JP4424744B2 - Bridge replacement method - Google Patents

Description

    The present invention relates to a bridge replacement method for replacing an existing bridge composed of an existing pier and an existing bridge girder with a new bridge composed of a new pier and a new bridge girder.

    Conventionally, in railways and roads, a bridge replacement work for replacing an existing bridge (referred to as “existing bridge” in this specification) with a new bridge (referred to as “new bridge” in this specification). Therefore, various construction methods have been proposed (for example, see Patent Document 1).

    Hereinafter, an example of a conventional bridge replacement method in a railway will be described with reference to FIGS. 6 and 7. Here, FIG. 6A is a cross-sectional view showing a state in which the temporary bridge 121 is constructed so as to support the existing bridge 101, and FIG. 6B shows that the vertical bridge 103a is formed in the existing bridge girder 103. It is sectional drawing which shows a state, The figure (c) is sectional drawing which shows the state which has arrange | positioned 2nd upper bridge pier 125 grade | etc., So that the sleeper 104 may be supported. FIG. 7A is a cross-sectional view showing the existing bridge 101 to be removed with diagonal lines, and FIG. 7B is a cross-sectional view showing a state where the existing bridge 101 is removed. (c) is sectional drawing which shows the state which constructed the new bridge 111. FIG.

    Reference numeral 101 in FIG. 6A indicates an existing bridge composed of an existing bridge pier 102 and an existing bridge girder 103. Reference numeral 104 denotes a sleeper, reference numeral 105 denotes a rail, and reference numeral 106 denotes a railroad vehicle limit. Further, reference numeral 121 denotes a temporary bridge constructed only during the construction period. The portion denoted by reference numeral 122 is referred to as a lower pier, the portion denoted by reference numeral 124 is referred to as a first upper pier, and the portion denoted by reference numeral 123 is referred to as a temporary bridge girder. In the stage shown in this figure, the first upper pier 124 is in a state of supporting the existing bridge girder 103.

    Next, as shown in FIG. 6 (b), a vertical hole 103 a is formed in the existing bridge girder 103 so as to coincide with the end of each sleeper 104. Then, as shown in FIG. 6 (c), an I-shaped construction girder 130 is arranged so as to sandwich both ends of each sleeper 104, and the vertical girder between each construction girder 130 and the temporary bridge girder 123 is arranged vertically. Two upper piers 125 are arranged respectively. In this state, the second upper pier 125, the temporary bridge girder 123, and the lower pier 122 constitute a bridge girder (temporary bridge girder) for supporting the rail 105 and the sleepers 104. Since the existing bridge 101 (shaded portion in FIG. 7A) and the first upper pier 124 are not necessary, they are removed (see FIGS. 7A and 7B).

Next, a new bridge 111 is constructed as shown in FIG. The temporary bridge 121 is then removed.
JP 2002-97608 A

    However, in the conventional construction method described above, the existing bridge girder 103 is sequentially dismantled at the installation location, and on the other hand, a temporary bridge girder for securing the operation of the train is constructed. There was a problem that the train operation had to be interrupted, which caused a considerable hindrance to train operation.

    In general, when the operation of trains and vehicles is suspended (especially in the case of trains), various operations (for example, operations for confirming the safety of train operations) are performed when operations are suspended or resumed. I need. In the case of the conventional method described above, the dismantling work of the existing bridge girder and the construction work of the temporary bridge girder (the work of drilling the vertical hole 103a in the existing bridge girder 103 as shown in FIG. There is a problem that the operation is complicated because the operation must be repeatedly stopped and resumed for the operation and the installation work of the second upper pier 125).

    An object of the present invention is to provide a bridge replacement method that shortens the period during which a train or the like is suspended, and reduces the number of operation suspensions to prevent complication of work.

