JP3663561B2 - Steel beam - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel beam suitable for use as a beam constituting a frame of various structures such as a building.
[0002]
[Prior art]
As is well known, in the case of various structural structures such as high-rise buildings, when the beam is a steel beam, if excessive external force due to an earthquake or strong wind acts on the steel beam, the energy from the external force is joined to the column. It concentrates on the beam end which is a part, reaches the yield point from this beam end and plasticizes. And this plasticization area | region expands sequentially from a beam edge part to a beam center part.
At this time, when the deformation due to plasticization of the beam proceeds, the steel beam may break at the junction with the column at the end partway along the way.
In order to avoid the occurrence of such a phenomenon, a technique of increasing the strength of the steel beam is basically taken.
[0003]
[Problems to be solved by the invention]
However, the conventional techniques as described above have the following problems.
That is, in order to increase the strength of the steel beam, the cross-sectional area of the steel beam is increased, which not only narrows the interior space, but also increases the material cost, increases the overall cost of the housing due to the increased weight of the member, etc. With the problem. In addition, energy from external forces due to earthquakes, strong winds, etc. concentrates on the end of the beam, so if the strength of the steel beam as a whole is increased based on this part, the center of the beam will have more strength than necessary. Will be.
The present invention has been made in consideration of the above points, and by efficiently absorbing energy due to external forces caused by earthquakes, strong winds, etc., it can prevent breakage of the beam and improve the earthquake resistance of the structure. It is an object to provide a steel beam that can contribute.
[0004]
[Means for Solving the Problems]
In the present invention, the beam constituting the frame of the structure is a steel beam made of an H-shaped steel material having flanges above and below, and at the end of the steel beam to be joined to the column constituting the frame, A deformation restraining member for restraining deformation of the steel beam is disposed between the upper and lower flanges, and the deformation restraining member is fastened to the column by a prestressed steel rod. , the upper and lower surfaces thereof, at the end of the steel beam is characterized by being formed by a curved surface that gradually spaced toward the center portion of the contact and the steel beam to said flange.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of a steel beam according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a frame of a structure such as a building, 2 denotes a column made of, for example, a steel pipe structure, and 3 denotes a beam (steel beam) made of H-shaped steel.
[0006]
In this figure, a deformation restraining member 5 for restraining deformation of the beam 3 is disposed at a portion where the column 2 and the beam 3 constituting the housing 1 are joined.
[0007]
The deformation restraining member 5 is provided so as to be positioned in a space surrounded by the upper and lower flanges 3a and 3a of the beam 3 and the web 3b. The deformation restraining member 5 is made of, for example, concrete, one surface of which is a fixed surface 5 a that contacts the side surface of the column 2, and two surfaces on both sides of the deformation restraining member 5 are constraining surfaces 5 b and 5 b facing the flanges 3 a and 3 a of the beam 3. It has become.
Each constraining surface 5 b is formed by a curved surface A that abuts on the flange 3 a on the fixed surface 5 a side, that is, on the end portion side of the beam 3 and gradually separates from the flange 3 a toward the center portion side of the beam 3.
[0008]
The curved surface A forming each constraining surface 5b has a curvature set based on, for example, the curvature of the flange 3a of the beam 3 when a yield strain occurs in the beam 3.
This will be described in detail. The curvature φ of the flange 3a when the yield strain is generated in the beam 3 in this case 1 is generally expressed as follows.
φ = (| ε _c | + | ε _t |) / H
(Where ε _c is the bending compressive strain of beam 3 and ε _t is the bending tensile strain)
It is represented by
The yield occurrence location in the beam 3 is an end portion on the column 2 side. Therefore, the curvature φf of the flange 3a of the beam 3 at the yield point when the maximum moment is generated in this portion is
_{φf = (| c ε y |} + | t ε y |) / H
(Where _c ε _y is the bending compressive strain at the yield point, and _t ε _y is the bending tensile strain at the yield point).
That is, the curvature φf ′ of the curved surface A forming the constraining surface 5b is set to coincide with, for example, the curvature φf at the yield point when the maximum moment is generated in the beam 3 (φf ′ = φf).
[0009]
Such deformation restraining members 5 are respectively disposed on the beams 3 and 3 located on both sides of the column 2, and these deformation restraining members 5 and 5 provided on both sides of the column 2 are prestressed. Is fastened to the column 2 by a steel rod 7 to which is attached and a nut 8 screwed to the steel rod 7.
[0010]
As described above, when the curvature of the restraining surface 5b of the deformation restraining member 5 is matched with the curvature φf of the flange 3a when the yield strain is generated in the beam 3, the beam 3 is subjected to the following forces due to an external force such as earthquake or wind power. Show good behavior.
When an external force caused by an earthquake or wind power is excessively applied, first, at the end of the flange 3a of the beam 3 where the maximum moment is generated, the end of the flange 3a on the column 2 side is strained at a small cross section at the end to the curvature φf. When it reaches, the minute cross section of the flange 3a comes into contact with the restraining surface 5b of the deformation restraining member 5, and the deformation is forcibly restrained. Then, the contact point between the flange 3 a of the beam 3 and the constraining surface 5 b of the deformation constraining member 5 shifts closer to the center in the length direction of the beam 3. Along with this, the position where the maximum moment occurs shifts to another fine cross section adjacent to the fine cross section, and the flange 3a of the beam 3 in that portion also comes into contact with the restraining surface 5b of the deformation restraining member 5. Therefore, the deformation is forcibly restrained.
