JPH09309105A - Manufacture of pc component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a use of a bar tendon material such as a tendon component of comparatively thick diameter or PC steel bars by providing an auxiliary anchoring means of the tendon material on a component end, setting the auxiliary anchoring means before prestress introduction and then introducing prestress into the component. SOLUTION: PC steel bars are provided as a tendon material 2 in a long line pretension bed manufacturing device, and a PPC component 4 is manufactured. A nut 5 and a pressure-bearing plate 6 are provided as an auxiliary anchoring means on the end face of the component 4 to protect the tendon material 2 from being drawn into the component 4 and introduce the prestress to the end of the component. A PC steel material cut into the length required for the length of the component 4 is used as the tendon material 2, and connected with a coupler 3. Namely five PC steel bars of ϕ26mm are used as the tendon material 2, and tension force of 150 tons is introduced. Five components 4 are manufactured simultaneously in the longitudinal direction on a pretension bed by the long line method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretensioning method for producing precast prestressed concrete members such as bridge girders, building members, sheet piles and sleepers.

[0002]

2. Description of the Related Art As a method of manufacturing a precast prestressed concrete (PPC) member, there are a manufacturing method such as a post-tensioning method, a pre-tensioning method, and a method using them in combination. The post-tension PPC member is advantageous when it is a large member or when the number is relatively limited. In comparison, the pre-tension PPC member requires considerably large equipment, but the equipment is versatile. In addition, there is an advantage that a large number of products can be manufactured efficiently, and products of many shapes and sizes are manufactured. FIG. 13 is an explanatory diagram of a long-line manufacturing apparatus 1 for a conventional pre-tension PPC member. This long line type manufacturing apparatus is capable of manufacturing a large number of members at the same time and is widely used.

The manufacturing sequence will be described below. First, as shown in FIG. 13, a required number of tension members 2 such as PC steel strands are stretched between the reaction force posts 13 and the tension posts 11 which are installed at intervals of 50 to 100 m. Next, a mold and a reinforcing bar (not shown) are assembled, and as shown in FIG. 14, a large hydraulic tension jack 12 (300-
500 tons) is urged in the direction of arrow 14 and all tension members 2
Get nervous at the same time. Place concrete in the formwork,
As shown in FIG. 15, the member 4 is formed, heat retention and steam curing are performed, and the strength development of concrete is awaited. When the concrete of the member reaches a predetermined strength, the prestress is introduced into the concrete of the member 4 by returning the hydraulic tension jack 12 in the direction indicated by the arrow 15 and gently unloading, as shown in FIG. FIG. 17 is a detailed view of part C of FIG. 16, after the prestress is introduced, the tension material 2 on the end surface of each member 4 is cut with a gas fusing device, the end part form 21 is removed, and the member 4 is taken out from the manufacturing apparatus. Move to product storage.

However, the greatest drawback of this excellent pre-tension system is as follows. That is, the tension member 2 to which tension is applied is embedded in the concrete member 4 to develop the strength of the concrete, and then the tension member 2 is cut at the end face of the member so that the contraction force of the released tension member 2 causes the concrete member 4 to contract. From the principle of applying a compressive force, the adhesion of the tension material 2 and the concrete is an essential condition. This time,
The adhesion length required to effectively transmit the tension of the tension member 2 to the concrete is slightly different depending on the concrete strength and the surface shape of the tension member, but the tension member 2 is generally used.
It is necessary to have a bond length of about 70 times the diameter (d).

FIG. 19 shows the vicinity of the end portion of such a member, and FIG. 18 shows a conceptual diagram of the prestress distribution at the end portion of the member of FIG. The design prestress amount gradually decreases from the position L = 70d from the end of the member toward the end of the member, and the prestress amount disappears at the end face. This means that the designed amount of prestress cannot be introduced into the portion of the PPC member manufactured by the pretensioning method from the both ends in the longitudinal direction toward the center of 70d. As an extreme example, in a pre-tensioning concrete member having a length of about 140 times or less the diameter of the tendon, most of the pre-stress introduction amount is lost.

Conventionally, a small-diameter tension member has been used to minimize the amount of prestress loss, but a large number of tension members are required to obtain the required design prestress amount.
There was a problem such as tensioning and tensioning of tension material.

