JP2005308212A - Bolt joint part structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolt joint part structure for achieving effective fastening force without generating flexural yielding in a bolt by giving fastening force to the bolt along the axial direction of the bolt when repairing a steel material structure with bolt-nut joint even if a bolt abutting face is uneven with corrosion due to long-time use. <P>SOLUTION: An unevenness correcting agent 2 constrained by a ring constraining member 15 is provided between a bolt washer 14 and a joined structure 100. The used unevenness correcting agent 2 is a curable cement mortar or resin or its mixture with inorganic particle or short fiber mixing agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a bolt joint for joining structures such as steel girders such as railway bridges and road bridges with bolts.

  For example, steel girders such as railway bridges and road bridges are joined by rivet joining, a welded structure, or high-strength bolt joining at the time of construction. In the case of rivet bonding, steel rivets that have been rivet-bonded will also be corroded in the rivet joints due to long-term use. In this case, the rivet is removed, and the rivet joint portion needs to be repaired in place of the bolt joint structure using high-strength bolts. 14 (a) and 14 (b) show a bolt joint structure 1a in a steel girder after repair work.

  In the bolt joint structure 1a of FIG. 14A, the steel beam 100 (100A, 100B) from which the rivet has been removed is used to connect the bolt shaft 12 of the bolt 10 using the previous rivet hole 101 (101A, 101B). It is penetrated and installed, and it is fastened and joined via a washer 14 by a bolt head 11 and a nut 13.

  However, as shown, the steel girder 100 (100A, 100B) itself has a corroded surface 102 (102A, 102B) similar to a rivet, for example, between the bolt head 11 and the steel girder surface 102B, Even when the washer 14 is interposed between the nut 13 and the steel girder surface 102A, when the bolt is tightened, a tightening force along the bolt axial direction cannot be obtained with respect to the bolt 10, and the bolt 10 Bending yield may occur, making it difficult to obtain a predetermined appropriate tightening force.

  As shown in FIG. 14B, this is because the centers of the rivet holes 101 (101A, 101B) formed in the steel beam 100 (100A, 100B) are shifted from each other. This is also true when bolts are tightened in the same manner as in a).

  Therefore, in such a case, it is necessary to regulate the vehicle and replace the steel girders 100 (100A, 100B) themselves.

  Accordingly, an object of the present invention is to provide a bolt joint structure capable of obtaining a tightening force along the bolt axial direction with respect to a bolt and achieving an effective tightening force without generating a bending yield in the bolt. That is.

  Another object of the present invention is to provide a bolt joint structure that suppresses a decrease in the axial force of the bolt and maintains an effective tightening force of the bolt over a long period of time.

  The above object is achieved by the bolt joint structure according to the present invention. In summary, the present invention relates to a bolt joint structure in which two or more joined structures are joined to each other with bolts and nuts. A bolt joint structure characterized by being provided between the body and the body.

  According to one embodiment of the present invention, the unevenness correcting agent is a curable cement mortar or resin.

  According to another embodiment of the present invention, the unevenness correcting agent is mixed with a mixing material in the curable cement mortar or resin.

  According to another embodiment of the present invention, the mixed material is mixed in a volume ratio of 20% to 85%.

  According to another embodiment of the present invention, the mixed material is a material selected from inorganic particles or short fibers, and is a simple substance or includes two or more kinds of materials.

  According to another embodiment of the present invention, the inorganic particles are ceramics, metal, or silica sand, and the short fibers are glass fibers or carbon fibers.

  According to another embodiment of the present invention, the mixed material includes two or more kinds of the inorganic particles having different particle diameters. Here, the inorganic particles having different particle diameters are preferably alumina and steel balls. The steel balls may be mixed in a volume ratio of 25% to 85%, and the alumina may be mixed in a volume ratio of 40% to 0%. Preferably, the diameter of the steel balls is 0 .3 mm to 2.8 mm.

  According to another embodiment of the invention, the ring-shaped restraining member is made of steel or fiber reinforced composite.

  According to another embodiment of the present invention, the ring-shaped restraining member has an inner peripheral surface shape that expands outward from the bonded structure side in the axial direction of the ring.

