JP3848557B2 - Structure of anchorage of prestressed concrete - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a fixing portion of prestressed concrete.
[0002]
[Prior art]
The PC method (prestressed concrete method) refers to a method in which concrete is introduced by applying a compressive force to the concrete in advance so as to cancel out the tensile stress generated in the concrete due to the dead load and live load loaded on the concrete structure. .
There are various methods for introducing prestress into PC steel and mechanisms for fixing.
[0003]
As a method for constructing a conventional prestressed concrete a, there is a method of applying tension to a PC steel material e such as a steel wire by a post tension method, for example (shown in FIG. 4). This applies a tensile force to the PC steel material e in the sheath tube f placed inside the placed ordinary concrete b after the ordinary concrete b is hardened, and fixes the end of the PC steel material e to the fixing tool d. The reaction force is transmitted to the ordinary concrete b through the, and a compressive force is applied.
As reinforcement of the ordinary concrete b against this reaction force, the spiral reinforcement c3 and the like are arranged in a range where the reaction force affects.
In addition, in the tension introducing method by the pre-tensioning method, unlike the fixing mechanism by the post-tensioning method, the fixing is performed by adhering the concrete and the PC steel material e. Therefore, the fixing length of the PC steel material e is required to be long. .
[0004]
[Problems to be solved by the invention]
The conventional prestressed concrete fixing portion structure has the following problems.
<A> In order to fix the PC steel material by the post-tension method, the end portion of the strained PC steel material is fixed to the fixing tool, and the reaction force is transmitted to the structure through the pressure bearing device.
For this reason, materials, labor, and time, such as a pressure bearing apparatus, are needed.
<B> In the post-tension method, a reinforcing material such as a spiral bar is disposed as a reinforcement to withstand the reaction force exerted on the concrete.
As a result, material costs are increased, and as the bar arrangement increases, assembly becomes complicated and it becomes difficult to place concrete. As a result, quality may be impaired.
<C> When tension is introduced by the pre-tension method, fixing is performed by the adhesive force between concrete and PC steel, so that the fixing length of PC steel is required to be long.
Therefore, fixing efficiency is deteriorated, and fixing of a large diameter PC steel material is difficult.
[0005]
OBJECT OF THE INVENTION
The present invention has been made to solve the above-described conventional problems, and provides an economical prestressed concrete anchoring part structure that does not require materials such as bearing members and spiral bars in fixing PC steel. The purpose is to do.
In addition, it is possible to reduce the fixing part size and the distance between PC steel fixings, and to shorten the fixing length of the pre-tension method, providing an economical and excellent workability of the prestressed concrete fixing part structure. The purpose is to do.
In particular, an object of the present invention is to provide a structure of a fixing portion of prestressed concrete that can achieve excellent quality by easily placing concrete.
The present invention achieves at least one of these objects.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, the structure of the fixing portion of the prestressed concrete according to the pretensioning method of the present invention includes a fixing portion that holds resistance to tension of the PC steel material made of a fiber reinforced cementitious composite material, The general part in contact with the fixing part is composed of ordinary concrete having a lower strength than the fiber reinforced cementitious composite material, a tensile force is applied to the PC steel material in advance, and a partition material is arranged on the joint surface between the fixing part and the general part. that Te blocked pouring range of both concrete immediately after Da設each concrete, it is constituted by integrating both as integrated both by removing the partition member eliminating the droplet seam It is a feature.
[0007]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1
Embodiments of the structure of a fixing portion of prestressed concrete according to the present invention will be described below with reference to the drawings.
[0008]
<A> Prestressed concrete Prestressed concrete 1 is composed of concrete and PC steel material 4, and the portion composed of concrete is divided into a fixing part 2 and a general part 3.
The fixing portion 2 is a portion that holds a resistance against the tension of the PC steel material 4 and is provided with a fiber reinforced cementitious composite material. The fixing unit 2 does not require reinforcing reinforcing bars such as main bars and hoop bars, but can also be used.
