JP2003213787A - Pier stud structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pier stud structure hard to suffer fatigue damage even if vibration repeatedly occurs over a long period of time. <P>SOLUTION: Each of a plurality of vertical ribs 14 arranged between the base of a steel pipe column 10 and a base plate 11 makes the shorter side at the top, an overhanging amount of each vertical rib 14 is gradually reduced upward until it makes less than the thickness of the vertical rib 14 and, at the same time, an angle makes 11.3° or less between the upper end outside edge of the vertical rib 14 and the steel pipe column outside. Since the upper end of the vertical rib 14 is easily deformed in the direction of the load, stress concentration is low in comparison with the conventional structure and the fatigue damage is hard to suffer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pedestal structure used for a base portion of a steel pipe column installed in a place subject to constant vibration such as an elevated road or a bridge.

[0002]

2. Description of the Related Art For example, as shown in FIG. 4, a plurality of steel pipe pillars are installed between a base portion of a steel pipe pillar 1 and a base plate 2 at the base portion of a steel pipe pillar which is erected as an illumination pillar or a road marking pillar on an elevated road or a bridge. The pedestal structure in which the vertical ribs 3 are welded and reinforced has been widely used. Although the base plate 2 has various shapes, it has a structure in which its upper end has sufficient rigidity in the load direction.

However, in this structure, when a bending load is applied to the steel pipe column 1 due to vibration due to wind or traffic vibration, a large stress concentration occurs in the steel pipe column 1 near the weld toe of the upper end of the vertical rib 3. However, there is a possibility that the strength of this portion may decrease due to the repeated stress. Further, there is a problem that the welded portion at the upper end of the vertical rib 3 is likely to be a structural defect due to the overlap of the tensile residual stress due to welding heat and the deterioration of the heat-affected member material, and the yield strength and fatigue performance are deteriorated.

This problem is common to a structure in which a vertical rib for reinforcement is welded to a structural member in a T-shape, and the gusset is a fillet even in the "Guideline for Fatigue Design of Steel Structures-Commentary" of the Japan Steel Structural Association. It has been pointed out that the welded joint reduces the yield strength and fatigue performance of the steel member, so that consideration should be given to the design.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and causes deterioration of proof strength and fatigue performance even when a steel pipe column is repeatedly vibrated for a long period due to wind or traffic vibration. It was made to provide a pedestal structure that does not exist.

[0006]

A pedestal structure of the present invention made to solve the above-mentioned problems is a pedestal structure in which a plurality of vertical ribs are arranged between a base of a steel pipe column and a base plate. In addition, the amount of protrusion of each vertical rib is gradually decreased upward until it becomes equal to or less than the plate thickness of the vertical rib, and the outer edge of each vertical rib and the steel pipe column are extended from the upper end of the rib to at least 5 times the rib plate thickness. Angle between outer surface and 11.3 °
It is characterized by the following. The angle between the outer edge of the upper end of each vertical rib and the outer surface of the steel pipe column is 5.7 °.
The following is preferable. Further, the pedestal structure of the present invention is particularly effective when it is installed in a place where a steel pipe column is subjected to vibration.

In the present invention, unlike the prior art, the vertical rib welded to the base of the steel pipe column has an angle of 1 at the upper end.
The vertical shape is set to 1.3 ° or less, and the overhang amount of the upper portion is gradually reduced to the plate thickness of the vertical rib or less. As a result, the rigidity of the vertical rib becomes smaller as it goes upward, and the vicinity of the upper end portion is easily elastically deformed in the load direction (direction of the plate thickness center plane of the vertical rib). For this reason, the stress concentration near the weld toe of the upper end of the vertical rib is significantly alleviated, and even if subjected to repeated vibration for a long period of time, the yield strength and fatigue performance will not be reduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention are shown below. 1 and 2 are views showing a first embodiment of the present invention, in which 10 is a steel pipe column which is installed in a place where vibration is constantly applied, such as an illumination pole of an elevated road, and 11 is this steel pipe column 10. Is a base plate made of steel plate, the base of which is fixed by welding. As shown in cross section in FIG. 1, a center hole 12 is formed in the base plate 11, and
The lower end of the is welded to the inner surface of the center hole 12. 1
Reference numeral 3 is an anchor bolt insertion hole for fixing the base plate 11 to a concrete frame such as a road.

A plurality of vertical ribs 14 are arranged between the base of the steel pipe column 10 and the base plate 11. The vertical rib 14 has a substantially right triangle shape,
The lower half of the outer edge is a gentle curve and the upper half is a straight line. In the embodiment shown in FIG. 1, the steel pipe column 10 has an outer diameter of 188 mm, a plate thickness of 5.6 mm, the vertical ribs 14 have a total height of 400 mm, a plate thickness of 5 mm, and a lower end protruding amount of 66 m.
m, the radius of curvature of the lower half of the outer edge is 500 mm.

