JPH0229131B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tensile joint in which a flange or web of a column and a flange of a beam are joined by high-strength bolts through a T-shaped metal fitting in joining a column and a beam of a steel structure. This is related to the improvement of

Figures 1 and 2 show the joint between a column and a beam using conventional T-shaped hardware. In the figures, 1 is a column of a steel structure, 1a is its flange, 1b is a web, 2 is a beam, and 2a is a Its flange, 2b is web, 3 is T
3a is the flange of the shaped hardware, and the thickness t is constant. 3b is a web of T-shaped hardware, and 4 is a high-strength bolt.

When the flange 1a of the column 1 and the flange 2a of the beam 2 are joined by the high-strength bolts 4 using this conventional T-shaped hardware 3, the force from the beam flange 2a is applied to the T-shaped hardware 3 by the lever principle. The force transmitted to the high-strength bolt 4 is transmitted to the high-strength bolt 4 using the tip A (see Fig. 2) of the flange 3a as a fulcrum, so the force transmitted to the high-strength bolt 4 is equal to the force from the beam flange 2a and the reaction force B added thereto. It's going to be. Therefore, when the bolts 4 are arranged in two rows on the flange 3a of the T-shaped hardware 3, the fulcrum A at the tip of the flange 3a and the flange 2 of the beam 2
The high-strength bolt 4 is connected between the point of application at a
Since there are two points of force, the high-strength bolts 4a in the outer row and the high-strength bolts 4b in the inner row (see Figure 2)
As a result of the difficulty in understanding the force transmission mechanism, such as the distribution of force transmitted to

(1) With the thickness of the flange 3a of the T-shaped hardware 3 that is normally used, the rigidity of the flange 3a is insufficient, and the fulcrum of the reaction force of the lever is generated near the position of the bolt 4a in the outer row. The bolt 4a could hardly resist the force from the beam 2.

(2) Even if the thickness t of the flange 3a of the T-shaped metal fitting 3 is relatively thick, since the flange 3a is composed of one plate, the base end of the flange 3a (the connecting part between the flange 3a and the web 3b) ), the lever reaction force increased due to the bending condition. Therefore, the lever reaction force accounts for a large proportion of the force applied to the high-strength bolt 4, resulting in a decrease in joint efficiency of the high-strength bolt 4.

(3) If the thickness t of the flange 3a of the T-shaped hardware 3 is sufficiently large, the mechanical problem in item (2) above will be solved, but the volume and weight of the T-shaped hardware 3 will increase. As a result, there was a drawback that economy and workability deteriorated.

(4) Theoretical explanation of the case where bolts 4 are arranged in two rows, inside and outside, on the flange 3a of the T-shaped hardware 3 has not been sufficiently investigated.

Generally, even if bolts 4 are arranged in two rows, inside and outside, on the flange 3a of the T-shaped hardware 3, only the bolts 4b in the outside row (see Figure 2) will resist the force, and the bolts 4 in the outside row will resist the force.
There was a concept that arranging the bolts 4 in two rows, inside and outside, would be wasteful because the bolts 4 would play, so in practice, the arrangement of the bolts 4 in two rows, inside and outside, was not adopted in the past.

If the bolts on the flange of the T-shaped hardware are arranged in one row, even if the mechanical behavior is clear, there is a limit to the number of high-strength bolts that can be used, so if the force transmitted from the flange of the beam is large. could not be applied.

