JP3260353B1 - Hot dip galvanizing method for I-shaped structural member - Google Patents

Abstract

A hot dip galvanizing process for an I-shaped structural member is provided.
Prevents deformation such as entanglement, twisting and bending. When an I-shaped structural member having a flange (2) above and below a web (1) is hot-dip galvanized, a deformation preventing restraint is made using a joint bolt hole (5) provided at a lateral end of the web (1). A material 6 is attached along the end of the web 1, and both ends of the two I-shaped structural members arranged in parallel with the web in the longitudinal direction are connected by attaching a restraining plate 9 to the restraining material with bolts 10. In this state, hot dip galvanization is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel hot dip galvanizing method for large I-shaped structural members, particularly, I-shaped structural members for bridges.

[0002]

2. Description of the Related Art Various types of steel structural members are used in various fields, for example, widely used as bridge main structural members. As the type of bridge main structural members,
Sheet girder type, box type, truss type and the like are known. Among them, the sheet girder type has a web 2 (also referred to as a belly plate) as shown in FIGS.
Are attached by welding or the like. These I-shaped structural members are usually welded to a vertical stiffener (also referred to as a stiffener) 3 as illustrated in FIG. 7 or a horizontal stiffener 4 as illustrated in FIG. Thereby, the I-shaped structural member is reinforced and its deformation is prevented. In order to connect and use such an I-shaped structural member in the lateral direction, a large number of joint bolt holes 5 are provided at the end of the web 1 as shown in FIG.

[0003] On the other hand, when the I-shaped structural member is used as a bridge or the like, it is coated or hot-dip galvanized (hereinafter simply referred to as galvanized) for rust prevention. The latter zinc plating is carried out by immersing the I-shaped structural member in a hot-dip galvanizing bath (about 440 ° C.) for usually 4 to 10 minutes, and then pulling up from the bath and cooling with hot water. Rust prevention by such hot-dip galvanizing has excellent corrosion resistance and economic efficiency as compared with painting, but has a serious problem of thermal deformation as described below.

That is, when a long, large, and thin cross-section I-shaped structural member, such as an I-shaped structural member for a sheet girder, is hot-dip galvanized, web skewing, torsion deformation, bending deformation, and the like of the girder are caused. More or less residual deformation always occurs. In the plating step of the I-shaped structural member, such deformation occurs due to thermal stress during immersion in a plating bath and during immersion in cooling water. Generally, it is considered that in the plating process, the I-shaped structural member undergoes entanglement deformation, and the compressive thermal stress generated in the upper and lower flanges in the next cooling process acts eccentrically under the influence of the entanglement, causing torsional buckling. Have been.

[0005] Such intrusion and twist in the I-shaped structural member change under the influence of the thickness and height of the web, the yield strength of the steel material, and the like, and as the thickness becomes smaller, the height becomes larger. Also, it increases as the yield strength decreases. In addition, the deformation varies depending on the thickness ratio of the flange and the web, the plating immersion conditions, and the like. These deformations tend to increase as the thickness ratio increases or the plating immersion speed decreases. In particular, torsion, in addition to these factors, naturally increases as the member becomes longer and larger.

Hitherto, as a measure for preventing deformation of such an I-shaped structural member at the time of galvanizing, a method has been proposed in which restraining members (hereinafter referred to as restraining members) for preventing deformation are attached to both lateral ends of a web. . 9 to 12 illustrate this method. 9 is a side view of an I-shaped structural member in which restraining members are attached to both ends used for a sheet girder, FIG. 10 is an enlarged view of a right end portion of the I-shaped structural member, FIG. 11 is a right side view of FIG. FIG. 12 is a partial cross-sectional view taken along a line AA in FIG. 11. The vertical stiffener 3 (see FIG. 7) or the horizontal stiffener 4 (see FIG. 8) is omitted from the I-shaped structural member in FIG.

According to the conventional method, a restraining member 6 made of a rigid angle steel is attached to both sides of a joint portion of the web 1 with bolts 7 tightly as shown in FIGS. Depending on the material used in the hot dip galvanizing process
An object of the present invention is to prevent or reduce thermal deformation generated in a bridge member.

