Girder rotation device and girder dismantling method

Abstract

To provide technologies for solving the problems of the prior art, i.e., to provide a technology that can remove the girder more easily than the conventional technologies.SOLUTION: The girder rotating device is a device for rotating a target girder connected to an existing girder and equipped with a moving body, a main tower, a main jack, a sub-jack, a traction device, and a connecting body. The main tower has a main tower column body, a main tower pedestal provided on the lower end of the main tower column body, and a main tower pulley mounted on the upper end of the main tower column body, and the two jacks whose rear ends are pin-connected to the moving body are stretchable to the front end side. The traction device installed on the moving body can wind and unwind a traction rope, and the connection body having an intermediate pulley can be attached to the target girder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to technology relating to girders such as bridge girders, and more specifically to a girder rotation device that can rotate girders, and a girder dismantling method that uses the device to remove girders. [Background technology]

[0002] It has been pointed out that the construction infrastructure (hereafter referred to as "construction infrastructure") that was developed intensively during the period of high economic growth is already showing signs of considerable deterioration. In 2014, the Council for Social Capital Development compiled a "Recommendation for Full-scale Implementation of Measures to Counteract Aging Roads," which cited the example of the Sasago Tunnel disaster in 2012 and sounded the alarm that "in the near future, this will lead to fatal incidents, such as bridge collapses, affecting human lives and social infrastructure," and strongly advocated the importance of maintaining and managing construction infrastructure.

[0003] Against this background, the government has promulgated a ministerial ordinance amending part of the Road Act Enforcement Regulations, formulating periodic inspection guidelines that outline specific construction infrastructure inspection methods, areas to look out for in major abnormalities, and photographs of case studies. These periodic inspection guidelines apply to bridges with a length of 2.0m or more, which is said to number around 700,000, and stipulate that the first inspection should be carried out within two years of opening to service, with periodic inspections thereafter to be carried out once every five years.

[0004] Meanwhile, the "Highway Bridge Specifications," which are the standards for designing road bridges, have been revised from time to time since the 1939 edition was published, and particularly after the Hyogo-ken Nanbu Earthquake, major revisions were made. As a result, there are many cases where bridges that previously had sufficient strength are found to have insufficient strength in light of current design standards.

[0005] Due to these two reasons, namely deterioration and insufficient strength, bridges are now frequently reinforced or rebuilt, or bridge girders are removed in order to be replaced. However, removing bridge girders requires large-scale construction machinery, is a complicated process, and tends to take a long time to complete, so it is unavoidable that construction costs will rise.

[0006] In addition to removing bridge girders to demolish existing bridges, girders are also removed when constructing new bridges. When the space below the girders cannot be used for construction, such as in bridges that span rivers or overpasses that are erected above roads, the launching erection method is often used to install the bridge girders. This launching erection method involves gradually launching the bridge girder from one support side until the tip of the bridge girder reaches the other support side, and a hand-stretching machine (erection girder) is usually installed at the tip of the bridge girder. Therefore, when the hand-stretching machine reaches its destination (for example, the abutment on the opposite bank), it must be removed from the bridge girder.

[0007] As with removing bridge girders, installing a new bridge requires a considerable amount of work and construction time. Therefore, various technologies have been proposed to make it easier to erect bridge girders. For example, Patent Documents 1 and 2 propose technologies for erecting bridge girders while rotating them. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4581131 [Patent Document 2] Patent No. 4649562 Summary of the Invention [Problem to be solved by the invention]

[0009] The techniques disclosed in Patent Documents 1 and 2 allow work to be carried out safely, easily, and efficiently compared to conventional techniques. As a result, the construction period for erecting bridge girders is shortened, and construction costs are reduced accordingly, making these techniques extremely suitable. However, until now, there have been few proposals for techniques that allow for the easy and efficient removal of bridge girders, including the techniques disclosed in Patent Documents 1 and 2.

[0010] The object of the present invention is to solve the problems of the prior art, that is, to provide a technology that allows for easier removal of beams compared to the prior art. [Means for solving the problem]

[0011] The present invention was made with a focus on the point that the beam can be removed while being rotated, and is an invention based on an idea that has not been seen before.