The present invention was made to solve the above-mentioned problems, and the bolts on the flange of the T-shaped hardware are arranged in two rows, inside and outside, and the plate thickness at the base end of the flange is made sufficiently thick. By providing T-shaped metal fittings for tensile joints using high-strength bolts with a reasonable plate thickness reduction from the end toward the tip of the flange, the high-strength bolts can be used even when the force from the flange of the beam is large. The purpose of this invention is to enable a tensile joint that maintains joint efficiency, and to improve economy and workability by minimizing the volume and weight of the T-shaped hardware to the necessary minimum.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 8. In the figure, the same reference numerals as the above-mentioned reference numerals indicate equivalent parts. 5 shows a T-shaped metal fitting according to the present invention, 5a is its flange, and 5b is a web. The contact surface 5c of the flange 5a to the column 1 is flat and the web 5b projects at right angles to the contact surface 5c. The thickness of the flange 5a is changed on the protruding side of the web 5b. In other words, the plate thickness is made sufficiently thick at the base end C of the flange 5a (joint part with the web 5b), and from there the bolt position D of the inner row is
The thickness is further reduced linearly from the bolt position D in the inner row to the bolt position E in the outer row at a slope that is less steep.
The plate thickness at the bolt position E of the outer row is made constant up to the tip F of the flange 5a. Note that 5d is the bolt hole in the inner row, 5e is the bolt hole in the outer row, and 5f is a pedestal formed around these bolt holes 5d and 5e parallel to the contact surface 5c of the column 1. 5
The pedestal 5f in the figure is formed by continuously forming the pedestals for the bolts in the outer row and the pedestals for the inner row of bolts with the same height, and also partially recesses the upper surface of the flange 5a on the web 5b side. It is something.

In addition, FIG. 4 shows the flange 5a of the T-shaped metal fitting 5
Fig. 5 shows an example of use in which the web 5b is extended and overlapped with the flange 2a of the beam 2 and connected with the high-strength bolt 4. This shows an example of use in which a vertical protrusion 5g (see FIG. 7) that abuts against the web 2b of the beam 2 is formed below the web 5b with a short protrusion amount, and is joined to the beam 2 by welding 6.

FIG. 6 shows a modification of the bolt pedestal formed on the flange 5a of the T-shaped hardware 5, in which a part of the pedestal 5f is not recessed from the upper surface of the flange 5a, and the upper surface of the pedestal 5f is entirely on the flange 5a. formed on the top surface.

Moreover, FIG. 7 shows various arrangement examples of bolt holes 5d and 5e provided in the flange 5a of the T-shaped hardware 5. FIG. 7a shows the case where 16 bolts are used, and FIG. 7b shows 12 bolt holes. This shows the case of a book.

In the above embodiment, the bolt pedestals in the outer row and the bolt pedestals in the inner row are continuously formed on the same plane, but if the distance between the two bolts is large, it may be necessary to reduce the weight. If necessary, a recessed portion may be provided in the intermediate portion.

Next, in carrying out the present invention, a method of determining the plate thickness of the flange of the T-shaped metal fitting in order to improve the bolt joint efficiency will be explained according to the designed level.

(1) Final level When all bolts reach their yield points, only the base end of the flange of the T-shaped metal fitting (or one point between the inner bolt and the base end) will be in a yield state (total plastic moment state). Make it. That is, the plate thickness of the flange at the point where the yielding state occurs is determined so as to obtain a predetermined bolt joint efficiency, and the plate thickness at each other point of the flange is reduced so as not to enter the yielding state.

(2) Short-term allowable stress level High-strength bolt tension joints (high-strength bolts and The thickness of the flange of the T-shaped hardware is determined so that the overall mechanical behavior of the T-shaped hardware does not result in residual deformation even after the force is removed.

(3) Long-term allowable stress level Up to the level of force that is calculated by multiplying the long-term allowable force of the bolt by the total number of bolts and further by the specified joint efficiency, the flange surface of the column and the Determine the plate thickness of the flange of the T-shaped metal fitting so that no separation occurs between the flange surface of the T-shaped metal fitting and the flange surface of the T-shaped metal fitting.

FIG. 8 is a schematic diagram showing the mechanical behavior of the T-shaped hardware according to the present invention, where the ordinate shows the tensile force T acting on the T-shaped hardware, and the abscissa shows the flange surface of the column and the T-shaped hardware. The distance δ between the flange surfaces is taken. Note that the symbols in the figure are as follows.

