JPH0426659B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a prestressed concrete girder (prestressed concrete girder) using a precast concrete block method.

[Conventional technology]

In recent years, PF has been applied to the tension and compression edges of concrete girders.
Place the steel materials, tension and fix the prestressing steel materials on the tensile edge (hereinafter referred to as tensile steel materials), apply compressive stress to the tensile edge of the concrete girder, and
A girder that can withstand large loads with a smaller girder height has been developed by pushing and fixing steel rods (hereinafter referred to as compression steel rods) and applying tensile stress to the compression edges of the concrete girder. . For convenience, this method is called the bipre-stressing method. PC girders using the bipre-stretching method are manufactured using the cast-in-place method or the precast method.

[Problem that the invention seeks to solve]

However, in urban areas of Japan, which has a small land area,
Because it is difficult to secure a large work space near the girder erection site, it is often difficult to manufacture PC girders in a yard near the girder erection site.
If PC girders are manufactured in a yard relatively far away from the girder erection site, the long and heavy manufactured PC girders will have to be transported over a long distance to the erection site.
A problem arises in that it takes a long time to transport the PC girder.

[Purpose and structure of the invention]

The object of the present invention is to provide a method for easily manufacturing PC girders using the precast concrete block method in a relatively narrow yard near the girder erection site using the bipre-stretching method. The gist of this invention is that when a precast concrete girder is manufactured by dividing it into a plurality of blocks, a tension edge sheath 1 is placed in advance at a predetermined position of each block, and a compression edge sheath 1 is placed in advance at a predetermined position of each block. The compressed edge sheath 3 into which the compressed steel rod 2 is inserted is placed at a predetermined position, and the manufactured blocks are arranged in series in the horizontal direction, and then one of the adjacent blocks is moved toward the other block. The compressed steel rods 2 of adjacent blocks are connected by a coupler 4, and the adjacent blocks are brought into close contact with each other. Next, the tension steel 5 inserted across the tension edge sheath 1 of each block is fixed under tension, and then the above-mentioned A method for manufacturing a PC girder using a precast concrete block method characterized by pressing and fixing compressed steel rods 2.

〔Example〕

Next, the present invention will be explained in detail using illustrated examples.

1 to 12 show a first embodiment of the present invention. First, as shown in FIGS. 1 and 2, a plurality of vertically extending A bottom formwork 12 supported via a support member 10 and a large number of sleepers 11 is installed,
Of the several blocks constituting the PC girder, every other block, that is, the end block 8 and the intermediate block 13 located in the center of the PC girder are manufactured.

In this case, the tension edge sheath 1 is arranged at predetermined positions on the tension edge of the intermediate block 13 and the end block 8, and the compression edge sheath 3, into which the compression steel rod 2 has been inserted in advance, is arranged at the compression edge of the intermediate block 13. In addition, a recess 14 for pushing a compressed steel bar is provided at the end of the end block 8 on the center side of the PC girder, and a recess 14 for pushing the compressed steel rod is provided at the end face and the upper face of the block, and a steel rod having a through hole at the rear of the recess 14 is provided. pressure receiving member 15
At the same time, an end sheath 17 with an injection pipe 16 is embedded in the end block 8 behind the steel pressure receiving member 15, and reinforcing bars (not shown) are installed in the end block 8 and the intermediate block 13.
bury it.

Next, after applying a release agent to the opposing end surfaces of the end block 8 and intermediate block 13, as shown in FIG.
A side formwork 18 is arranged over the side surface of the block, and the end block 8 and intermediate block 13 are connected to the side formwork 18.
Fresh concrete 20 is poured from a hopper 19 into the space surrounded by the blocks, and an intermediate block 21 is manufactured. In this case as well, the tension edge sheath 1 is placed on the tension edge of the intermediate block 21, and the compression edge sheath 3 into which the compression steel rod 2 has been inserted in advance is placed on the compression edge of the intermediate block 21.
At the compression edge of the central end of the PC girder in 1, a recess 22 for connecting compression steel rods that is open on the end and top surfaces of the block is provided, and reinforcing bars (not shown) are placed in the concrete pouring area. .

As the compressed edge sheath 3, a known squeezed sheath is used which is squeezed into an elliptical shape alternately at regular intervals in the longitudinal and lateral directions of the sheath cross section in order to prevent buckling of the compressed steel rod.

Next, each block manufactured as described above is transported by trailer or the like to an assembly yard near the bridge site.