[0012] The girder rotation device of the present invention is a device for rotating a target girder connected to an existing girder, and includes a movable body movable on the existing girder, a main tower, a main jack, a sub-jack, a traction device, and a connecting body. The main tower includes a main tower column, a main tower base attached to the lower end of the main tower column, and a main tower pulley attached to the upper end of the main tower column. The main jack has its front end pin-connected to a part of the main tower column and its rear end pin-connected to the movable body, and the sub-jack has its rear end pin-connected to the movable body, and these are extendable and retractable at their ends. The traction device installed on the movable body is capable of winding and unwinding a traction rope, and the connecting body with an intermediate pulley is attachable to the target girder. The main tower column is pin-connected to the main tower base. When the front end of the sub-jack is pin-connected to a part of the main tower column, the main tower column rotates as the sub-jack extends and retracts. Furthermore, when the main tower pedestal is fixed to the existing girder, the extension of the main jack causes the main tower column to rotate around the main tower pedestal.Furthermore, the main tower pedestal is fixed to the existing girder, a connector is installed on the target girder, and a part of the target girder that has been released from its connection to the existing girder is pin-connected to the main tower pedestal, a traction rope is looped around the main tower pulley and then around the intermediate pulley, and the tip of the traction rope is further fixed to a part of the main tower column, and the traction device winds up the traction rope, causing the target girder to rotate around the main tower pedestal.

[0013] The girder rotation device of the present invention can also be configured such that the main tower includes a left tower column body and a right tower column body (however, they are arranged apart in the direction perpendicular to the axis of the existing girder), the intermediate pulley of the connecting body includes a left intermediate pulley and a right intermediate pulley (however, they are arranged apart in the direction perpendicular to the axis of the target girder), and further, a left traction device and a right main traction device (however, they are arranged apart in the direction perpendicular to the axis of the existing girder) are installed on the moving body. In this case, the traction cable of the left traction device is reeled around the main tower pulley of the left tower column body and then reeled around the left intermediate pulley, with the tip of the traction cable being fixed to a part of the left tower column body when in use. Similarly, the traction cable of the right traction device is reeled around the main tower pulley of the right tower column body and then reeled around the right intermediate pulley, with the tip of the traction cable being fixed to a part of the right tower column when in use.

[0014] The girder dismantling method of the present invention is a method for removing a target girder connected to the front of an existing girder using the girder rotation device of the present invention, and includes a moving step, a connector installation step, a first forward rotation step, a second forward rotation step, a girder disconnection step, a first rearward rotation step, a second rearward rotation step, a third rearward rotation step, and a transport step. In the moving step, the front ends of the main jack and the sub-jack are pin-connected to a part of the main tower column that has fallen backward, and the moving body moves from rear to front on the existing girder. In the connector installation step, the connector is installed on the target girder that is connected to the existing girder. In the first forward rotation step, the sub-jack is extended to rotate the main tower column forward. In the second forward rotation step, the main tower base is fixed to the existing girder, the pin connection between the main tower column and the sub-jack is released, and the main jack is extended to rotate the main tower column forward until it assumes a substantially vertical (including vertical) position. In the girder disconnection process, a portion of the target girder is pin-connected to the main tower base and the connection between the target girder and the existing girder is released, in the first rear rotation process, the traction device reels in the traction rope to rotate the target girder backward until it abuts the main tower column, in the second rear rotation process, the main jack is contracted to rotate the target girder and the main tower column backward until they assume a backward-leaning position and the front end of the sub-jack is pin-connected to a portion of the main tower column, in the third rear rotation process, the main tower base is detached from the existing girder and the sub-jack is contracted to rotate the target girder and the main tower column backward until they assume a substantially horizontal position (including horizontal), and in the transportation process, the mobile body with the target girder loaded on it moves rearward over the existing girder.

[0015] The girder dismantling method of the present invention can also be a method of arranging the beam material of the connector perpendicular to the axis of the existing girder and fixing the beam material to the existing girder.

[0016] The girder dismantling method of the present invention can also be a method of connecting the target girder to the main tower pillar by fixing a beam abutting the main tower pillar to a part of the main tower pillar. In this case, in the second rear rotation step, the target girder connected to the main tower pillar rotates together with the main tower pillar. [Effects of the Invention]

