JP2018091093A - Bridge construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bridge construction method of constructing a main girder extended forward in the bridge axial direction by predetermined spans using a girder installed on a main girder under construction, which improves workability of erection.SOLUTION: Upon installing a crane 30 at a predetermined position on a main girder 20, the main girder 20 is moved for one minute forward in the bridge axial direction while the a diagonal member 40 is arranged between the crane 30 and fixing parts 22 in front and behind the main girder 20. Thereby, the crane 30 is used for the purpose of conventional pylon column. Furthermore, after the main girder 20 is moved, the arrangement of the diagonal member 40 is released and then the main girder 14 is extended and installed by using the crane 30. Thus, the crane 30 is used for the original purpose. The crane 30 is used for both the original purpose and the purpose of conventional pylon column, and therefore the movable range when the crane is moved in the bridge axial direction as conventional is prevented from being limited due to the pylon column standing in the way, thereby improving the degree of freedom of the construction work.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for laying a bridge using a girder.

  Conventionally, as described in, for example, “Patent Document 1”, a girder installed on a main girder being constructed is used as a method for erection of a bridge, and the main girder is directed to the front in the direction of the bridge axis. There is a known method of extending the extension every minute.

  In this erection method, in order to prevent an excessive load from being applied to the girder when moving the girder forward in the bridge axis direction, a pillar pillar is installed at a predetermined position of the girder, and diagonal materials are arranged on both sides of the girder. Thus, a device for securing the supporting strength for the girder has been devised.

JP 2004-270235 A

  When extending the main girder, the work of sequentially suspending and supporting each of the plurality of segments constituting the main girder for one span and moving it to the planned construction position is performed. If the above work is performed using a crane that can move on the girder in the direction of the bridge axis, the workability can be improved.

  However, if the fixed pillar pillar is installed in the girder as in the past, when the main girder is extended after the girder is moved, the pillar pillar gets in the way and moves the crane in the direction of the bridge axis. The movable range at the time is limited. For this reason, the freedom degree of construction work will become small and workability of construction cannot be improved.

  The present invention has been made in view of such circumstances, and using a girder installed on the main girder being installed, the main girder is extended by the required span in the bridge axis direction forward. It is an object of the present invention to provide a bridge erection method that can improve the workability of erection.

  This invention pays attention to the point that the crane used for the extension construction of the main girder does not function particularly when the girder is moved, and this crane can be used for both the original use and the conventional use of the pillar pillar. It is intended to achieve.

That is, the bridge erection method according to the present invention is:
In the method of erection of the bridge, the girder installed on the main girder being erected is used to extend the main girder for the required span in the forward direction of the bridge axis.
A first step of installing a crane movable on the girder in a bridge axis direction at a predetermined position of the girder;
After the completion of the first step, a second step of disposing diagonal materials between the crane and fixing portions located on both sides of the crane in the bridge axis direction of the girder,
After the completion of the second step, a third step of moving the girder by the required span toward the front in the bridge axis direction;
After the completion of the third step, a fourth step of canceling the arrangement of the diagonal material;
After completion of the fourth step, including a fifth step of extending the main girder using the crane,
The first to fifth steps are repeatedly performed.

  The “predetermined position of the girder” means that the girder is not subjected to an excessive load when the girder is moved forward in the direction of the bridge axis by disposing the diagonal material between the crane and the two fixing portions before and after the girder. The specific position is not particularly limited as long as the position can be adjusted.

  When “installing a crane” at a predetermined position of the girder, it is not always necessary to fix the crane to the girder.

  There is no particular limitation on the specific construction method in the above-mentioned case of “extending the main girder for the required span in the forward direction in the bridge axis direction”.

  The “required span portion” may be one span portion or a plurality of span portions.

  The construction area of the “required span” is not particularly limited. For example, when the “required span” is one span, the entire span of a single span may be used. A region straddling between two diameters adjacent in the bridge axis direction may be used.

  In the present invention, a crane is installed at a predetermined position of the girder, and the girder is directed forward in the direction of the bridge axis in a state in which diagonal members are disposed between the crane and the two fixing portions before and after the girder. Since it is made to move for a while, a crane can be used as a use of the conventional pyrone pillar.

  Further, in the present invention, after the girder is moved, the arrangement of the diagonal members is released and the crane is used to extend the main girder. Therefore, the crane can be used for its original use.