The invention according to claim 1 includes an existing bridge (see reference numeral 1 in the figure) composed of an existing pier (see reference numeral 2 in FIGS. 1A and 1B) and an existing bridge girder (see reference numeral 3 in the figure). In the bridge replacement method for replacing a new bridge (see reference numeral 11 in the figure) composed of a new pier (see reference numeral 12 in FIG. 5 (a)) and a new bridge girder (see reference numeral 13 in the figure),
A process of constructing a temporary pier (22) in the vicinity of each existing pier (2) (see FIGS. 1 (a) (b) (c));
A step of supporting the existing bridge girder (3) on the constructed temporary pier (22) (see FIG. 1 (b));
Cutting the existing pier (2) below (Z ₂ ) below the portion (Z ₁ ) supported by the temporary pier (22) (see FIGS. 2 (a) and (b));
Removing the existing pier (2) below the cut portion (Z ₂ ) (see FIGS. 3 (a) (b));
A step of constructing a new pier (12) in the space (S) below the existing bridge girder (3) (see FIGS. 4 (a) and (b));
A step (see FIGS. 5A and 5B) of extending and arranging a horizontal guide device (30) so as to pass through the space (S) below the existing bridge girder (3) in the bridge width direction (Y);
A step of removal by moving integrally (see reference symbol A ₁ in FIG. 5 (b)) in the form of the supported by the existing bridge beam (3) for the transverse-up guide device (30),
The new bridge beam (13), and the step of installing above the pre-emption guide device (30) in the moved in supporting form new pier (12) (reference symbol A ₂ in FIG. 5 (b)),
It is characterized by having.

In the invention according to claim 2, as illustrated in FIG. 1 (c), in the invention according to claim 1, at least two temporary piers (22) are provided along the bridge width direction (Y) (for example, 22a, 22b), arranged with a separation distance (ΔY ₂ ) wider than the maximum width (ΔY ₁ ) where the existing pier (2) is installed,
The intermediate frame (40) is bridged between these two temporary piers (for example, 22a and 22b)
The intermediate bridge (40) supports the existing bridge girder (3).

    The invention according to claim 3 is the invention according to claim 2, wherein a plurality of the temporary piers (22) are arranged along the longitudinal direction (X) of the bridge (for example, 22a, 22c, 22e, 22g), and these The intermediate frame (40) is bridged over a plurality of temporary piers (for example, 22a, 22c, 22e, 22g).

    According to a fourth aspect of the invention, in the invention of the second or third aspect, as illustrated in FIG. 5 (b), the movement for removing the existing bridge girder (3) is performed by the intermediate frame (40). Is performed in a state of being connected to the existing bridge girder (3).

    The numbers in parentheses are for the sake of convenience indicating the corresponding elements in the drawings, and therefore the present description is not limited to the descriptions on the drawings.

    According to the first aspect of the present invention, it is possible to proceed with the work without stopping the passage of the train or the vehicle until immediately before the removal work of the existing bridge girder is started. Although it is necessary to stop the passage of trains and vehicles from the start of the removal work of the existing bridge girder to the completion of the installation work of the new bridge girder, the time required to stop the passage may be shorter than in the case of the conventional construction method It is possible to reduce obstacles to the operation of trains and the like. By the way, generally, when stopping a train operation, various operations (for example, a task for confirming the safety of the train operation) are required when the operation is stopped or resumed. In the case of a conventional construction method in which existing bridge girders in the installed state are dismantled sequentially, it is necessary to repeatedly stop and resume train operation, so the work becomes complicated. According to this, dismantling of the existing bridge girder can be done in another place (place other than the place where the bridge is installed) after removal, so the number of times that the train operation is suspended can be reduced, and the work complexity can be reduced accordingly. .

    According to the invention according to claim 2, in the state where the existing pier is cut, the portion above the pier cutting portion (particularly, the existing bridge girder) is reinforced by the intermediate frame. It is possible to pass the vehicle safely. In addition, by adopting an intermediate frame, two temporary piers can be arranged to take a wider distance than the maximum width at which the existing pier is installed, so that the removal work of the existing pier under the existing bridge girder, Sufficient space for installing the new pier can be secured. At the same time, the intermediate frame and the existing bridge girder can be stably supported by the wide span temporary bridge pier.

    According to the invention of claim 3, the intermediate frame is supported by a plurality of temporary piers arranged along the bridge width direction and a plurality of temporary piers arranged along the longitudinal direction of the bridge; Therefore, a solid support structure can be constituted by the plurality of temporary bridge piers and the intermediate frame, and the existing bridge girder can be supported more stably.

    According to the invention which concerns on Claim 4, since the movement for removal of the said existing bridge girder is performed in the state which connected the said intermediate frame to this existing bridge girder, it will be in the state by which the existing bridge girder was reinforced by the intermediate frame. Therefore, even a bridge girder that is long in the longitudinal direction of the bridge can be removed stably. And since a long bridge girder can be removed at once, compared with the case where it removes in multiple steps, removal work time can be shortened and the time which stops the passage of a train and vehicles can also be shortened.

    Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS. 1 to 5.

1 (a) is a front view showing an example of a state of arranging the temporary piers and the intermediate frame in the vicinity of the existing bridges, Fig (b) is its B ₁ arrow view, FIG. (C ) Is a cross-sectional view taken along the line CC of FIG. 2 (a) is a front view showing an example of such disconnection point of the existing piers 2, FIG. (B) is a B ₂ arrow view. 3 (a) is a front view showing an example of a state after cutting of the existing piers, FIG (b) is a B ₃ arrow view. 4 (a) is a front view showing an example of a state in which to build a new bridge pier 12, FIG. (B) is a B ₄ arrow view. 5 (a) is a front view showing an example of how to install the new bridge girder, FIG. (B) is a B ₅ arrow view.

    In the present specification, a direction in which vehicles and trains pass through a bridge (X direction in the drawing) is referred to as a “bridge longitudinal direction”, and a horizontal direction (Y direction in the drawing) perpendicular to the direction is referred to as a “bridge width direction”. Shall.

The bridge replacement method according to the present invention is based on the existing bridge 1 (see FIG. 1 (b)) including the existing pier 2 and the existing bridge girder 3, and the new bridge 11 (see FIG. It is a construction method to replace (a)
(1) a step of constructing a temporary pier 22 in the vicinity of each existing pier 2 (see FIGS. 1 (a) (b) (c));
(2) supporting the existing bridge girder 3 on the constructed temporary pier 22 (see FIG. 1 (b));
(3) a step of cutting the existing pier 2 at a lower Z ₂ than the portion Z ₁ supported by the temporary pier 22 (see FIGS. 2A and 2B);
And (4) the cut portions Z ₂ the step of removing the existing piers second lower (FIG. 3 (a) (b) see)
(5) constructing a new pier 12 in the space below the existing bridge girder 3 (see S in FIG. 3B) (see FIGS. 4A and 4B);
(6) a step (see FIGS. 5A and 5B) of extending and arranging the side guide device 30 so as to pass through the space S below the existing bridge girder 3 in the bridge width direction Y;
And (7) the existing bridge girder 3 the step of removal by moving integrally with the form of being supported by the pre-emption guide device 30 (see reference numeral A ₁ in FIG. 5 (b)),
And (8) the new bridge girder 13 a step of installing the move by the support and form in intercepted guide device 30 above the new pier 12 (reference numeral A ₂ in FIG. 5 (b)),
Consists of. (1) Construction of temporary pier 22, (2) Support of existing bridge girder 3, (3) Cutting of existing pier 2, (4) Removal of existing pier 2, (5) Construction of new pier 12, (7) The removal of the existing bridge girder 3 and (8) installation of the new bridge girder 13 should be carried out in that order. (6) Installation of the side guide device 30 may be carried out by (7) removal of the existing bridge girder 3, but if the side guide device 30 is installed at an early stage, it may interfere with other operations. Therefore, from the viewpoint of work efficiency, the pre-installation guide device 30 is not installed until the construction of the temporary pier 22, the cutting and removal of the existing pier 2 and the construction of the new pier 12 are completed. Is preferred.

    According to the construction method according to the present invention, the existing bridge girder 3 can be moved and removed as a whole, so there is no need to dismantle it at the installation location and remove it as in the conventional construction method, and the removal work time is shortened. It is also possible to shorten the time required to stop the operation of the train and the like. In addition, unlike the conventional method, it is not necessary to construct a temporary bridge girder for securing operation of a train or the like, and it is possible to avoid the suspension of a train or the like accompanying the construction of a temporary bridge girder. In other words, until the start of the removal work of the existing bridge girder 3, the work (the construction work of the temporary pier 22, the cutting work and the removal work of the existing pier 2, and the new pier 12 are not required without stopping the passage of trains and vehicles). Therefore, it is possible to reduce troubles in the operation of trains and the like. Furthermore, when dismantling existing bridge girders or constructing temporary bridge girders at the place where the bridge is installed as in the conventional construction method, it is necessary to repeatedly stop and restart the operation of the train etc. However, in the case of the present invention, the dismantling of the existing bridge girder can be performed in another place after the bridge girder is removed, and there is no need to construct a temporary bridge girder. The number of times that the operation of the train or the like is stopped can be reduced, and the complication of the work can be reduced accordingly.