[0017] The girder rotation device and girder dismantling method of the present invention have the following effects. (1) The target girder can be removed simply by rotating it, making the work safer, easier, and more efficient than with conventional technology. (2) It can be used in a variety of construction methods, such as removing bridge girders to demolish existing bridges, as well as removing hand-stretching machines (construction girders) in launching construction methods. (3) As a result, the construction time required for installing and removing bridge girders is shortened, and construction costs are also reduced accordingly. (4) By using hydraulic clamps to connect the connecting body to the target girder, the main tower base to the existing girder, and the moving body to the existing girder, there is no need to create bolt insertion holes in the target girder or the existing girder, which means that damage to these girders can be prevented. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view schematically showing a girder rotation device according to the present invention. [Figure 2] FIG. 1 is a front view showing a schematic view of the main tower with a portal structure. [Figure 3] FIG. 10 is a plan view seen from above, schematically showing a connecting body having an intermediate pulley and a beam member. [Figure 4] FIG. 10 is a plan view seen from above, schematically showing a connecting body having two intermediate pulleys. [Figure 5] FIG. 1 is a step diagram showing an example of use of the girder rotation device of the present invention, from the movement of the moving body to the first forward rotation of the main tower column body. [Figure 6] FIG. 1 is a step diagram showing an example of use of the girder rotation device of the present invention, from the second forward rotation of the main tower column body to the first backward rotation of the existing girder GE. [Figure 7] FIG. 1 is a step diagram showing an example of use of the girder rotation device of the present invention, from the backward rotation of the integrated target girder and main tower column body to the movement of the moving body on which the target girder is placed. [Figure 8] FIG. 1 is a flow chart showing the flow of the main steps of the girder dismantling method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] An example of the girder rotation device and girder dismantling method of the present invention will be described with reference to the drawings. Although the present invention can be applied to various girder components, for convenience, the following description will be given using the example of a bridge girder.

[0020] 1. Girder rotation device First, we will explain the girder rotation device of the present invention. Note that the girder dismantling method of the present invention is a method of removing a target girder using the girder rotation device of the present invention, so we will first explain the girder rotation device of the present invention, and then explain the girder dismantling method of the present invention.

[0021] FIG. 1 is a side view of a girder rotation device 100 according to the present invention. The present invention can be used to remove a bridge girder (hereinafter referred to as the "target girder GS") connected to the leading end (left side in FIG. 1 ) of an already-installed bridge girder (hereinafter referred to as the "existing girder GE"). For example, when removing an existing bridge, the bridge girder to be removed this time is designated the target girder GS, and the bridge girder to be removed in the future is designated the existing girder GE. That is, the target girders GS are sequentially designated from the leading end of the existing girder GE. On the other hand, when erecting a bridge girder using the launching erection method, the leading hand stretcher (the erected girder) is designated the target girder GS, and the newly installed bridge girder is designated the existing girder GE. For convenience, the axial direction of the bridge girder (existing girder GE or target girder GS) is referred to as the "bridge axis direction." Furthermore, the side of the target girder GS (left side in FIG. 1 ) in the bridge axis direction is designated the "forward" side, and the opposite side (right side in FIG. 1 ) is designated the "rearward" side. Furthermore, the horizontal direction perpendicular to the bridge axis direction will be referred to as the "direction perpendicular to the bridge axis," and the left side facing forward in the direction perpendicular to the bridge axis will be referred to as the "left side," and the opposite side will be referred to as the "right side."

[0022] As shown in Figure 1, the girder rotation device 100 of the present invention includes a moving body 110, a main tower 120, a main jack 131, a sub-jack 132, a traction device 140, and a connecting body 150. Below, each of the main elements constituting the girder rotation device 100 will be explained in detail.

[0023] (Mobile) The mobile body 110 is composed of a main body frame and wheels, tires, crawlers, rollers, etc. attached to the bottom of the main body frame, and is capable of moving in the bridge axial direction. For example, if wheels are attached, it will run on a track laid on the existing girder GE, and if tires or crawlers are attached, it will run on the deck (or on the girder) laid on the existing girder GE. It can also be equipped with a motor or engine to make it self-propelled, or it can be configured to move using an externally installed horizontal jack, winch, etc.

[0024] The mobile body 110 is equipped with a main jack 131, a sub-jack 132, and a traction device 140, and naturally the mobile body 110 moves together with these. The mobile body 110 can also move together with the main tower 120, which is pin-connected to the main jack 131 and the sub-jack 132, or the connecting body 150 attached to the main tower 120, or can move with the target girder GS connected to the main tower 120 mounted thereon, as will be described later.

[0025] (main tower) The main tower 120 is composed of a column-shaped "main tower column body 121" made of H-shaped steel or the like, a "main tower base 122" provided at one end (hereinafter referred to as the "lower end") of the main tower column body 121, and a "main tower pulley 123" attached to the other end (hereinafter referred to as the "upper end") of the main tower column body 121.