A: Separation point of inner bolt B: Limit point at which no residual deformation occurs C: Separation point of outer bolt α: Bolt joint efficiency n: Number of bolts BT _y : Yield strength of one bolt BT _a : One bolt Short-term allowable yield strength The straight line O-B in the figure shows the slope when no tension is applied to the inner bolt.

As the invention has been described above, it enables tension joints in which high-strength bolts maintain high joint efficiency even in the case of high inputs from the beam flanges. By reducing the volume and weight of the T-shaped hardware to the necessary minimum, economic efficiency and workability are improved, and the height of the bolt pedestals is the same, making it easier to select the type of bolt when working at the assembly site. This is not necessary, and the excellent effect of improving workability more quickly can be obtained. Furthermore, the following advantages can be obtained compared to conventional T-shaped metal fittings of this type.

(1) The conventional T-shape hardware, which is practical and has high bolt joint efficiency, has a single row of bolts, so there is a limit to the level of force that can be used at the joint between a column and a beam. On the other hand, the present invention enables a two-row bolt arrangement that is both practical and highly efficient in bolt joints, so the proof strength of the joint increases dramatically (for example, by two times), resulting in a high-strength bolt tensile joint. It is possible to get rid of the conventional usage limitations on the yield strength of parts.

(2) If the present invention uses the same number of bolts as in the case of a conventional metal fitting with a single row of bolts, the local stress on the flanges and webs of the column can be reduced more than in the conventional type. In other words, when arranging bolts in a single row, the bolts are arranged and fixed close to the flange end of the column, which has low rigidity.
This is because the load is concentrated at bolt positions close to the web, which have high rigidity, whereas in the present invention, the bolts can be arranged at positions relatively close to the web along the column axis direction. Therefore, according to the present invention, the column flanges and webs can also be reinforced against local stress.

[Brief explanation of drawings]

Figures 1 and 2 are elevational views showing the joint between a column and a beam using a conventional T-shaped hardware, Figure 3a is a front view of the T-shaped hardware according to the present invention, and Figure 3b is a side view thereof. ,
Figures 4 and 5 are elevational views showing examples of the use of various T-shaped hardware, Figure 6 is a side view showing modified examples of bolt pedestals, and Figures 7 a and b are various T-types with different numbers of bolts used. FIG. 8, which is a front view of the hardware, is a schematic diagram showing the mechanical behavior of the T-shaped hardware according to the present invention. 1... Column, 1a... Flange, 1b... Web, 2... Beam, 2a... Flange, 2b... Web, 3... Conventional T-shaped hardware, 3a... Flange, 3b... Web, 4...High strength bolt, 5...
T-shaped hardware according to the present invention, 5a... flange, 5b
...Web, 5c...Contact surface, 5d, 5e...Bolt hole, 5f...Bolt pedestal, 5g...Vertical protrusion, 6...Welding.

Claims (1)

[Scope of Claims] 1. When joining columns and beams of a steel structure, when joining the flanges of columns or webs and flanges of beams via T-shaped metal fittings, a T with a thick base end and a thin tip is used.
Bolt holes are arranged in two rows in the part near the base end and the part near the tip of the flange of the shaped hardware, and the bolt holes in the part near the base end and the part near the tip are provided with pedestals of the same height, In addition, the plate thickness of the flange of the T-shaped hardware is different from the angle at which the plate thickness changes from the base end to the base end bolt hole and from the base end bolt hole to the tip bolt hole, and the angle at which the plate thickness changes from the base end bolt hole to the tip bolt hole is different. A T-shaped metal piece with the same thickness from the hole to the tip is formed by casting or die forging, and the flange of this T-shaped metal piece is fixed to the column with high-strength bolts, and the web is welded or high-strength to the beam flange. A tensile joint using high-strength bolts between a column and a beam via T-shaped metal fittings, characterized in that they are fixed with high-strength bolts. 2. A column and a beam via a T-shaped metal fitting according to claim 1, characterized in that the bolt pedestal surface on the base end side of the T-shaped metal fitting flange is partially or entirely recessed from the upper surface of the flange. tensile joints with high-strength bolts.