JPH0516328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a method for manufacturing a prestressed concrete (abbreviated as PS concrete) board using a fiber-based material such as carbon fiber or aramid fiber as a tendon.

<Conventional technology> In conventional PS concrete structures, PC steel wires and
PC steel rods were used. In other words, steel was used for the tension members.

This is because the steel material has high tensile strength and Young's modulus, and has extremely low elongation (%).

《Problems to be solved by the invention》 However, the specific gravity of tension members made of steel is 7.8.
Compared to carbon fiber and aramid fiber, which have a specific gravity of less than 1.9, it is extremely heavy and rusts easily. In particular, due to its tendency to rust, it was not reliable in terms of durability when used in structures along the coast.

Therefore, the use of plastic fibers or carbon fibers has been considered, but there is no fixing means that can withstand the introduction of prestress that fully takes advantage of the tensile strength that is characteristic of these fiber materials. This is because in fixing using conventional wedge-type fixing devices and flat jacks, the fixed portion of the fibrous material breaks due to stress concentration at the fixing portion.

The present invention has been made in view of the above circumstances, and its purpose is to use fiber-based materials as tension materials,
Moreover, it is an object of the present invention to provide a method for producing a PS concrete board using a fiber-based material with excellent workability without using a fixing tool.

<<Means for solving the problems>> In order to achieve the above object, the method for producing a PS concrete board using a fiber-based material according to the present invention is as follows:
A pair of rods are installed spaced apart between opposing formwork members in accordance with the adjustable length of the tendon, at least one of the rods is movable in the same plane direction away from the other rod, and then the pair of rods are moved apart from each other in the same plane direction. A tendon made of fiber material is wound and stretched between the rods, and then the movable rod is forcibly pulled in the direction of tensioning the tendon made of fiber material, and in this state the tendon is stretched. Concrete is poured into the formwork so as to fill it with concrete, and after the concrete has hardened, the means for tensioning the tendons and the formwork are removed.

《Operation》 Tension is applied to the tendons made of fibrous materials before concrete is poured, and the means of applying tension to the tendons is released after the poured concrete has hardened. Structural performance similar to that of Shion PS concrete board can be obtained.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1 to 5 sequentially show the construction procedure, and this order will be explained one by one. This embodiment is for obtaining a long plate-shaped precast concrete plate, and a pair of rectangular plate formworks 1 and 1a that determine the longitudinal direction thereof have the same size and shape.

Holes are formed at both ends of the formworks 1, 1a into which rods 3-3a for winding and locking the fiber tension material are loosely fitted. The holes are formed as circular holes 5, 5a at one end of the molds 1, 1a, and elongated holes 7, 7a long in the longitudinal direction of the molds 1, 1a at the other end. Then, the end of the rod 3 is inserted into the circular hole 5 of the formwork 1. Similarly, the rod 3a is loosely fitted into the elongated hole 7 on the opposite end (see FIG. 1).

Next, the formwork 1a on the opposite side of the formwork 1 is attached to the rods 3, 3a by inserting the circular hole 5 into the rod 3 and the end of the rod 3a into the elongated hole 7a. Fit and formwork 1
and the formwork 1a are parallel to each other, forming a spool shape with rods 3, 3a located at each end. The rod 3a moves freely in the elongated holes 7, 7a in the longitudinal direction of the formworks 1, 1a. In this state, the long carbon fibers 9 are wound around and around between the rods 3 and 3a while being gradually moved from the side of the mold 1 to the side of the mold 1a. The tension of the long carbon fibers 9 due to this winding is sufficient to keep it taut (as shown in Fig. 2).

When winding and tensioning of the carbon long fibers 9 is completed, short form members 11 and 11a having the same width as the forms 1 and 1a are installed between the ends of the forms 1 and 1a in the longitudinal direction. . In this way, the protruding ends of the rods 3a protruding from the elongated holes 7a to the outside of the formworks 1, 1a are pulled in a direction that applies tension to the carbon long fibers 9 using a flat jack or the like. Apply the required tension.

This is because the long carbon fibers 9 are used as tension materials for introducing prestress. Since the rod body 3a moves in the opposite direction to the rod body 3 due to traction by a jack or the like, the length in the longitudinal direction of the elongated holes 7, 7a should be long enough to apply the required prestress to the long carbon fibers 9. It is necessary to form the
figure).

Once the rods 3, 3a have been pulled, the wedges 13 are inserted into the elongated holes 7, 7a to remove the jam so that the rods 3, 3a do not return due to the tensile reaction force of the long carbon fibers 9.
The wedge 13 is effective in increasing the operating efficiency of the jack. Also, if there is not much distance between the rods 3 and 3a, the jacks are not used and the wedge 1
3 into the elongated holes 7, 7a, the required tension can be obtained. However, in the case of span cleats, etc., it is more reliable to use jacks.

After applying the desired tension to the long carbon fibers as described above, the formworks 1 and 1a and the formwork member 11,
Concrete 15 is poured into the formwork surrounded by 11a (see Fig. 4).

Once the concrete 15 has hardened, it is demolded and the wedges 13 are also removed. Both protruding ends of the rods 3 and 3a are cut off to obtain a PS concrete plate 15 (Fig. 5).
It is. When the wedge 13 is pulled out, some traces of the wedge 13 remain as depressions on both sides of the concrete plate 16, so these can be filled with mortar 19 and flattened.

Furthermore, it can be applied not only to such precast products but also to cast-in-place floor slabs and beams. In that case as well, rods are installed at both ends of the tension material made of fiber material in the direction of erection, and each end of the rods is supported by opposing formwork or embedded supporting hardware to form a spool-like structure. However, a fiber tendon material may be wound between the rods. The tensioning procedure is exactly the same as in the previous example.

<<Effects>> As described in detail above, according to the method of manufacturing a PS concrete board using a fiber-based material according to the present invention, a pair of rods are connected between opposing formwork members to extend the length of tension material. At least one of the rods can be moved in the same plane direction away from the other rod, so if you pull the moving rod, the winding between the rods will be completed. Tension can be applied to tendons made of fiber-based materials. The prestress introduced into the fibers is transferred to the concrete by the bearing pressure of the rod, eliminating the need for fixing devices such as fixing devices, and uniform stress is applied to the tendons made of fiber-based materials, resulting in The risk of stress concentrating on the parts and causing them to break has been eliminated.

In addition, since the fibrous material is continuously wound between the rods, the labor of arranging reinforcement is eliminated, and the prestress introduction work is simply by expanding the spacing between the rods, so there is no need to damage the fibers. It only requires expansion work, improves workability, and provides similar structural performance compared to conventional PS concrete. Carbon fiber, aramid fiber, etc. can be used as tendons, so it is not only lightweight, but also We can provide PS concrete plates that are extremely durable even when used for structures such as breakwaters and seawalls.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIGS. 1 to 5 are perspective views sequentially showing the steps of implementation. 1... a pair of formwork, 3... rod, 5... circular hole,
7...Long hole, 9...Carbon long fiber, 11...Formwork member, 13...Wedge, 15...Concrete, 17...
...PS concrete board, 19...mortar.

Claims (1)

[Claims] 1. A pair of rods are provided spaced apart between opposing formwork members in accordance with the adjustable length of the tendon, and at least one of the rods is movable in the same plane direction away from the other rod, Next, a tendon made of fiber material is wound and stretched between the pair of rods, and then the movable rod is forcibly pulled in a direction that tensions the tendon made of fiber material. concrete is poured into the formwork so as to fill the tendon material with concrete, and after the concrete has hardened, the means for tensioning the tendon material and the formwork are removed. using materials based on
How to make PS concrete plates.