[0026] The main tower pedestal 122 is structured so that it can be detachably installed on the existing girder GE using a hydraulic clamp jack or bolts (for example, bolts inserted into bolt holes in the existing joints), and is pin-connected to the main tower column body 121 and also to the target girder GS. For example, a clevis structure can be used to achieve pin-connection by inserting a pin into an insertion hole provided in each of the connecting components (in this case, the main tower column body 121 and the main tower pedestal 122, and the target girder GS and the main tower pedestal 122). This allows the main tower column body 121 and the target girder GS to rotate within a vertical plane in the bridge axis direction. For convenience, forward rotation within a vertical plane in the bridge axis direction will be referred to as "forward rotation" and backward rotation will be referred to as "backward rotation." In other words, the main tower column body 121 and the target girder GS can rotate forward and backward around a part of the main tower pedestal 122 (the pin position) as the center.

[0027] The main tower pulley 123 can be a conventional pulley and is attached to the side of the main tower 120. This allows the main tower pulley 123 to rotate within a vertical plane in the bridge axis direction.

[0028] The main tower 120 can be a structure consisting of a single main tower pillar 121 placed near the center in the direction perpendicular to the bridge axis, or it can be a so-called portal structure consisting of two main tower pillars 121 as shown in Figure 2. Figure 2 is a schematic diagram showing a portal-type main tower 120, and is a front view seen from the rear to the front. As shown in Figure 2, the portal-type main tower 120 is composed of a left main tower pillar 121L and a right main tower pillar 121R, and horizontal beams 124 placed at their upper ends. The left main tower pillar 121L is provided with a left main tower pedestal 122L and a left tower pulley 123L, and the right main tower pillar 121R is provided with a right main tower pedestal 122R and a right tower pulley 123R.

[0029] (jack) The main jack 131 is positioned forward of the sub-jack 132, and these jacks are installed on the movable body 110. The main jack 131 and the sub-jack 132 can be conventional hydraulic jacks or the like, and their rear ends (hereinafter simply referred to as "rear ends") are attached to the movable body 110 (e.g., the main frame). Therefore, the main jack 131 and the sub-jack 132 are extendable in the bridge axis direction; that is, when the main jack 131 or the sub-jack 132 extends, its front end (hereinafter simply referred to as "front end") moves forward, and when the main jack 131 or the sub-jack 132 contracts, its front end moves rearward. In addition, the rear ends of the main jack 131 and the sub-jack 132 are pin-connected to the movable body 110, so the main jack 131 and the sub-jack 132 can rotate forward and backward around their rear ends. Furthermore, the front end of the main jack 131 is pin-connected to a part of the main tower 120 (particularly, the main tower column body 121). For example, a pin connection can be achieved by inserting a pin into an insertion hole provided in the mutually connected members (in this case, the rear end of the main jack 131 or the sub-jack 132 and a part of the movable body 110), such as by using a clevis structure. Therefore, the main tower 120 can rotate forward when the main jack 131 or the sub-jack 132 extends, and the main tower 120 can rotate backward when the main jack 131 or the sub-jack 132 contracts. Note that one set of main jack 131 and sub-jack 132 can be arranged near the center in the direction perpendicular to the bridge axis, or two or more sets of main jacks 131 and sub-jacks 132 can be arranged at positions spaced apart in the direction perpendicular to the bridge axis.

[0030] (Traction device) The traction device 140 is installed at the rear of the moving body 110 (for example, the main frame) and is capable of winding in and unwinding a traction rope 141 such as a wire rope, and a conventional winch or the like can be used. When the girder rotation device 100 is used, the traction rope 141 unwound from the traction device 140 is reeled in around the main tower pulley 123 as shown in FIG. 1, and is also reeled in around an intermediate pulley 151 of a connecting body 150 (described later), folded back, and its tip is fixed at a fixed point FP above the main tower pillar body 121. Therefore, when the main tower 120 is composed of a single main tower pillar body 121, one traction device 140 is placed near the center in the direction perpendicular to the bridge axis, and when the main tower 120 has a portal structure as shown in FIG. 2, two traction devices 140 are preferably placed at positions spaced apart in the direction perpendicular to the bridge axis (the same positions as the main tower 120).