[0008]

In the conventional method using the above-mentioned restraining material, the amount of deformation of the fringes generated at the end of the web in the hot-dip galvanizing process is considerably reduced as compared with the case where the above method is not performed. Therefore, it can be said that this restraining member is one of the effective measures for preventing the entanglement deformation at the end of the web. However, this method only prevents the end of the I-shaped structural member from being entangled, and has no effect on the prevention of entanglement or twisting inside the member. Even if a restricting member is provided at the end of the I-shaped structural member, it is still an open end and has a degree of freedom of deformation. There is almost no effect on deformation such as bending, and these deformations occur substantially in the same manner as when no restraint member is provided.

[0009] Even if it is possible to prevent the web from being deformed at the end of the I-shaped structural member, if twisting or bending occurs, it is attempted to connect the I-shaped structural member when connecting the joint with a joint at the site and assembling a bridge. It is difficult to align the joints of the I-shaped structural members. In addition, if the amount of deformation exceeds the allowable amount, it becomes extremely difficult to mount the joint. In this case, a large-scale operation of mechanically correcting the deformation is required on site.

[0010] Therefore, such torsion or bending becomes a serious problem when the I-shaped structural member is used as a bridge member. This problem is caused by the structure of the I-shaped structural member itself, the thickness of the constituent members, and the like. Although it is conceivable to devise the shape, it is difficult at present to prevent these deformations. For example, increasing the thickness of the web is problematic in terms of weight, but to prevent deformation, even if the thickness of the web is increased by 1 mm, twisting and bending are avoided as long as galvanizing is applied. Can not. In particular, when the thickness of the flange is considerably large (for example, 1: 3 or more) or the length of the member is long (for example, 12 m or more) with respect to the thickness of the web, the twisting of the I-shaped structural member due to galvanization, Bends and skewing inside the member are even greater.

Until now, there is no known practical and effective deformation preventing method other than the above-mentioned restraint material in galvanizing I-shaped structural members. For this reason, at present, the spread of zinc-plated girder for bridge bridges has been delayed in spite of the fact that it is recognized that zinc-plated girder is superior in terms of service life, as compared with painted girder.

Accordingly, the present invention relates to a method for manufacturing a steel sheet girder such as
The present invention provides a simple and practical galvanizing method capable of preventing deformation such as entanglement, twisting and bending in galvanizing of a structural member, and the present invention provides a method of transporting and storing a galvanized I-shaped member. Or, it also facilitates erection.

[0013]

SUMMARY OF THE INVENTION The present invention has been achieved by various studies to achieve the above object, and the gist of the present invention is to galvanize an I-shaped structural member having flanges at upper and lower portions of a web. At this time, at least two of the I-shaped structural members are arranged in parallel with the web in the longitudinal direction, and the both ends of the I-shaped structural members in the horizontal direction are connected by restraining plates so as to be dipped in a galvanizing bath. Hot-dip galvanizing method for an I-shaped structural member.

Further, according to the present invention, a deformation preventing restraint is attached along the end of the web using a joint bolt hole provided at a lateral end of the web, and the restraint is inserted through the restraint. A galvanizing method for an I-shaped structural member, characterized in that both ends of the I-shaped structural member are connected by a restraint plate.

Further, according to the present invention, a spacer is interposed between the web and the restraint plate, or between the web and the restraint member for preventing deformation, to form a gap between the restraint plate or the restraint member for preventing deformation and the web. And hot-dip galvanizing the entire surface of the web as much as possible.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The hot dip galvanizing method for an I-shaped structural member of the present invention does not involve immersing the I-shaped structural member in a single state in a hot-dip galvanizing bath and galvanizing it. The method is characterized in that the I-shaped structural members are hot-dip galvanized with their lateral ends connected by restraining plates.

The reason why the present invention performs galvanizing in a state where the ends of the I-shaped structural members are connected by the restraint plates is that the two I-shaped structural members are connected by connecting the both ends by the restraint plates. This is to temporarily form a pseudo-single structure so that even if each I-shaped structural member receives a thermal stress in the hot-dip galvanizing process, the I-shaped structural member cannot be freely deformed as before. . In other words, by firmly connecting the lateral ends of the I-shaped structural member with the restraint plate, even if they are deformed by receiving thermal stress during the plating process, the restraint plates are mutually restricted and the deformation can be significantly suppressed. It has been found.

