JP4677059B2 - Rolled H-section steel - Google Patents

Description

The present invention relates to a rolled H-section steel that is applied to a small beam that directly supports a floor slab or a roof slab and is not directly connected to a column, or a beam used within an elastic design range.
This application claims priority in 2009/07/09 based on Japanese Patent Application No. 2009-162402 for which it applied to Japan, and uses the content here.

  Conventionally, various rolled H-section steels such as the following (1) to (5) are known as rolled H-section steels.

(1) After the flange width / thickness ratio is 10 or less and work hardening is started, the work hardening index in the strain range up to 6% is 0.2 or more, and the plastic deformation stress increases in the strain range of 6% or more. Rolled H-section steel excellent in earthquake resistance in which the gradient is larger than the moment gradient in the vicinity of the position where the maximum moment is generated, and the plastic zone generated at the position where the maximum moment is generated is expanded to the periphery thereof (for example, Patent Document 1) reference).

(2) Rolled H-section steel for a column having a web thickness / flange thickness ratio of 1.2 to 4 and capable of omitting reinforcement by a doubler plate, a diagonal stiffener, or the like in a column beam joint panel (for example, Patent Document 2) reference).

(3) For columns with a web thickness / flange thickness ratio of 1.1 to 2.0, which can be reinforced by horizontal stiffeners at beam flange joints at column beam joints, doubler plates in panels and diagonal stiffeners, etc. Rolled H-section steel (see, for example, Patent Document 3).

(4) A thin web rolled H-section steel with a web thickness / flange thickness ratio of 0.5 or less, and irregularities formed on the web at predetermined intervals to prevent web waviness during rolling production. Rolled H-section steel (see, for example, Patent Document 4).

(5) It is a thin web rolled H-section steel, the web thickness / flange thickness ratio is 0.5 or less, and in order to prevent the web undulation phenomenon at the time of rolling manufacture, Rolled H-section steel provided with at least one rib reinforcing rib (for example, see Patent Document 5).

  Moreover, the following techniques (A) to (D) are also known as techniques related to conventional rolled H-section steel.

(A) Since it is necessary to ensure the plastic deformation capacity of rolled H-section steel in order to obtain columns and beam members with excellent earthquake resistance, the flange width-thickness ratio and web width-thickness ratio can be set according to JIS G 3192 and patents. As shown in Document 6, a relatively small numerical range that is said to be deformable (in the main application is a beam, the side / height ratio is 0.77 or less, in the JIS standard, flange width thickness ratio) Of the web width / thickness ratio is 56.6).

(B) In order to improve the weight efficiency of the section moment of inertia and section modulus, the web thickness / flange thickness ratio of the rolled H-beam for beams is set to a relatively small numerical range as defined in JIS G 3192 ( The upper limit of the web thickness / flange thickness ratio is set to 0.75 in the range where the side / height ratio of the main application is a beam of 0.77 or less.

(C) Reducing the web thickness / flange thickness ratio of the rolled H-section steel for columns to a relatively large numerical range (web thickness / flange thickness) It is also known that the lower limit of the ratio is 1.1) (see, for example, Patent Document 2 and Patent Document 3).

(D) In order to realize a thin web rolled H-section steel while preventing web waviness during rolling production, the web thickness / flange thickness ratio is set to a relatively small numerical range (the upper limit of the web thickness / flange thickness ratio is 0). .5) (see, for example, Patent Document 4 and Patent Document 5).

(E) In addition to the above, the rolled H-shape standardized by ASTM (American Society for Testing and Materials), BS (British Standards), EN (European Standard, EN) There is steel (see Non-Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2002-88974 Japanese Unexamined Patent Publication No. 2000-54560 Japanese Unexamined Patent Publication No. 2003-15579 Japanese Unexamined Patent Publication No. 59-141658 Japanese Unexamined Patent Publication No. Sho 61-162658 Japanese Unexamined Patent Publication No. 2002-88974

ASTM (American Society for Testing and Materials) BS (British Standards) EN (European Standard, EN)

  As described above, the shape of the rolled H-section steel is standardized in various countries including the United States, the United Kingdom, Europe, and Japan. For example, in Japan, various rolled H-sections described in JIS G 3192 (shape, dimensions, mass and tolerance of hot-rolled section steel) are known.

