Steel box girder secondary girder falling construction method in complex environment

Abstract

The invention discloses a construction method for secondary girder falling of a steel box girder in a complex environment, which comprises the following steps of: S1, placing a bridge girder erection machine above a current bridge span, and arranging a cushion pier on a front side pier of the current bridge span; s2, feeding beams; s3, first-time beam falling: hoisting a current bridge span steel box beam by a hoisting crown block on the bridge girder erection machine, and falling the beam until the two ends of the beam are respectively supported on the constructed steel box beam and the cushion piers; s4, the bridge girder erection machine moves forwards to cross a span; s5, secondary beam falling: hoisting the steel box beam of the current bridge span again by the hoisting crown block and retreating, and hoisting the cushion pier to the front bridge pier of the next bridge span through the auxiliary trolley on the bridge girder erection machine; and then the current bridge span steel box girder is hoisted to the designed position, one side of the current bridge span steel box girder falls onto the pier, the end of the current bridge span steel box girder extends out of the pier, and the other side of the current bridge span steel box girder is separated from the hoisting crown block after being connected with the end of the constructed steel box girder in a matched mode. The erection process of secondary beam falling is adopted, the section division requirement of the steel box beam is met, and the field installation difficulty is lowered.

Description

Technical Field

[0001] The present invention relates to the technical field of steel box girder erection, and more particularly to a secondary beam-dropping construction method for steel box girders in complex environments. Background Art

[0002] With the rapid development of municipal bridges in my country, urban elevated roads are increasing in number, and urban roads are becoming increasingly complex. The elevated bridges on some major routes can no longer meet the increasing demand for traffic. The design loads and speeds of the original elevated bridges also cannot meet traffic requirements. Some road bridges are even damaged, necessitating the renovation and expansion of existing elevated bridges in this complex environment. In conventional projects, the steel box girders of the main bridge can generally be directly installed by crawler cranes in small sections, or by two crawler cranes for full-length installation. When crossing roads or rivers, jacking can also be used for installation. However, when installing steel box girders above existing elevated bridges, construction can only be carried out within the 3.5m center dividing strip. There is no space for crawler cranes to work, and jacking supports cannot be set up. During the construction of the steel box girder, the existing highway below is open to traffic. Although two lanes can be closed, certain construction safety risks still exist. Furthermore, the single-span steel box girder is an extremely large and heavy component weighing approximately 1,100 tons. To reduce stress concentration, the segmentation lines of the steel box girder sections pass over the bridge piers, further exacerbating the difficulty of installing and connecting the steel box girder. Conventional construction methods are no longer sufficient for installing steel box girders in this complex environment. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages of the present invention, a method for secondary beam drop construction of a steel box girder in a complex environment is provided, wherein one end of the steel box girder extends out of the pier body, comprising the following steps: S1. The bridge erection machine is positioned above the current span, and a cushion pier is set on the front pier of the current span; S2, feeding beam; S3, first beam drop: the lifting crane on the bridge erection machine lifts the steel box girder of the current bridge span and drops the beam until its two ends are supported on the constructed steel box girder and the piers respectively; S4, the bridge erecting machine moves forward over the span; S5. Second beam drop: the lifting crane lifts the steel box girder of the current span again and moves backward, and the auxiliary trolley on the bridge erection machine lifts the pad pier to the front pier of the next span; then the steel box girder of the current span is lifted to the designed position, and one side of the steel box girder of the current span falls onto the pier, and the end extends out of the pier, and the other side is separated from the lifting crane after the matching connection with the end of the constructed steel box girder is completed.

[0005] Preferably, the bridge-building machine includes a truss, a first leg, a second leg, a third leg and a fourth leg which are arranged in sequence from front to back at the bottom of the truss along the erection direction of the steel box girder; wherein, the first leg and the second leg are respectively slidably connected to the truss, the third leg and the fourth leg are foldable, and a walking device is provided at the bottom of the fourth leg.

