JPH0941327A - Erection method of pc bridge and erection girder employed therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to provide a specified rigidity and strength in an erection girder even when the elevation of the erection girder is subjected to limitations imposed by laying out a pair of reinforcing trusses below the main body of an erection girder and mounting turnably the reinforcing trusses around a horizontal longitudinal axis. SOLUTION: The main body 12 of an erection girder 11 is spanned over to a specified span and a pair of reinforcing trusses 13, which are located below the main body 12 and laid out as opposed alone the longitudinal direction of a bridge, are connected with each other with a PC steel rod 14. Then, one span of bride girder blocks 21 are placed side by side on the main body 12, thereby supporting the weight of the bridge girder blocks 21 with the reinforcing trusses 13 and the PC steel rod 14. Then, a prestress is introduced to a PC cable which is inserted through the bridge girder blocks 21, thereby integrating the bridge girder blocks 21. Then, the reinforcing trusses 13 are turned around the horizontal axis so that they may be jumped. After the erection girder 1 is moved to the next span, the reinforcing trusses 13 are turned in the opposite direction so that they may be returned to the position below the main body 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a PC bridge and a construction girder used therefor, and more particularly to a method for constructing a PC bridge using a precast block and a construction girder used therefor.

[0002]

2. Description of the Related Art A span-by-span method is one of the methods for constructing a bridge girder of a PC bridge having a center span. In the span-by-span method, 1 on the erection girder installed between the piers.
Precast blocks for spans are arranged, and prestress is introduced into these to construct bridge spans for one span. Next, the erection girder is moved to the next span, a bridge girder is constructed by the same procedure as described above, and thereafter, a bridge girder for all spans is constructed in the same manner.

FIG. 6 (a) is a cross-sectional view as seen from the bridge axis direction, in which the erection girder 3a is placed on the bracket 2 attached to the pier 1a and the bridge girder block 4 is supported by the erection girder 3a. Is shown.

[0004]

Here, until the prestress is introduced into the bridge girder block 4, the weight of the bridge girder block 4 directly acts on the erection girder 3a, and when the span length is large, the erection girder 3a is It may bend significantly. Therefore, as can be seen in the figure, the erection girder 3a
The height H must be increased to some extent to secure a predetermined rigidity and strength.

However, depending on the conditions such as the span length and the shape of the bridge pier, the bridge pier width becomes large as in the bridge pier 1b shown in FIG. 6 (b), and as a result, the height of the erection girder like the erection girder 3b is increased. There was a problem that it was not possible to secure the required rigidity and strength because of being restricted. Moreover, even if there were no such restrictions, the temporary girder was large and very uneconomical.

The present invention has been made in consideration of the above-mentioned circumstances, and a PC bridge capable of imparting predetermined rigidity and strength to the erection girder even when the height of the erection girder is limited. It is an object of the present invention to provide an erection method and an erection girder used therefor.

[0007]

In order to achieve the above object, the method of constructing a PC bridge according to the present invention is such that, as described in claim 1, the main body of the erection girder is bridged over a predetermined span and the And a pair of stiffening members located opposite to each other along the axial direction of the bridge are connected to each other by a predetermined connecting member, bridge span blocks for one span are arranged on the main body, and the weight of the bridge girder block is set to the main body, Supporting the stiffening member and the connecting member, introducing prestress to the PC cable inserted into the bridge girder block to integrate the bridge girder block, and rotating the stiffening member around a horizontal axis. Flip up, move the erection girder to the next span,
The stiffening member is rotated in the opposite direction and returned to the lower position of the main body.

The method of constructing a PC bridge according to the present invention is to connect a connecting member according to claim 1 to the stiffening member and then apply a predetermined tension to the connecting member.

Further, in the PC bridge construction method of the present invention, when the prestressing of claim 1 is introduced, the tension of the connecting member of claim 2 is gradually decreased as the prestressing progresses.

Further, as described in claim 4, the erection girder of the present invention comprises a main body spanning a predetermined span, and a pair of auxiliary members located below the main body and facing each other along the bridge axial direction. It comprises a rigid member and a connecting member capable of connecting the pair of stiffening members to each other. The pair of stiffening members are attached to the main body so as to be rotatable about a horizontal axis, and the stiffening member is rotated below the main body. In the moved position, the weight of the bridge girder block placed on the main body is supported.

