Method for dismantling a portal structure and method for manufacturing a portal structure

Abstract

Regarding the demolition of a portal structure having a beam section and two leg sections provided at each end of the beam section, the aim is to reduce costs and improve the flexibility of setting the construction period by not using large heavy machinery to raise and lower the portal structure itself. [Solution] A frame equipped with jacks that can raise and lower objects via wires is constructed near the portal structure. With the wires connected to the beams, a cutting and dismantling process is repeated in which a portion of the lower end of each leg is cut and removed, and a lowering process is repeated in which the portal structure is lowered using the jacks.

Description

Technical Field

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[0001] This invention relates to the disassembly and manufacture of a portal structure having a beam portion and leg portions respectively joined to lower portions of both ends of the beam portion.

Background Art

[0002] One of the portal structures is a goliath crane. The goliath crane is a huge portal crane mainly used for ship construction, repair, etc. in a shipyard, and has two leg portions called swing legs and rigid legs, and a gantry erected between them. Travel devices are provided at lower ends of the swing legs and the rigid legs, and travel on rails laid in the shipyard. Further, a lifting device capable of traveling on the gantry is provided on the gantry, and thus parts of a ship or the like can be lifted and transported.

[0003] By the way, when disassembling a goliath crane due to its lifespan or the like, a disassembly method different from that of ordinary buildings has been explored due to its large size. Among these, Patent Document 1 discloses a disassembly method of a goliath crane. Specifically, a temporary beam is erected between both legs at an intermediate height position of the swing legs and the rigid legs, then the gantry is removed, then the upper part above the temporary beam installation position of both leg portions is cut and removed, then the temporary beam is removed from both leg portions and removed, and then the lower parts of the remaining both leg portions are removed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0006] Furthermore, when constructing such massive portal structures, not only is demolition difficult, but the use of large heavy machinery to lift and lower heavy parts is also costly and limited in duration, resulting in high manufacturing costs and reduced flexibility in setting construction schedules.

[0007] Therefore, the object of this invention is to provide a method for dismantling a portal structure that does not require large heavy machinery to lift and lower ultra-heavy objects such as portal structures, thereby reducing dismantling costs and increasing the flexibility of setting the construction period, and a method for manufacturing a portal structure that does not require large heavy machinery to lift and lower ultra-heavy objects such as portal structures, thereby reducing manufacturing costs and increasing the flexibility of setting the construction period. [Means for solving the problem]

[0008] One embodiment of a method for dismantling a portal structure is a method for dismantling a portal structure having a beam section and two leg sections provided at both ends of the beam section, characterized in that it includes a frame construction step of constructing a frame equipped with jacks capable of raising and lowering objects via wires near the portal structure; a connection step of connecting the wires to the beam section; a cutting and dismantling step of cutting and dismantling the lower end of the portal structure; a lowering step of lowering the portal structure using the jacks; and a repeating step of repeating the cutting and dismantling step and the lowering step until the dismantling of the portal structure is completed.

[0009] One embodiment of a method for manufacturing a portal structure is a method for manufacturing a portal structure having a beam and two legs provided at both ends of the beam, and is characterized by comprising: a frame construction step of constructing a frame on which jacks capable of raising and lowering objects via wires are installed; a connection step of connecting the wires to the beam positioned near the frame; and an assembly step of repeatedly raising and stopping the beam using the jacks, and assembling each of the legs each time the raising of the beam stops. [Effects of the Invention]

[0010] According to one method of dismantling a portal structure, the portal structure is supported by jacks, and the lower part of the portal structure is cut and removed, followed by the lowering of the portal structure, in sequence, thereby dismantling the portal structure. This method is highly safe because dangerous cutting work can be performed near the ground, and it does not require large heavy machinery to lift or lower extremely heavy objects such as portal structures, thus reducing dismantling costs and increasing flexibility in setting the construction period.