[0006] Preferably, in step S1, when the bridge erection machine is in place at the current span, the first leg is suspended in the air, the second leg is supported on the front end of the pier on the front side of the current span, the pad pier is arranged at the rear end of the pier on the front side of the current span, and the third leg and the fourth leg are supported on the constructed steel box girder.

[0007] Preferably, in step S2, when feeding the beam, the fourth leg is folded and stowed, and the beam transport vehicle transports the beam to the rear of the third leg.

[0008] Preferably, step S3 specifically includes: S31, extending the fourth leg to support the beam surface of the constructed steel box girder, and folding and stowing the third leg; S32, the lifting crane lifts the steel box girder of the current bridge span from the beam transport vehicle, and lifts it to both ends and drops it onto the constructed steel box girder and the pier respectively; S33, extending the third leg to support the beam surface of the constructed steel box beam, folding and stowing the fourth leg, and the beam transport vehicle withdraws.

[0009] Preferably, step S4 specifically includes: S41. Install a running track on the constructed steel box girder; secure the second supporting leg to the bridge pier; S42: driving the fourth support leg to move along the travel track, driving the truss girder to move forward across the span, with the first support leg supported on the pier at the front side of the next span; S43, moving the second supporting leg to the front end of the front pier of the next bridge span, and moving the first supporting leg forward to be suspended in the air.

[0010] Preferably, when the cushion pier is installed on the bridge pier, its top surface is flush with the top surface of the constructed steel box girder.

[0011] The present invention has at least the following beneficial effects: The present invention provides a method for constructing steel box girders using a secondary beam drop in complex environments, resolving the challenges of conventional equipment in these environments. The secondary beam drop process not only meets the design unit's segmentation requirements but also reduces on-site installation complexity. The bridge erection machine uses a single-span steel box girder, providing clear working conditions and a robust force system for each drop. This significantly reduces project safety risks.

[0012] 2. The secondary beam-dropping construction method for steel box girders in complex environments provided by the present invention adopts a four-legged integrated bridge-erecting machine, which solves the problem that conventional equipment cannot be used for construction in complex environments, and has excellent reference value for subsequent renovation and expansion projects.

[0013] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the structure of the bridge erection machine in step S1 of the present invention when the current bridge span is in place; Figure 2 This is a structural diagram of the bridge erection machine after feeding beams in step S2 of the present invention; Figure 3 This is a schematic diagram of the position of the steel box girder of the current bridge span after the first beam drop in step S3 of the present invention; Figure 4 This is a schematic diagram of the position of the steel box girder of the current bridge span after the second beam drop in step S5 of the present invention; DETAILED DESCRIPTION

[0015] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0016] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "horizontal", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0017] like Figures 1 to 4 As shown, the present invention provides a secondary beam-dropping construction method for a steel box girder in a complex environment, wherein one end of the steel box girder extends out of the pier body, comprising the following steps: S1. The bridge erection machine is positioned above the current span and a cushion pier 13 is installed on the front pier N3 of the current span. S2, feeding beam; S3, first beam drop: the lifting crane on the bridge erection machine lifts the current span steel box girder 12, and drops the beam until its two ends are supported on the constructed steel box girder 11 and the pier 13 respectively; S4, the bridge erecting machine moves forward over the span; S5. Second beam drop: the lifting crane lifts the steel box girder 12 of the current span again and moves backward, and the auxiliary trolley on the bridge erection machine lifts the cushion pier 13 to the front pier N4 of the next span; then the steel box girder 12 of the current span is lifted to the designed position, and one side of the steel box girder 12 of the current span falls onto the pier N4, and the end extends out of the pier N4, and the other side is separated from the lifting crane after the matching connection with the end of the constructed steel box girder 11 is completed.

