Method for preventing fall of high strength bolt using paint

Abstract

To provide a construction method for more easily preventing the falling of a high-strength bolt due to delayed fracture than before.SOLUTION: The present invention relates to a method for preventing a drop of a high-strength bolt using a coating material for preventing the drop of the high-strength bolt attached to a predetermined attachment target, the method including a main material treatment of applying an anti-drop coating material having a tensile strength of 10 to 70N / mm2, an elongation at break of 100 to 500%, and a waterproofness of 3800 to 4500 g / m2 to a surface of the attachment target.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a construction method for preventing high-strength bolts from falling using paint. [Background technology]

[0002] Traditionally, F11T bolts (hereafter simply referred to as "F11T") have been used as a jointing method for steel bridges and other bridges. Numerous cases of F11T bolt breakage due to delayed fracture have been confirmed, making it necessary to replace the bolts, but due to the vast amount of remaining F11T, emergency measures such as fall prevention nets and bolt caps have been implemented. However, recent inspection reports have reported numerous instances of deterioration of fall prevention nets and bolt caps over time, making their maintenance and management a burden.

[0003] Patent document 1 also discloses that an optical fiber cable is arranged in the internal axial direction of the bolt as a material that is less susceptible to delayed fracture and has high elongation capacity, and the optical fiber cable prevents the bolt from falling off due to delayed fracture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-172127 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the high-strength bolt described in Patent Document 1 requires an optical fiber cable to be installed inside, resulting in a complex structure.

[0006] An object of the present invention is to provide a method for preventing high-strength bolts from falling off using paint, which makes it easier than ever to prevent high-strength bolts from falling off due to delayed fracture. [Means for solving the problem]

[0007] In order to solve this problem, the present invention provides a method for preventing high-strength bolts from falling off using paint that prevents high-strength bolts attached to a predetermined object from falling off, and the method is based on a method for preventing high-strength bolts from falling off using paint that prevents ... 2 ], elongation at break 100-500 [%], and coating amount 3800-4500 [g / m 2 The main material treatment is to apply a waterproof urethane resin-based anti-fall paint to the surface of the object to be attached.

[0008] In the construction method of the present invention, the main material treatment has a first step and a second step, and in the first step and the second step, a waterproof paint is applied at 1900 to 2250 g / m 2 The total amount of coating is 3800-4500g / m2 in the first and second processes. 2 It is preferable to apply the fall prevention paint in an amount of 1000 ppm.

[0009] In the construction method of the present invention, the high-strength bolts are preferably F11T or F13T. [Effects of the Invention]

[0010] The method for preventing high-strength bolts from falling using the paint of the present invention makes it possible to prevent high-strength bolts from falling due to delayed fracture more easily than conventional methods. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a flowchart showing the flow of a construction method for preventing high-strength bolts from falling using paint in this embodiment. [Figure 2] FIG. 10 is a diagram showing the surface condition of a high-strength bolt that has been treated to prevent falling. [Figure 3] 1 is a table showing the name of the paint, the painting method, and the amount of paint applied in each step of a construction method for preventing high-strength bolts from falling using a paint according to an embodiment of the present invention. [Figure 4]FIG. 1 is a diagram showing an outline of a test device for performing a drop weight test on a high-strength bolt with fall prevention measures. [Figure 5] FIG. 10 is a diagram showing the test results of a drop weight test using a test device, showing a state where there is no protrusion. [Figure 6] 1 is a table showing test results of an example and a comparative example. [Figure 7] FIG. 10 is a diagram showing the results of a drop weight test using a testing device, showing a state in which there is no protrusion but cracks have occurred. [Figure 8] FIG. 10 is a diagram showing the test results of a drop weight test in a comparative example, showing a state with a protrusion. [Figure 9] 1 is a chart showing the names of paints, painting methods, and application amounts used in each step of the conventional construction method. [Figure 10] 10 is a flowchart showing the flow of a construction method according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] An example of the present invention will be described below with reference to the drawings, but the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are specified for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range.