By the way, as a method of supporting the existing bridge girder 3 by the temporary bridge pier 22, as shown in FIG. 1 (b), an intermediate frame 40 constructed from on-site reinforced concrete is interposed between them, and the frame There is a method of supporting the existing bridge girder 3 through 40. For example, the intermediate frame 40 may be connected to the temporary pier 22 and the existing pier 2 (preferably, the upper end portion 2a of the existing pier 2). When using such an intermediate frame 40, in the state where the cut existing piers 2, from above the portion pier cuts Z ₂ (in particular, the existing bridge beam 3) Because the state of being reinforced by the intermediate frame 40 (That is, since the existing bridge girder 3 that originally has strength is in a state of being further reinforced), it is possible to safely pass trains and vehicles even after the pier is cut.

Note that at least two temporary piers 22 are preferably arranged along the bridge width direction Y (for example, two temporary piers denoted by reference numerals 22a and 22b in FIG. 1 (c), or denoted by reference numerals 22c and 22d. The two temporary piers, or two temporary piers labeled 22e and 22f, or two temporary piers labeled 22g and 22h). And these two temporary bridge piers (for example, 22a, 22b) have the maximum width in which the existing pier 2 is installed (the existing pier 2 is in the bridge width direction Y as shown in FIGS. 1B and 1C). 2, the distance between the outer surface of one existing pier 2 and the outer surface of the other existing pier 2, as shown by reference sign ΔY ₁ , for example, in FIG. As indicated by reference numeral 12, when only one is arranged instead of _two , the distance is larger than the distance between the two outer surfaces (as indicated by reference numeral ΔY2). And the intermediate frame 40 is bridged between the two temporary bridge piers (for example, 22a and 22b), and the existing bridge girder 3 is supported by the intermediate frame 40. Good. In order to support the intermediate frame 40 on such a temporary pier, the intermediate frame 40 extends in the bridge width direction Y longer than the separation distance ΔY _{2 of the} temporary pier as indicated by reference numeral 40Y in FIG. It is necessary to have a part provided. As described above, when the separation distance ΔY ₂ of the temporary pier is wider than the maximum width ΔY ₁ , the space for removing the existing pier 2 and installing the new pier 12 below the existing bridge girder 3. Can be ensured sufficiently (see symbol S in FIG. 1B). Further, it is possible to stably supported by temporary piers wide intermediate frame 40 and the existing bridge girder 3 Span (reference [Delta] Y ₃ in FIG. 1 (c)). In the example of FIG. 1 (c), two temporary piers arranged along the bridge width direction Y are arranged along the longitudinal direction X of the bridge, and these eight temporary piers 22a, One intermediate frame 40 is laid over each of the two temporary piers (for example, two temporary piers with reference numerals 22a and 22b, or two temporary piers with reference numerals 22c and 22d). Alternatively, separate intermediate frames may be bridged over two temporary piers labeled 22e and 22f, or two temporary piers labeled 22g and 22h.

    As illustrated by reference numerals 22a, 22c, 22e, and 22g and reference numerals 22b, 22d, 22f, and 22h in FIG. 1C, not only along the bridge width direction Y but also along the bridge longitudinal direction X. A plurality of temporary piers may be arranged, and the intermediate frame 40 may be bridged over the plurality of temporary piers (for example, 22a, 22c, 22e, 22g). In such a case, a solid support structure can be constituted by the plurality of temporary bridge piers 22 and the intermediate frame 40 which are two-dimensionally arranged, and the existing bridge girder 3 can be supported more stably.

    In such a case, the intermediate frame 40 may have a shape having a hole (for example, as shown in FIG. 1 (c), a cross beam shape having holes other than the portions denoted by reference numerals 40X and 40Y). In that case, the intermediate frame 40 can be reduced in weight while ensuring stable support of the existing bridge girder 3. In addition, it is not the meaning which excludes the flat shape which does not have such a hole part from the scope of the right of this invention. Further, a reinforcing column may be interposed between the intermediate frame 40 and the existing bridge girder 3.