Regarding JIS G 3192 “Shape, size, mass and tolerance of hot rolled shape steel”, in Table 1 below, “Appendix Table 8 Standard section dimensions of H-section steel and its cross-sectional area, published in JIS G 3192, The cross-sectional dimensions in “unit mass and cross-sectional properties” are transcribed, and the side / height ratio (B / H), flange width / thickness ratio (B / (2 × t ₂ )) shown in Table 1 and web From the width / thickness ratio ((H−2 × t ₂ ) / t ₁ ) and the web thickness / flange thickness ratio (t ₁ / t ₂ ), the following (a) to (c) are understood.
(A) The flange width / thickness ratio is in the range of 3.1 to 13.4.
(B) The web width / thickness ratio is in the range of 8.0 to 56.6.
(C) The web thickness / flange thickness ratio is in the range of 0.53 to 1.00.
Various conventional rolled H-section steels having a side / height ratio (B / H) of 0.77 or less in Table 1 are indicated by white circles in FIGS. Various conventional rolled H-section steels having a side-to-height ratio (B / H) of 1 exceeding 0.77 are plotted with x marks.
1 and 4 are graphs in which the horizontal axis represents the flange width-thickness ratio (B / (2 × t ₂ )) and the vertical axis represents the web width-thickness ratio ((H−2 × t ₂ ) / t ₁ ). It is.
2 and 5, the horizontal axis is the side / height ratio (B / H) and the vertical axis is the web thickness / flange thickness ratio (t ₁ / t ₂ ). A rolled H-section steel is plotted.

  Here, the side-to-height ratio is in the range of 0.77 or less (the width of the flange in the rolled H-section steel, which is commercially available in Japan as a narrow or medium-width rolled H-section steel). Rolled H-section steels are mainly classified as beams, and the side-to-height ratio is in the range of more than 0.77 (the flange width of H-section steel, which is commercially available as wide-series rolled H-section steel. ) Can be classified into pillars and braces. In Table 1, height × side (H × B) (unit: mm) is 150 × 100, 200 × 150, 250 × 175, 300 × 200, 350 × 250, 400 × 300, 450 × 300, 500. × 300, 600 × 300, 700 × 300, 800 × 300, 900 × 300 (mm) are medium width series, and the same dimension of height (H) and side (B) is a wide width series. It is a narrow series.

Therefore, the following (d) to (f) can be seen if the main application is a beam and the side / height ratio is limited to a range of 0.77 or less.
(D) The flange width / thickness ratio is in the range of 3.1 to 10.0;
(E) The web width thickness ratio is in the range of 17.2-56.6,
(F) The web thickness / flange thickness ratio is in the range of 0.53 to 0.75.

  The reason (d) to (f) are set for the following reasons (g) and (h).

  (G) The flange width / thickness ratio is in the range of 3.1 to 10.0, and the web width / thickness ratio is in the range of 17.2 to 56.6, which is a relatively small numerical range. When the ratio between the width and thickness of the plate element to be processed is large, local buckling occurs in the portion that receives the compressive force, and the yield strength of the cross section of the member is reduced, so that the necessary plastic deformation ability cannot be obtained.

  (H) Furthermore, the web thickness / flange thickness ratio is a relatively small numerical range of 0.53 to 0.75 because the beam is a member subjected to bending stress, so the flange is thickened and the web is thinned. This is because the secondary moment of inertia and the section modulus per unit cross-sectional area are increased.

Also, for various rolled H-sections standardized by ASTM (American Industrial Standards), BS (British Industrial Standards), and EN (European Standards), the side-to-height ratio (B / H) is 0.77 or less. It is divided into various rolled H-section steels in the range and various rolled H-section steels whose side / height ratio (B / H) exceeds 0.77, and the side / height ratio (B / H) is 0. In order to examine the upper limit of the flange width thickness ratio, web width thickness ratio, web thickness / flange thickness ratio (t ₁ / t ₂ ) for various rolled H-section steels in the range of 77 or less, FIG. Indicated.

6 and 7 show various rolled H-section steels having a side-to-height ratio (B / H) of 0.77 or less with respect to various rolled H-section steels compliant with ASTM (American Industrial Standards). (Rolled H-section steel belonging to medium width and narrow width) is plotted with white circles, and various rolled H-section steels with side / height ratio (B / H) exceeding 0.77 are plotted with crosses. It is shown. Tables of various rolled H-sections standardized by ASTM (American Industrial Standards) plotted in FIGS. 6 and 7 are omitted.
In FIG. 6, the horizontal axis is the flange width thickness ratio (B / (2 × t ₂ )) and the vertical axis is the web width thickness ratio ((H−2 × t ₂ ) / t ₁ ). It is the graph which plots and shows about the various rolled H-section steel. From this figure, it is understood that the upper limit of the flange width-thickness ratio is 9.4 for the rolled H-section steel indicated by white circles and belonging to the medium width and narrow width, and the upper limit of the web width-thickness ratio is 63. .5.

