HK1185638B - Steel structure reinforcement method and reinforcement body, and material for forming elastic layer for steel structure reinforcement - Google Patents

Description

Method for reinforcing steel structure, reinforcing structure, and material for forming elastic layer for reinforcing steel structure

Technical Field

The present invention relates to a method for reinforcing a steel structure, a reinforcing structure, and an elastic layer forming material for reinforcing a steel structure, in which a sheet-like reinforcing fiber-containing material (hereinafter referred to as a "fiber sheet") containing continuous reinforcing fibers is used to repair and reinforce (hereinafter referred to as "reinforcement") a steel structure such as a bridge, a trestle, a chimney, or the like, and further, a ship, a vehicle, an aircraft, or the like.

Background

In recent years, as reinforcing methods for existing or newly installed steel structures, there are methods for bonding a continuous fiber sheet, such as a carbon fiber sheet bonding method in which a continuous reinforcing fiber sheet such as a carbon fiber sheet or an aramid fiber sheet is bonded or wound on the surface, and a method for bonding a continuous fiber sheet such as an aramid fiber sheet bonding method. Further, there is a method of bonding fiber sheets in which an uncured matrix resin is impregnated with continuous fiber bundles and then curing the bonded fiber sheets.

In addition, in order to omit resin impregnation on site, an FRP plate bonding reinforcement method has been developed in which FRP plates produced in a factory and having a plate thickness of 1 to 2mm and a width of about 5cm are bonded with a putty-like bonding resin.

A steel structure reinforced by such a method can obtain a high reinforcing effect by the fiber sheet as long as the fiber sheet is integrally bonded to the steel structure. However, when the fiber sheet is peeled off from the surface of the steel structure before the fiber sheet breaks due to deformation of the steel structure by a load or the like, the intended purpose cannot be achieved.

Therefore, patent document 1 discloses a method of providing a cushion material layer on the surface of a steel structure and then bonding a fiber sheet with an adhesive to reinforce the fiber sheet. Further, it is disclosed that a thermosetting resin, a thermoplastic resin, or the like can be used as the buffer material layer. Further, it is disclosed that the tensile modulus at 23 ℃ of the resin alone when cured is 0.1 to 50N/mm²。

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3553865

Disclosure of Invention

Problems to be solved by the invention

However, as a result of research and experiments by the present inventors, it has been newly found that the problem of the fiber sheet peeling off from the surface of the steel structure when reinforcing the steel structure is different from the case of reinforcing the concrete structure with the fiber sheet, and the temperature of the surface of the steel structure has a large influence. Therefore, when reinforcing a steel structure with a fiber sheet, it is necessary to sufficiently consider the temperature of the surface of the steel structure. The steel structure (steel material) has a larger elongation due to temperature and a larger deflection due to vehicle passage than a concrete structure. Therefore, if a highly rigid continuous fiber sheet is bonded to a steel structure, there is a concern that the fiber sheet may be peeled off from the end portion thereof.

Among them, it is known that steel structures, for example, in our country, rise to temperatures around 60 ℃ on their surface due to direct sunlight in midsummer. Therefore, it is found that if a binder or the like used for reinforcement using a conventional fiber sheet is used, the binder softens due to the high surface temperature, and the necessary reinforcement effect may not be obtained.

In the reinforcement method of patent document 1, if the resin forming the cushion material layer has a low tensile modulus and is reinforced with a highly rigid continuous fiber sheet or the like, the cushion material layer may not transmit the stress that should be originally transmitted to the fiber sheet. That is, in this case, the fiber sheet does not function and cannot be reinforced.

Accordingly, an object of the present invention is to provide a method for reinforcing a steel structure, a reinforcing structure, and an elastic layer forming material for reinforcing a steel structure, which can prevent a fiber sheet from peeling off from the surface of a steel structure before the fiber sheet breaks while preventing a reinforcing effect by the fiber sheet from being unable to be obtained by irradiation of sunlight or the like and obtaining a sufficient reinforcing effect when the steel structure is reinforced with the fiber sheet.

Means for solving the problems

The above object is achieved by a method and a structure for reinforcing a steel structure, and an elastic layer forming material for reinforcing a steel structure according to the present invention. Briefly, according to the present invention of claim 1, there is provided a method for reinforcing a steel structure, which is characterized by bonding and integrating a fiber sheet including reinforcing fibers on a surface of the steel structure, comprising:

(a) coating the polyurea resin putty agent on the surface of the steel structure, curing the polyurea resin putty agent to form an elastic layer,

(b) the fiber sheet is bonded to the surface of the steel structure on which the elastic layer is formed with an adhesive.

According to an embodiment of the present invention as set forth in claim 1, the glass transition temperature of the adhesive used in the step (b) is adjusted so that the reinforcing effect can be maintained even at high temperatures. For example, the glass transition temperature of the binder is 60 ℃ or higher.

According to another embodiment of the present invention according to the 1 st aspect, the polyurea resin putty agent for forming the elastic layer in the step (a) includes a main agent, a curing agent, a filler, and an additive, and has a composition of:

(i) a main agent: the prepolymer is prepared by using isocyanate as a reaction component, and adjusting the content of isocyanate remaining at the end to 1-16 parts by weight in terms of NCO weight%.

(i i) curing agent: using a curing agent containing an aromatic amine as a main component, using the following formula (NCO: amine ratio as 1.0: 0.55 to 0.99 parts by weight of a curing agent.

(iii) Filling agent: contains silica powder, thixotropic agent, etc. in an amount of 1 to 500 parts by weight.