    When the intermediate frame has a cross beam shape as described above, the connection between the intermediate frame 40 and the existing pier 2 may be performed by a known “PC / cross beam fastening method”. In this method, a pair of beam portions in the intermediate frame 40 (in the case of FIG. 1 (c), the beam portions indicated by reference numerals 40x and 40x) are constructed and arranged so as to sandwich each existing bridge pier 2, and the pair of beam portions 40x. , 40x, the PC steel rods 40a,... Are stretched between the beam portions 40x and the contact surfaces of the existing piers 2 to be compressed, and the intermediate frames 40 and the existing piers 2 are caused by the compressive stresses. It is a method to connect with. In addition, you may make it connect the intermediate | middle frame 40 and the existing pier 2 by systems other than this system.

    In FIG. 1 (b), the intermediate frame 40 is connected to the upper part 2a of the existing pier 2 but may be directly connected to the existing bridge girder 3 instead of the existing pier upper part 2a.

In addition, although it is preferable to use the intermediate frame in terms of obtaining various effects as described above, an embodiment in which the intermediate frame is not used, that is,
A method of directly connecting the temporary pier 22 and the existing pier 2 without using an intermediate frame. A method of directly connecting the temporary pier 22 and the existing bridge girder 3 without using an intermediate frame. It is not intended to be excluded from the scope of rights of such invention.

    On the other hand, cutting of the existing pier 2, removal of the existing pier 2, and construction of the new pier 12 may be performed by various known methods.

    By the way, as long as the above-described guide device 30 for pre-emption can move the existing bridge girder 3 and the new bridge girder 13, any structure may be used. As an optimum one, as shown in FIG. 5 (b), a top plate member 31 for sliding the existing bridge girder 3 or the new bridge girder 13, and a number of legs 32 for supporting the top plate member 31; Can be mentioned.

    Since the horizontal guide apparatus 30 is configured to slide the existing bridge girder 3 and the new bridge girder 13, the driving means can apply a driving force to the bridge girders 3 and 13 in the horizontal direction. Such a thing (for example, a jack) may be used (see reference numeral 34 in FIG. 5B), and it is not necessary to suspend or lift the bridge girders 3 and 13 by a crane or the like. Accordingly, various effects can be obtained. Hereinafter, the effect will be described.

    When the bridge girders 3 and 13 are suspended or lifted, a large driving force is required, the driving means is enlarged, and a large installation space is also required. When the bridge girders 3 and 13 are slid as described above, the driving force may be small, the driving means may be small, and the installation space may not be wide. For example, when stainless steel is used for the top plate member 31, and a low friction member (for example, Teflon (registered trademark) processed) 33 is interposed between the top plate member 31 and the bridge girder 3 or 13 The driving force may be about 0.1% of the weight of the towed object. When the bridge girders 3 and 13 are suspended or lifted, a large driving force is required, and the length of the bridge girder that can be moved at one time is also easily limited. However, according to the present invention, the driving force is small. So it ’s hard to get those restrictions.

    By the way, in the example shown in FIG. 5B, when the existing bridge girder 3 is removed, the low friction member 33 is disposed between the lower surface (cut surface) of the existing bridge pier 2a and the top plate member 31, You may arrange | position between intermediate frame 40 'and the top-plate member 31. FIG. In this case, if the low friction members 33 and 33 are arranged as far as possible in the bridge width direction Y, the existing bridge girder 3 can be moved in a stable state.

    The movement for removing the existing bridge girder 3 may be performed in a state where the intermediate frame 40 is connected to the existing bridge girder 3 as illustrated in FIG. In this case, since the existing bridge girder 3 is reinforced by the intermediate frame 40, even the bridge girder 3 that is long in the longitudinal direction of the bridge can be removed stably. And since the long bridge girder 3 can be removed at once, compared with the case where it removes in multiple times, removal work time can be shortened and the time which stops the passage of a train and a vehicle can also be shortened.

    The intermediate frame 40 may be removed from the bridge girder 3 before the existing bridge girder 3 is moved, but it may be necessary to stop the operation of the train or the vehicle during the removal operation. When the removal of the intermediate frame 40 is performed after the existing bridge girder 3 is moved, the time for stopping the passage of the train or the vehicle can be shortened.