[0013] The following describes a construction method (application method) for preventing high-strength bolts from falling using paint according to this embodiment, with reference to the drawings. Note that the technical scope of the present invention is not limited to the following embodiment, but extends to the inventions set forth in the claims and their equivalents.

[0014] Figure 1 is a flowchart showing the flow of a construction method (hereinafter referred to as the present construction method) for preventing high-strength bolts from falling using paint according to this embodiment. The high-strength bolts that are the target of this construction method in this embodiment are, for example, F11T or F13T. A huge number of F11T or F13T bolts remain in steel bridges and other structures, and it is necessary to prevent these high-strength bolts from falling when they suffer delayed fracture and break.

[0015] Delayed fracture is a phenomenon in which a material subjected to a certain stress suddenly breaks after a certain period of time has passed. The material breaks suddenly and brittlely without any apparent plastic deformation, and it is said that it is difficult to accurately predict when the material will break.

[0016] The construction method according to the present embodiment can prevent high-strength bolts used in joints of steel bridges from falling when they break due to delayed fracture. This construction method will be described below.

[0017] First, the surfaces of the steel plates that make up the steel bridge and the high-strength bolts attached to the steel plates are subjected to surface preparation, which involves removing rust, dust, oil, and other contaminants that have adhered to the surfaces of the steel plates and the heads of the high-strength bolts, making the surfaces smooth.

[0018] Fig. 1 is a flowchart showing the flow of the method according to this embodiment. Next, as shown in Fig. 1, a first paint is applied to the surface of the high-strength bolt and the surface of the steel plate around the high-strength bolt, which have been subjected to the general surface preparation described above, as a surface preparation (step S11). The surface preparation is a treatment for improving adhesion to the second paint used in the primer treatment (step S12).

[0019] For the surface treatment, a paint containing, for example, a water-based organic zinc-rich paint is used as the first paint, and a total of 500 to 600 g / mm is applied by brush. 2As the first paint, a paint containing a water-based organic zinc-rich paint was used, but the present invention is not limited to this, and for example, an epoxy resin paint or a urethane resin paint may be used, and the epoxy resin paint or the urethane resin paint may be either a one-component or two-component type, and may be water-based or solvent-based.

[0020] The surface treatment may be applied multiple times. For example, the first layer of the surface treatment is a first paint containing a water-based organic zinc-rich paint applied with a brush at a rate of 250 to 300 g / mm 2 After the first paint applied in the first layer has dried and hardened, the second layer is similarly applied with a brush at a coating amount of 250 to 300 g / mm. 2 Apply in an amount of 1000 and cure.

[0021] Next, a primer treatment is performed (step S12) in which a second paint is applied to the surface of the steel plate and the surface of the high-strength bolts that have been subjected to the surface treatment (step S11). The primer treatment is a treatment for preparing the surface of the steel plate and the surface of the high-strength bolts to improve adhesion with the third paint, which is the main material treatment described below.

[0022] For primer treatment, a one-component moisture-curing urethane paint is used as the second paint, and a total of 50 to 150 g / mm is applied by brush. 2 Although a one-component moisture-curing urethane paint was used as the second paint, the present invention is not limited to this, and for example, a two-component urethane paint or a two-component epoxy paint may also be used.

[0023] Next, a main material treatment is carried out (step S13) in which a third paint having waterproof properties is applied over the second paint on the surface of the steel plate and the surface of the high-strength bolts that have been subjected to the primer treatment (step S12). The main material treatment carried out in step S13 is a so-called waterproof treatment. In the main material treatment, a paint that can form a coating film that is not only waterproof but also has excellent load-bearing properties is preferred as the third paint.