(iv) Additive: contains a colorant, a viscosity modifier, a plasticizer and the like, and is suitably blended in an amount of 1 to 50 parts by weight.

According to another embodiment of the present invention according to claim 1, the binder used in the step (b) is a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin. Further, preferably, the adhesive is an epoxy adhesive provided by 2-component molding of a main agent and a curing agent, and has a composition of:

(i) a main agent: a main agent containing an epoxy resin as a main component and, if necessary, a silane coupling agent or the like as an adhesion-enhancing agent is used.

(ii) Curing agent: epoxy resin containing amine as main component, main agent: each amine equivalent ratio of the curing agent was 1: 1.

according to another embodiment of the present invention according to claim 1, the method further comprises a step of performing a primer treatment and/or a step of applying a primer to the surface of the steel structure before the elastic layer is formed on the surface of the steel structure.

According to another embodiment of the present invention according to claim 1, the fiber sheet is a fiber sheet in which continuous reinforcing fibers laid in one direction are fixed to each other by a thread fixing material. Alternatively, the fiber sheet is a fiber sheet in which a plurality of continuous fiber-reinforced plastic strands obtained by impregnating reinforcing fibers with a matrix resin and curing the impregnated reinforcing fibers are arranged in a curtain shape in the longitudinal direction and the strands are fixed to each other by a strand fixing member. Alternatively, the fiber sheet is a fiber sheet obtained by impregnating a resin into a continuous reinforcing fiber sheet laid in one direction and curing the resin.

According to another embodiment of the present invention as set forth in claim 1, the fiber sheet is laminated and bonded to the surface of the steel structure in a plurality of layers, and is integrated with the steel structure.

According to the invention of claim 2, there is provided an elastic layer forming material for reinforcing a steel structure, which is composed of a polyurea resin putty agent for forming the elastic layer in the method for reinforcing a steel structure described above, wherein the polyurea resin putty agent contains a main agent, a curing agent, a filler, and an additive, and has a composition of:

(i) a main agent: the prepolymer is prepared by using isocyanate as a reaction component, and adjusting the content of isocyanate remaining at the end to 1-16 parts by weight in terms of NCO weight%.

(ii) Curing agent: using a curing agent containing an aromatic amine as a main component, using the following formula (NCO: amine ratio as 1.0: 0.55 to 0.99 parts by weight of a curing agent.

(iii) Filling agent: contains silica powder, thixotropic agent, etc. in an amount of 1 to 500 parts by weight.

(iv) Additive: contains a colorant, a viscosity modifier, a plasticizer and the like, and is suitably blended in an amount of 1 to 50 parts by weight. The polyurea resin putty agent has a tensile elongation of 400% or more and a tensile strength of 8N/mm when cured²Above, tensile modulus of 60N/mm²Above 500N/mm²The following.

According to the present invention of claim 3, there is provided a reinforcing structure for a steel structure, the reinforcing structure reinforcing the steel structure, comprising:

(a) an elastic layer formed by coating a polyurea resin putty agent on the surface of the steel structure,

(b) And a resin-impregnated fiber sheet layer bonded with an adhesive to the surface of the steel structure on which the elastic layer is formed.

In the present invention as defined in claim 3, the elastic layer has a tensile elongation of 400% or more and a tensile strength of 8N/mm when cured²Above, tensile modulus of 60N/mm²Above 500N/mm²The following.

In the present invention according to the 3 rd aspect, the glass transition temperature of the adhesive is adjusted so that the reinforcing effect can be maintained even at a high temperature. For example, the glass transition temperature of the binder is 60 ℃ or higher.

In the present invention of claim 3, the polyurea resin putty agent preferably contains a main agent, a curing agent, a filler, and an additive, and has a composition of:

(i) a main agent: the prepolymer is prepared by using isocyanate as a reaction component, and adjusting the content of isocyanate remaining at the end to 1-16 parts by weight in terms of NCO weight%.

(ii) Curing agent: using a curing agent containing an aromatic amine as a main component, using the following formula (NCO: amine ratio as 1.0: 0.55 to 0.99 parts by weight of a curing agent.

(iii) Filling agent: contains silica powder, thixotropic agent, etc. in an amount of 1 to 500 parts by weight.

(iv) Additive: contains a colorant, a viscosity modifier, a plasticizer and the like, and is suitably blended in an amount of 1 to 50 parts by weight. Further, as the adhesive, a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin is used. Preferably, the adhesive is an epoxy adhesive provided by 2-component molding of a main agent and a curing agent, and comprises the following components:

(i) a main agent: a main agent containing an epoxy resin as a main component and, if necessary, a silane coupling agent or the like as an adhesion-enhancing agent is used.

(ii) Curing agent: epoxy resin containing amine as main component, main agent: each amine equivalent ratio of the curing agent was 1: 1.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the reinforcing method and the reinforcing structure for a steel structure and the material for forming an elastic layer for reinforcing a steel structure of the present invention, it is possible to prevent a situation in which a reinforcing effect cannot be obtained due to irradiation of sunlight, obtain a sufficient reinforcing effect, and prevent a fiber sheet from peeling off from the surface of a steel structure before the fiber sheet reaches a breaking strength.

Drawings

Fig. 1 is a sectional view for explaining an example of a reinforced steel structure of the reinforcing structure and the reinforcing method of a steel structure according to the present invention.

Fig. 2 is a diagram showing an example of a fiber sheet usable in the reinforcing method for a steel structure of the present invention.

Fig. 3 is a diagram showing another example of a fiber sheet usable in the reinforcing method for a steel structure of the present invention.

Fig. 4 is a perspective view showing an example of a fiber sheet usable in the reinforcing method for a steel structure according to the present invention.

