JPH11277227A - Welded structure of steel structure and method for welding steel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the weld crack of root or plural layers without preheat management by forming the root or plural layers on the root side of the welded joint of the single bevel groove of a steel structure of a weld metal which is lower in strength and higher in ductility than a base metal and forming the remaining layers of a weld metal having the strength equivalent to or higher than the strength of the base metal. SOLUTION: A steel beam 3 is joined by welding to a steel column 2. The root or plural layers 1a on the root side of the welded joint of the single bevel groove 1 formed at the end of the flange part 3a of the steel beam 3 are formed of the weld metal which is lower in strength and higher in ductility than the base metal of the steel column 2 and the steel beam 3, etc. All of the remaining layers 1b are formed of the weld metal having the strength equivalent to or higher than the strength of the base metal. A backing strip 4 is used for welding. The root or plural layers 1a on the root side are welded by a MAG welding method or MIG welding method and all of the remaining layers 1b are welded by either of the MAG welding or the MIG welding method or TIG welding method. As a result, the stress concentration of the stress concentrated part is relieved and the brittle fracture against external force is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a welding structure for steel structures and a welding method therefor.
The present invention relates to a welding structure when a beam-to-column joint of a steel structure is joined by welding and a welding method thereof.

[0002]

2. Description of the Related Art In a steel-frame building, when a beam-to-column joint is joined by welding, brittle breakage due to a welded portion of a beam end flange of a beam-to-column joint and the vicinity of the welded portion or scallop is a problem. It has become. As a countermeasure,
The following known techniques have been proposed. A method of reinforcing the beam ends with ribs. A welding method that performs welding without providing scallops, which is one of the causes of brittle fracture of beam-column joints.

[0003] In addition, the following known techniques have been proposed. Japanese Patent Application Laid-Open No. 8-281486 discloses a method of welding a steel beam-column joint using a steel backing metal having a yield stress and a tensile strength less than a yield stress and a tensile strength of a column and a beam to be welded. In addition, a welding method for a steel beam-to-column joint in which welding is performed using a welding material having a yield stress and a tensile strength of a weld metal generated by welding equal to or higher than a yield stress and a tensile strength of a steel backing metal. Is disclosed. Japanese Patent Application Laid-Open No. 8-281487 discloses a method of welding a steel beam-to-column joint using a steel backing metal having a yield stress and a tensile strength higher than a yield stress and a tensile strength of a column and a beam to be welded. In addition, a welding method for a steel beam-to-column joint in which welding is performed using a welding material in which the yield stress and tensile strength of a weld metal generated by welding are less than the yield stress and tensile strength of a steel backing metal Is disclosed. In a paper on "Study on Static Tensile Strength of Soft Welded Joints" presented at the Autumn Meeting of the Shipbuilding Society of Japan in October 1972, a weld metal with lower strength than the base metal was welded with a K-shaped groove. The structure of a steel structure applied to the formation of the initial layer with the central portion of the steel layer as the initial layer and a welding method are disclosed.

[0004]

In the above-mentioned prior art, since the work of mounting the ribs must be performed after the welding work is completed, it is troublesome, the work efficiency is reduced, and the cost is high. In the prior art welding method without scallops, in terms of quality control, a bracket method in which a bracket is welded to a pillar in advance at a factory or the like must be adopted, and has recently been established as a cost reduction method. The non-bracket method of directly joining the beam to the column cannot be adopted. As a result, it is costly.

Further, in the above-mentioned prior art, and many other prior arts, and generally known art, a stress concentration portion of a welded joint (for example, a stress such as a first layer on the root side of a welded joint having a groove) is formed. A high yield point welding material is used for the concentrated portion) (high yield point weld metal is formed). In this case, it has been pointed out that the elastic strain energy, which is generally stored at the starting point of the fracture and released at the time of fracture, greatly affects the crack growth rate and the fracture mode. The use of high yield point welding consumables at stress concentrations, such as the first layer on the side, is problematic. That is, when the yield point of the weld metal is higher than the yield point of the base material such as a column or a beam, the energy released at the time of crack propagation increases, and brittle fracture is likely to occur.

