beam is first suspended for 3 minutes for observation. After it stabilizes, it can be lifted synchronously. When the lower surface of the main beam 11 is about 1 meter above the top of the outrigger 7, the lifting is stopped. After observing that the main beam 11 is not swaying, the two truck cranes swing their arms towards the outrigger 7 until they are directly above the alignment point of the outrigger 7. After the main beam 11 is stable and not swaying, it is slowly lowered. When the load sensor shows that it has contacted the outrigger 7, it is lifted a little more. The main beam 11 is guided to be accurately aligned with the outrigger 7 using a crowbar. The alignment is assisted by fine-tuning the hand chain hoist 9. The bolts are tightened one by one. Following the above steps, the other main beam 11 and the lifting trolley 12 are installed. After completion, all guy ropes 8 are removed.

[0060] Precautions: Before hoisting the main beam 11, recheck that all connecting pins are properly installed and that all platform railings are reliably connected. Also check for any loose small parts to prevent falling objects during hoisting. The lifting and swinging arm process requires unified command and close coordination. Maintain sufficient distance from the outriggers 7 and guy ropes 8 during hoisting. When hoisting the trolley 12, personnel working on the main beam 11 should avoid manually restricting its movement until it has come to a stable stop. Pay attention to the orientation of the main beam 11 and trolley 12. Personnel working at height must be firmly planted and reliably protected by safety belts before applying force. Disassembly can only proceed after confirming that the bolts are tightened.

[0061] In this embodiment, preferably, the installation of electrical auxiliary devices in step S4 specifically includes:

[0062] Connect all the motors, safety limit switches, control systems, etc., ensuring that all wiring is neat and consistent in positioning; install the lifting height limit switch, weight limit switch, travel limit switch, rail clamp, and other devices of the gantry crane into place one by one.

[0063] In this embodiment, preferably, the installation of the safety protection device in step S4 specifically includes:

[0064] Install according to the usage requirements of each part, including lifting height limiter, weight limiter, 12-stroke limit switch for large / small trolley, limit ruler, rail clamp, rail sweeper, and guy rope 8; the upper end of the guy rope 8 is fixed with rope clamp, and the lower end of the guy rope 8 is connected to the galvanized turnbuckle with rope clamp. In the non-anchored state, the excess length is coiled up.

[0065] In this embodiment, preferably, after step S4, the method further includes:

[0066] Typhoon prevention measures were implemented. In coastal areas prone to typhoons, gantry cranes are subjected to significant wind loads and overturning moments. To ensure the safe use of gantry cranes, cable anchor points were pre-embedded on the bridge deck. Anchor bolts 13 were used for the anchor points, which were set next to the track foundation 3. After the typhoon warning took effect, the rail clamps were locked, and cable guy ropes 8 were installed at the front and rear of the gantry crane.

[0067] In this embodiment, preferably, a load test is performed in step S5, specifically including:

[0068] Based on the weight of I-beam 2, load the rated lifting capacity at 80% of the rated lifting capacity, and complete the movements of the gantry crane, trolley traveling mechanism, and hoisting mechanism in each direction one by one, with each movement performed at least 3 times. First, stop the unloaded trolley 12 at its limit position, and take the midpoint of the main beam 11 span as the deflection measurement reference point, and measure the elevation of the reference point under unloaded conditions. Then, stop the hoisting mechanism of trolley 12 in the middle of the main beam 11 span, load it according to the rated lifting capacity, with the load 100mm~200mm off the ground, and maintain it for 10 minutes. Measure the downward deflection value of the reference point, and then unload it. Divide the downward deflection value of the main beam 11 base point by the span of the gantry crane to obtain the static rigidity of the gantry crane in the middle of the span.

[0069] Results Requirements: The lifting, lowering, trolley travel, and trolley 12 operation speeds must conform to the design documents and be within the tolerance range. The synchronous speed of each working mechanism must meet design requirements. The brakes must operate flexibly and reliably. The vertical static deflection at mid-span of the main beam must meet requirements. No visible damage should be observed in the major components.

[0070] In this embodiment, preferably, a no-load test is performed in step S5, specifically including:

[0071] First, use a 500V megohmmeter to measure the insulation resistance of the main circuit, control circuit, and ground of each mechanism. Then, turn on the power and start each mechanism, making the trolley 12 run along the entire length of the main beam 11 and the gantry crane run back and forth along the track at least 3 times each. There should be no jamming. Check whether the limit switches and buffers are working properly, and check whether the control system, safety devices, and lifting range meet the requirements. During the no-load test, start each mechanism and run it in both forward and reverse directions for a total time of not less than 5 minutes.

[0072] In this embodiment, preferably, a dynamic load test is performed in step S5, specifically including:

[0073] Each mechanism and each action should be repeatedly started and stopped within its stroke range; according to the duty cycle of the motor, the operation should be allowed for intermittent time, and the operation should be controlled according to the operating procedures. It is also necessary to ensure that the acceleration, deceleration, and speed are limited within the normal operating range of the gantry crane; according to the duty cycle and its working cycle, the total test time should last at least 0.5 hours.