  According to the bolt joint structure of the present invention, the unevenness correcting agent restrained by the ring-shaped restraining member is provided between the bolt washer and the structure to be joined. A tightening force can be obtained, and an effective tightening force can be achieved without generating a bending yield in the bolt. In addition, according to the bolt joint structure of the present invention, a decrease in the axial force of the bolt is suppressed, and an effective tightening force of the bolt is maintained for a long period.

  Hereinafter, the bolt joint structure according to the present invention will be described in more detail with reference to the drawings.

Example 1
Referring to FIGS. 1 (a) to (d), a plurality of steel girders 100 (100A, 100B) joined to each other by a railway bridge, a road bridge, etc. in this embodiment are used for many years. The repair work of the steel girder rivet joint when corrosion is observed on the girder surface 102 (102A, 102B) and the rivet joint will be described. FIG. 1 (d) shows an embodiment of a bolt joint structure 1 according to the present invention.

  According to the present embodiment, the surfaces of the two steel girders 100 (100A, 100B) joined to each other, which are the structures to be joined, are corroded in the same manner as the rivets. Therefore, first, as shown in FIG. 1 (a), the rivet 300 at the steel girder joint is removed, and the steel girder surface 102 (102A, 102B) and the rivet hole 101 (with the rivet holes 101 (101A, 101B) formed therein. 101A, 101B) are exposed. In the present invention, the rivet hole 101 (101A, 101B) is used as a bolt hole through which the bolt shaft 12 (FIG. 1D) passes, as will be described later.

  Next, as shown in FIG. 1B, after removing corroded portions of the steel girder 100A, 100B bolt holes 101A, 101B and the surrounding steel girder surfaces 102A, 102B with a brush or the like, the steel girder 100A, 100B is removed. In order to correct the unevenness of the bolt hole peripheral surfaces 102A and 102B, the unevenness correcting agent 2 is applied to the bolt hole peripheral surfaces 102A and 102B of the steel girders 100A and 100B.

  As the unevenness correcting agent 2, a material that has fluidity before curing and develops strength after curing, such as a hardened cement mortar or resin, is preferably used. As the resin, an epoxy resin, vinyl ester resin, unsaturated polyester resin, MMA resin, acrylic resin, urethane resin, melanin resin, or the like can be suitably used. In this example, a room temperature curing type epoxy resin was used.

  Further, according to the present embodiment, as shown in FIG. 1 (c), before the unevenness correcting agent 2 is cured, the ring-shaped restraining member is made to substantially coincide with the centers of the bolt holes 101A and 101B. 15 is pressed and installed on the steel girder surfaces 102A and 102B. At this time, the unevenness correcting agent 2 may be slightly present between the ring-shaped restraining member 15 and the steel beam surfaces 102A and 102B.

  As shown in the figure, the non-land surface correcting agent 2 is also filled inside the ring-shaped restraining member 15 by pressing and installing the ring-shaped restraining member 15 on the steel girder surfaces 102A, 102B shown in FIG. It becomes. If necessary, the unevenness correcting agent 2 may be replenished into the ring-shaped restraining member 15.

  In this embodiment, the ring-shaped restraining member 15 is a circular ring having an inner diameter d1, an outer diameter d2, and a thickness t. The ring-shaped restraining member 15, that is, the ring can be made of steel or a fiber reinforced composite material (FRP material). As the FRP material, carbon fibers, glass fibers, organic fibers, metal fibers, etc. can be used alone or in a hybrid as reinforcing fibers. As the matrix resin, an epoxy resin or the like can be suitably used.

  In this embodiment, the ring 15 is a steel ring having an inner diameter d1 of 36 mm, an outer diameter d2 of 54 mm, and a thickness t of 6 mm.

  Next, as shown in FIG. 1 (d), from one side of the steel girder, in this embodiment, from the outer surface 102B side of the steel girder 100B, through the ring-shaped restraining member 15 and the bolt hole 101B, the bolt 10 The bolt shaft 12 is inserted and protruded from the outer surface 102A of the steel beam 100A. A nut 13 is screwed onto the protruding bolt shaft 12.

  In this embodiment, washers 14 are arranged as bolt bases on the bolt head 11 side and the nut 13 side, respectively. Each of the washer 14, the bolt head 11, and the nut 13 has an outer shape smaller than the inner diameter d1 of the ring-shaped restraining member 15.

