JPH09122906A - Reinforcing method for increasing joint strength in inserting joint fitting into slit for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a joint to withstand tensile strength of a steel pipe by increasing weld quantity of the boxing welding zone of a steel pipe to a joint fitting and thereby increasing joint strength. SOLUTION: The reinforcing method is such that a joint fitting 3 is inserted into a slit 2 in the axial direction provided in the center at the end of a steel pipe so that this abutting line is welded, and that reinforcement is attained by increasing joint strength through the increase in the weld quantity of the boxing welding zone of a steel pipe 1 to a joint fitting 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing method for increasing the joint strength of inserting and welding a joint fitting into a slit of a steel pipe member used for constructing a truss structure with the steel pipe member.

[0002]

2. Description of the Related Art Conventionally, when constructing a truss structure using steel pipes, there have been considered a method of directly joining the steel pipes by welding and a method of connecting the steel pipes through joint fittings. When connecting via the latter fitting, it is common to cut a slit along the axis of the steel pipe at the end on the side where the steel pipe is connected, insert the fitting into the slit, and weld the surrounding area. Target.

[0003]

When a slit is cut in the steel pipe, a fitting is inserted, and the periphery thereof is welded,
The amount of welding is determined so as to withstand the tensile strength of the steel pipe, but stress concentration occurs in the "turned weld", and there is a gap between the joint metal fittings and the steel pipe at this part, causing insufficient welding. Since it occurs, a joint that cannot withstand the tensile strength of the steel pipe is produced, and when a full-scale experiment is performed, it breaks in a state where it is torn from the "turned weld".

Therefore, the member having the joint type in which the joint fitting is inserted in the slit of the steel pipe has to be designed so that the tensile strength is reduced to 80 to 85% of that of the steel pipe.

As a method of reinforcing the strength, as shown in FIG. 1, a method of inserting a joint metal fitting c into a slit b of a steel pipe a and attaching a ring plate d to the steel pipe a, or a reinforcing plate as shown in FIGS. Although a method of attaching e is considered, all of them are not only troublesome but uneconomical.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation and was devised in response to this problem. A joint fitting is inserted into an axial slit groove provided in an end portion of a steel pipe to form a steel pipe. In a joint structure of a steel pipe member that welds a tangent line of a pipe and a joint fitting, a reinforcing method is provided to increase the joint strength by increasing the welding amount of the "turned weld portion" of the welding of the steel pipe and the joint fitting. .

[0007]

Operation: The slit groove 2 is cut in the steel pipe 1, the fitting 3 is inserted into the slit groove 2 and the periphery thereof is welded (FIGS. 4 and 5). At this time, the required welding amount is the dimensions L and S. Is determined by. However, the "turned weld" is the boundary between the cross section of the steel pipe 1 and the cross section of the fitting 3, and the cross-sectional shape changes discontinuously, resulting in stress concentration and several times the average stress acting on the steel pipe 1. Is applied. In addition, "Mawashi welding part"
However, the throat thickness a is not always equal to or larger than the steel pipe thickness t, and if there is a gap δ, the true weld throat thickness a is reduced by 0.7δ (FIG. 6). In consideration of these matters, the "turn weld" is subjected to reinforcement welding as shown in FIGS. 7 and 8 so that the effective throat thickness a is twice or more the steel pipe thickness.

[0008]

FIG. 4 to FIG. 8 show an embodiment of the structure of a method of reinforcing a joint portion of a steel pipe provided with a slit and a joint fitting according to the present invention, which will be described with reference to the drawings.

Reference numeral 1 denotes a steel pipe, and a slit groove 2 is provided in the central portion from the end portion on the joint side of the steel pipe 1. This slit groove 2
Is to fit the plate thickness ta of the joint metal fitting 3 into the joint metal fitting 3 up to the base of the slit groove 2 and join the steel pipe 1 and the joint metal fitting 3 by fillet welding 4 around the steel pipe 1. Become.

Welding in the vicinity of the base 2a of the slit groove 2 for fillet welding is called a "turned weld" 5. The cross-section of the "mawashi weld" 5 is considered to be an isosceles triangle, and this fillet has a throat thickness a, which is generally the shortest distance from the intersection of the two sides of the isosceles triangle to the hypotenuse. When inserted in the groove 2, a gap δ generally occurs between the slit base portion 2a and the tip end portion into which the joint fitting 3 is inserted. In this case, δsin45 = 0.7δ is less than the predetermined throat thickness a (FIG. 6).

Further, since the steel pipe 1 and the joint metal fitting 3 have different cross-sectional shapes, stress concentration occurs in the "turned weld portion" 5, and the tensile strength of the joint portion becomes weak. Therefore, in order to increase the tensile strength, the leg length S of the "turning welded portion" 5 is subjected to a reinforcement welding 6 as shown in FIGS. 7 and 8 by a predetermined leg length S, and the effective throat thickness a is the thickness t of the steel pipe 1. Be more than double.

9 and 10 show another embodiment. In this embodiment, the bent pieces 3a, 3a are formed by bending the both sides of the joint fitting 3 for reinforcement.

Further, FIGS. 11 and 12 show still another embodiment. In this embodiment, the T-shaped metal fitting 3 is formed into a T-shaped fitting 3b, and the T-shaped metal fitting 3 is provided in the steel pipe 1 in a slit groove. In this case, the throat thickness a of the "turned welded portion" needs to be larger than the predetermined throat thickness a, just as in the first embodiment.

[0014]

As described above, according to the present invention, when a joint fitting is inserted into the slit groove of a steel pipe to form a joint, the joint strength is increased by reinforcing the turn welded portion of the base of the slit groove of the steel pipe. Therefore, it is not necessary to design by lowering the strength of the steel pipe member to 80% to 85% of the actual steel pipe tensile strength, so that all the tensile strength of the steel pipe can be utilized.

[Brief description of the drawings]

FIG. 1 is a plan view of a conventional example of reinforcing a steel pipe and a joint.

FIG. 2 is a plan view of another conventional reinforcing embodiment.

FIG. 3 is a side view of FIG. 2;

FIG. 4 is a plan view of a non-reinforced embodiment of a joint in which a slit groove is provided in a steel pipe.

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a cross-sectional view of a joint portion, and is an enlarged explanatory view of a turning weld portion.

FIG. 7 is an example of reinforcement welding of a joint in which a slit groove is provided in a steel pipe according to the present invention.

FIG. 8 is another embodiment of the reinforcement welding.

FIG. 9 is a plan view of an example in which both sides of the joint fitting are bent to provide reinforcing ribs.

FIG. 10 is a side view of FIG. 9;

FIG. 11 is a plan view of a T-type joint fitting.

FIG. 12 is a side view of FIG. 11;

[Explanation of symbols]

 1 Steel Pipe 2 Slit Groove 2a Slit Groove Base 3 Joint Fittings 3a, 3b Reinforcing Member 4 Fillet Welding 5 Turning Weld 6 Reinforcement Welding a Throat S Leg Length t Steel Pipe Wall Thickness ta Joint Fitting Plate Thickness δ Gap

Claims (1)

[Claims] 1. In a joint structure of a steel pipe member in which a joint fitting is inserted into an axial slit groove provided in an end portion of a steel pipe and a tangent line between the steel pipe and the joint fitting is welded, a "turned weld portion" of welding of the steel pipe and the joint fitting. A reinforcing method for increasing the joint strength by inserting and welding a joint fitting into a slit, which is characterized in that the joint strength is increased by increasing the welding amount.