[0011] According to one method of manufacturing a portal structure, the beam section is repeatedly raised and stopped using jacks, and each time the beam section stops rising, the legs are assembled to manufacture the portal structure. This method allows dangerous assembly work to be performed near the ground, thus increasing safety. Furthermore, it does not require large heavy machinery to raise and lower ultra-heavy objects such as portal structures, thus reducing manufacturing costs and increasing flexibility in setting construction periods. [Brief explanation of the drawing]

[0012] [Figure 1] (A) is a front view showing an example of the Goliath crane 1 according to this embodiment, (B) is a left side view thereof, (C) is a right side view thereof, and (D) is a top view thereof. [Figure 2] This is a front view of the Goliath crane 1 for explaining the frame construction process and other aspects according to this embodiment. [Figure 3] This is a plan view of the Goliath crane 1 for explaining the frame construction process and other aspects according to this embodiment. [Figure 4](A) and (B) are left side views of the Goliath crane 1 for illustrating the frame construction process and the like according to this embodiment. [Figure 5] (A) and (B) are right side views of the Goliath crane 1 for illustrating the frame construction process and the like according to this embodiment. [Figure 6] (A) is a front view of the Goliath crane 1 for explaining the cutting and dismantling process, etc., according to this embodiment; (B) is a left side view thereof; (C) is a right side view thereof; and (D) is a top view thereof. [Figure 7] (A) is a front view of the Goliath crane 1 for illustrating the repetitive processes, etc., according to this embodiment; (B) is a left side view thereof; (C) is a right side view thereof; and (D) is a top view thereof. [Figure 8] (A) is a front view of the Goliath crane 1 for explaining the frame removal process, etc., according to this embodiment; (B) is a left side view thereof; (C) is a right side view thereof; and (D) is a top view thereof. [Figure 9] This flowchart shows an example of a method for dismantling the Goliath crane 1 according to this embodiment. [Figure 10] (A) and (B) are examples of schematic exploded views of the Goliath crane 1 according to this embodiment. [Figure 11] (A)-(F) are explanatory diagrams showing an example of the manufacturing process for the Goliath crane 1 according to this embodiment. [Figure 12] This flowchart shows an example of a manufacturing method for the Goliath crane 1 according to this embodiment. [Modes for carrying out the invention]

[0013] The following describes embodiments of the dismantling and manufacturing methods for a portal structure according to the present invention, with reference to the drawings. A portal structure is a structure having two legs and a beam section erected on the two legs. In this embodiment, the dismantling and manufacturing methods for a Goliath crane 1, which is an example of a portal structure, will be described.

[0014] [1. Overview of the Goliath Crane 1] First, the overview of the Goliath Crane 1 will be described using FIGS. 1(A)-(D).

[0015] The Goliath Crane 1 has a rocking leg portion 2 and a rigid leg portion 3, and a girder portion 4 horizontally installed between the upper ends of the rocking leg portion 2 and the rigid leg portion 3. For example, it is a huge portal structure with a height of about 90 meters, a width of about 200 meters, and a total weight of about 6500 tons.

[0016] The rocking leg portion 2 is joined to the girder portion 4 via a joint (not shown) that can slide and rotate with respect to the girder portion 4, absorbing the expansion and contraction of the girder portion 4 and the deviation of the gauge span (width) of the left and right running rails, etc., to prevent derailment. On the other hand, the rigid leg portion 3 is rigidly joined to the girder portion 4, transmitting the horizontal force acting in the longitudinal direction of the girder portion 4 to the running rail to prevent overturning.

[0017] The Goliath Crane 1 is arranged such that the rocking leg portion 2 and the rigid leg portion 3 straddle the dock of the shipyard, and each traveling device of the rocking leg portion 2 and the rigid leg portion 3 uses a rail (not shown) laid along the dock to move the Goliath Crane 1. Further, on the girder portion 4, a trolley 5 as a lifting device capable of traveling on the girder portion 4 is provided. The trolley 5, for example, lifts the parts P outside the ship S and transports them onto the ship S inside the dock, or vice versa.