[0007]

In the PPC member manufactured by the pretensioning method, it is not possible to introduce a design amount of prestress into the concrete of the length 70d extending from both longitudinal ends toward the center. The present invention compensates for such deficiencies and causes the tension force of the pre-tension type PPC member to act on the concrete over the entire length, and
It is an object to provide a method for introducing prestress to the end of a PC member.

Another object of the present invention is to make it possible to use a tension material having a relatively large diameter or a rod-shaped tension material such as a PC steel rod in a pre-tension type PPC member, thereby reducing the number of tension materials. It is to solve the problem of reducing the number of arrangements and the like.

[0009]

According to the present invention, in manufacturing a precast precast prestressed concrete member, an auxiliary fixing means for a tension member is provided at the end of the member, and the auxiliary fixing means is provided before the introduction of prestress. A method for manufacturing a PC member is characterized in that it is set at a fixing position and then prestress is introduced into the member.

The auxiliary fixing means may be composed of a nut and a pressure plate screwed on the tension member, or may be composed of a wedge and a sleeve fitted on the tension member and a pressure plate. Further, it is preferable that the pressure bearing plate also serves as a reinforcing plate for reinforcing the end portion of the PC member. The tension member may be a bar member having a male screw made of steel or continuous fiber reinforcing material. Here, the member end means the end face of the member or a portion near the end face that is inside the member from the end face of the member. The continuous fiber reinforcing material is a generic term for carbon fiber, glass fiber, aramid fiber, vinylon fiber and the like bound with epoxy resin or the like.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of a long-line pretension bed (manufacturing apparatus) used for carrying out the method of the present invention. This device uses the conventional P as the tension member 2.
An example of manufacturing a PPC member by disposing a PC steel rod instead of the C steel strand is shown. The steps of the work are shown in FIGS.
The process is the same as that of the above-described conventional example described with reference to FIG. 1 to FIG. 4, but is different from the conventional example in the following points. As shown in the detailed view of the portion A in FIG. 1, a nut 5 and a pressure bearing plate 6 are provided on the end surface of the member 4 as auxiliary fixing means to prevent the tension member 2 from being drawn into the member 4 when prestressing is introduced. It prevents it and enables the introduction of prestress to the end of the member. The PC steel material used as the tension material 2 is cut into a length required for the length of the member 4 and is connected by the coupler 3. FIG. 6 shows the details of the portion B in FIG. 4 and shows the fixing state of the auxiliary fixing means with the connecting coupler removed.

As a concrete example, an example in which a beam for a building having a member length of 12 m is manufactured will be described. PC steel rod φ26 as tension material 2
Introduce a tension of 150 tons using 5 mm. As shown in FIG. 1, five members 4 are simultaneously manufactured in a longitudinal direction on a pre-tension bed (manufacturing apparatus 1) in a long line type. As shown in FIG. 2, ten end forms 21 are installed, the reinforcing bars are assembled, and the tension members 2 are placed at predetermined cross-sectional positions of the members.
As shown in FIG. 5, PC steel rods are arranged, holes are punched in each end form, and the PC steel rods 2 are inserted into the pressure plates 6 fitted in the holes as shown in FIG. The two ends of the PC steel rod to be connected are mutually connected by the coupler 3. Then, the PC at the end of the outermost member
The steel rods 2 are connected to the reaction force posts 13 and the tension bars of the tension posts 11 by couplers, respectively. Assemble the side formwork. At this time, the nut mounted in the extending direction due to the tension of the PC steel rod is loosened to a position sufficiently separated from the end form 21. The tension jack 12 simultaneously pulls five PC steel rods to introduce tension.

As shown in FIG. 3, the nut 5 of the PC steel rod 2 of each member, in which concrete has been poured into the form and loosened,
Tighten with a wrench and steam-cure to wait for concrete to develop its strength. When the predetermined concrete strength is obtained, the tension jack 12 is gradually released to transfer the tension force to the member. By removing the couplers of the reaction force posts and the tension bars of the tension posts, the member is taken out from the bed of the manufacturing apparatus 1 as a product (FIG. 4).