Fig. 5 is a sectional view of an example of a fiber-reinforced plastic wire constituting a fiber sheet usable in the reinforcing method for a steel structure of the present invention.

Fig. 6 is a perspective view showing another example of a fiber sheet usable in the reinforcing method for a steel structure according to the present invention.

Fig. 7 is a process diagram illustrating an embodiment of the method for reinforcing a steel structure according to the present invention.

Fig. 8 is a process diagram illustrating another embodiment of the method for reinforcing a steel structure according to the present invention.

Fig. 9 is a diagram illustrating the configuration of a bending strength testing apparatus for confirming the reinforcing method of the steel structure of the present invention.

Fig. 10 is a graph showing the results of a bending test of a steel structure reinforced according to the present invention.

Fig. 11 is a graph showing the results of a bending test of a reinforced steel structure for comparing the present invention with a comparative example.

Fig. 12 is a graph showing the results of a bending test of a reinforced steel structure for comparing the present invention with a comparative example.

Detailed Description

The reinforcing method and reinforcing structure for a steel structure and the elastic layer forming material for reinforcing a steel structure according to the present invention will be described in more detail below with reference to the drawings.

Referring to fig. 1, according to the reinforcing method of a steel structure according to the present invention, a steel structure 100 is integrated by bonding fiber sheets 1 including continuous reinforcing fibers f to the surface thereof through an elastic layer 104.

The method for reinforcing a steel structure according to the present invention is characterized by comprising:

(a) a step of applying and curing a polyurea resin putty agent to the surface 102 of the steel structure 100 to form an elastic layer 104 as a cushion layer,

(b) and a step of bonding the fiber sheet 1 to the surface of the steel structure 100 on which the elastic layer 104 is formed, using a binder 105 whose glass transition temperature is adjusted to 60 ℃ or higher as necessary.

That is, according to the present invention, there is provided a reinforcing structure for a steel structure, comprising:

(a) an elastic layer 104 formed by coating polyurea resin putty on the surface 102 of the steel structure 100,

(b) a resin-impregnated fiber sheet layer 106 bonded to the surface 102 of the steel structure 100 on which the elastic layer 104 is formed with a binder 105. The elastic layer 104 has a tensile elongation of 400% or more and a tensile strength of 8N/mm at the time of curing²Above, tensile modulus of 60N/mm²Above 500N/mm²The following.

According to the present invention, it is preferable that the surface 102 of the steel structure 1 is subjected to a primer treatment before the elastic layer 104 is formed on the surface of the steel structure 100, and then the primer is applied to the surface 102 of the steel structure.

Next, each material used in the present invention will be explained.

(fiber sheet)

Various forms of the fiber sheet 1 can be used in the present invention. Specifically, examples of the fiber sheet 1 will be described as specific examples 1 to 3, but the form of the fiber sheet 1 used in the present invention is not limited to the forms shown in these specific examples.

Example 1

Fig. 2 shows an embodiment of a fiber sheet 1 that can be used in the present invention. The fiber sheet 1 is a resin-unimpregnated fiber sheet 1A in which continuous reinforcing fibers f are aligned in one direction and formed in a sheet shape.

That is, the fiber sheet 1A can be configured to hold a reinforcing fiber sheet composed of continuous reinforcing fibers f aligned in one direction by the wire fixing member 3 serving as a mesh-like support sheet or the like. For example, when carbon fibers are used as the reinforcing fibers f, for example, the reinforcing fibers f are prepared by6000 to 24000 single fibers (carbon fiber single fibers) f having an average diameter of 7 μm and not impregnated with resin are bundled in parallel in one direction and used. The carbon fiber sheet 1A usually has a fiber basis weight of 30 to 1000g/m²。

The surfaces of the vertical lines 4 and the horizontal lines 5 constituting the mesh-like support sheet as the wire fixing material 3 are impregnated with a low-melting thermoplastic resin in advance, the mesh-like support sheet 3 is laminated on one or both surfaces of the carbon fibers arranged in a sheet form, and the carbon fiber sheet is fused at the portions of the vertical lines 4 and the horizontal lines 5 of the mesh-like support sheet 3 by heating and pressurizing.

The mesh-like support sheet 3 may be formed by orienting glass fibers along 3 axes, or may be formed by arranging only transverse lines 5 in which glass fibers are orthogonal to carbon fibers arranged in one direction, so-called 1-axis orientation, in addition to the 2-axis configuration, and may be bonded to the carbon fibers in a sheet-like arrangement.

As the strands of the wire fixing material 3, for example, a composite fiber having a double structure in which a core portion is made of glass fibers and a low-melting-point heat-fusible polyester is arranged around the core portion is also preferably used.

Example 2

As shown in fig. 3, the fiber sheet 1 may be a reinforcing fiber sheet in which a plurality of reinforcing fibers f are arranged in one direction, for example, a fiber sheet 1A shown in fig. 2 is impregnated with a resin Re and the resin is cured (so-called FRP plate) 1B.

In the fiber sheets 1A and 1B described in the above concrete examples 1 and 2, the reinforcing fibers f are not limited to carbon fibers, and glass fibers or basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and organic fibers such as aramid, PBO (poly p-phenylene benzobisoxazole), polyamide, polyarylate, polyester, and the like, singly or in combination.

As the resin Re in the case of the fiber sheet 1B in specific example 2, a thermosetting resin or a thermoplastic resin can be used, and as the thermosetting resin, an epoxy resin, a vinyl ester resin, an MMA resin, an acrylic resin, an unsaturated polyester resin, a phenol resin, or the like which is curable at room temperature or thermosetting is preferably used, and as the thermoplastic resin, nylon, vinylon, or the like can be suitably used. The resin impregnation amount is 30 to 70 wt%, preferably 40 to 60 wt%.