[0018] [2. Dismantling Method of the Goliath Crane 1] Next, the method for dismantling the Goliath crane 1 according to this embodiment will be described with reference to Figures 2-9. However, in Figure 4(A), the jack bases 11A and 11D are depicted in front of the rocking legs 2 for clarity (the same applies to Figure 6(B)). Also, in Figure 4(A), the depiction of the anti-tipping wires 16A-16D is omitted (the same applies to Figures 6-8(B)), while in Figure 4(B), the anti-tipping wires 16A-16D are depicted, but the depiction of the jack bases 11A, 11D and the anti-tipping wires 13B and 13G is omitted. Also, in Figure 5(A), the jack bases 11B and 11C are depicted in front of the rigid legs 3 for clarity (the same applies to Figure 6(C)). Furthermore, in Figure 5(A), the depiction of the anti-tipping wires 18A-18D is omitted (the same applies to (C) in Figures 6-8), while in Figure 5(B), the anti-tipping wires 18A-18D are depicted, but the depiction of the jack bases 11B and 11C is omitted.

[0019] [2.1. Frame Construction Process (Step S11 in Figure 9)] First, the frame construction process will be explained with reference to Figures 2-5. In the frame construction process, jack frames 11A-11D (sometimes referred to collectively as jack frame 11) are constructed near the Goliath crane 1. In this embodiment, as shown in Figure 3, jack frames 11A-11D are constructed at a total of four locations: left and right on the front side and left and right on the rear side of the Goliath crane 1. The jack frames 11 are made higher than the height of the Goliath crane 1. Then, jack beams 12 for installing jacks J, which will be described later, are placed across the upper surfaces of jack frames 11A and jack frames 11D. Similarly, jack beams 14 are placed across the upper surfaces of jack frames 11B and jack frames 11C. The jack frames 11 have the basic configuration of a general scaffolding and are constructed using steel members, etc.

[0020] Furthermore, to prevent tipping, one end of anti-tipping wires 13A-13D is connected to the upper end of the jack base 11A, and the other end of the anti-tipping wires 13A-13D is fixed to an anchor (not shown) installed in the ground. Similarly, anti-tipping wires 15A-15D are attached to the jack base 11B, anti-tipping wires 15E-15H are attached to the jack base 11C, and anti-tipping wires 13E-13H are attached to the jack base 11D. In this way, the anti-tipping wires 13A-13H and 15A-15H (sometimes collectively referred to as anti-tipping wires 13 and 15) connect the jack base 11 to the anchor, thereby preventing the jack base 11 from tipping over when the jack J installed on top of the jack base 11 supports the load of the Goliath crane 1. Note that, as long as the anti-tipping wires 13 and 15 can prevent the jack base 11 from tipping over, one end of the anti-tipping wires 13 and 15 may be connected to a part other than the upper end of the jack base 11, or the other end may be connected to a fixed object other than an anchor installed in the ground.

[0021] Next, multiple jacks J are installed on jack beams 12 and 14 erected on the upper end of the jack base 11. Each jack J is capable of raising and lowering an object via a wire W, and can raise, lower, and stop (stop raising and lowering) an object connected to the wire W. In this embodiment, the wire W is connected to the girder section 4 (see Figures 7(B) and (C)), and in order to support the load of the Goliath crane 1 with multiple jacks J, a number of jacks J (for example, 24) capable of lifting the entire load of the Goliath crane 1 are appropriately arranged on each jack base 11A-D.

[0022] Furthermore, in this embodiment, one end of anti-tipping wires 16A-16D is connected to the upper surface of the end of the girder section 4 on the swinging leg section 2 side to prevent tipping, and the other end of the anti-tipping wires 16A-16D is gripped by anti-tipping jacks 17A-17D fixed to the ground. Similarly, one end of anti-tipping wires 18A-18D is connected to the upper surface of the end of the girder section 4 on the rigid leg section 3 side to prevent tipping, and the other end of the anti-tipping wires 18A-18D is gripped by anti-tipping jacks 19A-19D fixed to the ground. In this way, by connecting the girder section 4 to the ground with anti-tipping wires 16A-16H and 18A-18H (sometimes collectively referred to as anti-tipping wires 16 and 18), the Goliath crane 1 can be prevented from tipping over. Furthermore, the anti-tipping jacks 17A-17D and 19A-19D not only grip the anti-tipping wires 16 and 18, but can also change the gripping position of the anti-tipping wires 16 and 18. Therefore, as will be described later, even when the girder section 4 descends, the tension of the anti-tipping wires 16 and 18 can be maintained by changing the gripping position of the anti-tipping wires 16 and 18.