[0031] (concatenation) The connector 150 is structured so that it can be detachably installed on the target girder GS using a hydraulic clamp jack, bolts, etc., and is configured to include at least an intermediate pulley 151, and can also be configured to include a beam 152 made of H-shaped steel or the like. This intermediate pulley 151 can be a conventional pulley and is installed so that it can rotate in a vertical plane in the bridge axis direction. Figure 3 is a plan view, viewed from above, that schematically shows the connector 150 having the intermediate pulley 151 and the beam 152. As shown in this figure, the intermediate pulley 151 is fixed to approximately the center of the beam 152, and the beam 152 can be detachably installed on the target girder GS with the beam 152 arranged in a direction perpendicular to the axis.

[0032] When the main tower 120 is composed of one main tower pillar body 121, it is preferable to place one intermediate pulley 151 near the center in the direction perpendicular to the bridge axis, as shown in Figure 3. On the other hand, when the main tower 120 has a portal structure as shown in Figure 2, it is preferable to place two intermediate pulleys 151 at positions separated in the direction perpendicular to the bridge axis (the same positions as the main tower 120), as shown in Figure 4. Figure 4 is a plan view seen from above that schematically shows a connecting body 150 having two intermediate pulleys 151, with a left intermediate pulley 151L fixed to the left side of the beam 152 and a right intermediate pulley 151R fixed to its right side.

[0033] As described above, when using a portal-type main tower 120, it is advisable to place the left intermediate pulley 151L on the left side of the target girder GS and the right intermediate pulley 151R on its right side, and to install the left traction device 140L on the left side of the moving body 110 and the right traction device 140R on its right side. When the girder rotation device 100 is in use, the left traction rope 141L unwound from the left traction device 140L is reeled around the left tower pulley 123L, reeled around the left intermediate pulley 151L and folded back, and its tip is fixed at a fixed point FP of the left main tower column body 121L. Similarly, the right traction rope 141R unwound from the right traction device 140R is reeled around the right tower pulley 123R, reeled around the right intermediate pulley 151R and folded back, and its tip is fixed at a fixed point FP of the right main tower column body 121R. Therefore, it is advisable to arrange the left traction device 140L, left main tower column 121L (left tower pulley 123L), and left intermediate pulley 151L so that they are aligned in the bridge axis direction (i.e., so that the left traction rope 141L is straight), and the right traction device 140R, right main tower column 121R (right tower pulley 123R), and right intermediate pulley 151R so that they are aligned in the bridge axis direction (i.e., so that the right traction rope 141R is straight).

[0034] (Example of use) An example of using the girder rotation device 100 described above will be described with reference to FIGS. 5 to 7. First, as shown in FIG. 5(a), the moving body 110 travels on the existing girder GE from rear to front (i.e., in the bridge axis direction). At this time, the front ends of the sub-jacks 132 are pin-connected (e.g., pin-connected using a clevis structure) to the main tower 120 (particularly, the main tower column 121) that is tilted backward, and the connecting body 150 is attached to the main tower 120, i.e., the girder rotation device 100 is then traveled as a single unit. When the connecting body 150 moves to its installation location, the moving body 110 (i.e., the girder rotation device 100) is stopped. Then, the connecting body 150 (particularly, the beam member 152) is detachably installed on the target girder GS using a hydraulic clamp jack or the like. At this time, the forward-most existing girder GE and the target girder GS are naturally connected by a splice plate or the like.

[0035] After the connecting body 150 is installed on the target girder GS, the movable body 110 is moved slightly rearward as shown in FIG. 5(b), and then detachably installed on the existing girder GE using a hydraulic clamp jack or the like. At this time, it is preferable to install the movable body 110 on the existing girder GE adjacent to the existing girder GE (i.e., the foremost existing girder GE). In addition, the traction rope 141 unwound from the traction device 140 is reeled around the main tower pulley 123, and is also reeled around the intermediate pulley 151 of the connecting body 150, folded back, and its tip is fixed to the fixed point FP of the main tower column body 121. Note that this series of reeling operations of the traction rope 141 can also be performed in advance before the movable body 110 travels. Furthermore, if the main tower 120 and the sub-jack 132 are not pin-connected when the movable body 110 travels, the front end of the sub-jack 132 is pin-connected to the main tower 120 (particularly the main tower column body 121).