  In other words, in the present invention, the crane is used for both the original use and the conventional use of the pillar pillar, so when the crane pillar is moved in the direction of the bridge axis because the pillar pillar is obstructive as in the past. It is possible to prevent the movable range from being limited. For this reason, the freedom degree of construction work can be enlarged and, thereby, the workability of construction can be improved.

  As described above, according to the present invention, in the bridge erection method, the girder installed on the main girder being erected is used to extend the main girder forward by a required span in the bridge axis direction front. Workability can be improved.

  Further, as in the present invention, the crane can be used for both the original use and the conventional use of the pillar pillar, so that the installation equipment can be simplified, thereby reducing the installation cost.

  In the present invention, if the sub-crane is installed on the upper part of the crane and the diagonal member is lifted by the sub-crane in the second step, and the diagonal member is suspended by the sub-crane in the fourth step, the diagonal member is arranged. And it can be easily released.

  In the present invention, a second crane that can move in the bridge axis direction on the girder is installed at a position rearward of the girder in the bridge axis direction, and the main girder is used in combination with the crane and the second crane. If the extension construction is performed, the workability of the construction can be further improved.

  At that time, if the extension construction of the main girder using the crane and the extension construction of the main girder using the second crane are performed in parallel between the two adjacent diameters in the bridge axis direction, The main girder can be extended efficiently.

  In the case where the second crane is used, the second diagonal member is disposed between the second crane and the two second fixing portions before and after the second crane in the second step, and the second diagonal member is disposed in the fourth step. If the arrangement of the material is released, the second crane can also be used for both the original use and the use of the conventional pyrone column. This makes it easier to prevent an excessive load from being applied to the girder when the girder is moved forward in the bridge axis direction. In addition, it is possible to reduce the size of the crane, thereby further simplifying the installation equipment.

The side view which shows the outline | summary of the construction method of the bridge which concerns on one Embodiment of this invention II-II direction arrow view of FIG. Detailed view of part III in Fig. 1 The figure which shows the 1st and 2nd process of the said erection method The figure which shows the 3rd process of the said erection method The figure which shows the 4th and 5th process of the said erection method The same figure as FIG. 1 which shows the outline | summary of the 1st modification of the said embodiment. The same figure as FIG. 1 which shows the outline | summary of the 2nd modification of the said embodiment. The same figure as FIG. 3 which shows the outline | summary of the 3rd modification of the said embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing an outline of a bridge erection method according to an embodiment of the present invention.

  As shown in the figure, the bridge to be erected in the present embodiment has a concrete main girder 14 continuously erected on the upper ends of a plurality of piers 12 installed at substantially equal intervals in the bridge axis direction. It is constructed as a passed multi-span continuous concrete bridge.

  In the present embodiment, the girder 20 installed on the main girder 14 being erected is used to extend the main girder 14 by one span from the front in the bridge axis direction (leftward in FIG. 1). It has become.

  The girder 20 is supported via a moving device 50 on a main girder head 14A that is installed in advance at the upper ends of the plurality of bridge piers 12 and can move forward in the bridge axis direction by driving the plurality of moving devices 50. It is like that. FIG. 1A shows the girder 20 in the middle of movement, and FIG. 1B shows the girder 20 after movement.

  In the present embodiment, after the girder 20 has moved by one span, each main pier segment 12 is sequentially extended with a plurality of main girder segments 14B between the spans located on both sides of the bridge axis direction. The main girder 14 is erected.

  Specifically, in the present embodiment, a first step of installing a crane 30 movable on the girder 20 in the bridge axis direction at a predetermined position of the girder 20, and after completion of the first step, the crane 30 And the second step of disposing the diagonal member 40 between the fixing portions 22 located on both sides in the bridge axis direction of the crane 30 in the girder 20, and after the completion of the second step, the girder 20 is directed forward in the bridge axis direction. The third step of moving the first span, the fourth step of releasing the arrangement of the diagonal member 40 after the completion of the third step, and the extension of the main girder 14 using the crane 30 after the completion of the fourth step. And a fifth step of erection, and the first to fifth steps are repeated.

  In the present embodiment, a PC cable disposed between the fixing portions 22 is used as the diagonal member 40, and can be placed on the upper portion of the crane 30 at the central portion thereof.

  2 is a view taken in the direction of arrow II-II in FIG. 1, and FIG. 3 is a detailed view of part III in FIG.

  As shown in these drawings, the girder 20 includes a pair of left and right truss structures 20A extending in the bridge axis direction, and connecting portions 20B that connect lower ends of both truss structures 20A at a plurality of locations in the bridge axis direction, It has an overhanging portion 20C that protrudes from the lower end portions of both truss structures 20A to the left and right sides.