In the above prior art, the yield stress and the tensile strength of the backing metal are made smaller than the yield stress and the tensile strength of the base material such as columns and beams and the weld metal, and the welded portion of the beam end flange and the vicinity of the welded portion are formed. In the prior art, the yield stress and the tensile strength of the backing metal are made larger than the yield stress and the tensile strength of the base material such as columns and beams and the weld metal, thereby welding the beam end flange. It is a configuration that alleviates stress concentration in the vicinity of the welded portion and the welded portion, and since ordinary steel is not used as a backing metal, it is costly.

Conventionally, a welding method using a welding material (weld metal) having lower strength and higher ductility than the base metal is effective for reducing the preheating temperature and preventing welding cracks and the like for high-tensile steel. It is known, and the main focus is on these effects and the improvement of proof stress by the triaxial restraint effect of the base material. However, the strength of welds where the weld metal of lower strength than the base metal is applied to all layers of the weld does not become greater than the strength of the base metal, and the building where columns and beams break the base material in principle. It is difficult to apply in the field.

In the above prior art, only the first layer located at the center of the K-shaped grooved welded joint is formed of a weld metal having a lower strength than the base metal, and the other layers are welded by a normal weld metal. In addition to the effects of reducing the preheating temperature and preventing welding cracks and the like, the K-shaped groove has a three-axis restraining effect to ensure a sufficient strength of the welded portion. However, the K-shaped groove is rarely used in the field of construction mainly for field work.

[0009] Next, 780N of steel (600 N / mm ² with a high tensile steel or the strength of 600N / mm ² class / mm ²
Up to 600 N / mm ² , although there is a welding material that forms a weld metal lower than its strength
Steel material having a strength less than that of high-grade steel (400 N / mm ²
490 N / mm ² to 490 N / mm ² ), there is no welding material that forms a weld metal of lower strength than its base metal. The yield strength of welded steel is 245
N / mm ² or more, and a welding metal having a proof strength of less than that, even if a pure iron material having a yield strength of 245 N / mm ² or less is used as a filler metal, deoxidation (Mn, Si This is because an increase in proof stress cannot be avoided in the process of (addition).

[0010] Accordingly, an object of the present invention is to perform welding capable of preventing welding cracks or the like in the first layer or a plurality of layers on the root side of a welded groove-shaped welded joint without preheating management. It can reduce the stress concentration at the stress concentration part such as the first layer or multiple layers on the root side of the joint, and the brittleness near the welded part of the beam end flange of the beam-column joint and the welded part generated when external force such as earthquake acts Another object of the present invention is to provide a welding structure for a steel structure and a method for welding a steel structure, which can prevent a severe breakage, can perform a welding operation efficiently, and is inexpensive.

[0011] It is a further object of the present invention to form a weld metal having a lower strength and a higher ductility than a steel material having a strength lower than that of a high-strength steel of 600 N / mm ² class, thereby forming a base metal having a strength of 600 N / mm ^2.
An object of the present invention is to provide a welding method for a steel structure, which can be performed even when using a steel material having a strength lower than high-strength steel of / mm ² class.

[0012]

According to a first aspect of the present invention, there is provided a welding structure for a steel structure, the method comprising: The first layer or a plurality of layers are formed of a weld metal having lower strength and higher ductility than the base material, and the remaining layers are formed of a weld metal having a strength equal to or higher than that of the base material. I do.

According to a second aspect of the present invention, there is provided a method for welding a steel structure, wherein the first layer on the root side of the welded joint of the groove of the steel structure is formed by a MAG welding method or a MIG welding method. Weld with lower strength and high ductility welding material, and the other layers with MAG welding method or MIG welding method or TIG welding method as above, with welding material having the same or higher strength as the base material. It is characterized by the following.

