JP2000186394A - Liquid-tight structure of terminal of pc-steel stranded wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To independently support a plurality of PC-steel stranded wires to the common through-hole of the end wall of a concrete girder, and to correct the injection of oil and tensile load even after completion. SOLUTION: The central sections of the bundles 22 of the PC-steel stranded wires 12 are inserted and supported to supporting members 8 formed to the central lower wall section of a concrete bridge girder 2. Both end sections of the bundles 22 of the PC-steel stranded wires 12 are inserted into a cylindrical protective tube 41 so that regular intervals are kept mutually. Disks 42 made of a rubber are pressed into both end sections of the protective tube 41, both end sides of the PC-steel stranded wires 12 are inserted into the through-holes 44 of the disks 42 made of the rubber, and the internal hollow section 43 of the protective tube 41 is filled with a curing agent. The protective tube 41 is put into the through-hole 21 of the end wall 20 of the concrete bridge girder 2. An opening between the protective tube 41 and the through-hole 21 is filled with curing agent 27. Each PC-steel stranded wire 12 is supported independently to a fixing member 28 closing the outlet end section of the through-hole 21 by a fixture 29.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete bridge girder reinforced by a plurality of PC steel strands (wires for post-tensioning) to which tension is applied after construction, and in particular, to a concrete bridge girder, the end of a PC steel strand. And a liquid-tight structure at the end of a PC steel stranded wire, which is supported in a liquid-tight manner.

[0002]

2. Description of the Related Art In order to reinforce a bending load, concrete bridge girder of section I type, T type, box type and the like are provided with a plurality of tensioned lower walls of a concrete bridge girder receiving a tensile load. PC steel strands are stretched. In long concrete bridge girders, PC steel strands are stretched at the bridge site for transportation and other reasons. In a conventional concrete bridge girder in which a PC steel strand is stretched, a support member for supporting a central part of the PC steel strand is provided on a lower wall of a central part in a longitudinal direction, and both ends of the PC steel strand are provided on both end walls. A fixing member for fixing the portion is provided. In other words, in a conventional concrete bridge girder, the ends of a plurality of PC stranded wires are inserted into through holes in the end wall, and a tensile load is applied by a tension device (hydraulic jack).
It is usual that the fixing tool is fastened to the outer wall surface of the end wall, and the gap between the through holes in the end wall is filled with mortar or the like and fixed.

However, it is difficult for the above-described structure to support the PC steel strands independently and evenly share the tensile load inside the through holes in the end walls of the concrete bridge girder. In particular, there are problems such as a change in the tensile load shared by each of the PC steel wires due to a change with time, and leakage of grease for lubricating the PC steel wires to generate rust. Also,
If the PC steel strand is fixed to the end wall of the concrete bridge girder with mortar, even if the tensile load decreases after completion, it cannot be recovered.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a structure in which each PC steel strand is supported in a liquid-tight manner on an end wall of a concrete bridge girder, and rust preventive oil is supplied from an oil supply box through the end wall. It is an object of the present invention to provide a liquid-tight structure at the end of a PC stranded wire that is supplied to a hole.

Another object of the present invention is to provide a PC steel stranded wire in which a tensile force is independently and uniformly applied to a fixing member fixed to an outer wall surface of an end wall of a concrete bridge girder. It is an object of the present invention to provide a liquid-tight structure of a strand end.

[0006]

In order to solve the above-mentioned problems, according to the structure of the present invention, both ends of a predetermined number of PC stranded wires are inserted into a cylindrical protective tube so as to keep an equal distance from each other. A rubber disc is press-fitted into both ends of the protective tube, and both ends of the PC steel stranded wire are inserted into through holes regularly juxtaposed to the rubber disc to form an inner space of the protective tube. Is filled with a curing agent.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a through hole formed in an end wall of a concrete bridge girder is inclined upwardly from an inlet end to an outlet end to reduce the cross-sectional area of the inlet end and cut off the outlet end. The area is enlarged. A plurality of PC steel strands (unbonded PC steel strands) are inserted into one protective tube, and a gap between the protective tube and the inlet end of the through hole is filled with a hardening agent such as foam mortar. Inside the through-hole, there is a gap between the respective PC steel strands, and the gap is filled with a rust preventive oil such as grease. The exit end of the through hole is closed by a disc-shaped fixing member. The fixing member is fixed to the outer wall surface of the end wall of the concrete bridge girder, and the end of the PC stranded wire is fixed to the fixing member by a known fixing tool.