[0011]
In this way, when the beam 3 reaches the yield point from the end and plasticizes, further deformation is constrained by the deformation restraining member 5, and the position reaching the yield point sequentially shifts closer to the center of the beam 3 As a result, the plasticization region is expanding.
[0012]
In the beam 3 described above, the deformation restraining member 5 for restraining the deformation of the beam 3 is disposed between the upper and lower flanges 3a, 3a of the end portion of the beam 3 made of H-shaped steel, and the upper and lower restraining surfaces 5b, 5b thereof are arranged. The end portion of the beam 3 is in contact with the flange 3a and is formed with a curved surface A that gradually separates toward the center portion.
Thus, when a strong external force is applied due to an earthquake or wind, when the beam 3 reaches the yield point and plasticizes, further deformation can be constrained by the deformation restraining member 5, and the plasticizing position is determined by the beam 3. It is possible to make a transition to the center part of each. In this way, the deformation restriction member 5 restrains further deformation at the end of the beam 3 while expanding the plasticizing region of the beam 3 closer to the center of the beam 3, so that the end of the beam 3 is constant. Without concentrating the above energy, it is possible to prevent the beam 3 from breaking from the end portion, and to disperse the energy to the central portion side of the beam 3, so that the entire beam 3 can efficiently absorb energy without waste. Can do. Therefore, in such a beam 3, it becomes possible to absorb much higher energy compared to a simple beam not provided with the deformation restraining member 5, and the seismic resistance of the housing 1 can be greatly improved.
Moreover, since the deformation restraining member 5 is configured to be accommodated between the upper and lower flanges 3a, 3a of the beam 3, it is not necessary to enlarge the cross-sectional area of the beam 3, narrowing the indoor space, High economic merit can be obtained without incurring problems such as cost increase due to weight increase.
[0013]
In the above-described embodiment, the steel beam according to the present invention may be applied to the entire case 1, or one of the cases 1 such as a specific layer that is predicted to be deformed when a strong earthquake occurs. You may apply only to a part.
In addition, the deformation restraining member 5 is not limited to concrete, and if it has a predetermined proof stress and rigidity, for example, the whole is formed only of metal, or only the surface is covered with metal. May be.
Further, the curvature of the curved surface A forming the restraining surface 5b of the deformation restraining member 5 is not limited to the curvature φf when the yield strain of the beam 3 is generated. For example, the beam 3 has a value smaller than the curvature φf. It may be set to constrain the deformation before reaching the yield point (within the elastic range), or after exceeding the yield point if within the range that does not cause fracture from the end of the beam 3 The plastic deformation of the beam 3 may be constrained so as not to exceed a certain level within the plastic region.
In addition, any configuration other than the above may be used in the above embodiments as long as it does not depart from the gist of the present invention.
[0014]
【The invention's effect】
As described above, according to the steel beam of the present invention, the deformation restraining member is disposed between the upper and lower flanges at the end of the steel beam made of H-shaped steel material , and the deformation restraining member is prestressed. The deformation restraining member is tightly coupled to the column by a rod , and the upper and lower surfaces thereof are configured to be curved surfaces that abut against the flange at the end of the beam and gradually move away toward the center. . As a result, when a strong external force is applied due to an earthquake or wind, the deformation that the steel beam reaches the yield point from the end can be constrained by the deformation restraining member, and the energy is concentrated on the end of the steel beam. It is possible to prevent the steel beam from being broken from the end portion by dispersing the steel beam at the center side of the steel beam. Therefore, it is possible to absorb much higher energy than a simple beam without a deformation restraining member, and the earthquake resistance of the structure including such a steel beam can be greatly improved.
Moreover, since the deformation restraining member is configured to be accommodated between the upper and lower flanges of the beam, there is no need to increase the cross-sectional area of the beam, the indoor space is narrowed, the cost increases due to a significant increase in the weight of the member, etc. It is possible to obtain high economic benefits without incurring such problems.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing a part of a structure of a structure to which a steel beam according to the present invention is applied.
[Explanation of symbols]
1 frame 2 pillar 3 beam (steel beam)
5 Deformation restraint member
7 Steel bar A Curved surface

Claims (1)

The beam constituting the structural frame is a steel beam made of H-shaped steel having flanges on the upper and lower sides thereof, and the upper and lower flanges are provided at the ends of the steel beam to be joined to the columns constituting the frame. It is a configuration in which a deformation restraining member for restraining deformation of the steel beam is disposed therebetween,
The deformation restraining member is fastened to the column by a prestressed steel rod, and the upper and lower surfaces thereof are in contact with the flange at the end of the steel beam and the central portion of the steel beam A steel beam characterized in that the steel beam is formed with a curved surface that gradually separates toward the surface.

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