Example 3

As shown in fig. 4 and 5, as the fiber sheet 1, a fiber sheet 1C in which a plurality of continuous fiber-reinforced plastic strands 2 having a small diameter and cured and impregnated with the matrix resin R are combined in a curtain shape in the longitudinal direction and the strands 2 are fixed to each other by the strand fixing member 3 can be used.

The fiber-reinforced plastic wire 2 may have a substantially circular cross-sectional shape with a diameter (d) of 0.5 to 3mm (FIG. 5 (a)), or may have a substantially rectangular cross-sectional shape with a width (w) of 1 to 10mm and a thickness (t) of 0.1 to 2mm (FIG. 5 (b)). Of course, other various cross-sectional shapes can be formed as necessary.

As described above, in the fiber sheet 1 which is formed into a curtain shape by doubling in one direction, the respective thread materials 2 are separated from each other only by the gap (g) =0.05 to 3.0mm, and are fixed by the thread material fixing member 3. The length (L) and width (W) of the fiber sheet 1 formed in this way are appropriately determined according to the size and shape of the structure to be reinforced, and the total width (W) is generally set to 100 to 1000mm in view of handling problems. Further, a long fiber sheet having a length (L) of about 1 to 5m or a fiber sheet having a length of 100m or more can be produced and cut appropriately for use.

The fiber sheet 1C may be manufactured so that the length (L) is about 1 to 5m and the width W is about 1 to 10m longer.

In the case of the fiber sheet 1C, carbon fibers, glass fibers, basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and organic fibers such as aramid, PBO (poly p-phenylene benzobisoxazole), polyamide, polyarylate, polyester, and the like, singly or in combination. The matrix resin R with which the fiber-reinforced plastic strand 2 is impregnated can be a thermosetting resin or a thermoplastic resin, and as the thermosetting resin, an epoxy resin, a vinyl ester resin, an MMA resin, an acrylic resin, an unsaturated polyester resin, a phenol resin, or the like which is curable at room temperature or thermosetting is preferably used, and as the thermoplastic resin, nylon, vinylon, or the like is preferably used. The resin is impregnated in an amount of 30 to 70 wt%, preferably 40 to 60 wt%.

Further, as a method of fixing each wire 2 with the wire fixing material 3, as shown in fig. 4, for example, the following method can be employed: a sheet-shaped wire material composed of a plurality of wires 2 arranged in a curtain shape in one direction, i.e., a continuous wire material sheet, is laid at a predetermined interval (P) perpendicular to the wires and is knitted by using a horizontal wire as the wire material fixing member 3. The beating-up interval (P) of the transverse threads 3 is not particularly limited, and is usually selected within the range of 10 to 100mm intervals in consideration of the handleability of the produced fiber sheet 1.

In this case, the transverse threads 3 are threads formed by bundling a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm, for example. As the organic fiber, nylon, vinylon, or the like is suitably used.

As another method of fixing the respective wires 2 in a curtain shape, as shown in fig. 6 (a), a mesh-like support sheet can be used as the wire fixing member 3.

That is, a plurality of wires 2, that is, a wire sheet, which are formed in a sheet form and are combined in a curtain shape, may be supported on one side or both sides by a mesh-like support sheet 3 having the same configuration as that described in the above-mentioned specific example 1, which is made of, for example, glass fibers or organic fibers having a diameter of 2 to 50 μm.

As another method for fixing the respective wires 2 in the form of a curtain, as shown in fig. 6 (b), a flexible tape such as a pressure-sensitive adhesive tape or an adhesive tape can be used as the wire fixing member 3. The flexible tape 3 is fixed by attaching one side surface or both surfaces of a plurality of fiber-reinforced plastic wires 2 in a direction perpendicular to the longitudinal direction of each of the fiber-reinforced plastic wires 2 formed in a sheet form and formed by cord-like doubling.

That is, as the flexible tape 3, a pressure-sensitive adhesive tape or an adhesive tape such as a vinyl chloride tape, a paper tape, a cloth tape, or a nonwoven fabric tape having a width (w 1) of about 2 to 30mm is used. The tapes 3 are bonded to each other at intervals (P) of usually 10 to 100mm in a direction perpendicular to the longitudinal direction of each fiber-reinforced plastic strand 2.

The flexible tape 3 is also formed by thermally fusing a thermoplastic resin such as nylon or EVA resin in a band shape on one side or both sides in a direction perpendicular to the longitudinal direction of the wire 2.

(reinforcing method)

Next, a method of reinforcing a steel structure will be described with reference to fig. 7. According to the present invention, the fiber sheet 1 manufactured as described above is used to reinforce a steel structure.

That is, according to the reinforcing method of a steel structure of the present invention, for example, the fiber sheet 1A prepared by laying reinforcing fibers f in one direction as described in the above-mentioned specific example 1 can be used as the fiber sheet 1, and the elastic layer 104 formed on the surface of the steel structure can be bonded and integrated with the adhesive 105. At this time, the fiber sheet 1A can be bonded to the steel structure and impregnated with the binder (matrix resin) of the fiber sheet 1A using the binder.

This forms a reinforcing structure 200 of a steel structure having an elastic layer 104 and a fiber sheet layer 106 to which the resin-impregnated fiber sheet 1 is bonded.