Further, the general part 3 is a part in contact with the fixing part 2, and ordinary concrete is placed thereon.
Here, the PC steel material 4 is a PC steel strand, a PC steel bar, a PC steel wire, a steel material, and the like, and any of them may be used.
As a method of introducing prestress, methods such as a post-tension method and a pre-tension method can be used.
Further, the fiber reinforced cementitious composite material and the ordinary concrete may be cast simultaneously, or a general method of jointing may be used.
As an example of construction of the prestressed concrete 1, for example, it can be constructed as a part of a bridge floor slab 9 as shown in FIG.
[0009]
<B> Fixing part The fixing part 2 is a part that holds the resistance against tension of the PC steel material 4 and is made of a fiber reinforced cementitious composite material. It is also possible to arrange the sheath tube 8 inside the fiber reinforced cementitious composite material, arrange the PC steel material 4 inside thereof, and fix it by the fixing tool 71.
At this time, the fiber reinforced cementitious composite material is a portion that receives a reaction force via the pressure plate 72 as a fixing base for the reaction force by the fixing tool 71.
Further, the PC steel material 4 can be arranged directly in the fiber reinforced cementitious composite material, adhered, and fixed.
[0010]
<C> Fiber Reinforced Cementitious Composite Material The fiber reinforced cementitious composite material exhibits high performance in compressive strength, bending strength, tensile strength, and the like, and is excellent in adhesion to ordinary concrete, PC steel material 4 and the like. The fiber-reinforced cement-based composites, for example, powder of cement and silica, silica fume, silica sand, 180 kg of about a water units guess the superplasticizer (finished concrete volume 1 m ³ per) (ratio of water / cement 20 The volume of ultra-high-strength steel fibers having a diameter of 0.1 to 0.3 mm, a length of 8 to 12 mm, and a tensile yield stress of 2500 to 2800 N / mm ² is added to a high-strength cement-based matrix to which about 22% is added. Fiber reinforced cement having properties of compressive strength of 200 to 220 MPa, bending strength of 40 to 45 MPa, adhesion strength of 15 to 90 MPa, air permeability coefficient of 2.5 × 10 ⁻¹⁸ m ² , elastic modulus of 55 GPa. A composite material can be used.
The ultra high strength steel fiber may be of a kind such as metal fiber or organic fiber, or may not be contained.
In addition, as a structure of a fiber reinforced cementitious composite material, it is not always necessary to have the above structure.
Further, by using the fiber reinforced cementitious composite material, it is possible to make the fixing portion 2 streakless. Further, a casting type fixing device is not required, and the reaction force from the PC steel material 4 can be received only by the bearing plate 72.
[0011]
<D> General part The general part 3 is a part in contact with the fixing part 2 and is usually provided with ordinary concrete.
In addition to ordinary concrete, known fiber reinforced concrete can also be used.
The general part 3 does not require as much strength as the fixing part 2. For this reason, it can be constituted by ordinary concrete having a strength lower than that of the fiber-occupied cement-based composite material of the fixing unit 2.
Like the fixing unit 2, it is not necessary to arrange reinforcing reinforcing bars such as main bars and hoop bars in the general part 3, but they can be used as needed.
By comprising in this way, material cost can be reduced.
[0012]
Second Embodiment of the Invention
The structure of the fiber reinforced cementitious composite material constituting the fixing unit 2 is an unreinforced structure that is not arranged in the first embodiment of the invention, but can be arranged as necessary.
FIG. 3 shows a prestressed concrete structure in which the fixing portion 2 is laid.
Here, the types of reinforcing bars to be arranged are the main reinforcement 52, the hoop reinforcement 51, and the like, and the necessary diameter and the required number can be arranged at predetermined positions as necessary.
[0013]
【Example】
Hereinafter, a method for constructing prestressed concrete will be described with reference to the drawings.