In the assembly yard, as shown in Figure 4,
A plurality of rails 25 are laid in parallel on the base 23 via a large number of sleepers 24, and each concrete block 8, 13, 21 is placed across a plurality of temporary carts 26 placed on the rails 25, respectively. place

Next, as shown in FIG. 5, after inserting a wedge 27 for preventing movement between the wheels of the temporary cart 26 supporting the end concrete block 8 and the rail 25, A lever swing type traction device (trade name: Lever Block) 29 is engaged across the hanging fitting 28 fixed in advance and the hanging fitting 28 fixed in advance to the intermediate block 21, and End face or intermediate block 21
After applying an adhesive such as epoxy resin to the end face or both end faces, the intermediate block 21 is moved to the end block 8 by the lever swing type traction device 29.
Pull each block 8, 2 toward the
1 are engaged and integrated with adhesive, and one end of the compressed steel rod 2 of the intermediate block 21 is connected to the steel pressure receiving member 15 and the end sheath 17 of the end block 8.
Insert into.

Next, as shown in FIG. 6, the lever swing type traction device 29 is engaged across the hanging fittings 28 of the intermediate block 21 and the hanging fittings 28 of the intermediate block 13, and 1
After applying the adhesive as described above to the end face or both end faces of the lever swing type traction device 2,
9, the intermediate block 13 is drawn toward the intermediate block 21, and as shown in FIGS.
3 and 21 are bonded and integrated with adhesive.

After each block is sequentially pulled together and connected as described above, and each compressed steel rod 2 is connected by a coupler 4, a tensile steel member 5 is connected across the tensile edge sheath 1 of each block as shown in FIG. After the insertion, a part of the tensile steel material 5 is tensioned and fixed, the compression steel rod 2 is pushed in and fixed, and then the remaining tensile steel material 5 is tensioned and fixed.

Note that after all the tensile steel members 5 have been tensioned and fixed, the compression steel rods 2 may be pushed and fixed, or the compression steel bars 2 may be connected by the coupler 4 after the tension steel members 5 are tensioned and fixed. .

After completing the introduction of prestress to the PC girder using the tensile steel material 5 and the compression steel rod 2, mortar grout is injected into the tension edge sheath 1 and the compression edge sheath 3, and the compression steel rod pushing recess 14 and the compression steel Post-filled concrete 3 in the rod connection recess 22
Complete the manufacture of the PC girder by filling it with 0. Furthermore, the ninth
In the figure, 42 is a support that supports the end of the PC girder 40.

The length of the compressed steel rod 2 placed in the intermediate blocks 13, 21 is adjusted by the coupler 4.
It is determined by taking into consideration the amount of shortening of the compressed steel rod 2 due to pushing so that the coupler 4 does not hit the end face of the intermediate block 13 when the compressed steel rod 2 is embedded after connecting the two. . Note that since the tension fixing means for the tensile steel material 5 is well known, detailed explanation thereof will be omitted.

In a small-span PC girder where the cross-sectional force due to the live load is relatively large compared to the girder's own weight, if all the tensile steel members 5 are tensioned at the same time, the stress at the compression edge will not have enough margin to the allowable value, and the compression When the steel rod 2 is pushed in, the stress at the compression edge may exceed the allowable stress level.

In such a case, in order to prevent cracks due to the introduction of prestress, it is preferable to press the compressed steel bar after loading the dead load of the cast-in-place concrete between the girders, the ground covering concrete, etc.

Next, an example of the push fixing means for the compressed steel rod 2 is shown in the 10th example.
This will be explained with reference to FIGS. 12 to 12.

First, as shown in FIGS. 10 and 12, the compressed steel rod 2 is
At the same time, a steel pushing nut 31 is screwed together, a steel pressing member 32 is fitted to the rear surface of the pushing nut 31, and a fixing nut 33 is fitted behind the steel pressing member 32. After screwing together, the end of the compressed steel rod 2 is inserted into the steel pressure receiving member 15 and the end sheath 17.

In this case, the distance L1 from the front surface of the steel pressure receiving member 15 to the end face of the compression steel rod 2 is calculated by adding the length approximately equal to the thickness of the steel pressure receiving member 15 to the shortening amount when the compression steel rod 2 is completely pushed. In addition, the distance L2 between the front surface of the pushing nut 31 and the front surface of the compressed steel bar pushing recess 14 before pushing the compressed steel bar 2 is set to be smaller than the shortening amount when the pushing of the compressed steel bar 2 is completed. It is set large so that the pushing nut 31 does not hit the front surface of the compressed steel bar pushing recess 14 before the pushing of the compressed steel bar 2 is completed.