[0018] In this technical solution, the current bridge span is the bridge span where the steel box girder is to be installed. Figure 1 The current span is between piers N2 and N3. In a certain expansion and reconstruction project, the upper viaduct needed to be constructed above the median divider of an existing highway. The median divider was approximately 3.5 meters wide, making it impossible to use large equipment for construction and insufficiently wide to accommodate jacking supports. During construction of the upper viaduct's steel box girder, only two lanes of the existing highway on either side were temporarily closed, and large equipment could not operate on the closed lanes. The steel box girder was 33.5 meters wide, and vehicles would pass below the projection during construction, making it difficult to set support points between piers. The segmentation line of each steel box girder span was 3 meters beyond the pier body, causing one end of the steel box girder to extend beyond the pier body. A single steel box girder section was 51 meters long and weighed 1,100 tons, making installation of the entire span quite challenging. Based on the above-mentioned complex environment, this application proposes a method for secondary beam dropping of steel box girders, wherein the first beam dropping is when the bridge erection machine lifts the steel box girder 12 of the current span and places it on the constructed steel box girder 11 and the cushion 13 on the top of pier N3. The second beam dropping is when the bridge erection machine completes the movement of the span, and then lifts the steel box girder 12 placed for the first time again and installs it to the designed position. The left end of the steel box girder 12 to be installed matches and connects with the end of the constructed steel box girder 11, and the right side is installed on the cushion 13 on the top of pier N3 and extends 3m out of the pier top. The secondary beam dropping construction method for steel box girders in complex environments solves the problem that conventional equipment cannot be used for construction in complex environments. The bridge erection machine erects the entire span steel box girder. The working conditions and force system of each beam dropping are clear, and the fulcrum is firmly placed, which greatly reduces the safety risk of the project.

[0019] Furthermore, when the cushion pier 13 is installed on the bridge pier, its top surface is flush with the top surface of the constructed steel box girder 11 to ensure the stability of the steel box girder when the girder is first lowered.

[0020] In another technical solution, the bridge erection machine includes a truss beam 8, and a first leg 1, a second leg 2, a third leg 3, and a fourth leg 4, arranged sequentially from front to back along the bottom of the truss beam 8. The first leg 1 and the second leg 2 are respectively slidably connected to the truss beam 8, the third leg 3 and the fourth leg 4 are foldable, and a walking device is provided at the bottom of the fourth leg 4. The bridge erection machine has four legs. Due to on-site construction conditions, none of the legs can touch the ground. During construction, all four legs are supported on the constructed steel box beam or the top of the bridge pier. Both the first leg 1 and the second leg 2 are equipped with a drive device that can drive them to move along the truss beam 8. The top of the bridge erection machine is also slidably connected to the hoisting crane and the auxiliary trolley. The hoisting crane includes a front hoisting crane 5 and a rear hoisting crane 6, which together lift the steel box beam. The auxiliary trolley is located in front of the hoisting crane and is used to lift the cushion 13. Preferably, the walking device at the bottom of the fourth leg 4 is a tire-type walking device.

[0021] In step S1, Figure 2 As shown, when the bridge-erecting machine is in place, the first leg 1 is suspended in the air, the second leg 2 is supported on the front end of the pier N3 at the front side of the current span, the cushion pier 13 is set at the rear end of the pier N3 at the front side of the current span, and the third leg 3 and the fourth leg 4 are supported on the constructed steel box girder 11. The beam is then transported to the rear end of the fourth leg 4 by the beam transport vehicle 7.

[0022] In step S2 , when feeding the beam, the fourth supporting leg 4 is folded and stowed, and the beam transport vehicle transports the beam to the rear of the third supporting leg 3 .

[0023] like Figure 2 and Figure 3 As shown, the process of first beam dropping in step S3 specifically includes: S31, extending the fourth leg 4 to support the beam surface of the constructed steel box girder, and folding and stowing the third leg 3; S32, the lifting crane lifts the current span steel box girder 12 from the beam transport vehicle 7, and hoists it to both ends and drops it onto the constructed steel box girder 11 and the cushion pier 13 respectively; S33, extend the third support leg 3 to support the beam surface of the constructed steel box beam, fold and retract the fourth support leg 4, and the beam transport vehicle 7 withdraws.