[0024] Here, the coating film formed by the third coating material has an elongation at break of 80% or more, preferably 130 to 1000%, particularly preferably 100 to 500%, and a tensile strength of 8 N / mm 2 or more, preferably 10 to 70 N / mm 2 , particularly preferably 12 to 50 N / mm 2 When the coating has such physical properties, it is also excellent in water resistance and load resistance. The thickness of the coating film is preferably 3000 to 4000 μm, and the total amount of coating required to form the coating film is 3800 to 4500 g / m at most. 2 It is preferable that the tensile strength is the maximum strength against a tensile force after the third paint has hardened. The elongation is the maximum elongation when pulled after the third paint has hardened until it breaks. The coating thickness is the thickness (height) of the waterproof coating per unit area. Since the coating thickness can be calculated from the amount applied per unit area, the physical properties of the coating film may be specified by either the coating thickness or the amount applied.

[0025] As a third paint capable of forming a coating film with excellent water resistance and load resistance, an oil-based paint (non-aqueous paint) called a one-component urethane resin-based waterproofing material is preferred, which contains resin components, pigment components, solvent components, and additive components in specified proportions.

[0026] The reason for waterproofing with the third paint is to prevent hydrogen embrittlement, which is one of the causes of delayed fracture. Hydrogen embrittlement is a phenomenon in which high-strength bolts become brittle due to a reaction between the steel material of the bolt and hydrogen when used in corrosive environments such as outdoors or underwater.

[0027] The main material treatment may be applied multiple times. For example, the first layer of the main material treatment is the third paint (one-component urethane resin waterproofing paint) applied with a brush at 1900 to 2250 g / m 2 After the third paint of the first layer has dried and hardened, the third paint (one-component urethane resin waterproofing paint) is similarly applied to the second layer with a brush at an application rate of 1900 to 2250 g / m. 2Apply the amount of this as the second layer of the main material and allow to harden.

[0028] In this case, the main material treatment involves applying the third paint in two layers, the first and second, at a total of 3800 to 4500 g / m. 2 The coating amount is as follows:

[0029] Next, a topcoat treatment is performed (step S14) to apply a paint to form a surface protective layer over the third paint on the surface of the steel plate and the surface of the high-strength bolt that have been subjected to the main material treatment (step S13). The surface protective layer is provided to improve the corrosion resistance, weather resistance, etc. of the surface of the steel plate and the surface of the high-strength bolt, and generally corresponds to a primer coating film, intermediate coating film, or topcoat coating film in the paint industry. The surface protective layer may be a topcoat coating film alone, or it may be a laminate of multiple layers of primer coating films and topcoats. It may also have two or more layers of each of primer coating films, intermediate coating films, and topcoat coating films. In this specification, the paint to form the primer coating film is referred to as the fourth paint, the paint to form the intermediate coating film is referred to as the fifth paint, and the paint to form the topcoat coating film is referred to as the sixth paint.

[0030] The paint used to form the surface protective layer is, for example, at least one selected from the group consisting of acrylic resin paints, urethane resin paints, epoxy resin paints, chlorinated polyolefin paints, silicone resin paints, and fluororesin paints, and the paint is preferably formed into a coating film consisting of 1 to 4 layers, and may be a water-based paint, a solvent-based paint, or a solventless paint. The primer paint and intermediate paint can be provided for the purpose of improving adhesion between the main material layer and the topcoat paint, and are preferably formed from a urethane resin paint or an epoxy resin paint. The topcoat paint can be provided for the purpose of imparting weather resistance, and is preferably formed from a urethane resin paint, a silicone resin paint, or a fluororesin paint.

[0031] FIG. 2 shows the surface condition of a high-strength bolt that has been treated for fall prevention using the present method. This figure shows the surface condition after the first coating material used in the base treatment (step S11), the second coating material used in the primer treatment (step S12), the third coating material used in the main material treatment (step S13), and the fourth through sixth coating materials used in the topcoat treatment have all been applied and cured to the surface 31a of the steel plate 31 and the head 32h of the high-strength bolt 32 using the present method. In the following description, the entire coating consisting of the first coating material used in the base treatment (step S11), the second coating material used in the primer treatment (step S12), the third coating material used in the main material treatment (step S13), and the fourth through sixth coating materials used in the topcoat treatment (step S14) may be referred to as fall prevention coating material 40. As can be seen from FIG. 2, the fall prevention coating material 40 is thickly applied to the surface 31a of the steel plate 31 and the head 32h of the high-strength bolt 32.