[0023] [2.2. Connection Process (Step S12 in Figure 9)] Next, the connection process will be explained. In the connection process, the wires W of the jacks J are connected to the girder section 4. For example, a lifting fitting is provided below each jack J in the girder section 4, and the lifting hooks at the ends of each wire W are attached to these lifting fittings. Each jack J exerts tension on the wire W, and each jack J supports the load of the Goliath crane 1.

[0024] [2.3. Cutting and Dismantling Process (Step S13 in Figure 9)] Next, the cutting and dismantling process will be explained with reference to Figure 6. In the cutting and dismantling process, the lower end of the Goliath crane 1 is cut and dismantled using a demolition heavy machine (not shown). At this time, since the load of the Goliath crane 1 is supported by jacks J, it will not fall even if the lower end of the Goliath crane 1 is cut. The rubble generated by the dismantling is loaded onto a transport vehicle (not shown) and removed.

[0025] [2.4. Lowering Process (Step S14 in Figure 9)] Next, the lowering process will be explained. In the lowering process, each jack J lowers the girder section 4 until the lower end of the Goliath crane 1 touches the ground. Alternatively, it may be lowered to a height where the lower end can be cut off with demolition equipment, even if it does not touch the ground completely.

[0026] [2.5. Repeated Process (Step S15 in Figure 9)] Next, the repeating process will be explained. In the repeating process, the cutting and dismantling process and the lowering process are repeated in order until the dismantling of Goliath Crane 1 is completed (Step S15: NO).

[0027] In this way, by repeating the cutting and dismantling process and the lowering process, the Goliath crane 1 is dismantled from the legs (see Figure 7), and finally the girder section 4 is dismantled. This allows the massive girder section 4 to be dismantled on the ground without using large heavy machinery to raise and lower the girder section 4 itself. The trolley 5 is removed from the girder section 4 during the dismantling of the girder section 4, dismantled if unnecessary, and preserved if to be reused.

[0028] [2.6. Frame Removal Process (Step S16 in Figure 9)] Next, the frame removal process will be explained. As shown in Figure 8, after the dismantling of the Goliath crane 1 is completed, in the frame removal process, all jacks J are lowered to the ground from the jack frame 11, and the jack beams 12 and 14 and the jack frame 11 are dismantled and removed.

[0029] As described above, the method for dismantling the Goliath crane 1 of this embodiment (an example of the "gantry structure" of the present invention) is a method for dismantling the Goliath crane 1 which has a girder section 4 (an example of the "beam section" of the present invention) and swinging leg sections 2 and rigid leg sections 3 (an example of the "two leg sections" of the present invention) provided at both ends of the girder section 4, and includes a jack frame construction step (step S11 in Figure 9) in which a jack frame 11 (an example of the "frame" of the present invention) on which a jack J capable of raising and lowering a wire W is installed is constructed near the Goliath crane 1; a connection step (step S12 in Figure 9) in which the wire W is connected to the girder section 4; a cutting and dismantling step (step S13 in Figure 9) in which the lower end of the Goliath crane 1 is cut and removed; a lowering step (step S14 in Figure 9) in which the Goliath crane 1 is lowered by the jack J; and a repeating step (step S15 in Figure 9) in which the cutting and dismantling step and the lowering step are repeated until the dismantling of the Goliath crane 1 is completed.

[0030] In particular, in this embodiment, the repeating process involves repeating the cutting and dismantling process and the lowering process to dismantle the swinging leg section 2 and the rigid leg section 3 until the girder section 4 descends to the ground. After the girder section 4 has descended to the ground, the girder section 4 is dismantled.

[0031] Therefore, according to the Goliath crane 1 dismantling method of this embodiment, the Goliath crane 1 is dismantled by repeatedly cutting and removing the lower end of the Goliath crane 1 and lowering the Goliath crane 1 in sequence while supporting the Goliath crane 1 with jacks J. This method is highly safe because dangerous cutting work can be performed near the ground. Furthermore, it does not require large heavy machinery to raise and lower the Goliath crane 1 itself or the girder section 4, thus reducing dismantling costs and increasing the flexibility of setting the construction period.