  In this example, the total thickness T before corrosion of the steel girders 100 (100A, 100B) was 10 mm, and the diameter D of the original rivet holes 101 (101A, 101B) was 18 mm. A bolt having a diameter M16 (screw outer diameter 16 (+0.7 to −0.2) mm) and a bolt shaft 12 having a length (below the neck) of 50 mm was used. The washer 14 had an outer diameter D0 of 32 mm and a washer thickness T0 of 4.5 mm.

  With the above-described configuration, the bolt head side washer 14, the steel girder surface 102B, and the ring-shaped restraining member 15 and the nut side washer 14, the steel girder surface 102A, and the ring-shaped restraining member 15 are not The land correction agent 2 is filled.

  Here, what is important is to prevent the upper surface 15a of the ring-shaped restraining member 15 and the washer 14 from contacting each other. However, an increase in the distance between the upper surface 15a of the ring-shaped restraining member 15 and the washer 14 is undesirable in that the restraining effect of the unevenness correcting agent 2 by the ring-shaped restraining member 15 is weakened. This distance should be maintained to such an extent that it prevents split fracture of the unevenness correcting agent 2 and maintains the axial compressive strength.

  In this embodiment, as shown in the drawing, the lower surface 14a of the washer substantially coincides with the position of the upper surface 15a of the ring-shaped restraining member 15, and the washer 14 is spaced from the ring-shaped restraining member 15 by a gap g = 0 to 2 mm. The distance was about 1 mm. This gap g will be further described later in relation to the axial force remaining rate (N / N0) with reference to FIG.

  At this stage, the bolt 10 and the nut 13 are not tightened tightly, and the bolt 10 and the nut 13 are screwed to such an extent that the steel girders 100 (100A, 100B) are loosely joined to each other.

  When the unevenness correcting agent 2 is semi-cured, temporary tightening is performed so that the bolt shaft 12 and the unevenness correcting surface are perpendicular to each other, and when cured, the nut 13 is rotated in the tightening direction so that the bolt 10 and the nut 13 are mutually connected. Tighten and introduce a predetermined axial force. Thereby, the two steel girders 100 (100A, 100B) are bolted with a predetermined tightening force.

  According to the present embodiment, as described above, the unevenness correcting agent 2 restrained by the ring-like restraining member 15 is placed between the washer 14 and the steel beam 100 (100A, 100B), that is, the structure to be joined. By using the provided configuration, a high axial force such as a high-strength bolt can be obtained.

  In FIG. 2, as a comparative example of this example, a bolt joint structure 1 b having the same structure as that of this example except that the ring-shaped restraining member 15 is not used was manufactured.

In this case, in an environment where a high axial force such as a high-strength bolt (for example, compressive stress 200 N / mm ² ) is applied, cement mortar, resin, etc. (uncommon, compressive strength is 100 N / mm ² or less), the unevenness correction agent 2 has insufficient compressive strength and caused split fracture.

  On the other hand, in this embodiment, the ring-like restraining member 15 is made of steel or a fiber reinforced composite material having a high strength in the circumferential direction. The compressive strength of the land correction agent 2 can be increased.

  In addition, according to the structure of a present Example, 39 test bodies used as the bolt-joint structure 1 which uses a steel ring as the ring-shaped restraint member 15 are produced, and the overload compression test of the unevenness correction agent 2 is carried out. did. At this time, in one test body, splitting fracture of the unevenness correcting agent 2 occurred due to deformation after the yielding of the steel ring. Since the splitting in this specimen occurs in the direction perpendicular to the circumference, it can be considered that the strength in the ring circumferential direction is dominant in the destruction of the unevenness correcting agent 2.

  Therefore, according to the present invention, the ring-shaped restraining member 15 is used. For example, in the case of a steel ring or a fiber reinforced composite ring, by changing the wall thickness t or by changing the ring outer diameter d2 ( It is possible to easily satisfy the strength in the circumferential direction with the ring inner diameter d1 being constant. That is, according to the present invention, by increasing the circumferential strength of the ring 15, the non-land correction agent 2 is restrained, the compressive strength of the non-land correction agent 2 is increased, and the non-land correction agent 2 is split and broken. It can be effectively prevented.