[0032] In this way, in the method of this embodiment, the third paint having the above-mentioned properties is applied in a total amount of 3800 to 4500 g / m 2 With this application amount, it is possible to apply a thicker coating than conventionally to the head 32h of the high-strength bolt 32 and the surrounding surface 31a of the steel plate 31. As a result, even if the high-strength bolt 32 breaks due to delayed fracture, the high-strength bolt 32 can remain attached to the surface 31a of the steel plate 31, and fragments of the high-strength bolt 32 can be prevented from falling off.

[0033] <One Example> Fig. 3 is a chart showing the names of paints, painting methods, and application amounts used in each step of this method in one embodiment. One embodiment of the present invention will be explained below using Fig. 3. In the surface preparation corresponding to the first step (first layer) of this method, a first paint containing a water-based organic zinc-rich paint is applied with a brush at 250 g / mm on the surface 31a of the steel plate 31 that has been subjected to surface preparation and on the surface of the head 32h of the high-strength bolt 32. 2After the first paint has dried and hardened, the second step (second layer) of the base treatment is similarly carried out by applying the first paint containing the water-based organic zinc-rich paint with a brush at a rate of 250 g / mm. 2 Therefore, in the surface preparation, a total of 500g / mm is applied in two steps. 2 The first paint containing the water-based organic zinc-rich paint is applied to the surface of the head 32h of the high-strength bolt 32 and the surface 31a of the steel plate 31 around the high-strength bolt 32, and then cured.

[0034] Next, in the primer treatment corresponding to the third step, a one-component moisture-curing urethane paint is used as the second paint, and a total of 100 g / mm is applied with a brush. 2 Apply in the amount of coating.

[0035] Next, in the first layer of the main material treatment corresponding to the fourth step, the third paint (a paint containing a one-component urethane resin-based waterproofing material) is applied by brushing at a concentration of 2000 g / m on the second paint on the surface 31a of the steel plate 31 that has been subjected to the primer treatment and on the surface of the head 32h of the high-strength bolt 32. 2 After the third paint of the first main layer has dried and hardened, the third paint (a paint containing a one-component urethane resin waterproofing material) is applied with a brush at a rate of 2000 g / m2 in the second layer of the main material treatment, which corresponds to the fifth step. 2 Therefore, in the main material treatment, it is divided into two layers (4th and 5th steps) and hardened with a total of 4000 g / m 2 The third paint is applied to the surface of the head 32h of the high-strength bolt 32 and the surface 31a of the steel plate 31 around the high-strength bolt 32, and then cured.

[0036] Finally, in the top coating treatment corresponding to the sixth step, fourth to sixth paints (for example, urethane resin paints) are applied by brush to the third paint on the surface 31a of the steel plate 31 that has been subjected to the main material treatment and on the surface of the head 32h of the high-strength bolt 32 in a total amount of 140 g / m. 2 Apply in an amount of 1000 and cure.

[0037] 4 is a diagram showing an outline of a test device 20 for conducting a drop weight test on a high-strength bolt 32 that has been treated with a fall prevention measure using a fall prevention paint 40. A drop weight test was conducted using the test device 20 on the high-strength bolt 32, which is the test object having the above-mentioned fall prevention paint 40 applied to the high-strength bolt 32 and the surface 31a of the steel plate 31 surrounding the high-strength bolt 32, in order to evaluate the protrusion protection performance of the high-strength bolt 32.