  A rail 20Aa for moving the crane 30 in the bridge axis direction is arranged at the upper end of each truss structure 20A so as to extend in the bridge axis direction.

  A plurality of reinforcing members 20Ab for reinforcing each truss structure 20A are arranged at a predetermined position of the girder 20 (that is, a position where the crane 30 is installed in the first step). Further, an oblique material holder 24 for temporarily placing the oblique material 40, which has been released in the fourth step, in a positioned state, is installed on the upper surface of the predetermined position in each overhang portion 20C. The pair of front and rear fixing portions 22 is installed at a position away from the predetermined position in each overhang portion 20C in the bridge axis direction.

  The crane 30 has a configuration in which a diagonal support frame 30B is installed on an upper portion of a crane main body 30A configured as a bridge crane.

  The crane main body 30A is placed on a pair of left and right rails 20Aa of the girder 20 in a plurality of pairs of wheels 30Aa arranged at the lower end thereof, and on the rails 20Aa in the bridge axis direction by a plurality of pairs of drive devices 30Ab. You can drive to.

  The hanging tool 32 of the crane main body 30A is configured to suspend and support the main girder segment 14B in a space between the pair of left and right truss structures 20A. At this time, in order to accommodate the main girder segment 14B in the space between the pair of left and right truss structures 20A, the hanging tool 32 rotates the main girder segment 14B by 90 ° with respect to the direction at the time of completion of the construction. It is configured so that it can be suspended and supported in a state.

  The diagonal material support frame 30B is a frame for supporting the diagonal material 40, and an upper end portion thereof is constituted by a beam member 30Ba extending in the left-right direction (that is, the direction orthogonal to the bridge axis). The beam member 30Ba is formed to be slightly shorter than the entire width of the pair of left and right truss structures 20A. A saddle member 34 for supporting the diagonal member 40 disposed between the crane 30 and the girder 20 in the second step is installed on the upper surfaces of the left and right ends of the beam member 30Ba. Yes. The saddle member 34 has a concave groove portion that is curved in a convex arc shape with a concave arc-shaped cross-sectional shape and extends in the bridge axis direction.

  A sub crane 60 is installed on the diagonal support frame 30B.

  The sub-crane 60 includes a pair of left and right suspension tools 62 and a traverse rail 64 that supports each suspension tool 62 so as to be movable in the left-right direction. The transverse rail 64 extends in parallel with the beam member 30Ba of the diagonal member support frame 30B, and is formed to be slightly longer than the entire width of the pair of left and right truss structures 20A.

  The sub-crane 60 lifts the diagonal member 40 temporarily placed on the upper surface of each overhanging portion 20 </ b> C of the girder 20 by each lifting tool 62 and places it on each saddle member 34, and places it on each saddle member 34. The work of returning the oblique material 40 to the upper surface of each overhanging portion 20C is performed.

  As shown in FIG. 1, in this embodiment, a second crane 70 is installed at a position on the rear side in the bridge axis direction with respect to the crane 30 in the girder 20, and this second crane 70 is used in combination with the crane 30. The main girder 14 is extended. At that time, the extension erection of the main girder 14 using the crane 30 and the extension erection of the main girder 14 using the second crane 70 are performed in parallel between two adjacent diameters in the bridge axis direction. Yes. The second crane 70 has the same configuration as the crane main body 30 </ b> A of the crane 30.

  Next, specific contents of the first to fifth steps will be described.

  First, in the first step, as shown in FIG. 4A, a crane 30 that can move on the girder 20 in the bridge axis direction is installed at a predetermined position of the girder 20, and the bridge axis direction rear side thereof. The second crane 70 is installed at the position. In that case, the crane 30 and the 2nd crane 70 are each fixed to the girder 20 with the fixing tool which is not shown in figure.

  At this time, the girder 20 is supported by the three main beam heads 14A via the moving device 50 so as to straddle the span Sn and the span Sn + 1 adjacent to the front side in the bridge axis direction. Yes.

  Next, in the second step, as shown in FIG. 4 (a), the diagonal member 40 temporarily placed on the upper surface of each overhang portion 20C of the girder 20 is lifted by the sub crane 60, and FIG. 4 (b). As shown in FIG. 4, the diagonal portion 40 is arranged between the crane 30 and the pair of front and rear fixing portions 22 of the girder 20 by placing the central portion on the saddle member 34. At that time, tension is introduced into the diagonal member 40 at both fixing portions 22.