  In the bolted joint structure 1 according to the present invention configured as described above, it is required to maintain a predetermined bolt axial force during the service period of the steel beam 100. However, the bolt axial force may be reduced by creep deformation or self-contraction of the unevenness correcting agent 2. In the experiment in which the unevenness correcting agent 2 was formed only from a resin, the bolt axial force was reduced by about 20%.

  Therefore, as the unevenness correction agent 2, a mixed material is added in order to reduce the amount of base material such as cement mortar and resin that easily undergoes creep deformation or self-shrinkage, and the volume ratio of resin or the like in the unevenness correction agent 2 is reduced. It is preferable to do this. Moreover, the effect is further increased by using a material that increases the rigidity, such as a resin, as the mixed material.

  Therefore, as shown in FIG. 3, the present inventors mixed in order to confirm the strength increasing effect of the non-land correction agent 2 when the mixture is mixed in the resin as the base material of the non-land correction agent 2. Using the material and volume ratio of the material as parameters, a compression test of the unevenness modifier using steel ring and resin was conducted, and the difference in axial compressive strength and rigidity was examined. As the mixing material, inorganic particles, for example, alumina as ceramics (average particle size 0.52 μm), iron powder as metal (average particle size 0.5 mm), and silica sand of No. 4, 5, and 6 In addition, carbon fibers having a fiber length of 6 mm were used as short fibers. An epoxy resin was used as the base resin for the unevenness correcting agent 2. In this example, the epoxy resin includes two types of epoxy resins, namely, an epoxy resin manufactured by Nippon Steel Composite Co., Ltd., trade name “FR-E5P”, an epoxy resin manufactured by Nagase ChemteX Corporation, and trade name. “AW136H” was used.

  As a result, inorganic particles (average particle diameter of about 0.52 μm to 0.5 mm) or short fibers (fiber length of about 5 mm to 10 mm) are suitable as the mixing material. In particular, the inorganic particles include ceramics, metal Or, silica sand is preferable, and it has been found that the short fiber is preferably glass fiber or carbon fiber. Further, as described in detail later, steel balls (diameter 0.3 mm to 2.8 mm) can be used as the inorganic particles.

  Moreover, the material selected from the inorganic particle | grains or short fiber used as these mixing materials may be used individually, and 2 or more types of materials can also be mixed and used.

All of the bolted joint structures 1 using the unevenness correction agent 2 containing inorganic particles or short fibers as the admixture had an axial compressive strength of 200 N / mm ² or more.

  Further, in the range of the mixed material amount of 20% to 85% (volume ratio), the rigidity did not decrease much compared to the specimen without mixed material. Therefore, it is considered that the axial compression strength and rigidity are not reduced in the range of 20% to 85% of the mixed material.

Here, the “volume ratio” of the unevenness correcting agent represents the ratio of the volume of the mixed material to the sum of the volume of the curable cement mortar or resin and the mixed material. That means
Volume ratio = mixing material volume / (curing cement mortar or resin volume + mixing material volume) × 100
It is.

  Furthermore, the present inventors conducted the following investigation on the ring-shaped restraining member 15.

  That is, assuming that the ring stress when receiving the internal pressure is a hydrostatic pressure state, the stress in the circumferential direction is calculated as a calculated value, and the stress in the circumferential direction in the experiment is compared with the elastic region of the ring 15. The experiment uses the mixed material mixed in the base resin, its volume ratio, and the type of the base resin as parameters.

  The calculated value was calculated from the stress calculation formula on the outer periphery of the ring that receives only the internal pressure in the hydrostatic pressure state shown in the following formula (1).

here,
σ _rcal ; Calculated value of stress in the circumferential direction P; Internal pressure (Axial stress due to hydrostatic pressure)
R _o ; ring outer radius R _i ; ring inner radius.

  The experimental value was calculated from the strain value measured in the experiment using the following formula (2).

here,
σ _rtest ; circumferential stress experimental value E; elastic modulus of ring ε; ring strain.

  FIG. 4 shows the relationship between the ratio between the experimental value and the calculated value obtained as described above, and the mixed material volume ratio. It can be seen from the graph of FIG. 4 that the ratio between the experimental value and the calculated value decreases as the mixed material volume ratio increases regardless of the type of mixed material. That is, the stress applied in the ring circumferential direction is reduced by increasing the volume ratio of the mixed material.