[0024] In step S4, the bridge erection machine moves forward to cross the span, specifically including: S41, installing a running track on the constructed steel box girder 11; fixing the second leg 2 to the pier N3; S42: Drive the fourth support leg 4 to move along the travel track, driving the truss beam 8 to move forward across the span, with the first support leg 1 supported on the pier N4 at the front side of the next span; S43, move the second supporting leg 2 to the front end of the pier N4 on the front side of the next bridge span, and move the first supporting leg 1 forward until it is suspended in the air.

[0025] like Figure 4 As shown, in step S5, the secondary beam dropping specifically includes: S51, the hoisting crane lifts the steel box girder 12 of the current span again and moves backward, and the auxiliary trolley on the bridge erection machine lifts the pier 13 to the rear end of the front pier N4 of the next span; S52. Hoist the current span steel box girder 12 to the designed position. When one side of the current span steel box girder 12 falls onto the pier N4 and the end extends out of the pier N4, the other side is separated from the hoisting crane after the matching connection with the end of the constructed steel box girder 11 is completed.

[0026] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A secondary drop beam construction method for a steel box girder in a complex environment, wherein one end of the steel box girder extends out of the pier body, characterized in that: The following steps are involved: S1. The bridge erection machine is positioned above the current span, and a cushion pier is set on the front pier of the current span; S2, feeding beam; S3, first beam drop: the lifting crane on the bridge erection machine lifts the steel box girder of the current bridge span and drops the beam until its two ends are supported on the constructed steel box girder and the piers respectively; S4, the bridge erecting machine moves forward over the span; S5. Second beam drop: the lifting crane lifts the steel box girder of the current span again and moves backward, and the auxiliary trolley on the bridge erection machine lifts the pad pier to the front pier of the next span; then the steel box girder of the current span is lifted to the designed position, and one side of the steel box girder of the current span falls onto the pier, and the end extends out of the pier, and the other side is separated from the lifting crane after the matching connection with the end of the constructed steel box girder is completed.

2. The method for secondary drop of steel box beams in complex environments according to claim 1, characterized in that: The bridge-building machine includes a truss, a first leg, a second leg, a third leg and a fourth leg which are arranged in sequence from front to back at the bottom of the truss along the erection direction of the steel box girder; wherein, the first leg and the second leg are respectively slidably connected to the truss, the third leg and the fourth leg are foldable, and a walking device is provided at the bottom of the fourth leg.

3. The method for secondary beam drop construction of steel box beams in complex environments according to claim 2, characterized in that: In step S1, when the bridge erection machine is in place at the current span, the first leg is suspended in the air, the second leg is supported on the front end of the pier on the front side of the current span, the pad pier is set at the rear end of the pier on the front side of the current span, and the third leg and the fourth leg are supported on the constructed steel box girder.

4. The method for secondary beam drop construction of steel box beams in complex environments according to claim 2, characterized in that: In step S2, when feeding the beam, the fourth leg is folded and stowed, and the beam transport vehicle transports the beam to the rear of the third leg.

5. The method for secondary beam drop construction of steel box beams in complex environments according to claim 2, characterized in that: Step S3 specifically includes: S31, extending the fourth leg to support the beam surface of the constructed steel box girder, and folding and stowing the third leg; S32, the lifting crane lifts the steel box girder of the current bridge span from the beam transport vehicle, and lifts it to both ends and drops it onto the constructed steel box girder and the pier respectively; S33, extending the third leg to support the beam surface of the constructed steel box beam, folding and stowing the fourth leg, and the beam transport vehicle withdraws.

6. The method for secondary drop of steel box beams in complex environments according to claim 2, characterized in that: Step S4 specifically includes: S41. Install a running track on the constructed steel box girder; secure the second supporting leg to the bridge pier; S42: driving the fourth support leg to move along the travel track, driving the truss girder to move forward across the span, with the first support leg supported on the pier at the front side of the next span; S43, moving the second supporting leg to the front end of the front pier of the next bridge span, and moving the first supporting leg forward to be suspended in the air.

7. The method for secondary drop of steel box beams in complex environments according to claim 1, characterized in that: When the cushion pier is installed on the bridge pier, its top surface is flush with the top surface of the constructed steel box girder.

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