[0074] Results Requirements: During the test, all mechanisms should operate normally and smoothly without any abnormal noise. The brakes should be effective and reliable during braking, with no reverse movement or slippage during air start-up. After the test, no damage should be found to any mechanisms or components, no loosening or damage to connections, no abnormal temperature rise in the motor reducer, and no leaks, seepage, or dripping in the hydraulic system.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of erecting a deck gantry crane, characterized in that: It comprises the following steps: S1: Constructing a lifting station area, using a truck crane to install I-beams on the bridge deck, and the I-beams are located on the left and right sides of the main line bridge, respectively, for supporting the two side legs of the gantry crane; S2: Arranging the installation site, replacing the unfixed area of the site with brick slag, laying prefabricated concrete slabs, pouring the track foundation on the left side of the main line bridge first, serving as the track foundation elevation, and then pouring the track foundation on the right side, so that both sides are in the same plane; S3: Laying the crane track, using pressing plates to fix the two sides of the track, and using a concrete enlarged foundation as a temporary anchor point, the truck crane lifts the enlarged foundation to the designated position on the bridge deck in advance; S4: First, assemble the leg and main beam components, then assemble the leg on the bridge deck, install the main beam and trolley, and finally install the electrical accessories and safety protection devices; The assembled leg specifically includes: determining the leg assembly positioning point on the site, the truck crane is at a suitable position on the ground, the leg assembly is performed first, and then the walking car, upper connecting beam, and lower connecting beam are assembled in sequence, the level meter is used to level the four corner points, the leg connecting frame is assembled, and finally the leg ladder, back cage, and anti-falling device are installed; The assembled main beam component specifically includes: according to the site requirements, choosing to assemble on the ground or after assembling into segments to be lifted to the bridge deck for assembly; choosing the area outside the lower connecting beam of the leg as the main beam assembly position to avoid the leg installation position; finding out the single segment number of the main beam, assembling the main beam segment by segment, and finally assembling the guardrail walkway and stop plate; The assembled leg specifically includes: the leg is lifted by the truck crane, and the two side legs are connected in advance to the top; a plumb line is set when the leg is installed, the length of which can reach the lower cross beam, which is used to observe the perpendicularity after being erected; the cable wind rope is reliably fixed with the respective ground anchor, the hand-operated hoist is adjusted so that the main leg is in a vertical state; the two side cable wind ropes are pre-tightened as synchronously as possible, and the plumb line hung from the midpoint of the top of the leg is observed to ensure that the leg is in a vertical state; the perpendicularity and straightness of the leg are adjusted, the hoist is released after the hand-operated hoist is pulled, the stability of the leg is observed, and the leg can be completely released after it is confirmed to be correct, and a channel steel is fixed to the lower cross beam of the leg to fix the leg; The installed main beam and trolley specifically include: the lifting points at both ends of the main beam are connected by lifting ropes, two truck cranes are used to lift simultaneously, the main beam is observed to hover for 3 minutes first, and then it is continuously and synchronously lifted after being stable; the lifting is stopped when the lower surface of the main beam exceeds the top of the leg by about 1m, the main beam is observed to be stable, and then the two truck cranes simultaneously swing towards the leg until they are directly above the leg; the main beam is slowly lowered after being stable, and then it is slightly lifted when the load sensor shows that it has contacted the leg; the main beam is accurately aligned with the leg by using a crowbar, the alignment is assisted by fine-tuning the hand-operated hoist, and the bolts are tightened one by one; another main beam and a trolley are installed according to the above steps, and all cable wind ropes are removed after the installation is completed; S5: After the gantry crane is installed, perform the no-load test, load test, and dynamic load test.

2. A method of erecting a portal crane on a bridge deck as claimed in claim 1, characterized in that: The unfixed area of the site in step S2 is replaced with brick slag, specifically including: In the working area, the brick slag is filled, compacted, the soft soil, drill slag pool, mud pool and other positions are replaced according to the requirements, in order to ensure that the bearing capacity and flatness of the foundation meet the walking requirements of the support leg, 50cm brick slag is paved for site treatment, and the completed site is repeatedly compacted.

3. The method of claim 1, wherein: The step S3 of laying the crane track specifically comprises: The longitudinal slope of the bridge deck meets the climbing ability of the gantry crane, and the steel rails are directly laid on the bridge deck; the lateral slope of the bridge deck is bidirectional offset, and rubber supports or steel plates are used for fine adjustment according to the track elevation; the lateral slope of the bridge deck is unidirectional offset, the unidirectional lateral slope of the bridge deck is leveled, first, the track position is roughened, the threaded steel bars are arranged at equal intervals according to the 5cm protective layer, then the wooden mold is installed, the arm of the sky pump is stretched from the beam lifting station to the bridge deck, the concrete is poured to form the track foundation, the track foundation and the crane track are ensured to be flat and straight, and do not follow the slope of the bridge deck.

4. The method of claim 1, wherein: The step S5 of performing the load test specifically comprises: According to the weight of the I-beam, the rated load is loaded according to 80% of the rated load, and the actions of the gantry crane, the trolley running mechanism and the lifting mechanism in each direction are completed one by one, each action is performed at least 3 times; first, the empty trolley is parked at the limit position, the midpoint of the main beam span is taken as the deflection measurement reference point, and the elevation of the reference point in the empty state is measured; then, the trolley lifting mechanism is parked at the main beam span, the load is loaded according to the rated load, the load is 100mm-200mm away from the ground, and is kept for 10min; the deflection value of the reference point is measured, then the load is unloaded, the deflection value of the main beam reference point is divided by the span of the gantry crane, and the static rigidity of the gantry crane in the span is obtained.

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