The first feature of the vertical rib 14 in the present invention is that the amount of protrusion thereof is gradually reduced upward, and the thickness of the vertical rib 14 is equal to or less than the plate thickness of the vertical rib 14 at the upper end portion. In this embodiment, the amount of protrusion at the upper end is 5 mm, which is the same as the plate thickness. Theoretically, it is best to set the amount of overhang at the upper end to zero,
In order to weld the vertical ribs 14 to the steel pipe column 10 up to the upper end portion, it is necessary to secure an overhang amount of the welding throat thickness at the upper end portion as well. Set the amount. Increasing the amount of overhang at the upper end is not preferable because the rigidity increases and stress concentration occurs as in the conventional product.

The second feature of the vertical rib 14 in the present invention is that the angle θ between the outer edge of the vertical rib 14 and the outer surface of the steel pipe column is 11. It is 3 degrees or less, and more preferably 5.7 degrees or less. Thus, by setting the angle θ of the upper end of the vertical rib 14 to 11.3 ° or less, the vertical rib 14
To reduce the rigidity in the load direction and make it easier to bend in the load direction. If this angle θ exceeds 11.3 ° or if this length is less than 5 times the rib plate thickness, the effect of deforming the upper ends of the vertical ribs 14 peculiar to the present invention in the load direction is lost.
On the other hand, if this angle θ is made too small over a long section, the rib becomes longer in the vertical direction, which leads to an increase in the amount of welding work, which is not desirable. In this embodiment, θ is 2.5 °. The angle θ = 11.3 ° is about 1/5.
And the angle θ = 5.7 ° corresponds to a slope of about 1/10.

In the second embodiment shown in FIG. 3, the vertical rib 14 is a right triangle having an upper end angle θ of about 8 °. Also in this second embodiment, the amount of protrusion at the upper end is the same as the plate thickness.

The pedestal column structure of the present invention thus constructed receives the bending load acting on the steel pipe column 10 by the plurality of vertical ribs 14 arranged around the base of the column structure, and stably holds the steel pipe column 10. What to do is the same as the conventional one. But Figure 4
In the conventional pedestal structure as shown in FIG. 2, the upper end of the vertical rib has a great rigidity in the load direction, and the deformation of the steel pipe column 10 is abruptly restrained at the upper end. By reducing the rigidity of the upper part, local deformation of steel pipe columns is avoided.

Therefore, when a bending load is applied to the steel pipe column 10, the upper ends of the vertical ribs 14 can be deformed in the load direction, and as a result, stress concentration at the upper ends of the vertical ribs 14 is eliminated. Therefore, even if a bending load is repeatedly applied for a long time due to wind or traffic vibration, the structure is less susceptible to fatigue damage. Specifically, the fatigue properties of the conventional structure shown in FIG. 4 were D to E grades of the design life curve by the Japan Steel Structural Association, but the structures of the above-described embodiments were improved to B grade or higher.

[0015]

As described above, in the pedestal structure of the present invention, the amount of protrusion of the vertical ribs is gradually reduced upward until the vertical rib thickness is equal to or less than the plate thickness of the vertical ribs. By adopting an unprecedented structure in which the angle between the outer edge of the upper end of the vertical rib and the outer surface of the steel pipe column is 11.3 ° or less over the length of 5 times the thickness, the upper end of the vertical rib is loaded in the load direction. It is designed to be elastically deformable. For this reason, the stress concentration near the weld toe of the upper end of the vertical rib is greatly alleviated, and the structure is less susceptible to fatigue damage even when installed in a place where vibration is repeatedly received for a long period of time. Therefore, the present invention is suitable as a pedestal structure for a steel pipe column installed in a place subject to constant vibration such as an elevated road or a bridge.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view showing a second embodiment.

FIG. 4 is a perspective view showing a conventional example.

[Explanation of symbols]

1 Steel pipe column in the prior art 2 base plate 3 vertical ribs 10 Steel pipe column in the present invention 11 base plate 12 Center hole 13 Anchor bolt insertion hole 14 vertical ribs

Claims (3)

[Claims] 1. A pedestal structure in which a plurality of vertical ribs are arranged between a base portion of a steel pipe column and a base plate, and the bulge amount of each vertical rib is directed upward until the plate thickness of the vertical rib is equal to or less than the plate thickness of the vertical rib. And the angle between the outer edge of each vertical rib and the outer surface of the steel pipe column is 11.3 ° or less from the upper end of the rib to at least 5 times the rib plate thickness. . 2. The pedestal structure according to claim 1, wherein an angle between an outer edge of an upper end portion of each vertical rib and an outer surface of the steel pipe column is 5.7 ° or less. 3. The pedestal structure according to claim 1, wherein the steel pipe column is installed in a place where vibration is likely to occur.