In reinforcing the steel structure 100, the member (structure) that receives mainly bending moment and axial force is bonded to the member by aligning the orientation direction of the reinforcing fibers substantially with the main stress direction of tensile stress or compressive stress generated by the bending moment, so that the fiber sheet 1 can effectively bear stress, and the load-bearing capacity of the structure can be improved efficiently.

When a bending moment acts in the orthogonal 2-direction, the 2 or more layers of the fiber sheets 1 are orthogonally laminated and bonded so that the orientation direction of the reinforcing fibers f of the fiber sheets 1 substantially coincides with the main stress generated by the bending moment, thereby efficiently improving the load resistance.

(step 1)

As shown in fig. 7 (a) and (b), the brittle portion 101a of the reinforced surface (i.e., the bonded surface) 101 of the steel structure 100 is removed by a grinding device 50 such as a disc grinder, sandblast, shot blast, or water spray, as necessary, and the bonded surface 101 of the steel structure 100 is subjected to a primer treatment.

(step 2)

An epoxy-modified urethane resin primer 103 is applied to the surface 102 subjected to the primer treatment (fig. 7 (c)). The primer 103 is not limited to the epoxy-modified urethane resin, but may be an MMA resin, and is appropriately selected depending on the material of the elastic layer 104 (fig. 7 (d)) and the steel structure 100 to be reinforced.

The step of applying the primer 103 can be omitted.

(step 3)

The polyurea resin putty agent 104 is applied to the surface 102 having been subjected to the base treatment in a desired thickness (T) and cured to form the elastic layer 104 (fig. 7 (d)). The coating thickness (T) is appropriately set according to the unevenness of the surface 102 to be bonded and the thickness T of the fiber sheet 1, and is generally about T =0.2 to 10 mm.

In the present invention, the polyurea resin putty agent having a low elastic modulus, that is, the material forming the elastic layer 104 (elastic layer forming material) contains a main agent, a curing agent, a filler, an additive, and the like, and one example of the composition thereof is as follows.

(i) A main agent: the prepolymer is prepared by using isocyanate (such as 4, 4' -diphenylmethane diisocyanate) as a reaction component, and adjusting the amount of isocyanate remaining at the terminal to 1-16 parts by weight based on NCO wt%.

(ii) Curing agent: a curing agent containing an aromatic amine (for example, an amine value of 80 to 90) as a main component is used, and the ratio of NCO: amine ratio was 1.0: 0.55 to 0.99 parts by weight of a curing agent. In addition, p-toluenesulfonate and the like can be contained as a curing accelerator.

(iii) Filling agent: contains silica powder and thixotropic agent in an amount of 1-500 parts by weight.

(iv) Additive: contains a colorant, a viscosity modifier, a plasticizer and the like, and is suitably blended in an amount of 1 to 50 parts by weight.

Wherein the polyurea resin putty agent has a tensile elongation of 400% or more (usually, 400 to 600%) and a tensile strength of 8N/mm when cured²Above (usually, 8 to 10N/mm)²) Tensile modulus of 60N/mm²Above 500N/mm²The following (usually, 60 to 100N/mm)²）。

If the modulus of elasticity is less than 60N/mm²It is impossible to transmit the necessary reinforcing stress, and conversely, if it exceeds 100N/mm²In particular, if it exceeds 500N/mm²The problem of insufficient elongation performance arises.

Further, since the polyurea resin is used as the putty agent, it is desirable that the viscosity at 23 ℃ at 2 revolutions measured by a BM type viscometer is 200 to 700 pas, the rotation number at 20 revolutions is in the range of 60 to 100 pas, and the ratio of the thixotropic index, i.e., the measured values of the viscosity at different revolutions measured by a rotational viscometer (viscosity at 20 revolutions divided by 2 revolutions) is 4 to 7.

That is, if the viscosity is less than 60 pas, the thixotropic index is less than 4, sagging occurs after coating, and the smoothness of the coated surface and the coating on the roof surface and wall surface become difficult, whereas if the viscosity is greater than 100 pas, the thixotropic index exceeds 7, the resin becomes hard, mixing becomes problematic, and smooth coating also becomes difficult.

Here, table 1 below shows the results of comparing the physical properties of the epoxy resin putty agent having the above composition, which is a material for forming the cushion material layer described in patent document 1, and the polyurea resin putty agent having the above composition, which is a material for forming the elastic layer used in the present invention.

[ Table 1]

	Prior Art	The invention	Remarks for note
				Tensile elongation of the buffer layer	100-200％	423％	Large deviation
Tensile strength of the buffer layer	0.1-50N/mm2	8.04N/mm2	Uniformity
				Tensile modulus of the buffer layer	0.1-50N/mm2	61.3N/mm2	Deviation from
Amount of filler	0 to 50% by mass	33.1% by mass	Uniformity
				Specification of coating thickness	100～2000μm	1000μm	Uniformity

[ Table 2]

Temperature dependence of buffer layer on tensile modulus

Test temperature	Prior Art	The invention
			-20℃	1600N/mm2	99.2N/mm2
0℃	1500N/mm2	85.1N/mm2
			23℃	100N/mm2	61.3N/mm2
40℃	12N/mm2	61.0N/mm2
			60℃	12N/mm2	61.0N/mm2

From the above table 1 and the results of the table of the relationship between the temperature and the elastic modulus of the cushion layer (table 2), it is understood that when the epoxy resin putty agent is used, the elongation and the toughness cannot be made to coexist, and particularly, the raw material strength of the epoxy resin is lowered at a high temperature, and the steel reinforcing effect cannot be exerted. In addition, the tensile properties are extremely reduced at low temperatures in winter, and the film becomes hard and early peeling is achieved.

