JPH02136235A - Prestressed concrete anchorage and production thereof - Google Patents

Abstract

PURPOSE:To obtain a prestressed concrete anchorage excellent in corrosion resistance and strength by constituting the anchorage of a metal substrate and the coating layer composed of a fiber reinforced thermosetting resin covering the metal substrate. CONSTITUTION:This prestressed concrete anchorage is constituted of a metal substrate 2 having high strength and plastic deformation and the coating layer composed of a fiber reinforced thermosetting resin excellent in corrosion resistance and fixability covering said substrate 2. This anchorage sufficiently corresponds to hoop pressure or compression pressure applied in use by the metal substrate 2 and shows markedly excellent strength. The metal substrate 2 is protected from corrosion by the coating layer 3 composed of the fiber reinforced thermosetting resin and shows markedly excellent corrosion resistance. By this method, the sleeve (outside cone) 1 of the prestressed concrete anchorage excellent in corrosion resistance and strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a prestressed concrete anchor and a method for producing the same, and particularly to a prestressed concrete anchor with excellent corrosion resistance and extremely high strength, and a method for manufacturing the same.

[Prior Art] As is well known, prestressed concrete is a concrete product that is subjected to compressive loads.

As a method of applying this compressive load, a wire rod such as steel is inserted into the through hole of a concrete body provided with a through hole in the longitudinal direction, the wire rod is tensed, and then both ends of the wire rod are fixed to both ends of the concrete body. There is a method of fixing using a fixing body such as a support plate or a bearing plate.

The structure or composition of the fixing body such as the fixing device and the bearing pressure plate,
An extremely large number of types are known.

Fig. 2 is a plan view showing an example of the fixing body, Fig. 3 is Fig. 2 I
FIG. 3 is a sectional view taken along line II-III. Reference numeral 11 indicates an outer cone (sleeve), which has a tapered inner hole 11a. Reference numeral 12 denotes a truncated cone-shaped inner cone that fits into the inner hole 11a and has a center hole of equal diameter. This inner cone 12 is divided into two wedges 12a.
, 12b. The wire rod 13 is inserted into the center hole of the inner cone 12, and the wire rod 13 is pulled out through the wedges 12a and 12b.
Tightening of the wire rod is prevented by force, thereby fixing the wire rod.

In addition, Hochtief, Bilfinger
, Held u.

Various anchors are known, such as Franke, Moraudi, Bauwens, etc.

As described above, a large number of types of fixing devices are known, but steel is widely used as a material because it requires high strength.

Fixtures and bearing plates made of W4 have considerable durability under normal use environments, but in highly corrosive environments they will rust and reduce their strength. At the same time, the deterioration of the surrounding concrete 1 progresses due to the occurrence of rust. (For example, when rust occurs, it undergoes volumetric expansion, which can cause fine racks in the concrete.) Therefore, when conventional prestressed concrete is used, for example, in offshore structures or structures near the coast,
The disadvantage of prestress decreasing relatively early was likely to occur. In addition, it also caused problems in its use in acidic gas environments.

As a countermeasure against this problem, the fixing device and the bearing plate are sometimes made of stainless steel, and a corresponding improvement in durability has been achieved, but the corrosion resistance under strong environments such as salt damage is still insufficient.

For these reasons, the i2 plan has recently been proposed to adopt fiber-reinforced resins such as FRP as anchors for prestressed concrete (Japanese Patent Laid-Open No. 60-2
No. 05117).

[Problems to be solved by the invention] Although prestressed concrete anchors made of FRP have better corrosion resistance than those made of metal, their strength is insufficient, so when compared at the same tension force , must be considerably larger than the metal prestressed concrete constant.

For example, a prestressed concrete anchor made of CFRP (carbon fiber reinforced resin), which has a higher strength than GFRP (glass ia f, 1 reinforced resin), has a higher strength against the same tension than a metal prestressed concrete anchor. It was necessary to make it two to three times the size, and the top and bottom were separated for construction and handling.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a prestressed concrete anchor having excellent corrosion resistance and extremely high strength, and a method for manufacturing the same.