  Next, a method for designing the ring-shaped restraining member 15 in this embodiment, that is, the circular ring used in this embodiment will be described.

Since the load applied to the ring 15 depends on the volume ratio of the mixed material, the ratio between the experimental value and the calculated value in the graph shown in FIG. 4 is set as a coefficient f (R _V ).

here,
σ _r ; circumferential direction stress R _v ; volume ratio of the mixed material (%)
It is.

  From the above formulas (1) and (2), the following formula (4) is obtained.

  From the above formula (4), the ring circumferential stress (hoop stress) can be calculated from the inner diameter d1 and outer diameter d2 of the ring, the acting bolt axial force, and the volume ratio of the mixed material.

  Since it is considered that the ring 15 can maintain the binding force of the ring 15 when the circumferential strength is less than the yield strength in the case of the steel ring and less than the breaking strength in the case of the FRP ring, the following formula (5) is satisfied. It is preferable to design with the ring material and wall thickness (inner diameter and outer diameter).

here,
σ _y ; yield strength σ _f ; breaking strength.

According to the knowledge obtained by the present inventors, as shown in FIG. 4, the coefficient f (R _V ) is 0.3 or more in the volume ratio range of 0% to 85%. The upper limit is 1 because it is considered to be a pure hydrostatic pressure state. The factor f (R _v ) range is 0.3 to 1.5 in consideration of the multiplication of the safety factor 1 to 1.5 at the time of design.

In this embodiment, the applicable range is a ring thickness (radius in the ring, which can be designed in a range where the volume ratio is 0% to 85% and the coefficient f (R _V ) is 0.3 to 1.5. Outer radius).

  As a calculation example, calculation was performed using bolt nominal diameters M16 and M30. Tables 1 and 2 show the physical properties of steel material SS400 and high-strength carbon fiber UT500 (trade name of carbon fiber manufactured by Toho Tenax Co., Ltd.). The results are shown in FIG.

  From the graph shown in FIG. 5, it can be seen that the ratio between the experimental value and the calculated value decreases as the volume ratio increases regardless of the type of the mixed material. That is, it is shown that the stress (hoop stress) applied in the ring circumferential direction is reduced by increasing the volume ratio of the mixed material. Therefore, assuming that the relationship between the ratio between the experimental value and the calculated value and the volume ratio is uniform regardless of the material of the mixed material, and the relationship is linear, the following formula (6) is obtained.

  FIG. 6 shows the axial compressive strength when the ring yields. The results of FIG. 6 indicate that the higher the axial compressive strength at the time of ring yielding, the smaller the circumferential stress of the ring and the less the burden on the ring when the axial compressive stress is equal.

  FIG. 6 shows that the relationship between the volume ratio and the axial compressive strength stress at the time of yielding of the ring increases with an increase in the volume ratio, and has a tendency similar to the above-described relationship between the volume ratio and the hoop stress. .

Example 2
In the bolt joint structure according to the present invention, as described in the first embodiment, a mixed material such as an inorganic particle or a short fiber that mixes a decrease in the axial force when the bolt axial force is introduced into the unevenness correcting agent. It can be suppressed by increasing the mixing ratio.

  As a result of further research experiments, the present inventors have found the following.

  In other words, in the bolt joint structure 1 of the present invention, in the configuration in which the steel ring is used as the ring-shaped restraining member 15 and the unevenness correction is performed using the epoxy resin as the unevenness correction agent 2, after the elapse of one month or more, There is a case where the axial force is reduced by about 59%. As a factor, it is considered that the creep deformation of the resin has a great influence.

  In addition, as described in Example 1, it is clear that mixing of contaminants such as alumina into the unevenness correcting agent reduces the reduction in axial force, but in the prediction after 10 years, It has been found that a reduction in axial force of about 32% may occur.

  Therefore, as a result of further experimental studies, the present inventors further mixed a steel ball having a diameter of 0.3 to 2.8 mm, for example, about 2 mm in diameter, in addition to alumina in the unevenness correcting agent. As a result, it was found that the reduction rate of the axial force can be suppressed. When the diameter of the steel ball exceeds about 80% of the height of the restraint ring, it is considered that unevenness along the non-land surface is generated by the steel ball arranged on the non-land surface.