In FIG. 7, the horizontal axis represents the side / height ratio (B / H) and the vertical axis represents the web thickness / flange thickness ratio (t ₁ / t ₂ ) for various rolled H-section steels compliant with ASTM. ) And plotted for various rolled H-section steels. From this graph, in the rolled H-section steel indicated by white circles and belonging to the medium width and narrow width, the upper limit of the side / height ratio (B / H) is 0.72, and the web thickness / flange thickness ratio ( It was found that the upper limit of (t ₁ / t ₂ ) was 0.82.

8 and 9 show various rolled H-section steels having a side-to-height ratio (B / H) of 0.77 or less for various rolled H-section steels specified in BS (British Industrial Standards). (Rolled H-section steel belonging to medium width and narrow width) is plotted with white circles, and various rolled H-section steels with side / height ratio (B / H) exceeding 0.77 are plotted with crosses. It is shown. Tables of various rolled H-sections standardized by BS (British Industrial Standard) plotted in FIGS. 8 and 9 are omitted.
In FIG. 8, the horizontal axis is the flange width / thickness ratio (B / (2 × t ₂ )), and the vertical axis is the web width / thickness ratio ((H−2 × t ₂ ) / t ₁ ). It is the graph which plots and shows about the various rolled H-section steel. From this figure, it is understood that the upper limit of the flange width / thickness ratio is 8.6 and the upper limit of the web width / thickness ratio is 63.3 in the rolled H-section steel belonging to the medium width and the narrow width. all right.
Further, in FIG. 9, for various rolled H-section steels compliant with BS (British Industrial Standards), the horizontal axis is the side / height ratio (B / H), and the vertical axis is the web thickness / flange thickness ratio ( It is a graph plotted as t ₁ / t ₂ ). From this graph, in the rolled H-section steel indicated by white circles and belonging to the medium width and narrow width, the upper limit of the side / height ratio (B / H) is 0.66, and the web thickness / flange thickness ratio ( It was found that the upper limit of (t ₁ / t ₂ ) was 0.86.

10 and 11 show various rolled H-section steels having a side-to-height ratio (B / H) of 0.77 or less for various rolled H-section steels compliant with EN (European standard). Rolled H-section steels belonging to medium width and narrow width are plotted with white circles, and various rolled H-section steels with side / height ratio (B / H) exceeding 0.77 are plotted with crosses. Has been. Tables of various rolled H-sections standardized in EN (European standard) plotted in FIGS. 10 and 11 are omitted.
FIG. 10 shows EN (European Standard) with the horizontal axis as flange width / thickness ratio (B / (2 × t ₂ )) and the vertical axis as web width / thickness ratio ((H−2 × t ₂ ) / t ₁ ). It is the graph which plots and shows about the various rolled H-section steels which are standardized. From this figure, it is understood that the upper limit of the flange width-thickness ratio is 11.1 and the upper limit of the web width-thickness ratio is 58.0 in the rolled H-section steel belonging to the medium width and the narrow width. all right.
Further, in FIG. 11, for various rolled H-section steels compliant with EN (European standard), the horizontal axis is the side / height ratio (B / H), and the vertical axis is the web thickness / flange thickness ratio (t ₁ / t ₂ ) and plotted. From this graph, in the rolled H-section steel indicated by white circles and belonging to the middle width and narrow width, the upper limit of the side / height ratio (B / H) is 0.77, and the web thickness / flange thickness ratio ( It was found that the upper limit of (t ₁ / t ₂ ) was 0.78.

By the way, because the number of small beams used is larger than that of large beams, if the weight per one can be reduced without reducing the required cross-sectional performance, even if the cost reduction per one is small, This can greatly contribute to the cost reduction of the main body of the structure.
For example, if the beam weight of a small beam or the like can be reduced by 10% or more without deteriorating its seismic performance, the unit price of the beam can be reduced by about 10%, for example. Therefore, not only can the cost of the structure body be significantly reduced, but the structure can be reduced in weight, and the weight of the structure is reduced, reducing the burden on the pillars, contributing to the improvement in the earthquake resistance performance of the structure. can do.
In addition, a rolled H-section steel that is lighter for a small beam and does not deteriorate the cross-sectional performance is desired rather than a rolled H-section steel standardized in major advanced countries including the United States, the United Kingdom, Europe, and Japan. It is.
An object of this invention is to provide the rolling H-section steel advantageous to the solution of the above problems.