[0014]
<A> Construction by post-tension method This method is one of the methods of introducing pre-stress. After hardening the cast fiber reinforced cement composite material and ordinary concrete, the sheath tube 8 is used with the fiber reinforced cement composite material as a fixing base. This is a method in which a tensile force is applied to the PC steel material 4 disposed therein and fixed by a fixing tool 71, which is fixed to a fiber reinforced cementitious composite material via a support plate 72 and prestressed. It is also possible to construct the sheath tube 8 without using it.
At this time, the reaction force received by the fixing tool 71 can be covered by the bearing plate 72 having a smaller area. This is because the structure can sufficiently resist the concentrated reaction force applied to the fiber-reinforced cementitious composite material.
[0015]
<B> Construction by pre-tension method The pre-stress introduction method by this method is to apply a tensile force to the PC steel material 4 before placing the fiber reinforced cementitious composite material and ordinary concrete, and to set the PC steel material after hardening both the concrete materials. This is a method of constructing prestressed concrete 1 by cutting 4.
This is a method of applying prestress by adhesion of PC steel material 4 to concrete. As a result, the fixing length can be shortened from the properties such as adhesion and compressive strength of the fiber reinforced cementitious composite material. Moreover, the diameter of the PC steel material 4 which can be fixed by adhesion can be made larger than before.
[0016]
<C> Construction of the joint As a method for placing concrete, a partition material is disposed on the joint end face 6 which is a joint surface between the fiber reinforced cementitious composite material and ordinary concrete to block the placement range of both concretes, Immediately after placing each concrete, it is possible to remove the partition material and integrate them together.
Further, it can be performed by a general joining method using a lath net or the like. In this case, remove the loose aggregate and latency of the concrete surface that will become the joint surface, and after sufficiently supplying water, apply cement paste or mortar, and immediately after that, place the fiber reinforced cementitious composite material and tighten it sufficiently. It may be hardened.
[0017]
There are no particular restrictions on the curing method for fiber reinforced cementitious composite materials such as normal temperature curing and high temperature curing.
In addition, the place where curing is performed is not particularly limited by factory / production yard curing, on-site curing, and the like, and can be performed by a method necessary for design.
[0018]
【The invention's effect】
Since the structure of the fixing portion of the prestressed concrete according to the present invention is as described above, the following effects can be obtained.
<A> When prestressed concrete is constructed by the post-tension method, materials such as a pressure bearing device and a spiral bar for reinforcing the tension of the PC steel material can be eliminated, leading to cost reduction.
Moreover, the complicated assembly accompanying installation of a spiral reinforcement etc. becomes unnecessary, and workability and work safety are improved, and the construction period is shortened.
Furthermore, since the structure is simplified, it is easy to place concrete, and the quality can be more reliably ensured.
<B> When introducing tension by the pre-tension method, the fixing length can be shortened because the fiber-reinforced cement-based composite material with high adhesion can be used, and the diameter of the PC steel material that can be fixed can be increased. This will also lead to cost reduction and the range of use will be expanded.
[Brief description of the drawings]
FIG. 1 is an explanatory view of an embodiment of an unreinforced structure of a fixing portion of prestressed concrete according to the present invention.
FIG. 2 is an explanatory diagram of an example of prestressed concrete.
FIG. 3 is an explanatory diagram of an example of a reinforcing bar arrangement structure of a prestressed concrete fixing portion according to a second embodiment;
FIG. 4 is an explanatory diagram of a structure of a fixing portion of a conventional prestressed concrete.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Prestressed concrete 2 ... Fixing part 3 ... General part 4 ... PC steel

Claims (1)

In the structure of anchorage of prestressed concrete by the pretension method,
The fixing part that holds the resistance to the tension of the PC steel is composed of a fiber reinforced cementitious composite material,
The general part in contact with the fixing part is composed of ordinary concrete having a lower strength than the fiber reinforced cementitious composite material,
Apply tensile force to PC steel in advance,
A partition material is arranged on the joint surface between the fixing part and the general part to block the placement range of both concrete,
Immediately after Da設each concrete, characterized in that are constituted by integrating both to eliminate the droplet seams by removing the partition member,
Structure of anchorage part of prestressed concrete.

Images