The polyurea resin putty agent used in the present invention can exhibit stable performance from-20 ℃ to + 70 ℃. Therefore, the polyurea resin putty agent can be used as an elastic layer forming material for reinforcing a steel structure, can achieve the effects of preventing peeling and repairing reinforcement without being affected by temperature, and can be very suitably used in a reinforcing construction method for a steel structure.

(step 4)

As shown in fig. 7 (e) and (f), when the resin putty agent is cured to form the elastic layer 104, the adhesive 105 is applied to the elastic layer 104, and the fiber sheet 1 is pressed against the surface and bonded to the surface 102 of the concrete structure to be reinforced 100 via the elastic layer 104.

The binder 105 is preferably a binder having a glass transition temperature adjusted to 60 ℃ or higher, usually 70 to 100 ℃, for application at high temperatures. As described above, the steel structure 100, i.e., the steel material, in our country, has a surface temperature of about 60 ℃ due to direct sunlight in midsummer. Therefore, it is found that the binder used for reinforcement using a fiber sheet according to the conventional method is softened at this temperature, and the necessary repair reinforcement effect may not be obtained.

Therefore, by using a binder having a glass transition temperature of preferably 60 ℃ or higher, and usually 70 to 100 ℃, as the binder 105, it is possible to avoid the situation where the reinforcing effect cannot be obtained by irradiation of sunlight, to obtain a sufficient reinforcing effect, and to avoid peeling from the surface of the steel structure before the fiber sheet reaches the breaking strength.

As the adhesive having such characteristics, a room temperature curing type epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, a photo-curing type resin, and the like can be mentioned, and specifically, a room temperature curing type epoxy resin and an MMA resin are preferable.

In this example, an epoxy adhesive was used. The epoxy resin adhesive is provided by 2-component molding of a main agent and a curing agent, and one example of the composition thereof is as follows.

(i) A main agent: a main agent containing an epoxy resin as a main component and, if necessary, a silane coupling agent as an adhesion-enhancing agent is used. The epoxy resin may be, for example, a bisphenol type epoxy resin, particularly a rubber-modified epoxy resin for imparting toughness, and further, a reactive diluent and a thixotropic agent may be added according to the use.

(ii) Curing agent: using a curing agent containing an amine as a main component, a curing accelerator if necessary, a colorant or the like as an additive, an epoxy resin as a main component: the amine equivalent ratio of the curing agent is 1: 1. the amine may be, for example, an aliphatic amine comprising m-xylylenediamine and isophoronediamine. The glass transition temperature of the epoxy resin having the composition is 70 ℃ or higher (74 ℃).

The adhesive 105 is described as an adhesive applied to the elastic layer 104, and may be applied to the fiber sheet 1, or may be applied to both the surface of the elastic layer 104 and the surface to which the fiber sheet 1 is bonded.

When the necessary reinforcement amount is large, a plurality of layers of the fiber sheet 1 may be bonded to the surface of the structure. However, if a plurality of fiber sheets 1 are laminated and bonded, stress concentration may occur at the end portions, and the peel failure resistance may be lowered.

Therefore, in order to prevent the peel failure, as shown in fig. 8, it is preferable to change the sheet length (L) (see fig. 1) of the fiber sheet 1 of each layer. For example, the length of the fiber sheets 1 stacked in multiple layers becomes shorter in the order from the structure surface 102 to the outer layer distant therefrom, and the end portions 1a of the fiber sheets 1 are stacked in a stepwise manner. The offset length (h) of the end portion 1a is preferably about 30mm to 300 mm. For example, good results can be obtained by bonding the sheet ends 1a so that they are shortened by 100mm on average.

That is, by sequentially shortening the length (L) of the multi-layered fiber sheet 1 to the outer layer by about 30 to 300mm and laminating the end portions 1a in a step shape, the stress concentration at the sheet end portions 1a can be reduced, and the peeling resistance can be improved.

Next, the following experiments were performed in order to confirm the effects of the reinforcing method and the reinforcing structure for a structure and the elastic layer forming material for reinforcing a steel structure according to the present invention.

Experimental example 1

In this experimental example, a steel material as the steel structure 100 was reinforced by the bonding method using the fiber sheet 1. The fiber sheet 1 used in the present experimental example is the fiber sheet 1A having the configuration described as specific example 1 with reference to fig. 2.

As the reinforcing fibers f in the fiber sheet 1A, pitch-based carbon fiber bundles having an average diameter of 10 μm and a number of 6000 bundles of fibers not impregnated with resin were arranged in one direction to form fibersWeight per unit area 300g/m²And making into tablet. A 2-axis mesh support 3 made of glass fibers was welded to one side of the sheet-like reinforcing fibers to prepare a fiber sheet 1A.

The fiber sheet 1 of the fiber sheet 1A thus prepared had a width (W) of 500mm and a length (L) of 50 m. In the present embodiment, the fiber sheet is cut out as appropriate and used.

Next, using the fiber sheet 1, the steel material 100 as a steel structure is reinforced as described below by a fiber sheet bonding method similar to the method described with reference to fig. 7. However, in this experimental example, the fiber sheet 1 was attached to the lower surface side of the steel material 100.

First, in the present experimental example, the lower surface of the steel material 100 was ground and swept by shot blasting to have an appropriate rough surface. The surface 102 of the steel material 100 was coated with 0.15kg/m²The epoxy-modified polyurethane primer (FORCAUL-1 (trade name) manufactured by Nippon iron マテリアルズ Co., Ltd.) 103.