In the PC bridge erection method and the erection girder used for the same of the present invention, first, the main body of the erection girder is bridged over a predetermined span, and the main body of the erection girder is located below the main body and is arranged to face each other along the bridge axis direction. The pair of stiffening members are connected to each other by a connecting member such as a PC steel rod. Next, the bridge girder blocks for one span are arranged on the main body, and the weight of the bridge girder block is supported by the main body, the stiffening member and the connecting member.

Since the stiffening member and the connecting member are provided on the erection girder, sufficient rigidity and strength are ensured for the entire girder even when the main body has a small cross section, and the bridge girder blocks are arranged side by side. Deflection at the time of hitting can be kept small.

Next, prestress is introduced into the PC cable inserted through the bridge girder block to integrate the bridge girder block.

Next, the stiffening member is rotated about the horizontal axis to flip it up.

Then, the erection girder can be smoothly moved to the next span without causing the stiffening member and the bridge pier to interfere with each other.

After moving the erection girder to the next span, the stiffening member is rotated in the opposite direction to return to the lower position of the main body, and the above procedure is repeated again to erect the span girder on the span.

Here, when the above-mentioned connecting member is connected to the stiffening member and a predetermined tension is introduced into the connecting member, the amount of bending of the erection girder when the bridge girder block is loaded is desired. It can be adjusted to any size.

Further, when the tension introduced in advance to the connecting member is gradually reduced as the prestress progresses, the rebound behavior of the erection girder due to the reduction of the applied load can be prevented. it can.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for erection of a PC bridge and an erection girder used therefor according to the present invention will be described below.
This will be described with reference to the accompanying drawings. It should be noted that parts and the like which are substantially the same as those of the conventional technique are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a flow chart showing the procedure of a method of erection of a PC bridge according to this embodiment, and FIGS. 2 and 3 are a side view and a sectional view showing an erection girder used in the method. As can be seen in FIG. 2, the erection girder 11 includes a body 12
And a pair of stiffening trusses 13 as a stiffening member disposed below the main truss 13, and the main body 12 is supported by the piers 15 and spans a predetermined span. The stiffening trusses 13 and 13 are configured as triangular trusses and are arranged to face each other along the bridge axial direction, as can be seen from the detailed view of FIG. Moreover, the vicinity of the lower end thereof is connected to each other by a PC steel rod 14 as a connecting member.

The body 12 is adapted to support the bridge girder block 21 via an adjustment jack 22, as best seen in FIG. 3 (a). In addition, the stiffening truss 13 has a pin 25.
It is attached to the main body 12 via a rotary jack 23 and is provided with a rotary jack 23 between the main body 12 and the rotary jack 23. By operating the rotary jack 23, the rotary jack 23 can be rotated around a pin 25 which is a horizontal axis. ing. And
Lower the stiffening trusses 13, 13 below the main body 12,
When the trusses 13 and 13 are connected to each other by the PC steel rods 14 (FIGS. 2 (b) and 3 (a)), the erection girder 11 is installed.
The overall height increases at the center of the span, and the main body 12
Rigidity and strength are greater than in the case of only.

On the other hand, when the rotating jack 23 is activated to flip up the stiffening truss 13 substantially horizontally (FIG. 3 (b)), the stiffening truss 13 and the bridge pier 15 are prevented from interfering with each other and installed. The entire girder 11 can be moved smoothly.

In the PC bridge erection method of this embodiment, first, as shown in FIG. 2A, the main body 12 of the erection girder 11 is bridged over a predetermined span (FIG. 1, step 10).
1), the stiffening trusses 13, 13 are connected to each other by the PC steel rod 14 to introduce a predetermined tension (step 102).

The magnitude of the tension is appropriately set so that the bending amount of the erection girder when the bridge girder block is placed later is within a desired amount.

Next, as shown in FIG. 4 (a), the bridge girder block 21 for one span manufactured in the manufacturing yard near the factory or the site is carried in by the trailer 32, and this is transferred to the crane 3
3 is hoisted and hoisted down on the main body 12. Then, the suspended bridge girder blocks 21 are sequentially forwarded by the winches 34 and arranged on the main body 12 (step 103).

In the span under operation, since the stiffening trusses 13, 13 connected by the PC steel rod 14 are arranged below the main body 12 of the erection girder 11, the main body 12 has a small cross section. Even if there is enough girder, sufficient rigidity and strength are secured, and the bridge girder block 21 for one span
It is possible to suppress the deflection when the are arranged side by side.