The I-shaped structural member according to the present invention is a metal member which requires hot-dip galvanizing for rust prevention and which can obtain required strength as various structural materials, and is usually formed of steel. A long thin plate structural member having a substantially I-shaped cross section having a flange attached to the upper and lower portions of a web usually by welding or the like, and a typical example thereof is a plate girder for a bridge. Of course, an I-shaped structural member other than the sheet girder may be used.

The above-mentioned I-shaped structural member is a large-sized I-shaped structural member in which the above-mentioned entangled deformation or torsional deformation occurs in the hot-dip galvanizing step, and the member length is usually 4 m.
The above is effective for the present invention. The thickness and dimensions of the web and flange of the I-shaped structural member are appropriately determined mainly depending on the application, but as a practical range, the thickness of the web is 5 to 20 mm and the height is 1000 to 3000 m.
m, the thickness of the flange is 10 to 50 mm, and the width is 200
Those having a size of about 800 mm are generally used.

In the present invention, the number of I-shaped structural members to be connected is not limited, but usually two I-shaped structural members are connected. As the number of connected I-shaped structural members increases, the apparent volume becomes more than twice as large as a single I-shaped structural member, so not only a large hot-dip galvanizing bath is required, but also the overall weight is significantly increased. In order to increase the load, the load into and out of the plating bath increases, and the workability of hot-dip galvanizing deteriorates. Furthermore, in a preferred embodiment, even after plating, the restraint plate is not removed from the I-shaped structural member, and the I-shaped structural member is stored and transported in the connected state, so that the number of connected I-shaped structural members is three. If the number is more than one, troubles increase in these aspects as well. Therefore, it is usually best to connect two I-shaped structural members.

When the I-shaped structural members are connected by a restraining plate, the two I-shaped structural members are preferably 0.5 to 1.5 m, particularly 0.8 to 1. The webs are arranged side by side at an interval of 0 m, and in this state, both ends of the web are connected by a restraining plate. When the I-shaped structural member is for a sheet girder, at least the webs at both ends are provided with the joint bolt holes as described above, so that the restraint plates can be easily connected by using the bolt holes of the joints. . of course,
If there is no such bolt hole, such a bolt hole is formed as needed. Further, as described above, it is conventionally known to attach constraining members to both ends of the web as a measure to prevent entanglement deformation during hot-dip galvanizing, as described above, but in the most preferred embodiment of the present invention, It is particularly preferable to connect the I-shaped structural members with a restraining plate via such a restraining material, preferably a restraining material made of angle iron. In this case, the attachment of the restraint plate becomes extremely simple, and the effect of preventing the deformation by the restraint material itself is more firmly achieved. However, in the present invention, both ends of the two I-shaped structural members may be directly connected by the restraint plate without such a restraint member.

In the present invention, the hot dip galvanizing condition and the cooling condition of the I-shaped structural member can be substantially the same as those in the conventional method. Therefore, although these conditions are not described in detail, in general, the plating conditions are bath temperature: 435 to 445.
C., immersion speed in the plating bath: 10 to 30 m / min, immersion angle: 15 to 25 degrees, pulling speed: 1 to 10 m / min, and the pulling angle is preferably gradually increased from the initial 5 degrees to the final 30 degrees. The cooling conditions were as follows: water temperature: 60 to 80 ° C., immersion speed:
The immersion angle is preferably about 20 to 30 degrees, and the pulling speed and angle are arbitrarily selected. next,
The present invention will be specifically described with reference to the drawings.

FIG. 1 is a plan view in which both ends of two I-shaped structural members are connected by restraint plates 9. In this example, two I-shaped structural members for sheet girder are connected by a restraining plate 9 via a restraining member 6 shown in FIG. 11, FIG. 2 is a right side view of FIG. 1, and FIG. It is sectional drawing of the BB part of FIG. The left end of the I-shaped structural member of FIG. 1 is exactly the same as the right end.