As a result, it is possible to prevent the PC steel rod from being drawn into the member at the time of introducing the tension force by the bearing plate 6 and the nut 5, and to introduce the prestress to the end portion of the member. 7 to 10 show another example of means for introducing prestress to the entire length of the member of the present invention. In FIG. 7, a concave portion is provided on the end surface of the member, and after the tendon 2 is cut, the end surface of the member can be finished flush by burying. In FIG. 8, the bearing plate 6 and the nut 5 are left on the end surface of the member in a protruding state. FIG.
Is engraved with a washer-shaped bearing plate 6 by engraving a female screw which is screwed into a tension member, and is fixed flush with the end face of the member. In FIG. 10, the washer-shaped bearing plate of FIG. 9 is buried in the shallow end face.

FIG. 11 shows still another embodiment, which is an example using the PC steel strand 2 as in the conventional example of FIG. The end surface of the member 4 is provided with auxiliary fixing means 7 composed of a known wedge, sleeve and pressure plate, and the wedge is sleeved before the PC steel strand is cut in the gap between the ends of the member 4 after the unloading of the tension jack. It is press-fitted inside with a hammer, etc., and the pressure plate prevents the PC steel wire from getting into the concrete due to cutting.
Even with the auxiliary fixing method using the wedge and the sleeve, as shown in FIG.
~ The method shown in Fig. 10 can be realized.

In the above embodiments, the long line type pre-tension type manufacturing apparatus has been described, but it is needless to say that the same can be done in the short line type, that is, when the members are manufactured one by one. Further, the tension material, the fixing type, and the fixing method can be freely selected without departing from the spirit of installing the auxiliary fixing member at the end.

[0017]

EFFECTS OF THE INVENTION According to the method of the present invention, the problem of loss of prestress near the end of the member, which is peculiar to the precast prestressed concrete member manufactured by the conventional pretensioning method, is solved, and the precast having higher durability Since it becomes possible to manufacture a prestressed concrete member and at the same time, a large-diameter tension material can be used, so that it is possible to expect an effect such as a reduction of the labor for disposing the tension material.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of an example.

FIG. 2 is an explanatory diagram of a manufacturing process of an example.

FIG. 3 is an explanatory diagram of a manufacturing process of an example.

FIG. 4 is an explanatory diagram of the manufacturing process of the example.

FIG. 5 is an enlarged view of a portion A in FIG. 1;

FIG. 6 is an enlarged view of a portion B in FIG. 4;

FIG. 7 is an explanatory diagram of another embodiment.

FIG. 8 is an explanatory diagram of another embodiment.

FIG. 9 is an explanatory diagram of another embodiment.

FIG. 10 is an explanatory diagram of another embodiment.

FIG. 11 is an explanatory diagram of another embodiment.

FIG. 12 is a front view of FIG. 11;

FIG. 13 is an explanatory diagram of a conventional manufacturing process.

FIG. 14 is an explanatory diagram of a conventional manufacturing process.

FIG. 15 is an explanatory diagram of a conventional manufacturing process.

FIG. 16 is an explanatory diagram of a conventional manufacturing process.

FIG. 17 is an explanatory view of a conventional end portion.

FIG. 18 is a graph of a conventional amount of prestress at the end portion.

FIG. 19 is a side view of the end portion.

[Explanation of symbols]

 1 Manufacturing Equipment 2 Tension Material (PC Steel Rod, PC Steel Strand) 3 Coupler 4 Member 5 Nut 7 Auxiliary Fixing Means 11 Tension Post 12 Jack 13 Reaction Force Post 14, 15 Arrow 21 End Form

Claims (5)

[Claims] 1. When manufacturing a precast precast prestressed concrete member, an auxiliary fixing means for a tension material is provided at the end of the member, and the auxiliary fixing means is set at a fixing position at the end of the member before introducing prestressing. A method for manufacturing a PC member, which comprises introducing prestress into the member. 2. The method for manufacturing a PC member according to claim 1, wherein the auxiliary fixing means includes a nut and a pressure plate that are screwed into the tension member. 3. The method for manufacturing a PC member according to claim 1, wherein the auxiliary fixing means includes a wedge and a sleeve fitted on the tension member and a pressure plate. 4. The method of manufacturing a PC member according to claim 1, wherein the pressure bearing plate also serves as a reinforcing plate for reinforcing the end portion of the PC member. 5. The method for manufacturing a PC member according to claim 1, wherein the tension member is a bar member made of steel or continuous fiber reinforcing material and formed with a male screw.