Next, the bridge girder blocks 21 arranged on the main body 12 are drawn together as shown in FIG. 4 (b), and if necessary, an epoxy resin adhesive is applied to the joint surface, and this is pressure-bonded. Join the bridge girder blocks 21 (step 10)
4). As for the method of crimping, the bridge girder blocks 21 may be pulled together by connecting them with a PC steel rod by a jack and introducing a tension into this.

Next, as shown in FIG. 5 (a), a pre-stress is introduced into the PC cable inserted into the bridge girder block 21 using the tension jacks 41, and the bridge girder block 21
Unify. Since the load acting on the erection girder 11 gradually decreases with the progress of the prestress, the tension of the PC steel rod 14 is gradually decreased to prevent the rebound behavior (step 10).
5).

Next, after the introduction of prestress, the PC steel rod 14
Is released from the stiffening trusses 13, 13 (step 106).

As described above, the installation of the bridge girder 42 in the span is completed as shown in FIG. 5 (b), and subsequently, the stiffening trusses 13, 13 are rotated about the horizontal axis as shown in FIG. This is flipped up (step 107).

Next, as shown in FIG. 5 (c), a winch 44
The wire 43 drawn from is attached to the erection girder 11, and the winch 44 is operated to move the erection girder 11 to the next span (step 108). Here, since the stiffening trusses 13 and 13 are flipped up, it is possible to smoothly move the entire installation girder 11 to the next span without the stiffening trusses 13 and 13 and the pier 15 interfering with each other. it can.

Prior to the movement of the erection girder 11, the adjustment jack 22 is appropriately operated as necessary to make the bridge girder 42
The weight of is transferred to the pier 15 in advance.

After moving the erection girder 11 to the next span, the stiffening trusses 13 and 13 are rotated in the opposite direction to return to the lower position of the main body 12 (step 109), and the above-mentioned procedure is repeated again. Bridge girders will be installed on the span.

After the bridge girder installation for all spans is completed by the above-mentioned procedure, PC continuous cables (outer cables) are arranged over all spans as necessary, and prestressing is performed (step 111).

As described above, P according to the present embodiment
According to the erection method of the C bridge and the erection girder used for it, a pair of stiffening trusses are arranged below the main body of the erection girder, and the stiffening trusses are attached to the main body rotatably around the horizontal axis. Rotate the rigid truss below the body,
When the trusses are connected to each other with PC steel rods, the overall height of the erection girder increases at the center of the span. Therefore, in the span during work, even if the main body has a small cross section, sufficient rigidity and strength are ensured for the entire girder, and bending when arranging the bridge girder blocks for one span can be suppressed to be small. . On the other hand, when the stiffening truss is flipped up horizontally, interference between the stiffening truss and the pier is avoided, and the entire installation girder can be moved smoothly.

Therefore, even when the height of the erection girder is limited by the width of the pier or the like, it is possible to provide the erection girder with sufficient rigidity and strength.

Since the PC steel rod is connected to the stiffening truss and a predetermined tension is introduced into the PC steel rod, the amount of bending of the erection girder when the bridge girder block is loaded is desired. Can be adjusted to size.

Further, since the tension introduced in advance to the PC steel rod is gradually reduced as the prestress progresses, it is possible to prevent the rebound behavior of the erection girder due to the reduction of the applied load. .

Further, by exchanging the length of the PC steel rod and the main member of the stiffening truss, it can be diverted to the construction work with different spans. In this embodiment, the tension is introduced in advance to the PC steel rod as the connecting member and the tension is reduced as the prestress progresses. However, the allowable bending amount of the erection girder when the bridge girder block is loaded. The tension does not necessarily have to be introduced in advance, if is not so severe. If tension is not introduced in advance,
It is not necessary to use a PC steel rod as the connecting member, and a normal steel frame or the like may be used so as to be integrated with the stiffening truss.

Further, even when tension is introduced into the PC steel bar in advance, if the rebound behavior due to the decrease in the applied load does not substantially affect the safety of construction, etc., it is accompanied by the progress of prestress. The work of reducing the tension may be omitted.

Further, in the present embodiment, the PC steel rod from which the tension is released is removed prior to the rotation of the stiffening truss, but it is not always necessary to remove it if the rotation can be performed smoothly.

Further, in the present embodiment, the main body of the temporary girder has a truss structure, but it may have another structure, for example, a box girder structure.