    By the way, the existing bridge girder 3 in the present invention must be fixed at a fixed position in a state where it cannot move because it must pass through a train or a vehicle until just before being removed. It is necessary to be able to move along the side guide device 30 as described above. Hereinafter, an example of the construction method will be described in detail.

    The height adjusting jacks 25 are disposed on the upper surfaces of the temporary bridge piers 22 described above, and the above-described cross-girder-shaped intermediate frame 40 is placed on the temporary bridge piers 22 while being lifted by the jacks 25. Keep it like that. In this state, the existing bridge girder 3 is firmly placed on the temporary pier 22 with its own weight (in a state where it cannot move), and a train or the like can be passed. On the other hand, in order to move the existing bridge girder 3 after the sideways guide device 30 is extended and arranged as described above, the existing bridge girder 3 is lifted by the height adjusting jack 25 and the existing bridge pier (portion 2a) is moved. The above-described low friction member 33 is disposed between the lower surface and the top plate member 31 or between the intermediate frame 40 and the top plate member 31, and the existing bridge girder 3 is lowered by operating the height adjusting jack 25. The weight of the bridge girder 3 and the intermediate frame 40 is supported by the guide device 30 by the low friction member 33 and is not supported by the temporary bridge pier 22. Thereafter, the jack (jack for pre-emption) 34 is driven to move the existing bridge girder 3 and the like in the horizontal direction.

    The present invention can be used for a purpose of replacing a railway or a road bridge.

1 (a) is a front view showing an example of a state of arranging the temporary piers and the intermediate frame in the vicinity of the existing bridges, Fig (b) is its B ₁ arrow view, FIG. (C ) Is a cross-sectional view taken along the line CC of FIG. 2 (a) is a front view showing an example of such disconnection point of the existing piers 2, FIG. (B) is a B ₂ arrow view. 3 (a) is a front view showing an example of a state after cutting of the existing piers, FIG (b) is a B ₃ arrow view. 4 (a) is a front view showing an example of a state in which to build a new bridge pier 12, FIG. (B) is a B ₄ arrow view. 5 (a) is a front view showing an example of how to install the new bridge girder, FIG. (B) is a B ₅ arrow view. FIG. 6A is a cross-sectional view showing a state where the temporary bridge 121 is constructed so as to support the existing bridge 101, and FIG. 6B shows a state where the vertical hole 103a is formed in the existing bridge girder 103. FIG. 4C is a cross-sectional view showing a state in which the second upper pier 125 and the like are arranged so as to support the sleepers 104. FIG. 7 (a) is a cross-sectional view showing the existing bridge 101 to be removed with diagonal lines, and FIG. 7 (b) is a cross-sectional view showing the state where the existing bridge 101 is removed. ) Is a cross-sectional view showing a state where the new bridge 111 is constructed.

Explanation of symbols

1 Existing bridge 2 Existing bridge pier 3 Existing bridge girder 11 New bridge 12 New bridge pier 13 New bridge girder 22 Temporary pier 40 Intermediate frame S Space X Bridge longitudinal direction Y Bridge width direction

Claims (4)

In the bridge replacement method to replace an existing bridge consisting of an existing pier and an existing bridge girder with a new bridge consisting of a new pier and a new bridge girder,
Building a temporary pier in the vicinity of each existing pier;
Supporting the existing bridge girder on the constructed temporary pier;
Cutting the existing pier below the portion supported by the temporary pier, and
Removing the existing pier below the cut portion;
Building a new pier in the space below the existing bridge girder;
Extending and arranging a side guide device so as to pass through the space below the existing bridge girder in the bridge width direction;
Removing the existing bridge girder by integrally moving in a form supported by the side guide device;
Moving the new bridge girder in a form supported by the side guide device and installing it above the new bridge pier;
Bridge replacement method characterized by having The temporary piers are arranged at a separation distance wider than the maximum width at which the existing piers are installed, at least two along the bridge width direction,
Intermediate frame between these two temporary piers,
Supporting the existing bridge girder on the intermediate frame;
The bridge replacement method according to claim 1, wherein: A plurality of the temporary piers are arranged along the longitudinal direction of the bridge,
The intermediate frame was bridged over these multiple temporary piers,
The bridge replacement method according to claim 2, wherein: The movement for removing the existing bridge girder is performed with the intermediate frame connected to the existing bridge girder.
The bridge replacement method according to claim 2 or 3, characterized in that

Images