[0038] This test device 20 is a device for evaluating whether or not a high-strength bolt 32 has protrusion protection performance that prevents fragments of the high-strength bolt 32 from protruding and falling from the surface 31a of the steel plate 31 to which it is attached when delayed fracture occurs in the high-strength bolt 32. The test device 20 reproduces the state in which the high-strength bolt 32 protrudes from the surface 31a of the steel plate 31 when a weight 22 is dropped from above and hits the high-strength bolt 32. Therefore, the steel plate 31 and the high-strength bolt 32 are not threadedly connected, and are fixed together only by the fall-prevention paint 40.

[0039] As shown in FIG. 4 , the testing apparatus 20 includes two fixed bases 21, a weight 22, and a support base 23. The fixed bases 21 are two H-shaped steel beams spaced a predetermined distance apart to match the width of the steel plate 31. The weight 22 is, for example, a spherical or block-shaped metal mass that is dropped from a predetermined height above the fixed bases 21. The weight 22 is naturally dropped in the vertical direction indicated by arrow E from a predetermined height on the opposite side of the steel plate 31 from the fixed bases 21. The support base 23 is a cylindrical body that is arranged on the fixed bases 21 so that the weight 22 collides with the central axis of the high-strength bolt 32 when dropped. Specifically, the weight 22 is placed on the support base 23 above the fixed base 21, at a height of, for example, 32 cm from the fixed base 21. However, this is not limited to this, and the weight 22 may be dropped from a height of 32 cm from the fixed base 21 by an operator.

[0040] In the high-strength bolt 32 being the test object, the head 32h of the high-strength bolt 32 is exposed from the surface 31a of the steel plate 31. In addition, in the high-strength bolt 32, the shank 32s of the high-strength bolt 32 is inserted through a through-hole in the steel plate 31, and the shank 32s and the nut 33 attached to the end of the shank 32s are exposed from the back surface 31b. In this case, the high-strength bolt 32 is simply inserted through the through-hole in the steel plate 31 and is not screwed together, but is fixed to the surface 31a of the steel plate 31 only by the fall prevention paint 40. The thickness of the steel plate 31 is 16 mm.

[0041] In this test device 20, the formula for calculating the energy when a vertical PC steel rod protrudes was applied as the energy that protrudes from the steel plate 31 when the high-strength bolt 32 breaks due to delayed fracture. In this case, the required performance of the high-strength bolt 32 was set to be that the high-strength bolt 32 would not protrude from the surface 31a of the steel plate 31 even when a weight 22 weighing 5 kg was dropped from a support stand 23 with a height of 32 cm.

[0042] The calculation formula for energy W when the high-strength bolt 32 protrudes from the surface 31a of the steel plate 31 is given by the following formula (1). W=(N 2 L) / (4EA)………………………………………………………………(1) Here, as shown in the table below, N means axial force, and for example, the standard axial force for F11T is set to 238kN, which is the design axial force multiplied by 1.1. L means the thickness of the fastening member, and is set to 85mm, which is the thickness of the fastening member for M22 (bolt diameter 22mm). E is the elastic modulus, and the elastic modulus of steel is set to 205kN / mm. 2 A is the cross-sectional area of ​​the high-strength bolt 32, and the cross-sectional area of ​​M22 (bolt diameter 22 mm) is 380.1 mm 2 It was decided. [Table 1]

[0043] This energy calculation formula (1) can be replaced with the following formula (2) according to the law of conservation of energy. W=mgh…………………………………………………………………………………(2) m: mass of weight = 5 kg, g: gravitational acceleration (m / s 2 ), h: Fall height of the weight (mm) By modifying this equation (2), the height h to which the weight 22 is dropped in the testing device 20 can be calculated using the following equation (3). h=W / mg…………………………………………………………………………(3)

[0044] From this, the height h from which the weight 22 is dropped in the testing device 20 can be calculated to be approximately 32 cm.