[0043]

As described above, in the PC bridge erection method of the present invention, the main body of the erection girder is bridged over a predetermined span, and is located below the main body and is arranged to face each other along the bridge axial direction. A pair of stiffening members are mutually connected by a predetermined connecting member, bridge span blocks for one span are arranged on the main body, and the weight of the bridge girder block is supported by the main body, the stiffening member and the connecting member, Prestress is introduced into the PC cable inserted in the bridge girder block to integrate the bridge girder block, the stiffening member is rotated around the horizontal axis and flipped up to move the erection girder to the next span. Since the stiffening member is rotated in the opposite direction to return to the lower position of the main body, even when the height of the erection girder is restricted, the erection girder is provided with predetermined rigidity and strength. It can be.

Further, the erection girder of the present invention comprises a main body bridged over a predetermined span, a pair of stiffening members located below the main body and facing each other along the bridge axis direction, and the pair of stiffening members. It consists of a connecting member that can connect rigid members to each other,
The pair of stiffening members are rotatably attached to the main body about a horizontal axis, and are configured to support the weight of a bridge girder block placed on the main body in a position where the stiffening members are rotated downwardly of the main body. Therefore, even when the height of the erection girder is limited, the erection girder can be provided with predetermined rigidity and strength.

[0045]

[Brief description of drawings]

FIG. 1 is a flowchart showing a procedure of a method of constructing a PC bridge according to the present embodiment.

2A and 2B are diagrams showing an installation girder according to the present embodiment, where FIG. 2A is an overall side view and FIG. 2B is a detailed side view of the same.

FIG. 3 is also a view showing the erection girder according to the present embodiment, (a) is a detailed cross-sectional view taken along the line AA of FIG. 2 (b),
(b) is an explanatory view showing a state in which the stiffening truss of the erection girder is rotated and flipped up.

FIG. 4 is an explanatory view showing how the bridge girder is erected by using the PC bridge erection method according to the present embodiment, and FIG. 4 (a) is a diagram in which the bridge girder block is suspended on the main body of the erection girder; (b) is a drawing of the bridge girder block.

FIG. 5 is an explanatory view showing how a bridge girder is erected using the PC bridge erection method according to the present embodiment,
(a) is a diagram in which the bridge girder block is integrated by prestressing, (b) is a diagram in which the stiffening truss of the erection girder is flipped up, and (c) is a diagram in which the erection girder is moved.

FIG. 6 is a sectional view showing the structure of a conventional installation girder.

[Explanation of symbols]

 11 Installation Girder 12 Main Body 13 Stiffening Truss (Stiffening Member) 14 PC Steel Rod (Coupling Member) 15 Pier 21 Bridge Girder Block 23 Rotating Jack 101 Arrangement Process of Erection Girder 102 PC Steel Rod Connection Process 103 Parallel Installation of Bridge Girder Blocks Step 105 Step of introducing prestress of bridge girder block 106 Step of removing PC steel rod 107 Step of flipping up stiffening truss 108 Step of moving erection girder 109 Step of lowering and lowering stiffening truss

Claims (4)

[Claims] 1. A main body of an erection girder is spanned over a predetermined span, and a pair of stiffening members located below the main body and arranged to face each other along the bridge axis direction are connected to each other by a predetermined connecting member, The bridge girder blocks for one span are arranged on the main body, and the weight of the bridge girder block is supported by the main body, the stiffening member and the connecting member, and prestress is introduced into the PC cable inserted into the bridge girder block. The bridge girder block is integrated, the stiffening member is rotated around the horizontal axis and flipped up, the erection girder is moved to the next span, and the stiffening member is rotated in the opposite direction to lower the main body position. PC bridge construction method characterized by returning to 2. The method of constructing a PC bridge according to claim 1, wherein after connecting the connecting member to the stiffening member, a predetermined tension is introduced into the connecting member. 3. The method of constructing a PC bridge according to claim 2, wherein, when the prestress is introduced, the tension of the connecting member is gradually reduced as the prestress progresses. 4. A main body spanning a predetermined span, a pair of stiffening members located below the main body and facing each other along the bridge axis direction, and the pair of stiffening members can be connected to each other. The pair of stiffening members are attached to the main body so as to be rotatable about a horizontal axis, and in a position where the stiffening members are rotated downward, the bridge girder block placed on the main body is attached. An erection girder characterized by being designed to support weight.