In order to solve the above-mentioned problem advantageously, the following means are adopted.
(A) A rolled H-section steel according to an aspect of the present invention has a web and a flange; when the height dimension is H and the width dimension of the flange is B, the following formula (1) is satisfied; When the tensile strength is 400 to 510 N / mm ² ; and the plate thickness dimension of the flange is t _2, and the design yield stress of the steel material of this rolled H-section steel is F (N / mm ² ). The following expressions (2) and (3) are satisfied.
(B / H) ≦ 0.77 (1)
11.1 <B / (2 × t ₂ ) ≦ 215 / √ (F) (2)
235 ≦ F ≦ 275 (3)

(B) The rolled H-section steel described in (a) above may satisfy the following formula (4) when the thickness of the web is t ₁ .
63.5 <((H−2 × t ₂ ) / t ₁ ) ≦ 1100 / √ (F) (4)

(C) In the rolled H-section steel described in (a) above, the thickness t _{1 of the} web and the thickness t _{2 of the} flange may satisfy the following expression (5).
0.75 <(t ₁ / t ₂ ) <1.0 (5)

  According to the rolled H-section steel described in (a) above, the flange of a rolled H-section steel belonging to a narrow or medium width in major countries, even if a material whose design yield stress F changes in the above range is used. The width-to-thickness ratio can be easily dimensioned to define the cross-sectional shape of the rolled H-section steel.

Moreover, this rolled H-section steel can be made lighter than the conventional rolled H-section steel defined in the major countries of the United States, United Kingdom, Europe or Japan. Moreover, the cross-sectional performance of the rolled H-section steel can be maintained equal to or higher than that of the corresponding rolled H-section steel in the major countries. Therefore, according to this rolled H-section steel, it can be easily dimensioned and applied in various countries including the major countries.
Further, the flange width-thickness ratio (B / (2 × t ₂ )) based on the flange width dimension B of the rolled H-section steel and the plate thickness dimension t ₂ of the flange may be set within the range of the above formula (2). Even if the design yield stress F of the steel material used for the rolled H-section steel changes, the flange width-thickness ratio (B / (2 × t ₂ )) of the rolled H-section steel can be easily set.
That is, this rolled H-section steel has a height dimension H of the H-section steel, a width dimension B of the flange, a plate thickness dimension t _{2 of the} flange, and a design yield stress F (N / mm ² ) of the steel material. From the relationship, the dimensions of the rolled H-section steel are easily set. Therefore, compared with the conventional rolled H-section steel, it is possible to obtain a rolled H-section steel having a new size and shape that is reduced in weight by reducing the sectional area without degrading the section performance.

Further, in the case of (2) above, ((H−2 × t ₂ ) / t ₁ ), which is the web width-thickness ratio of the rolled H-section steel, is the height dimension H of the H-section steel and the sheet thickness dimension t of the web. ₁ and the thickness t _{2 of the} flange and the design yield stress F (N / mm ² ) of the steel material can be set within a predetermined range. As a result, the weight of the steel material can be reduced without reducing the cross-sectional performance as compared with a conventionally known rolled H-section steel, and a rolled H-section steel having a new dimension and shape can be provided.
For example, the rolled H-section steel whose dimensions are set as described above can reduce the weight of each rolled H-section steel by about 10% compared to the conventional one. As a result, the cost per rolled H-section steel can be reduced, which can greatly contribute to the cost reduction of a structure using the rolled H-section steel. For example, the small beam can be reduced in weight by 10% or more without deteriorating its seismic performance, and the unit price of the small beam can be reduced by about 10%, for example. Therefore, not only can the construction cost of the structure be remarkably reduced, but also the weight of the structure can be reduced by reducing the weight of the beam, and the seismic performance can be improved.
In particular, since it can be applied to a highly versatile rolled H-section steel for small beams, the cross-sectional area is reduced by about 10% as compared with the conventional rolled H-section steel, and a small beam having a cross-sectional performance equal to or higher than that of the conventional can do. As a result, although it is inexpensive, it is possible to obtain a small beam whose sectional moment is improved by 15% or more and about 60% at the maximum, and further, whose section modulus is improved by about the same level or more and up to 15%.