[0032] Furthermore, in the method for dismantling the Goliath crane 1 of this embodiment, the anti-tipping wires 13 and 15, which prevent the jack base 11 from tipping over, connect the jack base 11 to anchors other than the jack base 11 (an example of the "fixed object" of the present invention). This prevents the jack base 11 from tipping over even when the load of the Goliath crane 1 is supported by the jacks J. In addition, the anti-tipping wires 13 and 15 may also connect the upper end of the jack base 11 to anchors fixed to the ground, as in this embodiment.

[0033] [3. Manufacturing method of Goliath Crane 1] Next, the manufacturing method of the Goliath crane 1 according to this embodiment will be described with reference to Figures 2-8 and 10-12. In the manufacturing method according to this embodiment, as shown in Figure 10(A), the rocking leg section 2 is composed of a plurality of rocking leg section / leg members 2A-2C divided in the height direction, and the rigid leg section 3 is composed of a plurality of rigid leg section / leg members 3A-3C divided in the height direction. That is, the rocking leg section 2 is formed by joining the plurality of rocking leg section / leg members 2A-2C in an appropriate order in the height direction, and the rigid leg section 3 is formed by joining the plurality of rigid leg section / leg members 3A-3C in an appropriate order in the height direction. Furthermore, the uppermost rocking leg section / leg member 2C can be joined to one end of the girder section 4, and the uppermost member of the rigid leg section / leg member 3C can be joined to the other end of the girder section 4. This allows the Goliath crane 1 to be assembled by joining the uppermost rocking leg member 2C and the uppermost rigid leg member 3C to both ends of the girder section 4, then joining the rocking leg members 2B and 2A below the uppermost rocking leg member 2C in the appropriate order, and joining the rigid leg members 3B and 3A below the uppermost rigid leg member 3C in the appropriate order.

[0034] Here, with reference to Figure 11, we will briefly explain the manufacturing method of the Goliath crane 1, which consists of the components shown in Figure 10(A). Note that in Figure 11, for the sake of clarity in the explanation, the jack bases 11A-11D and jacks J, etc., have been omitted from the illustration.

[0035] First, as shown in Figure 11(A), the girder section 4 and trolley 5 are positioned at their assembly locations on the ground, and the wire W that the jack J will use to raise and lower them is attached.

[0036] Next, the height of the uppermost rocking leg member 2C and the uppermost rigid leg member 3C are compared to identify the lower leg member. Here, the rocking leg member 2C is identified. Then, as shown in Figure 11(B), the girder section 4 is raised to a height that makes it easy to join the identified rocking leg member 2C to the girder section 4, and then stopped. Next, the rocking leg member 2C is joined to the girder section 4.

[0037] Next, it is determined which of the rocking leg member 2B and the rigid leg member 3C will be joined next. Specifically, the lower end position of the one whose lower end is higher from the ground when both are joined simultaneously is determined. In other words, the lower end position when the rocking leg member 2B is joined to the rocking leg member 2C is higher than the lower end position when the rigid leg member 3C is joined to the girder section 4, so the rigid leg member 3C is determined to be the next leg member to be joined. Then, as shown in Figure 11(C), the girder section 4 is raised to a height that makes it easy to join the determined rigid leg member 3C to the girder section 4, and then stopped. Next, the rigid leg member 3C is joined to the girder section 4.

[0038] Next, it is determined which of the rocking leg member 2B and the rigid leg member 3B will be joined next. Specifically, the lower end position of the one whose lower end is higher from the ground when both are joined simultaneously is determined. In other words, the lower end position when rocking leg member 3B is joined to rocking leg member 2C is higher than the lower end position when rigid leg member 3B is joined to rigid leg member 3C, so rocking leg member 2B is determined to be the next leg member to be joined. Next, as shown in Figure 11(D), the girder section 4 is raised to a height that makes it easy to join the determined rocking leg member 2B to rocking leg member 2C, and then stopped. Next, rocking leg member 2B is joined to rocking leg member 2C.