[0036] Once all the preparations up to this point are complete, first the sub-jack 132 is extended as shown in Figure 5(c) to rotate the main tower pillar body 121 forward. At this time, since the traction rope 141 is slightly stretched (slackened) as the sub-jack 132 is extended, an operation may be performed to wind up the traction rope 141 by the amount of extension using the pulling device 140. As a result, the main tower pillar body 121 that has fallen backward is raised up higher than it was initially. For convenience, the forward rotation of the main tower pillar body 121 due to the extension of the sub-jack 132 is referred to as the "first forward rotation" here.

[0037] When the first forward rotation of the main tower column body 121 by the sub-jack 132 is completed, the main tower base 122 is detachably installed on the existing girder GE using a hydraulic clamp jack or bolts (for example, bolts inserted into bolt holes of the existing joint), and the pin connection between the main tower 120 and the sub-jack 132 is released, and then the main jack 131 is extended. At this time, since the traction rope 141 is slightly stretched (slackened) as the main jack 131 is extended, an operation may be performed to reel in the traction rope 141 by the amount of stretch using the pulling device 140. As a result, the main tower column body 121 further rotates forward, and becomes approximately vertical (including vertical) as shown in Figure 6(d). Note that the forward rotation until the main tower column body 121 becomes approximately vertical after the first forward rotation is referred to here as the "second forward rotation" for convenience.

[0038] When the second forward rotation of the main tower column body 121 by the main jack 131 is completed, the extension of the main jack 131 is stopped, and a part of the rear of the target girder GS (hereinafter referred to as the "locking body LP") is pin-connected to the main tower base 122 so that the target girder GS rotates backward. For example, a clevis structure can be used to achieve the pin connection by inserting a pin into an insertion hole provided in each of the connecting components (in this case, the locking body LP and the main tower base 122). In addition, the connection between the foremost existing girder GE and the target girder GS is released. For example, as shown in Figure 6(d), if the existing girder GE and the target girder GS are connected by a splice plate BS, the connection can be released by removing the bolt securing the splice plate BS.

[0039] When the connection between the existing girder GE and the target girder GS is released, the traction rope 141 is reeled in by the traction device 140, as shown in Figure 6(e). Because the locking body LP of the target girder GS is pin-connected to the main tower base 122 and the connection between the existing girder GE and the target girder GS has been released, the target girder GS rotates backward. At this time, because the main tower column body 121 is supported by the main jack 131, the main tower column body 121 maintains an approximately vertical state without rotating backward. When the traction rope 141 is further reeled in by the traction device 140, the target girder GS abuts against the main tower column body 121, as shown in Figure 6(f), that is, the target girder GS also becomes approximately vertical (including vertical). For convenience, the backward rotation until the target girder GS becomes approximately vertical is referred to here as the "first backward rotation." Then, the beam material 152 is fixed to the main tower column body 121 to form the fixed part CP shown in FIG. 6(f), that is, the target girder GS and the main tower column body 121 are integrated.

[0040] When the beam 152 is fixed to the main tower column body 121, the main jack 131 is contracted. As a result, the target girder GS and the main tower 120, which are integrated, rotate backward as shown in Figure 7(g). At this time, the traction rope 141 stretches (slackens) slightly as the main jack 131 contracts, so an operation may be performed to reel in the traction rope 141 by the amount of stretching using the pulling device 140. Meanwhile, the sub-jack 132 is extended forward in advance, so to speak, to meet the main tower 120. Then, when the main tower column body 121 rotates backward until it comes into contact with the front end of the extended sub-jack 132, the contraction operation of the main jack 131 is stopped, and the front end of the sub-jack 132 is pin-connected to the main tower 120 (particularly the main tower column body 121). For convenience, the backward rotation until the main tower column body 121 comes into contact with the front end of the sub-jack 132 is referred to as the "second backward rotation."

[0041] When the second backward rotation of the target girder GS and the main tower 120 by the main jack 131 is completed, the main tower base 122 is removed from the existing girder GE, and then only the sub-jack 132 is retracted as shown in Figure 7(h) (the main jack 131 does not extend or retract). As a result, the target girder GS and the main tower 120 rotate backward around the front end of the main jack 131. That is, in the second backward rotation, the main tower column body 121 rotates around the main tower base 122, and in the third backward rotation, the main tower column body 121 rotates around the front end of the main jack 131. At this time, as the sub-jack 132 retracts, the traction rope 141 stretches (slackens) slightly, and therefore, an operation may be performed to retract the traction rope 141 by the amount of stretch using the pulling device 140. Then, when the target girder GS and the main tower 120 (particularly the main tower column body 121) reach a substantially horizontal (including horizontal) position as shown in Figure 7(i), contraction of the sub-jack 132 is stopped. For convenience, the backward rotation until the target girder GS and the main tower 120 reach a substantially horizontal position is referred to here as the "third backward rotation."