Moreover, when the dimension of rolled H-section steel was set by the combination of said (a)-(c), the said yield stress F for design F (N / mm < ² >) was expanded with 235 <= F <= 275 as reference strength of steel materials. Even in this case, the weight per rolled H-section steel can be reduced by at least about 5% or more and about 15% at maximum compared to the conventional product, and the cost per rolled H-section steel can be reduced. Therefore, it can greatly contribute to the reduction of the construction cost of the structure using this rolled H-section steel. For example, the weight of the small beam can be reduced to at least about 5% or more and up to 15% without deteriorating its seismic performance. Therefore, the unit price of the beam can be reduced to, for example, about 5% or more and about 15%. Therefore, not only can the cost of the structure be remarkably reduced, but also the weight of the structure can be reduced by reducing the weight of the beam, and the seismic performance can be improved.

  It is most suitable for rolled H-section steel for small beams, which is a member with less load burden, and has a weight reduced to at least about 5% and up to about 15% compared to conventional rolled H-section steel. A small beam having a cross-sectional performance equal to or higher than that can be obtained. Therefore, it is possible to obtain a small beam whose cross-sectional secondary moment is about 5% or more and about 65% at the maximum and whose section modulus is improved from about the same level or more to about 20% at the same level as the conventional product.

It is a graph which shows the relationship between the web width thickness ratio and the flange width thickness ratio in the various rolled H-section steel which concerns on one Embodiment of this invention, and the various rolled H-section steel according to JIS specification. It is a graph which shows the relationship between the web thickness and flange thickness ratio, and the side and height ratio of various rolled H-section steels according to the embodiment and various rolled H-section steels conforming to JIS standards. It is a figure which shows the representative dimension of each part of rolled H-section steel, Comprising: It is an external view at the time of seeing in the cross section perpendicular | vertical to the longitudinal direction. It is a graph which shows the relationship between the web width thickness ratio and the flange width thickness ratio of the various rolled H-section steel according to JIS specification. It is a graph which shows the relationship between the web thickness / flange thickness ratio and the side / height ratio of various rolled H-section steels conforming to JIS standards. It is a graph which shows the relationship between the web width thickness ratio and the flange width thickness ratio of the various rolled H-section steels according to ASTM specification. It is a graph which shows the relationship between web thickness / flange thickness ratio and side / height ratio of various rolled H-section steels according to the ASTM standard. It is a graph which shows the relationship between the web width thickness ratio and the flange width thickness ratio of various rolled H-section steel according to BS specification. It is a graph which shows the relationship between web thickness / flange thickness ratio and edge | side / height ratio with various rolling H-section steels according to BS specification. It is a graph which shows the relationship between the web width thickness ratio and flange width thickness ratio of various rolled H-section steels according to EN specification. It is a graph which shows the relationship between web thickness / flange thickness ratio and side / height ratio with various rolled H-section steels conforming to EN standards.

  Next, an embodiment of the rolled H-section steel of the present invention will be described in detail.

First, FIG. 3 shows representative dimensions of each part of the rolled H-section steel 1 of the present embodiment and the rolled H-section steel 2 of the conventional example. The code H is H-shaped steel 1 (2) of the height dimension (mm), the symbol B is the flange width of the H-shaped steel 1, 2 sides of length (mm), reference numeral _{t 1} is the web 3 The thickness dimension (mm), the symbol t ₂ indicates the thickness dimension (mm) of the flange 4, and the symbol r indicates the radius of curvature R (mm) of the inner corner of the web 3 and the flange 4.

And in order to use the main application as a beam, the rolled H-section steel of this embodiment is the height dimension H of the H-section steel 1 and the side length dimension B, which is the flange width, in the same manner as the conventional case. (Hereinafter, the length of a side is also simply referred to as a side) satisfies the following expression (1).
(B / H) ≦ 0.77 (1)

  As described above, the reason for defining the relationship between the height dimension H of the rolled H-section steel 1 and the length dimension B of the side that is the flange width is the same as the reason for the above-described conventional product. That is, whether the side / height ratio B / H, which is the ratio of the height dimension H of the rolled H-section steel 1 and the length dimension B of the side that is the flange width, is less than or equal to 0.77. Depends on its use. In other words, when the side / height ratio B / H exceeds a width of 0.77, it is mainly used for a column, and when the side / height ratio B / H is a medium width or a small width of 0.77 or less. Is mainly used for beams, and such a practical index is also adopted in this embodiment.