[0039] Next, it is determined which of the rocking leg member 2A and the rigid leg member 3B will be joined next. Specifically, the lower end position of the one whose lower end is higher from the ground when both are joined simultaneously is determined. In other words, the lower end position when rocking leg member 2A is joined to rocking leg member 2B is higher than the lower end position when rigid leg member 3B is joined to rigid leg member 3C, so rigid leg member 3B is determined to be the next leg member to be joined. Next, as shown in Figure 11(E), the girder section 4 is raised to a height that makes it easy to join the determined rigid leg member 3B to rigid leg member 3C, and then stopped. Next, rigid leg member 3B is joined to rigid leg member 3C.

[0040] Next, it is determined which of the rocking leg member 2A and the rigid leg member 3A will be joined next. Specifically, the lower end of the one whose position is higher from the ground when both are joined simultaneously is determined. However, in the example in Figure 10, the lower end position when rocking leg member 2A is joined to rocking leg member 2B and the lower end position when rigid leg member 3A is joined to rigid leg member 3B are at the same height, so it is not possible to determine which one is which. In this case, both rocking leg member 2A and rigid leg member 3A are determined as the leg members to be joined next. Then, as shown in Figure 11(F), the girder section 4 is raised to a height that makes it easy to join the determined rocking leg member 2A and rigid leg member 3A to rocking leg member 2B and rigid leg member 3B, and then stopped. Next, the rocking leg member 2A is joined to the rocking leg member 2B, and the rigid leg member 3A is joined to the rigid leg member 3B. In this way, the rocking leg member 2 and the rigid leg member 3 are attached to the girder section 4, and the Goliath crane 1 is completed.

[0041] Thus, the next leg member to be joined is determined according to the height of each leg member of the rocking leg 2 and the rigid leg 3. Therefore, a joining sequence is predetermined to indicate which leg member to join each time the rise of the girder 4 stops, and the members are joined sequentially according to this sequence. For example, in the examples of Figures 10(A) and 11, the joining sequence is as follows. (1st) Swivel leg section / leg member 2C (Second) Rigid leg section / leg component 3C (3rd) Swivel leg section / leg member 2B (4th) Rigid leg section / leg component 3B (5th) Swivel leg section / leg member 2A and rigid leg section / leg member 3A

[0042] Regarding the trolley 5, instead of installing it on the girder section 4 at the stage shown in Figure 11(A), it may be possible to lift and install the trolley 5 onto the girder section 4 after the Goliath crane 1, excluding the trolley 5, has been completed.

[0043] Here, we will describe the case where, as shown in Figure 10(B), the rocking leg section 2 is composed of multiple rocking leg section / leg members 2D-2F divided in the height direction, and the rigid leg section 3 is composed of multiple rigid leg section / leg members 3D-3F divided in the height direction. The rocking leg section / leg member 2D and the rigid leg section / leg member 3D are at the same height, and similarly, the rocking leg section / leg member 2E and the rigid leg section / leg member 3E, and the rocking leg section / leg member 2F and the rigid leg section / leg member 3F are at the same height. In this case, when identifying the next leg member to be joined for each leg section, if both are joined at the same time, the positions of their lower ends are compared and they are both at the same height, so it is not possible to identify one or the other. Therefore, both are identified as the next leg member to be joined. Therefore, first, the girder section 4 is raised to a height that facilitates joining the rocking leg section / leg member 2F and the rigid leg section / leg member 3F, and then the rocking leg section / leg member 2F and the rigid leg section / leg member 3F are joined. Next, the girder section 4 is raised to a height that facilitates joining the rocking leg section / leg member 2E and the rigid leg section / leg member 3E, and then the rocking leg section / leg member 2E and the rigid leg section / leg member 3E are joined. Next, the girder section 4 is raised to a height that facilitates joining the rocking leg section / leg member 2D and the rigid leg section / leg member 3D, and then the girder section 4 is raised to a height that facilitates joining the rocking leg section / leg member 2D and the rigid leg section / leg member 3D, and then the rocking leg section / leg member 2D and the rigid leg section / leg member 3D are joined. In this way, the rocking leg section 2 and the rigid leg section 3 are attached to the girder section 4, and the Goliath crane 1 is completed.