[Means for solving the problem] The prestressed concrete fixing body of claim (1) comprises:
The method for producing a prestressed concrete fixing body according to claim (2), characterized in that it is composed of a metal base and a NF5 made of fiber-reinforced thermosetting resin that covers the metal base, The method for manufacturing a prestressed concrete fixing body according to claim (3), characterized in that the outer surface of the prestressed concrete fixing body is impregnated with a thermosetting synthetic resin liquid while being wound with fibers, and then the impregnated resin liquid is cured. In the method for manufacturing a body, a cylindrical metal base is fitted onto a cylindrical fiber-reinforced thermosetting resin inner member, and then the outer peripheral surface of the metal base is impregnated with a thermosetting synthetic resin liquid. While wrapping the fibers, the end surface portion of the metal base is covered with a thermosetting synthetic resin liquid containing fibers or fibers impregnated with a thermosetting resin liquid,
The method is characterized in that the thermosetting resin liquid is then cured.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a sectional view of a sleeve of a prestressed concrete fixing body according to an embodiment of the present invention. In FIG. 1, a sleeve (outer cone) 1 includes a metal base 2 and a cover made of IA fiber-reinforced thermosetting resin that covers the metal base 2. It is composed of a W layer 3.

The metal base 2 may be made of a material generally used for metal prestressed concrete fixing bodies, and is usually made of steel or stainless steel.

The thermosetting synthetic resin of the fiber-reinforced thermosetting resin that makes up the coating layer has low deformation due to external stress and is weather resistant.
Those with excellent chemical resistance are suitable, and specific examples include epoxy acrylate resins, phenol resins, and amino resins.

As reinforcing fibers for such thermosetting synthetic resins, various inorganic fibers, organic fibers, and carbon fibers may be used alone or in combination. Among them, carbon fiber is preferably used. In this case, the carbon fibers are preferably long fibers with a diameter of about 5 to 10 μm. Carbon fibers with a diameter smaller than the above range are expensive, and carbon fibers with a diameter larger than the above range have poor flexibility.

If the content of such reinforcing fibers is too small, the strength of the resulting coating layer will be insufficient, and if the content is too large, moldability will be impaired.

In the present invention, the reinforcing fiber content in the fiber-reinforced thermosetting resin is preferably 15 to 40% by weight based on the total weight.

If the thickness of the N layer 3 is too thin, the effect of improving corrosion resistance will not be sufficient, and if it is too thick, the metal base will become relatively small and the strength will be insufficient. Therefore, the thickness of the coating layer 3 varies depending on the size and shape of the prestressed concrete anchorage body, or the degree of stress applied to the relevant part, but in the normal case, the thickness of the coating layer 3 is 2 to 10 mm, preferably 5 mm on the side peripheral surface.
The thickness is approximately 10 mm, and the thickness of the end face portion is approximately 10 mm or more.

Such a prestressed concrete anchorage of the present invention is easily manufactured according to the following method.

First, a fiber-reinforced thermosetting resin inner member 3a is molded,
A cylindrical metal base 2 is fitted into this. Here, the inner member 3a may be manufactured by a conventional method, and can be easily manufactured by, for example, a filament winding method. Alternatively, carbon fiber cloth may be laminated, impregnated with thermosetting synthetic resin, and molded. If compression molding is performed during this molding, a molded product with extremely high strength can be obtained.

Then, the fibers are further wound around the side circumference of the metal base 2 while being impregnated with a thermosetting synthetic resin. This winding is preferably radial winding or bias-type multilayer winding in which the winding direction of each layer is alternately reversed. Note that radial winding and bias winding may be alternately laminated. At the same time, both end surfaces of the metal base 2 are covered with a thermosetting synthetic resin liquid containing reinforcing fibers or an in-fiber impregnated with a thermosetting synthetic resin liquid. Thereafter, the sleeve 1 is obtained by curing the thermosetting resin.

In the present invention, pigments and powder fillers may be mixed into the thermosetting resin within a range that does not impair its properties.

In the above description, the sleeve of the fixing device was exemplified, but it goes without saying that the prestressed concrete fixing body of the present invention can also be used for inner cones, bearing plates, etc.

[The prestressed concrete fixing body of claim (1) has the following features:
It is made of a composite material consisting of a metal base with high strength and excellent plastic deformation, and a coating layer made of fiber-reinforced thermosetting resin with excellent corrosion resistance and fixing properties, so it is resistant to hoop stress and compression pressure applied during use. It is fully compatible with metal substrates and exhibits remarkable strength. Furthermore, the metal substrate is protected from corrosion by the coating layer of fiber-reinforced thermosetting resin, and exhibits extremely excellent corrosion resistance. The fixing properties of prestressed concrete are similar to those of fiber-reinforced thermosetting resin fixing bodies.
It has extremely good fixing performance, especially for carbon wood (carbon cable), and does not cause slipping or the like when under tension. Furthermore, since the amount of fiber-reinforced thermosetting resin used is small, material costs can be kept down and the cost of the product can be reduced.