Each I-shaped structural member before connection usually has joint bolt holes (see FIG. 7) at both end portions of the web 1 in order to splice the girder laterally on site. And
As described in detail with reference to FIGS. 9 to 12, it is preferable that rigid members 6 made of angle steel are firmly attached to the joint portion of the web 1 with bolts 7 on both sides of the web 1 in advance. In this case, since the restraining member 6 can also obtain the effect of preventing the web from being deformed, it is preferable to provide the restraining members 6 on both sides of the web 1 as in this example. Among the restraint members 6 attached to both sides of the web 1, the restraint member on the side to which the restraint plate 9 is fixed, that is, the restraint member located inside the two parallel I-shaped structural members is provided with the restraint plate 9. There is a bolt hole for attaching a.

When the restricting member 6 comes into close contact with the web 1,
This portion of the web is covered with the restraining material 6 and cannot be hot-dip galvanized. Therefore, in order to separate the restraining material from the web so that the entire surface of the web can be hot-dip galvanized, in this example, the web is hot-dip galvanized. A pipe washer 8 is inserted as a spacer between 1 and the restraining member 6. FIG. 6 shows an example of the pipe washer 8. A semicircular hole 12 for zinc outflow, preferably having a diameter of preferably 5 to 15 mm, is provided on the four ends of the pipe body for convenience. The pipe washer 8 may be tack-welded to the restraining member 6.

FIG. 5 shows the restraint plate 9 of this embodiment. Normally, the restraint plate 9 is formed of a steel square thick plate, and bolt holes 11 are provided at both ends of the restraint plate 9 in accordance with the positions of the bolt holes of the restraint member 6. Here, the height of the restraint plate 9 is substantially the same as the height of the web 1 of the I-shaped structural member to be connected, and the width can be appropriately determined. Are defined. If the width of the restraint plate is too large, the width of the I-shaped structural member after connection becomes unnecessarily large, which affects the size of the hot-dip galvanizing bath, the storage space after plating, and the transportation in the factory. On the other hand, if the width is too small, the workability at the time of attaching the restraining plate to the structural member becomes worse, and the resistance when immersing in the plating bath increases, and the immersion speed of the structural member into the plating bath must be reduced. May not get. If the immersion speed in the plating bath is low, the amount of twist generated in the structural member increases. In consideration of these, the width of the restraint plate 9 is usually 50 to 150 cm.
It is about.

The thickness of the restraint plate 9 is determined so as to obtain a strength that can withstand the stress generated in the hot-dip galvanizing process. If the thickness is small, the required strength cannot be obtained, so that the restraint plate is deformed due to the thermal stress of the hot-dip galvanizing process, and the deformation such as fringing, twisting, bending, etc. occurring in the I-shaped structural member is sufficiently suppressed. Can not. However, since the deformation of the I-shaped structural member mainly depends on the member length, the web thickness, the flange thickness, etc., it is practical to determine the thickness of the restraint plate 9 based on the design specification of the I-shaped structural member. It is. In the case of a restraining plate for connecting I-shaped structural members for bridges, its thickness is preferably 10 to 50 mm.

Next, a method of actually connecting the two I-shaped structural members with the restraint plate 9 will be described. First, two I-shaped structural members in which the restraining members 6 are attached to the joints at the ends in advance are arranged side by side at an interval corresponding to the width of the restraining plate 9 with the web in the vertical direction. Next, the inside of the restraining member 6 (FIG. 3)
In this case, the restraint plate 9 is brought into contact with the upper portion of the restraint member 6), and the restraint member 6 and the restraint plate 9 of each I-shaped structural member are tightened by bolts 10. The number of bolts to be tightened may be appropriately selected depending on the size of the structural member, the mounting strength of the restraint plate, and the like.
If the attachment of such a restraining plate is performed on both sides of the I-shaped structural member, the two I-shaped structural members can be connected by the restraining plate 9 as shown in FIG.

When an I-shaped structural member in which a vertical stiffener or a horizontal stiffener is attached to only one side of the web is combined, when the I-shaped structural members are juxtaposed, the stiffener is not used. It is preferable to arrange them symmetrically. In this example, the restraint plate 9 is attached to the inside of the restraint 6, but the restraint plate 9 can be mounted to the outside of the restraint 6 by changing the mounting direction of the restraint 6 to the web 1.