[0044] Next, referring to the flowchart in Figure 12, we will explain the manufacturing process of the Goliath crane 1.

[0045] [3.1. Frame Construction Process (Step S51 in Figure 12)] The frame construction process is the same as the frame construction process for the dismantling method of Goliath Crane 1 (step S11 in Figure 9), so the explanation is omitted. However, the jack frame 11 is constructed at the location where Goliath Crane 1 will be assembled.

[0046] [3.2. Connection Process (Step S52 in Figure 12)] Next, the connection process will be explained. In the connection process, the wire W is connected to the girder section 4 located in the center of the jack bases 11A-11D, as shown in Figure 7. For example, a hanging fitting is provided below each jack J in the girder section 4, and the hanging hooks at the ends of each wire W are attached to these hanging fittings.

[0047] [3.3. Lifting Process (Step S53 in Figure 12)] Next, the lifting process will be explained. In the lifting process, the girder section 4 is raised and stopped using multiple jacks J. Specifically, based on a predetermined joining sequence for the swaying leg section 2 and the rigid leg section 3, the girder section 4 is raised to a height where the next leg member to be joined can be attached and then stopped.

[0048] [3.4. Joining Process (Step S54 in Figure 12)] Next, the joining process will be explained. In the joining process, with the girder section 4 stopped rising, the next leg member to be joined is joined according to a predetermined joining sequence. When the leg to be joined is the uppermost leg member of the rocking leg section 2 and the rigid leg section 3 (rocking leg section / leg member 2C and rigid leg section / leg member 3C in Figure 10), it is joined to the girder section 4, respectively. When the leg member to be joined is a leg member other than the uppermost leg member of the rocking leg section 2 and the rigid leg section 3, it is joined to the leg member immediately above it that has already been joined.

[0049] [3.5. Repeated Process (Step S55 in Figure 12)] Next, the repeating process will be explained. In the repeating process, the lifting process (step S53) and the joining process (step S54) are repeated for each leg (rocking leg 2 and rigid leg 3) until all leg members (rocking leg / leg member and rigid leg / leg member) are joined (step S55:NO).

[0050] [3.6. Frame Removal Process (Step S56 in Figure 12)] Next, the frame removal process will be explained. Once all the leg members (rocking leg members and rigid leg members) are joined to each leg (rocking leg 2 and rigid leg 3) (Step S55: YES), the Goliath crane 1 is completed, and the frame removal process is then carried out. The frame removal process is the same as the frame removal process in the dismantling method of the Goliath crane 1 (Step S16 in Figure 9), so the explanation will be omitted.

[0051] As described above, the method for manufacturing the Goliath crane 1 of this embodiment (an example of the "gantry structure" of the present invention) is a method for manufacturing a Goliath crane 1 having a girder section 4 (an example of the "beam section" of the present invention) and a swinging leg section 2 and a rigid leg section 3 (an example of the "two legs" of the present invention) provided at both ends of the girder section 4, and includes a frame construction step (step S51 in Figure 12) for constructing a jack frame 11 on which a jack J capable of raising and lowering a wire W is installed; a connection step (step S52 in Figure 12) for connecting the wire W to the girder section 4 located near the jack frame 11; and an raising step (step S53 in Figure 12) and a joining step (step S54 in Figure 12) (an example of the "assembly step" of the present invention) for repeatedly raising and stopping the girder section 4 using the jack J, and assembling the swinging leg section 2 and the rigid leg section 3 each time the raising of the girder section 4 stops.

[0052] Therefore, according to the manufacturing method of the Goliath crane 1 of this embodiment, the girder section 4 is repeatedly raised and stopped by the jack J, and each time the rise of the girder section 4 stops, the rocking leg section 2 and the rigid leg section 3 are assembled to manufacture the Goliath crane 1. This allows dangerous assembly work to be performed near the ground, thus providing high safety. Furthermore, since it does not require large heavy machinery to raise and lower the Goliath crane 1 itself, manufacturing costs can be reduced, and the flexibility of setting the construction period can be increased.