  Next, in the third step, as shown in FIG. 5 (c), the girder 20 is moved forward in the direction of the bridge axis, and stopped when moved by one span as shown in FIG. 5 (d). It is supposed to let you.

  At this time, the girder 20 is supported by the three main girder heads 14A via the moving device 50 so as to straddle the span Sn + 1 and the span Sn + 2 adjacent to the bridge axis direction front side. Yes.

  In the middle of moving the girder 20 by one distance in this way, as shown in FIG. 5C, a time zone in which the tip of the girder 20 protrudes greatly into the distance Sn + 2 occurs. The diagonal member 40 extending from the front prevents the girder 20 from being overloaded. FIG. 1 (a) shows a state where the girder 20 has moved somewhat further forward in the bridge axis direction than the state shown in FIG. 5 (c).

  Next, in the fourth step, as shown in FIG. 6E, after the tension introduced into the diagonal member 40 is released, the diagonal member 40 placed on the saddle member 34 is suspended by the sub crane 60. Then, as shown in FIG. 6 (f), the diagonal member 40 is returned to the upper surface of each overhanging portion 20C of the girder 20, thereby releasing the arrangement of the diagonal member 40.

  At that time, the slack member 40 is prevented from slackening in both fixing portions 22, and the central portion thereof is placed on the slant member holder 24 installed on the upper surface of each overhanging portion 20C, so that the temporary placement state is achieved. The diagonal member 40 is not accidentally dropped from the girder 20.

  Next, in the fifth step, as shown in FIG. 6 (f), the crane 30 and the second crane 70 that have been fixed to the girder 20 are unlocked and then moved in the bridge axis direction. 30 and the second crane 70 are used to extend the main girder 14 in parallel at two spans Sn + 1 and Sn + 2 adjacent in the bridge axis direction. FIG. 1B shows a state in which this extension construction work has progressed to a certain extent from the state shown in FIG.

  Next, the effect of this embodiment is demonstrated.

  In the present embodiment, the crane 30 is installed at a predetermined position of the girder 20, and the girder 20 is bridged with the diagonal member 40 disposed between the crane 30 and the two fixing portions 22 before and after the girder 20. The crane 30 can be used as an application of a conventional pillar, because it is moved by one span toward the front in the axial direction.

  Further, in this embodiment, after the girder 20 is moved, the disposition of the diagonal member 40 is released, and then the main girder 14 is extended by using the crane 30. Can be used.

  In other words, in the present embodiment, the crane 30 is used for both the original use and the conventional use of the pillar pillar, and thus the crane pillar is obstructed and the crane 30 is moved in the bridge axis direction as in the past. It is possible to prevent the movable range from being limited. For this reason, the freedom degree of construction work can be enlarged and, thereby, the workability of construction can be improved.

  As described above, according to the present embodiment, the bridge erection method for extending the main girder 14 by one span from the front in the bridge axis direction using the girder 20 installed on the main girder 14 being erected. Therefore, the workability of erection can be improved.

  In addition, as in this embodiment, the crane 30 can be used for both the original use and the conventional use of the pillar pillar, thereby simplifying the installation equipment, thereby reducing the installation cost. it can.

  Moreover, in the present embodiment, the sub crane 60 is installed above the crane 30, and the diagonal member 40 is lifted by the sub crane 60 in the second step, and the diagonal member 40 is suspended by the sub crane 60 in the fourth step. Thus, the diagonal member 40 can be easily placed and released.

  Moreover, in this embodiment, the 2nd crane 70 which can move on this girder 20 on a bridge axis direction is installed in the position of the bridge axis direction back side rather than the crane 30 in the girder 20, and the crane 30 and 2nd Since the main girder 14 is extended and installed together with the crane 70, the workability of the installation can be further improved.

  In that case, in this embodiment, the extension installation of the main girder 14 using the crane 30 and the extension installation of the main girder 14 using the second crane 70 are performed in parallel between two adjacent diameters in the bridge axis direction. Therefore, the extension construction of the main girder 14 can be efficiently performed by the overhanging method.

  In the embodiment described above, a pair of diagonal members 40 are disposed on both the left and right sides of the girder 20, but a configuration in which a plurality of pairs of diagonal members 40 are disposed is also possible.

  In the said embodiment, it demonstrates as what fixes the crane 30 installed in the predetermined position of the girder 20 and the 2nd crane 70 installed in the position of the bridge axial direction back side to the girder 20 in a 1st process, respectively. However, in some cases, it is possible not to fix the girder 20.