The prestressed concrete fixing body of claim (1) includes:
Due to the strength improvement effect of embedding the metal base,
The size of the fixing body can be reduced, and with the same tension, it can be made about 1/2 to 1/3 the size of a conventional carbon fiber reinforced thermosetting resin fixing body. Take.

Corrosion resistance can also be improved by forming a coating layer of thermosetting resin on a metal substrate, but in this case, the strength of the coating layer is low, and when the coating layer is under stress during use, easily peels off from the metal substrate, making it impractical.

According to the method for manufacturing a prestressed concrete anchoring body of claims (2) and (3), such a high-strength, highly corrosion-resistant prestressed concrete anchoring body can be efficiently manufactured.

[Example] Examples and comparative examples will be described below.

Example 1 The sleeve shown in FIG. 1 was manufactured according to the following procedure.

(2): Manufacturing of the inner member A mold having a shape that matches the tapered inner hole of the sleeve 1 shown in FIG. 1 is prepared. Carbon fiber roving (count: No. 400) was wound around the outer periphery of the mold in 20 layers using a bias method at a rate of 300 times per layer, and at this time, the above-mentioned epoxy acrylate resin (containing a curing agent) was impregnated. In addition,
This mold has flanges at both ends, and the carbon fiber roving is wound around the outer circumferential surface of the mold between the flanges.

In addition, one flange (on the small diameter side of the mold) is removable, and when molding the bottom of the base in step (1) below, the one flange was removed, and then the one flange was attached again and step (2) was performed.

■Mating of two metal bases A metal base was fitted to the inner member (2).

■: Formation of outer covering layer ■ Carbon fiber roving (count: 4
00) by a bias method at a rate of 300 times per layer, and at this time, the above epoxy acrylate resin (containing a curing agent) was impregnated. Further, during this wrapping, the resin-impregnated roving was wrapped so as to also cover the end face portion of the metal base. Thereafter, this was heated to 150°C to harden the resin.

The dimensions of each part of the manufactured sleeve are as follows.

a: 33mm b: 20mm c: 140mm d: 120mm e: 10mm f: 20mm g: 60mm h: 7mm When the obtained sleeve was put to practical use as a prestressed concrete anchor, it was found to be able to withstand a strain of 30 tons. , it was extremely strong.

Comparative Example 1 A carbon fiber reinforced thermosetting resin sleeve having the same shape as the sleeve shown in FIG. The tension was at its limit.

[Effects of the Invention] As detailed above, the prestressed concrete fixing body of claim (1) has both high stress resistance performance due to the metal base and high corrosion resistance and high fixing performance due to the fiber reinforced thermosetting resin coating layer. It is extremely durable. Moreover, according to the prestressed concrete fixing body of the present invention, the amount of fiber-reinforced thermosetting resin used can be reduced, thereby reducing the cost of the product.

Therefore, according to the prestressed concrete fixing body of the present invention, it is possible to provide a prestressed concrete fixing body having high strength and excellent corrosion resistance at a low cost.

Moreover, according to the method for manufacturing a prestressed concrete anchoring body of claims (2) and (3), it is possible to easily and efficiently manufacture such a high-performance prestressed concrete anchoring body.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a prestressed concrete fixing body according to an embodiment of the present invention. FIGS. 2 and 3 are explanatory diagrams of the structure of the fixing device. DESCRIPTION OF SYMBOLS 1... Sleeve, 2... Metal base, 3... Covering layer. Agent Patent Attorney Tsuyoshi Shigeno

Claims (3)

[Claims] (1) A prestressed concrete fixing body composed of a metal base and a coating layer made of a fiber-reinforced thermosetting resin that covers the metal base. (2) A method for manufacturing a prestressed concrete fixing body, which comprises: impregnating the outer surface of a metal base with a thermosetting synthetic resin liquid while wrapping fibers around it, and then curing the impregnated resin liquid. (3) In a method for manufacturing a cylindrical fixing body, a cylindrical metal base is fitted onto a cylindrical inner member made of fiber-reinforced thermosetting resin, and then thermoset is applied to the outer peripheral surface of the metal base. At the same time, the end face of the metal substrate is covered with a thermosetting resin liquid containing the fibers or fibers impregnated with a thermosetting synthetic resin liquid, and then the fibers are impregnated with a thermosetting synthetic resin liquid. A method for producing a prestressed concrete fixing body, characterized by curing a resin liquid.