Next, the pushing fixing member 34 is slidably fitted.
and a pushing jig 3 consisting of a movable member 35 for pushing.
The pushing jack 37 is interposed between the jack receiving part of the pushing fixed member 34 and the jack receiving part of the pushing movable member 35 in 6, and is fixed with a bolt, and the fixed locking arm 38 of the pushing fixed member 34 is fixed. and the movable locking arm 39 of the movable pushing member 35 are inserted into the compressed steel bar pushing recess 14, the fixed locking arm 38 is engaged with the steel pressure receiving member 15, and the movable locking arm 39 of the movable pushing member 35 is inserted. With the arm 39 engaged with the steel pressing member 32, the pushing jack 37 is extended to push the compressed steel rod 2 toward the center of the PC member 40.

In this case, the jacking reaction force is applied to the pushing fixing member 34.
and the end block 8 via the steel pressure receiving member 15.
The fixing nut 33 moves in a direction away from the steel pressure receiving member 15 as the compressed steel rod 2 shortens.

Next, by rotating the fixing nut 33 and bringing it into close contact with the steel pressure receiving member 15, the compressed steel rod 2 is prevented from moving back, and the end of the compressed steel rod 2 is inserted through the steel pressure receiving member 15. The image is fixed on the part block 8.

Next, after shortening the pushing jack 37 and removing the movable locking arm 39 from the steel pressing member 32, the pushing jig 36 is removed, and then, as shown in FIG. 14 and the compression steel rod connection recess 22 into the compression edge sheath 3, and at the same time injecting the mortar grout 41 into the end sheath 17 from the injection pipe 16,
Furthermore, the post-filling concrete 30 is filled into the compressed steel rod pushing recess 14 and the compressed steel rod connecting recess 22.

FIG. 13 and FIG. 14 show a second embodiment of the present invention, and in this embodiment,
It is composed of an intermediate block 6 having the maximum length that allows the PC girder 40 to be transported, and end blocks 8 placed at both ends thereof. The compressed steel rods 2 and the compressed edge sheath 3 with a coupler storage sheath inserted through the compressed steel rods 2 are arranged, and the length of the compressed steel rods 2 connected by the coupler 4 and the length of the intermediate block 6 are determined. are set to be substantially the same, and a tension edge sheath 1 is disposed at a predetermined position on the tension edge of the intermediate block 6. Furthermore, the ends of the compressed steel rod 2 are accommodated at both ends of the intermediate block 6, and A recess 7 for connecting a compressed steel bar is provided at the end face of the compressed steel rod.

Further, a compression edge sheath 3 through which a compression steel rod 2 is inserted is disposed at a predetermined position on the compression edge of the end block 8.
At the end of the end block 8 on the intermediate block side, there is provided a compressed steel rod connecting recess 7 which accommodates the end of the compressed steel rod 3 and is open to the end face of the end block 8. In the middle part of the block 8, there is a concave part 1 for pushing a compressed steel bar that opens upward.
4 is provided, and a tensioning edge sheath 1 is arranged in position on the end block 8.

In the case of the second embodiment, the end block 8 is pulled and moved toward the intermediate block 6, and the compressed steel rods 2 attached to the intermediate block 6 and the end block 8 are connected via the coupler 4. The intermediate block 6 and the end blocks 8 are bonded together by an epoxy resin adhesive, and the tension edge sheath 1 and each end block 8 in the intermediate block 6 are bonded together.
a tensile edge sheath 1 and a tensile steel member 5 at
is inserted, and then tension fixing of a part of the tensile steel bars 5, push fixing of the compression steel rods 2, and tension fixing of the remaining tensile steel bars 5 are performed in sequence, or tension fixing and compression of all the tensile steel bars 5 are performed. Although the steel rod 2 is pressed and fixed in sequence, the other configurations are the same as in the first embodiment.

In the case of the second embodiment, the compressed steel bar pushing recess 14
When mortar grout is injected into the compression edge sheath 3, the mortar grout is also injected into the compression steel rod connection recess 7.
It is possible to omit the separate step of filling the interior with post-filling concrete.

In the case of the second embodiment, since the compressed steel rod connecting recess 22 is not provided across the joint end of the intermediate block 6 and the end block 8, it is provided only at the end of the intermediate block 6, as shown in FIG. A recess 7 for connecting a compressed steel rod may be provided.

In the case of this invention, the coupler 4 that connects the compressed steel rod 2 is arranged at the joint of each adjacent block, so the compressed steel rod 2 connected by the coupler 4 and the compressed edge sheath 3 consisting of a drawn sheath are combined. can be used.