According to a third aspect of the present invention, there is provided a method for welding a steel structure, wherein the first layer or the plurality of layers on the root side of the welded joint of the groove of the steel structure is lower than the base material by the TIG welding method. Weld with a high-strength, high-ductility welding material, and use the TIG welding method, MAG welding method, or MIG welding method to weld the remaining layers with a welding material having a strength equal to or greater than that of the base material as described above. Features.

According to a fourth aspect of the present invention, there is provided a method for welding a steel structure according to the second or third aspect, wherein
A steel material having a strength of less than 0 N / mm ² class high-strength steel is used, and the steel material is placed in an active gas atmosphere such as carbon dioxide gas or a mixed gas of argon gas and carbon dioxide gas, or in an inert gas atmosphere such as argon gas. , The carbon content is 0.01% or less,
Silicon content is 0.02% or less, manganese content is 0.2
% Or less, a phosphorus content of 0.01% or less, and a sulfur content of 0.01% or less by using industrial pure iron as a filler material, and melting and solidifying the industrial pure iron by arc heat. It is characterized in that a weld metal having lower strength and higher ductility than the base metal is formed in the first layer or a plurality of layers on the root side of the welded joint of the groove-shaped groove of the steel structure.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A welding structure for a steel structure according to the invention as set forth in claim 1 has a structure as shown in FIGS.
When the steel beam 3 is joined to the steel column 2 by welding, the groove 1 formed at one end of the flange 3a of the steel beam 3
The first layer or multiple layers 1a on the root side of the welded joint of
A weld metal with lower strength and higher ductility is formed than the base material such as the steel column 2 and the steel beam 3, and the remaining layers 1 b are all equal in strength to or higher than the base material such as the steel column 2 and the steel beam 3. Is formed of a weld metal having Reference numeral 4 in the figure is a backing money, and reference numeral 5 is a scallops.

The embodiment shown in FIGS. 1 to 3 is of a non-bracket type in which one end of a flange 3a of a steel beam 3 is directly welded to the side surface of a steel column 2 by a welding method of the present invention. Is shown. In the embodiment of FIG.
You are using In the embodiment of FIG. 3, the backing metal 4 provided with the notch 4a in advance is used to form the first layer or the plurality of layers 1a on the root side in the welded joint of the grooved groove 1.

In the embodiment shown in FIGS. 4 to 6, the flange 3'a of the bracket 3 'is previously attached to the steel column 2 in a factory or the like.
Is shown, and the steel column 2 and the steel beam 3 are joined by the welding method of the present invention using the bracket 3 ′ at the site. In the embodiment of FIG. 5, a normal backing metal 4 is used. In the embodiment of FIG. 6, a backing metal 4 provided with a notch 4a in advance is used to form the first layer or a plurality of layers 1a on the root side in the welded joint of the grooved groove 1.

The welding method for realizing the above-mentioned welding structure is roughly divided into the following two welding methods. First
The welding method according to the second aspect of the present invention relates to the first layer 1 on the root side of the weld joint of the groove 1 of the steel structure.
a is welded by a MAG welding method or a MIG welding method with a welding material having a lower strength and a higher ductility than the base material such as the steel column 2 and the steel beam 3, and the other layers 1b are all MAG similar to the above.
Welding is performed using a welding material having a strength equal to or higher than that of the base material such as the steel column 2 and the steel beam 3 by any of the welding method, the MIG welding method, and the TIG welding method.

The second welding method according to the third aspect of the present invention relates to the invention described in claim 3, wherein the first layer or the plurality of layers 1a on the root side of the weld joint of the grooved groove 1 of the steel structure is formed by a TIG welding method. Welding is performed with a welding material having a lower strength and a higher ductility than the base material such as the column 2 and the steel beam 3, and all the remaining layers 1b are formed by the same TIG welding method, MAG welding method or MIG welding method as described above. The welding is performed with a welding material having a strength equal to or higher than that of the base material such as the steel column 2 and the steel beam 3.

Comparing the above two welding methods, the first welding method is more efficient than the second welding method.
However, compared to the first welding method in which a welding material having a lower strength and a higher ductility than the base material is welded only to the first layer in the weld joint of the groove 1, the same material is welded not only to the first layer but also to a plurality of layers. The second welding method is superior in welding precisely as designed. However, in other respects, there is no difference between the above-mentioned effects.