[0008] A cup-shaped refueling box is connected to the fixing member. The grease in the refueling box is supplied to the inside of the through hole in the end wall of the concrete bridge girder. Within the through-hole, each PC steel strand shares a tensile load independently of each other. If the tensile load shared by the PC strands changes after completion, the tensile load is increased by a tension device (hydraulic jack). In this case, since a gap is secured between the PC strands inside the through-hole, the tensile load of each PC strand can be independently adjusted.

[0009]

FIG. 1 is a front sectional view of a box-type concrete bridge girder of an outer wire type to which the present invention is applied, and FIG. 2 is a side sectional view showing the right half of the concrete bridge girder. The concrete bridge girder 2 is formed by bolting a number of blocks integrally comprising an upper wall member 4 having a projecting portion 4a on the left and right and a road surface 3 above, a lower wall member 6 and a pair of left and right side walls 5. A plurality of (six in the illustrated embodiment) PC steel strand bundles 22 are disposed in the inner space 7. For this reason, the flanges 10 protruding from the inner surface of the end of the side wall 5 of each block are abutted with each other, bolts are inserted into the bolt insertion holes 10a of the flanges 10 and fastened by nuts to be connected to each other. At the center of the lower wall member 6 of the concrete bridge girder 2 in the longitudinal direction, a bundle 22 of
Support member 8 having six through holes 9 for inserting
Is provided. For example, a bundle 22 of 19 twisted unbonded PC steel wires 12 shown in FIG. 6 is inserted into and supported by each through hole 9 of the central support member 8. Each unbonded PC steel strand 1
As shown in FIG. 5, 6 is twisted by arranging six strands 15 around a core 16 and covering the periphery with two inner and outer tubes 12b and 12a made of a synthetic resin such as polyester. Thus, the gap 17 between the tube 12a and the tube 12b and the inner space 18 of the tube 12b are filled with grease.

As shown in FIGS. 2 and 3, both ends of a bundle of PC stranded wires 22 are suspended in the hollow space 7 of the concrete bridge girder 2, and the ends of the bundle of PC stranded wires 22 are concrete bridge girder. The second end wall 20 is supported by the through hole 21. Through hole 2
Reference numeral 1 denotes an upward slope from the inlet end to the outlet end, and has a wrapper shape having a narrow cross-sectional area at the inlet end and a wide cross-sectional area at the outlet end. At the entrance end of the through-hole 21, the bundle 22 of PC steel strands is disintegrated into 19 PC steel strands 12, and each PC steel strand 12 is independently formed of one protective tube 41 made of stainless steel or polyethylene. Is supported. As shown in FIG. 3, the protection tube 41 is inserted into the entrance end of the through hole 21, and a gap between the through hole 21 and the protection tube 41 is filled with a curing agent 27 such as urethane foam.

In the inner space at the outlet side of the through hole 21, each of the PC steel strands 12 is drawn out of the protective tube 41 into the inside of the through hole 21, the tubes 12 a and 12 b are removed and separated from each other. Fixing member 28 supported on outer wall surface 20b
Fixed to. The inside of the through hole 21 is filled with grease, and each PC steel strand 12 is configured to receive a tensile load independently. The fixing member 28 is an outer wall surface 20 b of the end wall 20.
It is fixed with a bolt.

As shown in FIG. 4, the fixing member 28 is provided with a wedge-shaped fixing tool 29 for individually holding the strands 12 of each PC steel at predetermined intervals. The fixing device 29 has three wedges 29a fitted into the conical holes 28b of the fixing member 28. The wedge 29a is divided into three in the circumferential direction. The end of the PC stranded wire 12 pulled out of the fixing member 28 is pulled outward by a known tensioning device composed of a hydraulic jack, and the wedge 29a is moved inward of the conical hole 28b (to the left in FIG. 4). When pushed in, the three wedges 29a become P
Strongly engages the outer peripheral surface of C steel strand 12 and PC strand 1
2 is fixed to the fixing member 28. Thus, the required tensile load is applied to the PC steel strand 12. Each PC steel strand 1
2 is tensioned by a tensioning device so as to equally share the tensile load. The fixing member 28 has a cup-shaped oil supply cylinder 32.
Is externally fitted to define an oil injection chamber 33, and P
The end of the C steel strand 12 and the grease are stored. The grease in the oil injection chamber 33 can be changed periodically, and grease is replenished from the oil injection chamber 33 to the through hole 21. The respective PC steel strands 12 can move relative to each other inside the through-hole 21, and with respect to a change in bending load supported by the concrete bridge girder 2,
Each PC steel strand 12 equally distributes the tensile load and acts to suppress the deflection of the concrete bridge girder 2.