[0053] Furthermore, in the manufacturing method of the Goliath crane 1 of this embodiment, each of the rocking leg section 2 and the rigid leg section 3 includes a plurality of leg members 2A-2C and 3A-3C divided in the height direction, and a predetermined joining sequence is set indicating which leg members 2A-2C and 3A-3C to join each time the rise of the girder section 4 stops. In the rising process, the girder section 4 is raised to a height where the next leg member to be joined can be joined based on the joining sequence and then stopped. In the joining process, the next leg member to be joined is joined at the time of the stop. As a result, each of the rocking leg section 2 and the rigid leg section 3 is divided in advance into a plurality of leg members 2A-2C and 3A-3C in the height direction, and by joining them in a predetermined appropriate joining sequence at the manufacturing site, the rocking leg section 2 and the rigid leg section 3 can be assembled in a short time, and the manufacturing time until the completion of the Goliath crane 1 can be shortened. [Explanation of Symbols]

[0054] 1: Goliath Crane 2: Rocking leg part 2A-2F: Swing leg / leg member 3: Rigid leg 3A-3F: Rigid leg section / leg component 4: Girder section 5: Trolley 11: Jack stand 11A-11D: Jack stand 12: Beam for jacks 13A-13H: Anti-tip wire 14: Beam for jacks 15A-15H: Anti-tip wire 16A-16D: Anti-tip wire 17A-17D: Anti-tip jack 18A-18D: Anti-tip wire 19A-19D: Anti-tip jack J: Jack P: Parts S :Ship W: Wire

Claims

1. A method for dismantling a portal structure having a beam and two legs provided at both ends of the beam, A frame construction step involves constructing a frame equipped with jacks capable of raising and lowering objects via wires near the aforementioned gantry structure, A connection step of connecting the wire to the beam section, A cutting and dismantling process in which the lower end of the aforementioned portal structure is cut and dismantled, A lowering step in which the portal structure is lowered using the jack, The process involves repeating the cutting and demolition process and the lowering process until the demolition of the portal structure is completed. A method for dismantling a portal structure, characterized by including the following:

2. A method for dismantling a portal structure according to claim 1, A method for dismantling a portal structure, characterized in that, in the repeated process, the cutting and dismantling process and the lowering process are repeated to dismantle each of the legs until the beam section is lowered to the ground, and after the beam section has been lowered to the ground, the beam section is dismantled.

3. A method for dismantling a portal structure according to claim 1, A method for dismantling a portal structure, characterized in that a fall prevention wire, which prevents the frame from tipping over, connects the frame to other fixed objects.

4. A method for dismantling a portal structure according to claim 3, A method for dismantling a portal structure, characterized in that the anti-tipping wire connects the upper end of the frame to the fixed object fixed to the ground.

5. A method for manufacturing a portal structure, comprising a beam section and two leg sections provided at both ends of the beam section, The process of constructing a frame, which involves building a frame equipped with jacks that can raise and lower objects via wires, A connection step of connecting the wire to the beam portion located near the frame, The assembly process involves repeatedly raising and stopping the beam using the jack, and assembling each of the legs each time the beam stops rising. A method for manufacturing a portal structure, characterized by including the following:

6. A method for manufacturing a portal structure according to claim 5, Each of the aforementioned legs includes a plurality of leg members divided in the height direction, and a predetermined joining sequence is set indicating which of the aforementioned leg members to join each time the upward movement of the beam stops. A method for manufacturing a portal structure, characterized in that, in the assembly step, the beam is raised to a height at which the next leg member to be joined can be joined based on the joining sequence, and then stopped, and the next leg member to be joined is joined at the time of the stop.

7. A method for manufacturing a portal structure according to claim 5, A method for manufacturing a portal structure, characterized in that a tipping prevention wire, which prevents the tipping of the frame, connects the frame to a fixed object other than the frame.

8. A method for manufacturing a portal structure according to claim 7, A method for manufacturing a gate-shaped structure, characterized in that the anti-tipping wire connects the upper end of the frame to the fixed object fixed to the ground.

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