  In the above-described embodiment, the extension of the main girder 14 using the crane 30 and the extension of the main girder 14 using the second crane 70 are performed in parallel between two adjacent diameters in the bridge axis direction. Although the construction method is adopted, instead of doing this, the extension construction of the main girder 14 using the crane 30 and the extension construction of the main girder 14 using the second crane 70 have the same diameter by the span-by-span construction method. The main girder 14 can be extended by a span-by-span construction method using only the crane 30.

  Next, a modification of the above embodiment will be described.

  First, a first modification of the above embodiment will be described.

  FIG. 7 is a view similar to FIG. 1 showing an outline of a bridge laying method according to this modification.

  As shown in the figure, also in this modification, the girder 20 installed on the main girder 14 being installed is used to extend the main girder 14 by one span toward the front in the bridge axis direction. It has become.

  Also in this modified example, the second crane 170 that can move in the bridge axis direction on the girder 20 is installed at a position on the rear side in the bridge axis direction with respect to the crane 30 in the girder 20. The main girder 14 is extended in combination with the crane 170.

  Furthermore, also in this modified example, the extension erection of the main girder 14 using the crane 30 and the extension erection of the main girder 14 using the second crane 170 are performed in parallel between two adjacent diameters in the bridge axis direction. It is like that.

  However, the second crane 170 of this modification example has a configuration in which an oblique material support frame 170B is installed on the upper part of the crane body 170A, like the crane 30, and further, on the upper part of the second crane 170, A second sub crane 160 similar to the sub crane 60 of the crane 30 is installed.

  In this modification, in the second process, the second sub-crane 160 disposes the second diagonal member 140 similar to the diagonal member 40 between the second crane 170 and the two second fixing portions 122 at the front and rear thereof. In addition, in the fourth step, the arrangement of the second diagonal member 140 is canceled by the second sub crane 160.

  By adopting the erection method of this modification, the second crane 170 can also be used for both the original use and the use of the conventional pyrone column. As a result, when the girder 20 is moved forward in the bridge axis direction, it is possible to more easily prevent the girder 20 from being overloaded.

  Further, when the second crane 170 having the same function as that of the crane 30 is used as in this modification, both can be reduced in size, and in this case, the installation equipment Further simplification can be achieved.

  Next, a second modification of the above embodiment will be described.

  FIG. 8 is a view similar to FIG. 1 showing an outline of a bridge laying method according to this modification.

  As shown in the figure, also in this modified example, the bridge to be laid is a multi-layer structure in which a main girder 214 made of concrete is continuously bridged on top of a plurality of bridge piers 212 installed at required intervals. Although it is configured as a span continuous concrete bridge, the length between the spans is shorter than that of the above embodiment.

  In this modified example, the girder 20 installed on the main girder 214 being installed is used to extend and extend the main girder 214 by two spans toward the front in the bridge axis direction.

  Also in this modified example, the second crane 70 that can move in the bridge axis direction on the girder 20 is installed at a position on the rear side in the bridge axis direction of the crane 30 in the girder 20. 70 is used in combination with the main girder 214 for extension.

  In this modification, every time the girder 20 is moved forward in the bridge axis direction, the extension construction of the main girder 214 using the crane 30 and the extension construction of the main girder 214 using the second crane 70 are performed in the bridge axis direction. Are performed in parallel between two adjacent diameters, and this operation is repeated twice.

  That is, as shown in FIG. 8 (b), a construction is performed in which a plurality of main girder segments 214B are sequentially projected from the main girder head 214A by the second crane 70 in the span Sn, and the main girder head in the span Sn + 1. After the construction of sequentially extending the plurality of main girder segments 214B from 214A by the crane 30, as shown in FIG. 8C, the second plurality of main girder segments 214B from the main girder column head 214A is secondly inserted in the span Sn + 1. In addition to the construction of sequentially projecting by the crane 70, the construction of sequentially projecting the plurality of main girder segments 214B from the main girder column head 214A by the crane 30 in the span Sn + 2 is performed.

  By adopting the erection method of this modified example, every time the girder 20 is moved forward in the bridge axis direction, the extension of the main girder 214 can be performed for two diameters, so that the efficiency of the erection work is further improved. Can be achieved.