[0022] When using a steel having a high tensile steel or the strength of 600N / mm ² class in the base material such as a steel column 2 and steel beam 3 by welding method of the two, for example, 600N / mm in the base material
Using a grade ² steel material, the yield strength is 2
Using 45 N / mm ² of industrial pure iron, the thickness of the weld metal of the first layer or the plurality of layers 1 a on the root side in the welded joint of the grooved groove 1 is reduced to 1 / th of the thickness of the flange portion of the beam 3. Form up to 3.

When a steel material having a strength of less than 600 N / mm ² class high-strength steel is used as a base material such as the steel column 2 and the steel beam 3 by the above two welding methods, the steel material is replaced with carbon dioxide gas or argon gas. In an active gas atmosphere such as a mixed gas of carbon dioxide gas or an inert gas atmosphere such as an argon gas, the carbon content is 0.01% or less, the silicon content is 0.02% or less, and the manganese content is 0.1% or less. 2% or less, phosphorus content 0.01%
Hereinafter, the industrial pure iron having a sulfur content of 0.01% or less is used as a filler metal, and the industrial pure iron is melted and solidified by arc heat to obtain a solid material that is less than the base material such as the column 2 and the beam 3. A low-strength, high-ductility weld metal can be formed in the first layer or the plurality of layers 1a on the root side in the welded joint of the grooved groove 1 of the steel structure. The weld metal has a yield strength of 245N.
/ Mm ² or less, and the tensile strength is 400 N / mm ² or less.

The experimental results of the welding structure of the steel structure to which the welding method according to the present invention was applied are shown below. Experimental data 1: Effect of base metal deterioration prevention and improvement of weldability deformation ability CTOD test (-50 to-
At 30 ° C.), the crack opening displacement of the specimen (welded structure) using the low-strength and high-ductility welding material described above was 1.1 in the heat-affected zone as compared with the specimen of the ordinary welding method. 5 times,
It was about three times as large at the welded portion, confirming the effect of deteriorating the base metal and improving the deformability of the welded portion.

Experimental data 2: Base metal deterioration prevention effect In a hardness test, which is one index of brittle fracture, the hardness of a test piece using the above-described low-strength and high-ductility welding material is as follows.
It was 10 to 20% lower than that of the test piece of the normal welding method, and it was confirmed that the deterioration of the base material was prevented. Experimental data 3: Assurance of base metal fracture In order to confirm base metal fracture, a welded joint with a groove-shaped groove having a weld metal of lower strength and higher ductility than the base metal in the first layer or multiple layers on the root side (the present invention) (Welded joints) were subjected to a tensile test.
490 N / mm ² grade steel was used as the base material. in this case,
In a test body to which a welding material having low strength and high ductility was applied by t / 6 of the plate thickness (flange thickness of the steel beam 3) t, base material fracture was confirmed. In addition, t of plate thickness (flange thickness of steel beam 3) t
In the test specimen to which a low-strength and high-ductility welding material was applied, the tensile strength exceeded the JIS standard value of the base metal tensile strength, but the weld was broken, and the base metal and the weld were broken. Could be confirmed. From the above, the base material was 490
When a steel material of N / mm ² class is used, the welding method according to the present invention (the root side of the welded joint of the groove 1) up to a range of less than t / 3 of the plate thickness (flange thickness of the steel beam 3) t. When the first layer or the plurality of layers 1a were formed of a weld metal having lower strength and higher ductility than the base material), the base material was confirmed to break. t
If it is less than / 3, the effect of the present invention is exhibited, and the base material is broken. Normally, the thickness of one layer is often constituted by welding of about 5 mm, so that the plate thickness (the flange thickness of the steel beam 3) is 20 mm.
With the above, the welding method of the present invention can be applied.