〔Effect of the invention〕

According to this invention, when manufacturing a precast concrete girder by dividing it into a plurality of blocks, a tension edge sheath 1 is placed in advance at a predetermined position of each block.
At the same time, a compressed edge sheath 3 with a compressed steel rod 2 inserted therein is placed at a predetermined position on the compressed edge of at least the middle block, and after arranging the manufactured blocks in series in the lateral direction, one of the adjacent blocks is placed. one block towards the other block, the compressed steel rods 2 of the adjacent blocks are connected by the coupler 4, and the adjacent blocks are brought into close contact with each other, and then the tensile edge sheath 1 of each block is moved. After the tensile steel material 5 inserted through the girder is fixed under tension, the compression steel bar 2 is pushed in and fixed, so it is possible to easily manufacture a PC girder using the bi-pre-stressing method using the pre-cast concrete block method, and it is possible to use the bi-pre-stretching method in a narrow space. Effects such as being able to manufacture pre-stressing type PC girders can be obtained.

[Brief explanation of drawings]

1 to 12 show a first embodiment of the present invention, in which FIG. 1 is a vertical cross-sectional side view showing a manufactured state of every other block constituting a PC girder, and FIG. Fig. 3 is a partially longitudinal side view showing an enlarged view of a portion of the end block; Fig. 3 is a partially longitudinal side view showing the state in which the remaining blocks are being manufactured; Figures 5 and 6 are side views showing the blocks placed on a temporary trolley, side views showing the blocks being pulled and joined, and Figure 7 is an enlarged view of the compressed steel bar joint area. The longitudinal side view shown in FIG. 8 is A- in FIG. 7.
A cross-sectional view taken along line A, Fig. 9 is a vertical cross-sectional side view showing the completed PC girder using the precast concrete block method, Fig. 10 is a vertical cross-sectional view showing the state in which compressed steel bars are being pushed in, and Fig. 11 is a vertical cross-sectional view showing the state in which compressed steel bars are being pushed. FIG. 10 is a sectional view taken along the line B-B, and FIG. 12 is a longitudinal sectional view showing a state where mortar grout has been poured and post-filling concrete has been filled. FIG. 13 is a longitudinal side view of a PC girder manufactured by the method of the second embodiment of the present invention, and FIG. 14 is an enlarged longitudinal side view showing the vicinity of the compressed steel bar joint in FIG. 13. . FIG. 15 is a longitudinal sectional side view showing an example in which a compressed steel rod connection recess is provided only at the end of the intermediate block. In the figure, 1 is a tension edge sheath, 2 is a compression steel rod, 3 is a compression edge sheath, 4 is a coupler, 5 is a tension steel material, 6 is an intermediate block, 7 is a recess for connecting a compression steel rod, 8 is an end block, 12 is the bottom formwork, 13
1 is an intermediate block, 14 is a recess for pushing a compressed steel bar, 1
5 is a steel pressure receiving member, 17 is an end sheath, 18 is a side formwork, 21 is an intermediate block, 22 is a recess for connecting a compressed steel bar, 25 is a rail, 26 is a temporary cart, 27
is a wedge for preventing movement, 28 is a hanging fitting, 29 is a lever swing type traction device, 30 is a post-filled concrete, 31
32 is a pushing nut, 32 is a steel pressing member, 33 is a fixing nut, 34 is a fixed member for pushing, 35 is a movable member for pushing, 36 is a pushing jig, 37 is a pushing jack, and 38 is a fixed lock. Arm, 39 is a movable locking arm,
40 is a PC digit.

Claims (1)

[Claims] 1. When manufacturing a precast concrete girder by dividing it into a plurality of blocks in advance, a tension edge sheath 1 is placed in advance at a predetermined position of each block, and
A compression edge sheath 3 into which a compression steel rod 2 is inserted is placed at a predetermined position on the compression edge of at least an intermediate block, and each manufactured block is arranged in series in the lateral direction, and then one of the adjacent blocks is placed next to the other block. The tensile steel rods 5 are moved towards the blocks, connecting the compression steel rods 2 of adjacent blocks by means of a coupler 4, bringing the adjacent blocks into close contact with each other, and then passing through the tensile edge sheath 1 of each block. A method for manufacturing a PC girder using a precast concrete block method, characterized in that after the compressed steel rod 2 is fixed under tension, the compressed steel bar 2 is pushed and fixed. 2. A method for manufacturing a PC girder using a precast concrete block method according to claim 1, wherein the length of the compressed steel rod 2 arranged in the intermediate block 6 is approximately equal to the length of the intermediate block. 3. Claim 1, characterized in that the end of the intermediate block 6 is provided with a compressed steel rod connection recess 7 that opens on the end face of the intermediate block 6.
A method for manufacturing PC girders using the precast concrete block method described in Section 1. 4. The precast according to claim 1, characterized in that the ends of the intermediate block 6 and the end block 8 are provided with recesses 7 for connecting compressed steel rods that open on the end faces of these blocks. A method for manufacturing PC girders using the concrete block method.