[0045] Fig. 5 shows the results of a drop weight test using the test apparatus 20. Fig. 5 shows a state in which high-strength bolt 32 coated with fall-prevention coating 40 according to one embodiment of the present invention was subjected to an impact from a weight 22 dropped from a height of 96 cm (height h × 3), but the high-strength bolt 32 did not protrude from the surface 31a of the steel plate 31. In this way, the applicant confirmed that high-strength bolt 32 did not protrude from the surface 31a of the steel plate 31, even when weight 22 was dropped from a support stand 23 with a height of 96 cm (32 cm × 3) using the test apparatus 20.

[0046] <Comparison results> FIG. 6 is a table showing the comparative results of the evaluation test using the test device 20 of FIG. 4. In the case of the fall prevention paint 40 used in this step of Example 1 and Example 2, even when the weight 22 was dropped, the high-strength bolt 32 did not protrude from the surface 31a of the steel plate 31 in both cases. Example 1 and Example 2 had a tensile strength of 10 (N / mm 2 ), elongation at break (250%), and coating weight (4000 g / m 2 ) had the same values, with the only difference being whether or not the surface was primed. In this case, in Example 2, where the surface was not primed, the high-strength bolts 32 did not protrude, but cracks occurred on the surface of the fall prevention paint 40.

[0047] 7 shows the results of the drop weight test for Example 2, which was not subjected to a surface treatment, and shows that there was no protrusion, but cracks 43 occurred on the surface of the fall prevention paint 40. In this case, although cracks 43 occurred in the fall prevention paint 40, the high-strength bolts 32 did not protrude, and no fragments fell.

[0048] In contrast, the fall prevention paint of Comparative Example 1 had an elongation rate of 250% at break, which was within the range of 100 to 500%, and the coating amount was 4000 g / m 2 However, the tensile strength is 10N / mm 2 Less than 8N / mm 2 In the case of the fall prevention paint of Comparative Example 1, when the weight 22 was dropped, the high-strength bolt 32 ended up protruding from the surface 31 a of the steel plate 31 .

[0049] 8 is a diagram showing the state in which the high-strength bolt 32 protrudes from the surface 31a of the steel plate 31 as a result of the drop weight test. 2 If the thickness is less than 1 / 3, it is not possible to prevent the high-strength bolts 32 from protruding from the surface 31a of the steel plate 31.

[0050] The fall prevention paint of Comparative Example 2 had an elongation rate of 250% at break, which was within the range of 100 to 500%, and the coating amount was 4000 g / m 2 However, the tensile strength is the upper limit of 60N / mm 2 Exceeded 61N / mm 2 In the case of the fall prevention paint of Comparative Example 2, when the weight 22 was dropped, the high-strength bolt 32 ended up protruding from the surface 31 a of the steel plate 31 .

[0051] The fall prevention paint of Comparative Example 3 has a tensile strength of 10 N / mm 2 The coating amount is 4000g / m 2 However, the elongation at break was 80%, which is less than 100%. With the fall prevention paint of Comparative Example 3, when the weight 22 was dropped, the high-strength bolt 32 protruded from the surface 31a of the steel plate 31, as shown in FIG.

[0052] The fall prevention paint of Comparative Example 4 has a tensile strength of 10 N / mm 2 The coating amount is 4000g / m 2 However, the elongation rate was 600%, exceeding 500%. With the fall prevention paint of Comparative Example 4, when the weight 22 was dropped, the high-strength bolt 32 protruded from the surface 31a of the steel plate 31, as shown in FIG.

[0053] The fall prevention paint of Comparative Example 5 has a tensile strength of 10 N / mm 2 The elongation rate is 250%, but the coating amount is 3800 g / m, which is the lower limit. 2 Less than 3500g / m 2 In the case of the fall prevention paint of Comparative Example 5, when the weight 22 was dropped, the high-strength bolt 32 ended up protruding from the surface 31a of the steel plate 31 as shown in FIG.