  In the unevenness correcting agent, the steel balls are mixed in a volume ratio of 25% to 85%, and the alumina is mixed in a volume ratio of 40% to 0%. As will be described in detail later, for example, by mixing 10% alumina and 75% steel balls having a diameter of 2 mm into a resin (epoxy resin 15%) as a base material in a volume ratio, the reduction ratio of the axial force is 50 It was found that it could be reduced to about 16% even after a year.

  An example of an experiment conducted to verify the above fact is shown below.

Experimental Example FIG. 7 shows a test body having the bolt joint structure 1A used in this experimental example. The bolt joint structure 1A used in this experimental example is the same as the bolt joint structure 1 described with reference to FIG. 1 (d) in Example 1, except that the steel beam 100 (100A, 100B). It is different in that a steel plate 100 is used instead of. Therefore, members having the same functions and actions are described with the same reference numerals.

  In the test body used in this experimental example, that is, the test body having the bolt joint structure 1A using various unevenness correcting agents 2 described later, as shown in FIG. The bolt shaft 12 of the bolt 10 is inserted through the ring-shaped restraining member 15 and the bolt hole 101 from the side, protruded from the other side surface 102A of the steel plate 100, and the nut 13 is screwed onto the protruded bolt shaft 12. .

In this experimental example, washers 14 are arranged as bolt bases on the bolt head 11 side and the nut 13 side, respectively. All of the washer 14, the bolt head 11 and the nut 13 have an outer shape smaller than the inner diameter d1 of the ring-shaped restraining member 15. The specific dimensions of each member are as follows.
Steel plate 100
Material Steel (SS400)
Thickness 10mm
Bolt hole diameter 18mm
Bolt 10
Nominal diameter M16
Grade F10T
Washer 14
Grade F10T
Outside diameter 32mm
Inner diameter 17mm
Thickness 4.5mm
Ring-shaped restraining member 15
Material Steel (S45C)
Outer diameter 54mm
34mm inside diameter
Thickness 6mm

  In the bolt joint structure 1A having the above configuration, when the unevenness correcting agent 2 is filled between the steel ring 15 and the nut side washer 14 and cured, the bolt axial force 116 kN is applied to the bolt structure with a torque wrench. The axial strain of the bolt 10 and the hoop stress of the steel ring 15 were measured for 720 hours. A gap (g) of 1 mm was formed between the steel ring 15 and the upper washer 14.

  Experiments were conducted to investigate the residual ratio of axial force with the gap (g) being 0.05 mm, 1 mm, and 3 mm. As a result of the experiment, as shown in FIG. 8, there was no difference between the gaps (g) of 0.05 mm and 1 mm, and when the gap (g) was 3 mm, a large reduction in axial force was observed.

  Therefore, as described above, the washer 14 is separated from the steel ring 15 by a gap g = 0 to 2 mm, usually about 1 mm.

  Table 3 shows the unevenness correcting agent 2 used in this experimental example. The unevenness correcting agent 2 used was an inorganic resin particle having a different particle diameter as an admixture with respect to the epoxy resin (AW136H) as a base material, in this example, AL-160SG- having an average particle diameter of 0.52 μm. 3 and alumina balls having a diameter of 2 mm were mixed in various proportions as shown in Table 3.

  That is, the steel balls are mixed in a volume ratio of 25% to 85%, preferably 25% to 75%, whereas alumina is 40% to 0%, preferably 40% to 40% by volume. 10% was mixed. Therefore, the mixing material is 40% to 85% by volume.

  Table 4 shows the residual axial force ratio (%) when the steel ball mixture ratio is changed, and FIG. 9 shows the relationship between the elapsed time and the axial force residual ratio when the steel ball mixture ratio is changed. . FIG. 9 is a graph with the residual ratio of axial force and the time axis as common logarithms.

  From Table 4 and FIG. 9, it can be seen that the axial force greatly decreases at the initial stage, and that the axial force decrease is suppressed as the steel ball ratio increases.

  For comparison, in FIG. 10, the residual axial force and the time axis for the case where 40% alumina is mixed in the epoxy resin (AW136H) and the case where only the epoxy resin is not mixed with alumina are used as the common logarithm. A graph is shown. From FIG. 9 and FIG. 10, it can be seen that a decrease in the bolt axial force can be suppressed by mixing a plurality of particles having different particle sizes into the unevenness correcting agent.