FIG. 4 shows another embodiment of the present invention. In this example, as is apparent from the figure, both ends of the I-shaped structural member are connected by the constraint plates 9 without the intervention of the constraint members 6 described above. The restraint plate 9 of this example is a thick plate having a U-shaped cross section having ribs 14 formed on both sides, and the restraint plate 9 is formed by utilizing a bolt hole provided in the rib and a joint bolt hole of the web 1. 9
Are directly attached to the web 1 by bolts 7. In the figure, reference numeral 13 denotes a nut stopper plate.

Further, in the present invention, the restraint plate is not limited to the single plate shown in FIG. 3 or the thick plate having a U-shaped cross section shown in FIG. Although not shown, a frame-shaped or composite panel can be used as long as the required strength is ensured. Further, the object can be substantially achieved only by connecting both ends of the I-shaped structural member with the restraint plates. However, if necessary, for example, a flange other than both ends of the I-shaped structural member may be fixed by other means. You may.

[0032]

(Example 1) For a bridge having a flange thickness of 20 mm, a web height of 2400 mm, a web thickness of 12 mm and a web length of 6.7 to 11.7 m as shown in Table 1 below. An I-shaped structural member was manufactured using a steel material. And
As shown in Table 1, each of the two I-shaped structural members was subjected to the method shown in FIGS.
Four sets of (1) having ends connected by a steel restraining plate having a width of 0 mm and a width of 80 cm were produced. Each of these I-shaped structural members was hot-dip galvanized according to a conventional method. After the hot-dip galvanizing, the relationship between the member length and the twist was measured.
Table 1 shows the results. The I-shaped structural member after plating has twists in both directions of the web. Table 1 shows the amount of twist on one side of the web where the maximum twist occurred, as shown in FIG. I asked by doing.

[0033]

[Table 1] As is clear from FIG. 1, it was found that the amount of torsion could be suppressed to less than 100 mm within the practically acceptable range in both cases where the constraint plate thickness was 20 mm and the constraint plate thickness was 30 mm. When the restraint plate thickness is 30 mm, the member length is 1 mm.
It has been found that even in the case of an extremely large length of 1 m or more, the amount of twist can be suppressed to a small value.

Furthermore, in the case of the present invention, it was found that, in addition to the amount of twist, the deformation of the members (flatness of the web) can be suppressed to a small range. For example, member length 8.8
As can be seen from Table 1, the I-shaped structural member having an amount of twist of 42 mm has a flatness of the web of H /
400 (H is the height of the web). Note that the flatness of the web is obtained by dividing the height of the web by the maximum length of the web on both sides as viewed from the lateral direction, and expressing this as H / X. Has a maximum length of 6 mm.

On the other hand, in order to compare the method of the present invention with the conventional method, an I-shaped structural member having a member length of 8.8 m was subjected to the same conditions as those of the present embodiment in the conventional method in which only the restraining members shown in FIGS. When the amount of twist and the flatness of the web were measured after plating, the amount of twist was 130.
mm, and the flatness of the web was H / 229. From this, it can be seen that the method of the present invention can significantly reduce the deformation in the hot-dip galvanizing process as compared with the conventional method.

(Embodiment 2) The member length of Embodiment 1 is 8.8 m.
The thickness of the flange was changed for the I-shaped structural member of
The thickness of the shaped structural member is 20 mm by the same method as in the first embodiment.
And a 30 mm steel restraining plate, hot-dip galvanizing with the two parallel end portions connected. After plating, the relationship between the ratio of the web thickness to the flange thickness and the twist was investigated. Table 2 shows the results. The method of measuring the amount of twist is the same as in the first embodiment.

[0037]

[Table 2] From Table 2, the constraint plate having a plate thickness of 20 mm and the plate thickness of 30 mm
In each case, it was confirmed that the amount of twist could be suppressed to less than 100 mm within the practically acceptable range. Also, the ratio of the web thickness to the flange thickness has a close relationship with the amount of torsion, and the greater the flange thickness, the greater the amount of torsion, but a 30 mm thick restraint plate becomes a 20 mm thick restraint plate. In comparison, it was found to have a greater torsional suppression effect.