[0054] The fall prevention paint of Comparative Example 6 has a tensile strength of 10 N / mm 2 The elongation rate is 250%, but the coating amount is 4500g / m 2 Over 4600g / m 2 In this way, in Comparative Example 6, the coating amount was 4500 g / m 2 Over 4600g / m 2 However, the film thickness becomes too thick, making it difficult to form a coating film of substantially uniform thickness during the curing process. With the fall prevention paint of Comparative Example 6, when the weight 22 was dropped, the high-strength bolt 32 protruded from the surface 31a of the steel plate 31, as shown in Figure 8.

[0055] 9 is a chart showing the names of the paints, painting methods, and application amounts used in each step of a conventional general construction method. In the conventional construction method, the anti-fall paint 40 containing the third paint of the main material treatment of this embodiment is not used, and only the water-based epoxy resin paint is applied in the primer treatment.

[0056] As such, the conventional method required a total of eight steps: base treatment (two layers), undercoat treatment (four layers), intermediate coating treatment, and top coating treatment. Furthermore, the conventional method allowed for application not only with a brush, but also with a spray.

[0057] In one example of this method, the main material treatment carried out in the fourth and fifth steps involves applying 2000g / m of oil-based third paint, a one-component urethane resin waterproofing material. 2 Apply the amount of coating (first main layer) and let it harden, then apply 2000g / m 2 This allows the fall prevention paint 40 to be applied to both the head 32h of the high-strength bolt 32 and the surface 31a of the steel plate 31 in a total amount of 4000 g / m 2 Since the amount of coating can be made thicker than with conventional methods, even when the impact of the weight 22 is applied to the high-strength bolt 32, it is possible to prevent the high-strength bolt 32 from protruding from the surface 31a of the steel plate 31, as shown in FIG. 5.

[0058] Furthermore, in one example of this construction method, waterproofing is performed using a third oil-based paint called a one-component urethane resin waterproofing material, a treatment of the main material that is not used in conventional construction methods, which also makes it possible to prevent the occurrence of hydrogen embrittlement, one of the causes of delayed fracture in F11T.

[0059] Although a preferred embodiment has been described above, this embodiment is not limited to the above example. In this embodiment, the high-strength bolts to be applied are F11T or F13T, but the present invention is not limited to this and various other high-strength bolts, such as F10T and S10T, may also be applied.

[0060] In this embodiment, the case where the base treatment (step S11) is performed first has been described, but the present invention is not limited to this, and as shown in Fig. 10, only the primer treatment (step S12) and the main material treatment (step S13) or only the main material treatment may be performed without performing the base treatment (step S11) and / or the topcoat treatment (step S14). In this case, the fall prevention paint 40 includes only the second paint and / or the third paint.

[0061] It should be understood that those skilled in the art can make various changes, substitutions, and alterations to the present invention without departing from the spirit and scope of the present invention. The above-described embodiments and modifications may be implemented in any suitable combination within the scope of the present invention. [Explanation of symbols]

[0062] 31 Steel plate 32 High-strength bolt 40 Fall prevention paint

Claims

1. A construction method for preventing high-strength bolts from falling using paint to prevent high-strength bolts attached to a predetermined object from falling, Prescribed tensile strength: 10 to 70 N / mm ２ ], elongation at break 100 to 500 [%], and coating amount 3800 to 4500 [g / m ２ a main material treatment in which a waterproof urethane resin-based anti-fall paint is applied to the surface of the object to be attached; A construction method for preventing high-strength bolts from falling using paint, characterized by having:

2. The main material treatment includes a first step and a second step, In the first and second steps, the anti-fall coating is applied in an amount of 1900 to 2250 g / m ２ Each was applied in the amount of The total of the first and second steps is up to 3800 g / m ２ ~4500g / m ２ The anti-fall coating is applied in an amount of A construction method for preventing high-strength bolts from falling, using the paint according to claim 1.

3. 3. A construction method for preventing high-strength bolts from falling using the paint according to claim 1 or 2, wherein the high-strength bolts are F11T or F13T.

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