[0042] When the third backward rotation of the target girder GS and the main tower 120 by the sub-jack 132 is completed, the moving body 110 (i.e., the girder rotation device 100) carrying the target girder GS travels on the existing girder GE from front to rear (i.e., in the bridge axis direction). Then, when it reaches a predetermined position, the target girder GS is lowered from the moving body 110. When the existing bridge is to be removed, the moving body 110 moves forward again and removes a new target girder GS by performing the above-mentioned series of operations.

[0043] 2. Girder dismantling method Next, the girder dismantling method of the present invention will be described with reference to Figure 8. The girder dismantling method of the present invention is a method of removing the target girder GS using the girder rotation device 100 described up to this point. Therefore, we will avoid any explanation that overlaps with the content explained about the girder rotation device 100, and will only explain the content unique to the girder dismantling method of the present invention. In other words, the content not described here is the same as that explained in "1. Girder Rotation Device."

[0044] To carry out the girder dismantling method of the present invention, first, a moving body 110 (girder rotation device 100) travels on the existing girder GE from rear to front (in the bridge axis direction) as shown in Fig. 8 (Step 10 in Fig. 8). When the moving body 110 moves to a predetermined position, a connecting body 150 (beam material 152) is installed on the target girder GS connected to the foremost existing girder GE (Step 20 in Fig. 8).

[0045] Once the connector 150 is installed on the target girder GS, the sub-jack 132 connected with a pin to the main tower 120 (main tower column body 121) is extended to perform the first forward rotation (Step 30 in Figure 8). Once the first forward rotation is complete, the main tower base 122 is installed on the existing girder GE, the pin connection between the main tower 120 and the sub-jack 132 is released, and the main jack 131 is extended to perform the second forward rotation (Step 40 in Figure 8).

[0046] When the second forward rotation is completed, the locking body LP of the target girder GS is pinned to the main tower base 122, and the connection between the foremost existing girder GE and the target girder GS is released (Step 50 in Figure 8). Then, the traction device 140 performs the first backward rotation while winding up the traction rope 141 (Step 60 in Figure 8).

[0047] Once the first rearward rotation is complete, the beam 152 is fixed to the main tower column 121, and the second rearward rotation is performed while the main jack 131 is contracted (Step 70 in Figure 8). Once the second rearward rotation is complete, the front end of the sub-jack 132 is pin-connected to the main tower 120 (main tower column 121), and the main tower base 122 is removed from the existing girder GE. Then, the third rearward rotation is performed while the sub-jack 132 is contracted (Step 80 in Figure 8).

[0048] Once the third backward rotation is complete, the moving body 110 (girder rotation device 100) carrying the target girder GS travels from front to rear (in the bridge axis direction) on the existing girder GE (Step 90 in Figure 8). Then, when it reaches a predetermined position, the target girder GS is lowered from the moving body 110. When the existing bridge is to be removed, the moving body 110 moves forward again, and a new target girder GS is removed by performing the above-mentioned series of steps. [Industrial Applicability]

[0049] The girder rotation device and girder dismantling method of the present invention can be used for bridges of all types, such as road bridges and railway bridges, and can also be used for bridges that cross various types of structures, such as river bridges, overpass bridges, and railway bridges. Considering that the present invention provides a safer working environment for workers, it can be said that the present invention is not only applicable industrially but also has the potential to make a significant contribution to society. [Explanation of symbols]

[0050] 100 Beam rotation device of the present invention 110 (Girder Rotation Device) Moving Body 120 Main tower (of the girder rotation device) 121 (Main Tower) Main Tower Column 121L Left main tower column 121R Right main tower column 122 (Main Tower) Main Tower Base 122L (main tower) left main tower pedestal 122R (main tower) right main tower pedestal 123 (Main Tower) Tower Pulley 123L (Main Tower) Left Tower Pulley 123R (Main Tower) Right Tower Pulley 124 (Main tower) horizontal beam 131 Main jack (for girder rotation device) 132 Sub-jack (for girder rotation device) 140 Traction device (for girder rotation device) 140L Left traction device (for spar rotation device) 140R Right traction device (for spar rotation device) 141 (towing device) tow rope 141L Left tow rope (left towing device) 141R Right tow rope (right towing device) 150 (Girder Rotation Device) Connector 151 (Connector) Intermediate pulley 151L (Connector) Left intermediate pulley 151R Right intermediate pulley (connector) 152 (Connector) Beam BS attachment plate CP fixed part FP fixed point GE Existing Girder GS target digit LP body lock