In a state where the epoxy modified urethane resin primer 103 is touch-dried and the coated surface is a back surface, the polyurea resin putty agent having the above composition is applied to a steel material (test sample) 100 to have a thickness (T) of about 1mm by a doctor blade so as to form the elastic layer 104. In this case, the polyurea resin putty does not drip down by its own weight even after the coating is completed, and adheres to the steel material sample 100.

The putty-like polyurea resin used as the resin for forming the elastic layer 104 had a viscosity of 600 pas at 23 ℃ with a BM type viscometer at 2 revolutions and 95 pas at 20 revolutions.

The thixotropic index (viscosity at 20 revolutions/viscosity at 2 revolutions) was 6.32.

Next, the polyurea resin putty agent applied to the steel material surface 102 is cured to form the elastic layer 104. The elastic layer 104 was coated with a coating weight of 0.4kg/m²Coated with the above composition having a glass transition temperature of 74 DEG CEpoxy resin (as a primer layer for each layer when the fiber sheet 1 is laminated in multiple layers). Next, the fiber sheet 1 was lightly pressed against the epoxy resin-coated surface, and then a plastic roll having a width of 100mm and a diameter of 10mm was moved while applying a pressing force of about 100N to the fiber sheet 1. The fiber sheet was formed by laminating all 7 layers of the fiber sheet with the binder. Specifically, 5 layers of "carbon fiber sheet C830" (trade name)) made by seiki iron マテリアルズ (ltd) were stacked, and 2 layers of "carbon fiber sheet C160" (trade name)) made by seiki iron マテリアルズ (ltd) were stacked.

By rolling the sheet 1 with a plastic roller, the epoxy resin is in a state of bleeding out from the gaps between the fibers of the fiber sheet 1, and is not peeled off in a state of being stuck to the steel material 100 even if it is not held at all.

Further, in the case of laminating a plurality of fiber sheets 1 as in the case of the present example, the coating amount of each layer was 0.2kg/m as the top coat layer of each layer²The epoxy resin 105 was applied to the surface of the fiber sheet 1, and the surface was finished flat with a rubber blade. Then, it was aged at room temperature for 1 week. No voids are formed on the bonded surface of the fiber sheet 1, and the fiber sheet can be bonded to the steel material 100 extremely well.

Using the fiber-sheet-reinforced steel material (invention) 100 produced as described above and an epoxy-impregnated adhesive having a glass transition temperature of 48 ℃ as an adhesive, a 3-point bending test was performed using a test apparatus shown in fig. 9, in which the distance Ls between the fulcrums was 80mm, for the fiber-sheet-reinforced steel material 100 using a urethane resin putty agent (comparative example 1) and a soft epoxy resin putty agent (comparative example 2) as putty agents. The steel material 100 had a cross section of W0=25mm in width, T0=2.0mm in thickness, and L0=100mm in total length. The 3 test pieces were produced using the same structure and material, except that the adhesive 105 for bonding the fiber sheet to the steel surface and the putty agent 104 were different as described above.

The constituent materials of the present invention and comparative examples 1 and 2 in this experiment are summarized as shown in table 3 below.

[ Table 3]

	Putty agent	Impregnated adhesive	Continuous fiber sheet
				The invention	Polyurea resin putty	Tg74 ℃ epoxy	C830 × 5 layers + C160 × 2 layers
Comparative example 1	Polyurethane resin putty	Tg48 ℃ epoxy	C830 × 5 layers + C160 × 2 layers
				Comparative example 2	Soft epoxy putty	Tg48 ℃ epoxy	C830 × 5 layers + C160 × 2 layers

The results of the bending test are shown in fig. 10 and 11. The following is focused on the bending test chart of the temperature/load change shown in fig. 11.

That is, in the case of comparative example 1, the load was reduced at around 30 ℃ and the epoxy resin impregnated adhesive was softened. On the other hand, the properties of epoxy resins which harden at low temperatures are utilized, showing high loads. In this situation, the weather conditions and the repair reinforcement performance in japan cannot be satisfied on the high temperature side.

In the case of comparative example 2, the soft epoxy resin putty was hardened at a low temperature by the temperature, and the separation was achieved early before the load was increased. This indicates a failure to reinforce the condition. The high temperature side comes to peel due to early material failure of the soft epoxy putty.

In contrast, the polyurea resin putty agent of the present invention exhibits stable performance from low temperatures to high temperatures, and confirms the establishment of a repair reinforcing material and a construction method that meet the national weather conditions in Japan.

Experimental example 2

In this experimental example, a steel material as the steel structure 100 was reinforced by the bonding method using the same fiber sheet 1 as described in the above experimental example 1.

That is, in the fiber sheet reinforced steel material (invention) 100 of the present invention, similarly to the above experimental example 1, the fiber sheet 1 prepared as described above was attached to the steel material 100 by using the urethane-modified epoxy resin primer as the primer 103, the polyurea resin putty agent having the above composition as the putty agent for the elastic layer 104, and the epoxy resin having the above composition with the glass transition temperature of 74 ℃ as the binder 105.

Comparative example 3 the fiber sheet 1 produced as described above was attached to the steel material 100 by using an epoxy resin primer as the primer 103, without using a putty agent for the elastic layer 104, and further using an epoxy resin having the above-described composition with a glass transition temperature of 74 ℃ as the binder 105.

Comparative example 4 the fiber sheet 1 prepared as described above was bonded by using an epoxy-modified urethane resin primer as the primer 103 and a polyurea resin putty agent as the putty agent for the elastic layer 104, as in the same manner as used in the above experimental example 1, but using an epoxy resin having a glass transition temperature of 48 ℃ (FR-E3P (trade name) manufactured by seiki iron マテリアルズ, ltd.) as the binder.