In the present invention, in order to obtain liquid tightness particularly at the entrance end of the through hole 21 of the end wall 20, as shown in FIGS. The PC steel wire 12 is inserted into and supported by the 19 through-holes 44 arranged in parallel in each rubber disc 42, and the hardening agent is filled in the inner space 43 of the protective tube 41. In practice, a pair of rubber discs 42 is first fitted over the end of the PC steel strand 12, and then the protective tube 41 is fitted over the pair of rubber discs 42. Then, a curing agent is filled into the inner space 43 of the protection tube 41 through an injection hole (not shown) provided in the protection tube 41 and is cured. At this time, the air in the inner space 42 of the protection tube 41 is discharged to the outside from a relief hole (not shown).

[0014]

As described above, according to the present invention, both ends of a predetermined number of PC stranded wires are inserted into a cylindrical protective tube so as to keep the both ends of the protective tube at equal intervals. A disc made by press-fitting, both ends of the PC steel stranded wire are inserted into through holes regularly arranged in the rubber disc, and a hardener is filled in the inner space of the protective tube. At the entrance end of the through hole in the end wall of the concrete bridge girder, a plurality of PC steel strands are covered with a protective tube, and the gap between the entrance end of the through hole and the protective tube is filled with a hardening agent such as urethane foam. And sealed,
Intrusion of water from the outside and leakage of grease filled in the through hole are suppressed.

[0015] Inside the through hole filled with grease, each P
Since the C steel strands are separated from each other and the ends of each PC strand are independently fixed to the fixing member by the fixing tool,
The strands of steel work to share the tensile load evenly.

Each PC has a gap inside the through hole in the end wall.
Since steel strands are lined up, some PCs were inspected after completion.
If there is play in the steel stranded wire, the tensile load of the PC steel stranded wire can be adjusted by a tension device so that all the PC steel stranded wires can share the tensile load evenly.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a central portion of a concrete bridge girder to which the present invention is applied.

FIG. 2 is a side sectional view showing the right half of the concrete bridge girder.

FIG. 3 is a side sectional view showing a liquid-tight structure of a PC stranded wire end according to the present invention.

FIG. 4 is a side sectional view of the fixing device.

FIG. 5 is a front sectional view of a PC steel strand.

FIG. 6 is a front sectional view of a protection tube for accommodating a terminal of a PC stranded wire.

FIG. 7 is a side sectional view of a protective tube for accommodating a terminal of a PC stranded wire.

[Explanation of symbols]

2: Concrete bridge girder 3: Road surface 4: Upper wall member
5: Side wall 6: Lower wall member 7: Inner space 8: Central support member 9: Through hole 10: Flange 10a: Through hole 12: P
C steel stranded wire 12a, 12a: tube 13: inner space 14, 15: strand 16: core wire 17: gap 18:
Inner space 20: End wall 20b: Outer wall 21: Through hole 2
2: bundle of PC steel strands 27: hardener 28: fixing member 28b: conical hole 29: fixing tool 29a: wedge 3
2: Refueling cylinder 33: Oil injection chamber 41: Protection tube 42: Rubber disk 43: Inner space 44: Through hole

Claims (4)

[Claims] 1. A predetermined number of PC steel stranded wires are inserted into a cylindrical protective tube so as to keep both ends thereof at equal intervals,
Rubber discs are press-fitted into both ends of the protection tube, and both ends of the PC steel stranded wire are inserted into through holes regularly arranged in the rubber disc, and into the inner space of the protection tube. A liquid-tight structure at the end of a PC stranded wire, characterized by being filled with a curing agent. 2. The method according to claim 1, wherein the protective tube is inserted into through holes provided in both end walls of a concrete bridge girder, and a space between the through hole and the protective tube is filled with a hardening agent for obtaining liquid tightness. The liquid-tight structure of the end of the described PC steel strand. 3. The end of the PC stranded wire drawn out of the protection tube is inserted and supported in each fixing device of a fixing member provided on an outer wall surface of an end wall of a concrete bridge girder, and the fixing member of the through hole and the fixing member are connected to each other. The liquid-tight structure at the end of a PC steel stranded wire according to claim 1, wherein rust-preventive oil is filled in an inner space between the protective tube and the protective tube. 4. A center portion of a PC steel stranded wire is inserted into and supported by a plurality of holes of a support member formed in a central lower wall portion of a concrete bridge girder, and a terminal of the PC steel stranded wire is provided on an end wall of the concrete bridge girder. Through the through hole, insert a protective tube covering the PC stranded wire into the inlet end of the through hole, fill a gap between the protective tube and the through hole with a hardening agent, Is closed by a fixing member, each PC steel strand is independently supported by a fixing member by the fixing member, and a refueling box surrounding the fixing member is supported on an outer wall surface of the end wall. A liquid-tight structure at the end of a PC steel stranded wire, wherein the rust-preventive oil filled into the end wall is supplied to the through hole of the end wall via the fixing member.