Claims

1. A device for rotating a target girder connected to an existing girder, A movable body that can move on the existing girder in the bridge axial direction; a main tower having a main tower column, a main tower base provided at the lower end of the main tower column, and a main tower pulley attached to the upper end of the main tower column; a main jack whose rear end is pin-connected to the movable body and whose front end is pin-connected to a part of the main tower column body and is extendable toward the front end; a sub-jack whose rear end is connected to the movable body by a pin and which is extendable toward its front end; a traction device that is installed on the moving body and that is capable of winding and unwinding a traction rope; A connector that can be attached to the target girder and has an intermediate pulley; The main tower column is pin-connected to the main tower base, When the front end of the sub-jack is pin-connected to a part of the main tower pillar, the main tower pillar rotates as the sub-jack extends and retracts, In addition, when the main tower base is fixed to the existing girder, the main jack extends, causing the main tower column to rotate forward around a part of the main tower base, Furthermore, the main tower base is fixed to the existing girder, the connector is installed on the target girder, and a part of the target girder that has been released from the connection with the existing girder is pin-connected to the main tower base, the traction rope is looped around the main tower pulley and then around the intermediate pulley, and the tip of the traction rope is fixed to a part of the main tower column body, and the traction device winds up the traction rope, causing the target girder to rotate backward around a part of the main tower base. A girder rotation device characterized by:

2. The main tower is configured to include a left main tower column and a right main tower column arranged apart in a direction perpendicular to the axis of the existing girder, The intermediate pulley of the connecting body includes a left intermediate pulley and a right intermediate pulley arranged apart in the axis perpendicular direction of the target girder, The moving body is provided with a left traction device and a right traction device that are arranged apart in a direction perpendicular to the axis of the existing girder, The traction rope of the left traction device is wound around the main tower pulley of the left main tower pillar body and then wound around the left intermediate pulley, and further, a tip of the traction rope is fixed to a part of the left main tower pillar body, The traction rope of the right traction device is reeled around the main tower pulley of the right main tower pillar and then reeled around the right intermediate pulley, and further, the tip of the traction rope is fixed to a part of the right main tower pillar.

2. The girder rotation device according to claim 1.

3. A method for removing the target girder connected to the front of the existing girder using the girder rotation device according to claim 1 or 2, a moving process in which the front ends of the main jack and the sub-jack are pin-connected to a part of the main tower column body in a state of being tilted backward, and the moving body moves from the rear to the front on the existing girder; a connector installation process in which the connector is installed on the target girder in a state connected to the existing girder; a forward first rotation step of rotating the main tower pillar body forward by extending the sub-jack; a forward second rotation process in which the main tower pedestal is fixed to the existing girder, the pin connection between the main tower column and the sub-jack is released, and the main jack is then extended to rotate the main tower column forward until it assumes a vertical or approximately vertical position; a girder disconnection process in which a part of the target girder is pin-connected to the main tower base and the connection between the target girder and the existing girder is released; a first backward rotation step in which the traction device reels in the traction rope to rotate the target girder backward until the target girder abuts against the main tower pillar; a second rearward rotation process in which the target girder and the main tower pillar are rotated rearward by contracting the main jack until they assume a rearward tilted posture, and the front end of the sub-jack is pin-connected to a part of the main tower pillar; a third rearward rotation process in which the main tower base is removed from the existing girder and the target girder and the main tower column body are rotated rearward by contracting the sub-jack until they assume a horizontal or approximately horizontal position; and a transporting process in which the moving body moves on the existing girder from the front to the rear with the target girder placed thereon. A girder dismantling method characterized by the above.

4. The connecting body is composed of a beam and the intermediate pulley attached to the beam, In the connector installation step, the beam material arranged in the axis perpendicular direction of the existing girder is fixed to the existing girder. The girder dismantling method according to claim 3.

5. In the first rearward rotation process, the beam member abutting against the main tower pillar is fixed to a part of the main tower pillar, thereby connecting the target girder to the main tower pillar, In the second rearward rotation process, the target girder connected to the main tower pillar rotates together with the main tower pillar. The girder dismantling method according to claim 4.

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