The bending test was performed in the same manner as in experimental example 1 using 3 test bodies prepared as described above. The results of the test are shown in table 4 and fig. 12.

[ Table 4]

Unit (N)

The following can be understood from the bending test chart with temperature/load change shown in fig. 12.

Comparative example 3 the fiber sheet 1 was adhered to the steel material 100 using the same high Tg epoxy resin adhesive with a glass transition temperature of 74 ℃ as the present invention as the adhesive, but without using the polyurea resin putty agent. Therefore, in comparative example 3, the effect of the polyurea resin putty agent (elastic layer 104) was not obtained, and the steel material was not sufficiently reinforced at the same time as the temperature was increased, as compared with the present invention. In comparative example 3, the epoxy resin adhesive was also finally peeled off in the same manner as in comparative example 2.

Comparative example 4 used the same polyurea resin putty agent as the present invention, but used a relatively low Tg epoxy adhesive with a glass transition temperature of 48 ℃ as the adhesive. In this case as well, the peeling of the fiber sheet layer 106 does not occur similarly to the present invention due to the effect of the polyurea resin putty agent (elastic layer 104), but the bending load is gradually reduced from about 48 ℃. That is, in comparative example 4, the fiber sheet layer 106 using the carbon fiber showed a curved state together with the steel material. Therefore, at high temperatures, the glass transition temperature of the binder must be adjusted in order to obtain a reinforcing effect, and in order to cope with the temperature required for the climate conditions, the glass transition temperature of the binder is required to be 60 ℃ or higher, preferably 70 ℃ or higher.

As described above, according to the method for reinforcing a steel structure, the reinforcing structure, and the material for forming an elastic layer for reinforcing a steel structure according to the present invention, the steel structure 100 can be effectively reinforced.

Description of the reference numerals

1 fiber sheet

2 fiber reinforced plastic wire

3 wire fixing material (horizontal line, screen support sheet, flexible strip)

100 steel structure

103 primer

104 elastic layer

105 adhesive

106 fiber sheet layers

200 reinforcing structure

Claims (10)

1. A method for reinforcing a steel structure, which is a method for reinforcing a steel structure in which a fiber sheet containing reinforcing fibers is bonded to the surface of a steel structure and integrated, the method comprising the steps of:

(a) coating the polyurea resin putty agent on the surface of the steel structure, curing the polyurea resin putty agent to form an elastic layer,

(b) bonding the fiber sheet to the surface of the steel structure on which the elastic layer is formed by an adhesive,

the stretching at the time of curing of the polyurea resin putty agentThe length rate is more than 400 percent, and the tensile strength is 8N/mm²Above, tensile modulus of 60N/mm²Above 500N/mm²In the following, the following description is given,

the glass transition temperature of the binder is 60 ℃ or higher.

2. The method for reinforcing a steel structure according to claim 1, wherein the adhesive is a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin.

3. A method of reinforcing a steel structure according to claim 1, wherein a step of treating the surface of the steel structure with a primer and/or a step of applying a primer is provided before the elastic layer is formed on the surface of the steel structure.

4. The method of reinforcing a steel structure according to claim 1, wherein the fiber sheet is a fiber sheet in which continuous reinforcing fibers laid in one direction are fixed to each other with a wire fixing material.

5. A reinforcing method for a steel structure according to claim 1, wherein said fiber sheet is a fiber sheet obtained by arranging a plurality of continuous fiber-reinforced plastic strands, which are obtained by impregnating reinforcing fibers with a matrix resin and curing, in a cord-like manner in a longitudinal direction and fixing the strands to each other with a strand fixing material.

6. The method for reinforcing a steel structure according to claim 1, wherein the fiber sheet is a fiber sheet obtained by impregnating a resin into a continuous reinforcing fiber sheet laid in one direction and curing the resin.

7. The method for reinforcing a steel structure according to claim 1, wherein the fiber sheet is laminated and bonded to the surface of the steel structure in a plurality of layers, and is integrated with the steel structure.

8. The elastic layer forming material for reinforcing a steel structure is an elastic layer forming material for reinforcing a steel structure, which is composed of a polyurea resin putty agent for forming an elastic layer in the following method for reinforcing a steel structure,

the method for reinforcing a steel structure, which is a method for reinforcing a steel structure in which a fiber sheet containing reinforcing fibers is bonded to the surface of a steel structure and integrated, is characterized by comprising the steps of:

(a) coating the polyurea resin putty agent on the surface of the steel structure, curing the polyurea resin putty agent to form an elastic layer,

(b) bonding the fiber sheet to the surface of the steel structure on which the elastic layer is formed by an adhesive,

the polyurea resin putty agent has a tensile elongation of 400% or more and a tensile strength of 8N/mm when cured²Above, tensile modulus of 60N/mm²Above 500N/mm²The following.

9. A reinforcing structure for a steel structure, which is a reinforcing structure for reinforcing a steel structure, is characterized by comprising:

(a) an elastic layer formed by coating polyurea resin putty agent on the surface of the steel structure,

(b) a resin-impregnated fiber sheet layer bonded to the surface of the steel structure on which the elastic layer is formed with a binder having a glass transition temperature of 60 ℃ or higher,

the elastic layer has a tensile elongation of 400% or more and a tensile strength of 8N/mm when cured²Above, tensile modulus of 60N/mm²Above 500N/mm²The following.

10. The reinforcing structure for a steel structure according to claim 9, wherein the binder is a room temperature curable epoxy resin, an epoxy acrylate resin, an acrylic resin, an MMA resin, a vinyl ester resin, an unsaturated polyester resin, or a photocurable resin.