Further, in order to make a long-term prediction of the axial force residual rate, predictions were made 10 years and 50 years later using the following axial force residual rate prediction formula (N / N ₀ ).

Here, the coefficient α is shown in Table 5. Moreover, FIG. 11 shows the axial force remaining rate when steel balls are mixed in the unevenness correcting agent while changing the mixing ratio.

  From Table 4 and FIG. 11, it can be seen that the specimens with a steel ball mixing ratio of 50% or more are within the allowable range of 20% with respect to the prediction after 50 years.

  From the above, it can be seen that the reduction in the axial force of the bolt can be reduced according to the steel ball ratio. In addition, in the specimen having a steel ball ratio of 75%, an axial force residual ratio of about 84% is predicted after 50 years.

  In the present embodiment, in the above description, the base material in the unevenness correcting agent has been described as being an epoxy resin, but other resins of the curable type shown in Example 1, that is, vinyl ester resin, unsaturated Polyester resin, MMA resin, acrylic resin, urethane resin, melanin resin, etc. can be suitably used. Furthermore, curable cement mortar can also be used, and contaminants such as steel balls can be used. The effects described in the first embodiment and the functions and effects described above can be achieved in the same manner.

  Further, in this example, the steel ball as a contaminant in the unevenness correcting agent is mixed with alumina, but may be mixed alone in the base material. The same effect can be achieved even if it is mixed with ceramics, metal, or silica sand other than the described alumina.

  If the particle size is large, such as a steel ball used in this example, an effect is obtained in the range of about 25% to 85%, but if it is a very small particle, it is considered that it is the limit of manual stirring. About 40% is preferable.

  In addition, as a result of the research experiment of the present inventors, it has been found that the larger the volume ratio of the mixed particles, the lower the axial force can be suppressed. From this, the closer the closer to the closest packing, the lower the bolt axial force. Is considered to be suppressed. In particular, this example demonstrates that by mixing a plurality of particles having different particle sizes into the unevenness correcting agent, it is possible to arrange the mixed material more densely, thereby suppressing a decrease in bolt axial force. did it.

Example 3
According to the knowledge of the present inventors, axial perpendicular stress acting 0.6 times or more with respect to axial compressive stress acts on the ring as the ring-shaped restraining member 15. However, considering the construction and operation under repeated vibrations such as railway bridges and road bridges, there is a possibility that the ring 15 may come off. In particular, there is a high possibility that the ring 15 is pulled out by vibration before the resin is cured during the construction.

  Therefore, in the present embodiment, as shown in FIG. 12, the inner peripheral surface shape of the ring 15 is outward from the surface 102 </ b> A (102 </ b> B) side of the steel beam 100 in the axial direction of the ring 15. It is preferable that the tapered surface 15b expands in a trumpet shape. With this configuration, it is possible to prevent the ring from coming out.

  Moreover, since a high stress acts on the steel girder surface 102A (102B) side, the ring 15 can be designed to have a thinner ring thickness t by adopting the above configuration.

  When the washer 14 and the ring 15 are in contact with each other when the inner peripheral surface 15b of the ring 15 is tapered as in the present embodiment, the bolt joint structure 1A of the present invention in which the unevenness correction is performed is realized. There is a fear that it cannot be done.

  As a method for avoiding such a situation, there is a method of increasing the ring inner diameter d1. However, the increase in the distance between the upper surface 15a of the ring-shaped restraining member 15 and the lower surface 14a of the washer 14 is not due to the ring-shaped restraining member 15. Undesirable in reducing the restraining effect of land modifiers.

  Therefore, the ring side can also be shaved and a taper 14b can be applied to the washer 14 as shown by an imaginary line in FIG.

Example 4
FIG. 13 shows another embodiment of the bolt joint structure of the present invention. In the present embodiment, as described above with reference to FIG. 14B, the center of the rivet hole 101 (101A, 101B) formed in the steel beam 100 (100A, 100B) has shifted. In this case, repair work is carried out by applying the bolt joint structure 1 of the present invention.