In the embodiment shown in FIG. 3 or FIG. 6 to which the form of the backing metal 4 corresponds, the first layer or the plurality of layers 1a on the root side of the welded joint of the groove 1 is connected to the steel beam 3 as shown. Welding is performed only up to the boundary with the backing metal 4, but is not limited to this.
Base material strength, plate thickness (flange thickness of steel beam 3) and backing metal 4
Depending on the size of the notch and the like, it is performed in a range suitable for each.

[0027]

According to the welding structure for a steel structure and the method for welding a steel structure according to the present invention, the first or multiple layers on the root side of a welded joint having a groove-shaped groove without preheating management can be used. Welding can be performed to prevent welding cracks, etc., and the stress concentration at the stress concentration part such as the first layer or the plurality of layers on the root side of the welded joint of the concave groove is reduced, and this occurs when external force such as an earthquake acts. It is possible to prevent brittle breakage in the welded portion of the beam end flange of the beam-column joint and in the vicinity of the welded portion. In addition, the welding operation can be performed efficiently and at a low cost.

Further, according to the welding method for a steel structure according to the present invention, according to the welding method using a steel material having a strength of less than 600 N / mm ² class high-strength steel as a base material, there is no conventional method. Welding metal can be formed with a lower strength than a steel material having a strength less than 600 N / mm ² class high-strength steel, and therefore has a strength less than 600 N / mm ² class high-strength steel for base materials such as columns and beams. Even if a steel material is used, the welding structure for a steel structure according to the present invention can be implemented.

[Brief description of the drawings]

FIG. 1 is a front view showing a welded structure of a steel structure in which the present invention is applied to a non-bracket method.

FIG. 2 is an enlarged view of a portion X in FIG.

FIG. 3 is an enlarged view of a different embodiment of a part X in FIG. 1;

FIG. 4 is a front view showing a welding structure of a steel structure in which the present invention is applied to a bracket method.

FIG. 5 is an enlarged view of a portion X ′ in FIG. 4;

FIG. 6 is an enlarged view of a different embodiment of a part X ′ of FIG. 4;

[Explanation of symbols]

 1 Re-groove 1a First layer or multiple layers on the root side 1b Additional layers

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 35/30 320 B23K 35/30 320F C22C 38/00 301 C22C 38/00 301Y 38/04 38/04

Claims (4)

[Claims] A first layer or a plurality of layers on the root side of a welded joint of a groove-shaped groove of a steel structure is formed of a weld metal having a lower strength and a higher ductility than a base metal, and the remaining layers are formed of a base metal and a base metal. A welded structure for a steel structure, wherein the welded structure is formed of a weld metal having the same or higher strength. 2. The method according to claim 1, wherein the first layer on the root side of the welded joint of the groove of the steel structure is welded by a MAG welding method or a MIG welding method with a welding material having a lower strength and a higher ductility than the base material. Is welded by a MAG welding method, a MIG welding method, or a TIG welding method with a welding material having a strength equal to or higher than that of the base material as described above. 3. A root layer-side first layer or a plurality of layers in a welded joint of a groove-shaped groove of a steel structure is welded by a TIG welding method with a welding material having a lower strength and a higher ductility than a base material, and the remaining layers. Is a method for welding a steel structure by using a TIG welding method, a MAG welding method, or a MIG welding method as described above, using a welding material having a strength equal to or higher than that of the base material. 4. A steel material having a strength of less than 600 N / mm ² class high-strength steel is used as a base material, and the steel material is placed in an active gas atmosphere such as carbon dioxide gas or a mixed gas of argon gas and carbon dioxide gas, or argon gas. In an inert gas atmosphere such as the above, the carbon content is 0.01% or less, the silicon content is 0.02% or less, the manganese content is 0.2% or less, and the phosphorus content is 0.01%.
In the following, a weld metal having lower strength and higher ductility than the base metal is obtained by using industrial pure iron having a sulfur content of 0.01% or less as a filler material and melting and solidifying the industrial pure iron by arc heat. 3 is formed on the first layer or a plurality of layers on the root side of the welded joint of the grooved groove of the steel structure.
Or the welding method of steel structure described in 3.