  Note that, as in this modification, the extension construction of the main girder 214 using the crane 30 and the extension construction of the main girder 214 using the second crane 70 are carried out by the overhanging method. Instead of performing this operation in parallel and repeating this operation twice, the span girder method is used to extend the main girder 214 using the crane 30 and the main crane 214 using the second crane 70. Can be performed in parallel between two diameters adjacent to each other in the bridge axis direction.

  Next, a third modification of the above embodiment will be described.

  FIG. 9 is a view similar to FIG. 3, showing an outline of a bridge laying method according to this modification.

  As shown in the figure, the bridge construction method according to this modification is basically the same as that of the above embodiment, but in the above embodiment, the diagonal member 40 made of a PC cable is used. On the other hand, this modified example is different from the above embodiment in that a pair of front and rear diagonal members 340 made of a steel material having a cross-sectional area larger than that of the PC cable is used.

  Accordingly, in this modification, one end of each diagonal member 340 is connected to the upper surface of the beam member 30Ba in the diagonal member support frame 30B installed on the upper portion of the crane 30 instead of the saddle member 34 of the above embodiment. An oblique member connecting member 366 is installed on the upper surface of the overhanging portion 20C of each overhanging portion 20C of the girder 20, and the other end portion of each oblique material 340 is replaced with the fixing portion 22 of the above embodiment. An oblique member connecting member (not shown) for connecting the two is installed.

  Also in the present modification, the diagonal member 340 is suspended by the sub crane 60 installed on the upper portion of the crane 30 in the second step, and the diagonal member 340 is suspended by the sub crane 60 in the fourth step. .

  At this time, in the present modification, the diagonal member 340 is lifted and suspended sequentially for each of the diagonal members 340 located on both the front and rear sides of the crane 30.

  By adopting the erection method of this modification, it is possible to place and release the diagonal member 340 simply by connecting and releasing one end of the diagonal member 340 to the crane 30. In the case of the above embodiment Thus, since it is not necessary to introduce and release the tension to the diagonal member 40, the efficiency of the construction work can be improved.

  In addition, the numerical value shown as a specification in the said embodiment and its modification is only an example, and of course, you may set these to a different value suitably.

  The invention of the present application is not limited to the configuration described in the above-described embodiment and its modifications, and a configuration with various other changes can be adopted.

12, 212 Bridge piers 14, 214 Main girder 14A, 214A Main girder column head 14B, 214B Main girder segment 20 Girder 20A Truss structure 20Aa Rail 20Ab Reinforcement material 20B Connecting portion 20C Overhang portion 22 Fixing portion 24 Diagonal material holder 30 Crane 30A , 170A Crane body 30Aa Wheel 30Ab Drive device 30B, 170B Diagonal material support frame 30Ba Beam member 32, 62 Lifting tool 34 Saddle member 40, 340 Diagonal material 50 Moving device 60 Sub crane 64 Traverse rail 70, 170 Second crane 122 Second Fixing portion 140 Second diagonal member 160 Second sub crane 366 Diagonal member connecting member Sn, Sn + 1, Sn + 2, Sn + 3

Claims (5)

In the method of erection of the bridge, the girder installed on the main girder being erected is used to extend the main girder for the required span in the forward direction of the bridge axis.
A first step of installing a crane movable on the girder in a bridge axis direction at a predetermined position of the girder;
After the completion of the first step, a second step of disposing diagonal materials between the crane and fixing portions located on both sides of the crane in the bridge axis direction of the girder,
After the completion of the second step, a third step of moving the girder by the required span toward the front in the bridge axis direction;
After the completion of the third step, a fourth step of canceling the arrangement of the diagonal material;
After completion of the fourth step, including a fifth step of extending the main girder using the crane,
A bridge erection method, wherein the first to fifth steps are repeated. Install a sub-crane above the crane,
2. The bridge erection method according to claim 1, wherein the diagonal member is lifted by the sub crane in the second step, and the diagonal member is suspended by the sub crane in the fourth step. A second crane that can move in the bridge axis direction on the girder is installed at a position on the rear side in the bridge axis direction from the crane in the girder,
The bridge erection method according to claim 1, wherein the main girder is extended by using the crane and the second crane in combination.   The extension installation of the main girder using the crane and the extension installation of the main girder using the second crane are performed in parallel between two adjacent diameters in the bridge axis direction. The bridge construction method according to Item 3. In the second step, the second diagonal member is disposed between the second crane and the second fixing portion located on both sides in the bridge axis direction of the second crane in the girder,
5. The method of laying a bridge according to claim 3, wherein in the fourth step, the arrangement of the second diagonal member is canceled.

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