  Also in the present embodiment, the unevenness correcting agent 2 constrained by the ring-shaped constraining member 15 is bonded to the bolt washer 14 and the structures to be joined such as the steel girders 100A and 100B by the same work process as described in the first embodiment. A high axial force such as a high-strength bolt can be obtained by adopting a configuration provided between the body and the body.

  Also in the present embodiment, as described in the second embodiment, as shown in FIG. 12, the ring 15 has an inner peripheral surface shape of the surface 102 </ b> A ( 102B) The structure may be widened so as to be a trumpet from the side to the outside, and the washer 14 may be provided with a tapered surface 14b.

  The bolt joint structure of the present invention is not limited to repairing rivet joints, but can be used when changing from a high-strength bolt to a high-strength bolt. The bolt joint structure of the present invention is not only a bolt joint for joining structures such as steel girders such as railway bridges and road bridges with bolts, but also steel joints for marine structures, buildings, etc. Can also be used.

It is a schematic process drawing explaining the process of the repair construction for implement | achieving the bolt junction part structure which concerns on one Example of this invention. It is sectional drawing which shows the structure of the bolt junction part structure of a comparative example. It is a graph which shows the compression test result of the unevenness correction agent containing an admixture. It is a graph which shows the hoop stress of the unevenness correction agent containing an admixture. It is a graph which shows the hoop stress of the unevenness correction agent containing an admixture. It is a graph for demonstrating the axial compressive strength at the time of ring yielding. It is sectional drawing explaining the structure of the test body for proving the effect of the other Example of the bolt junction part structure of this invention. It is a graph which shows the relationship between the clearance gap between a ring-shaped restraining member and a washer, and axial force residual rate. It is a graph which shows the axial force residual rate at the time of mixing a steel ball in the unevenness correction agent. It is a graph which shows the axial force residual rate at the time of mixing alumina with a non-land correction agent. It is a graph which shows the axial force residual rate at the time of mixing a steel ball in the unevenness correction agent. It is sectional drawing which shows a part of bolt junction part structure which concerns on the other Example of this invention. It is sectional drawing which shows a part of bolt junction part structure which concerns on the other Example of this invention. It is sectional drawing which shows the conventional bolt junction part structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bolt junction part structure 2 Unevenness correction agent 10 Bolt 11 Bolt head 12 Bolt shaft 13 Nut 14 Washer 15 Ring (ring-shaped restraint member)
100 (100A, 100B) Steel girder (bonded structure)
101 (101A, 101B) Bolt hole (rivet hole)
102 (102A, 102B) Steel girder surface

Claims (12)

In the bolt joint structure that joins two or more joined structures together with bolts and nuts,
A bolt joint structure characterized in that an unevenness correcting agent restrained by a ring-shaped restraining member is provided between a bolt washer and a structure to be joined.   The bolt joint structure according to claim 1, wherein the unevenness correcting agent is a curable cement mortar or resin.   The bolt joint structure according to claim 1 or 2, wherein the unevenness correcting agent is mixed with the hardened cement mortar or resin.   The bolt joint structure according to claim 3, wherein the mixed material is mixed in a volume ratio of 20% to 85%.   The bolt joint structure according to claim 3 or 4, wherein the mixed material is a material selected from inorganic particles or short fibers, and is a single material or includes two or more kinds of materials.   6. The bolt joint structure according to claim 5, wherein the inorganic particles are ceramics, metal, or silica sand, and the short fibers are glass fibers or carbon fibers.   The bolt joint structure according to claim 5 or 6, wherein the mixed material includes two or more kinds of inorganic particles having different particle diameters.   The bolt joint structure according to claim 7, wherein the inorganic particles having different particle diameters are alumina and a steel ball.   The bolt joint structure according to claim 8, wherein the steel balls are mixed in a volume ratio of 25% to 85%, and the alumina is mixed in a volume ratio of 40% to 0%.   The bolt joint structure according to claim 8 or 9, wherein the steel ball has a diameter of 0.3 mm to 2.8 mm.   11. The bolt joint structure according to claim 1, wherein the ring-shaped restraining member is made of steel or a fiber reinforced composite material.   The ring-shaped restraining member has an inner peripheral surface shape that expands outward from the bonded structure side in the axial direction of the ring. The bolt joint structure according to any of the above sections.

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