[0038]

According to the present invention, as described above, the ends of at least two I-shaped structural members to be hot-dip galvanized are firmly connected with a restraining plate to form a pseudo unitary structure. Since each of the I-shaped structural members is deformed due to thermal stress in the hot-dip galvanizing process, the deformation is suppressed due to the single structure, and the deformation such as entanglement, twisting, bending, etc. Can be significantly prevented or reduced. Above all, these deformations are most likely to occur,
In addition, by connecting the ends of the I-shaped structural members, which are more strongly required to prevent the deformation than the other parts as joints, with a restraining plate, the deformation, which could not be solved by the conventional method, can be reduced extremely effectively to an allowable range. Can be done.

Further, the connection of the end of the I-shaped structural member by the restraining plate can be performed simply and firmly by utilizing the bolt holes of the joint portion. It is more preferable to attach and connect with a restraining plate via the restraining material, because not only the connecting operation becomes easy, but also the deformation preventing effect by the restraining material is added.

Further, according to the present invention, even after the hot-dip galvanizing, the constraining plate is not removed until the bridge is erected and is held as it is, so that the conventional method of hot-dip galvanizing the I-shaped structural member alone cannot be obtained at all. Many additional effects can be obtained.

That is, in the present invention, the torsion of the I-shaped structural member is extremely small, and at least two I-shaped structural members are unitized with their ends connected by a restraining plate at a desired interval. Compared with the conventional method, a great merit that is larger than expected can be obtained, for example, the shape structural member can be stored and transported in an upright stable state. Table 3 summarizes the advantages of the present invention other than deformation prevention in the hot-dip galvanizing process and the advantages over the conventional method.

[0042]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a plan view of an I-shaped structural member obtained according to the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a sectional view taken along a line BB in FIG. 2;

FIG. 4 is a cross-sectional view corresponding to FIG. 3 in another embodiment of the present invention.

FIG. 5 is a perspective view of an embodiment of a restraint plate according to the present invention.

FIG. 6 is a perspective view of a pipe washer according to the present invention.

FIG. 7 is a perspective view showing an embodiment of an I-shaped structural member.

FIG. 8 is a perspective view showing another embodiment of the I-shaped structural member.

FIG. 9 is a front view of an I-shaped structural member according to a conventional method.

FIG. 10 is a partially enlarged view of a right end portion of FIG. 9;

FIG. 11 is a right side view of FIG. 9;

FIG. 12 is a sectional view taken along the line AA in FIG. 10;

FIG. 13 is an explanatory view of measuring the amount of twist of an I-shaped structural member.

[Explanation of symbols]

 1: Web 2: Flange 5: Bolt hole at joint 6: Restraint material 7: Bolt 8: Pipe washer 9: Restraint plate 10: Bolt

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Fujimoto 383, Jingu-ko, Imabari-shi, Ehime (72) Inventor Koji Yanagawa 4315, Hongo-cho, Hongo-cho, Toyota-gun, Hiroshima 4315 (72) Inventor Kohei Kikukawa Numata-nishimachi, Mihara-shi, Hiroshima Sojyo 1043-30 (56) References JP-A-64-143591 (JP, A) JP-A-58-100666 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 2 / 00-2/40

Claims (4)

(57) [Claims] 1. A method of galvanizing an I-shaped structural member having a flange on upper and lower portions of a web, comprising: arranging at least two of the I-shaped structural members with the web in a longitudinal direction;
A hot dip galvanizing method for an I-shaped structural member, wherein the I-shaped structural member is immersed in a hot-dip galvanizing bath and galvanized in a state where both lateral ends of the I-shaped structural member are connected by a restraining plate. 2. A deformation preventing restraint is attached along the end of the web using a joint bolt hole provided at a lateral end of the web, and the I-shape is connected through the restraint. The I of claim 1, wherein both ends of a structural member are connected by the restraint plate.
Hot-dip galvanizing method for structural members. 3. A gap is provided between the restraining plate or the restraining member for preventing deformation and the web by interposing a spacer between the web and the restraining plate or between the web and the restraining member for preventing deformation. 3. The hot-dip galvanizing method for an I-shaped structural member according to 1 or 2. 4. The galvanizing method for an I-shaped structural member according to claim 1, wherein the I-shaped structural member is a bridge girder.