The rolled H-section steel of interest in the present embodiment is a rolled H-section steel mainly for small beams belonging to a side / height ratio B / H of 0.77 or less, and the tensile strength of the steel material is 400 to 510 N / hour. mm ² (yield stress F for steel material design is 235 N / mm ^{2 to} 275 N / mm ² ). That is, in JIS G 3101 SS400 (tensile strength ^{400N / mm 2 ~510N / mm 2} ), SM400A in JIS G 3106, B, C (tensile strength ^{400N / mm 2 ~510N / mm 2} ), in JIS G 3136 It is a rolled H-section steel made of a steel material corresponding to SN400A, B, C (tensile strength 400 N / mm ^{2 to} 510 N / mm ² ).

In addition, the rolled H-section steel of this embodiment is a rolled H-section steel that is used in its elastic range. For example, the rolled H-section steel can be used for a small beam, so that it can be used within the elastic range. A deformation capacity of zero (plasticity factor 1.0) is sufficient.
Thus, the rolled H-section steel 1 targeted in the present embodiment is a rolled H-section steel used within an elastic range, and the required plastic deformation capacity is set to zero (plasticity ratio 1.0). The width-thickness ratio B / (2 × t ₂ ) is a numerical range shown in JIS G 3192 or Japanese Patent Laid-Open No. 2002-88974, that is, the upper limit value 10 of the flange width-thickness ratio B / (2 × t ₂ ). It is conceivable that .0 is the lowest value. However, in addition to this value, the flange width-thickness ratio B / (2 × t ₂ ) is 9.4 in the graph showing various ASTM H-section steels according to ASTM standards shown in FIG. Since the upper limit of the flange width-thickness ratio is 11.1 in the graph shown by plotting various rolled H-section steels of EN standards shown in FIG. 2, in this embodiment, the flange width-thickness ratio B / (2 × t ₂ ) is It is larger than 11.1.

Similarly, the web width-thickness ratio (H-2 × t ₂ ) / (t ₁ ) is a numerical range shown in JIS G 3192 and Japanese Patent Laid-Open No. 2002-88974. That is, in the graphs plotting various JIS standard rolled H-section steels shown in FIGS. 1 and 4, the upper limit value of the web width-thickness ratio (H−2 × t ₂ ) / (t ₁ ) is 56.6. Yes, it is 63.5 for the various rolled H-section steels of the ASTM standard shown in FIG. 6, and 63.3 for the various rolled H-section steels of the BS standard shown in FIG. 8. From these, the standard of the ASTM standard shown in FIG. Since the upper limit 63.5 of various rolled H-section steels is the largest, in this embodiment, it is larger than the upper limit 63.5 of various rolled H-section steels of the ASTM standard.

As an upper limit value of the flange width-thickness ratio B / (2 × t ₂ ) and the web width-thickness ratio (H−2 × t ₂ ) / (t ₁ ) of the rolled H-section steel 1 in the present embodiment, the building standard method ( (May 18, 2007, Ministry of Land, Infrastructure, Transport and Tourism Notification No. 596) The limit value (same as defined in the AIJ Design Standard) is 400 to 510 N / mm ² in tensile strength. When F is 235 N / mm ² , the flange width / thickness ratio B / (2 × t ₂ ) is 15.5 or less, so the web width / thickness ratio (H−2 × t ₂ ) / (t ₁ ) is 71. 0 or less.

As an upper limit value of the flange width-thickness ratio B / (2 × t ₂ ) and the web width-thickness ratio (H−2 × t ₂ ) / (t ₁ ) of the rolled H-section steel 1, the design yield stress F of the steel material is 235N. In the case of / mm ² , as shown in Table 1, it is defined as 16.5 in the AISC design standard, 16.2 in the BS design standard, and 14.0 in the EN design standard. EN design standards in Europe are considered the strictest design standards. From this, in this embodiment, 14.0 is adopted as the flange width-thickness ratio B / (2 × t ₂ ) of the rolled H-section steel, and this value is generalized using the design yield stress F. 215 / √ (F).
When designing the allowable stress level, the web width-thickness ratio (H-2 × t ₂ ) / (t ₁ ) of the rolled H-section steel is not stipulated by the AISC design standard and the BS design standard. The standard specifies 124.0. Therefore, in this embodiment, the web width thickness ratio (H−2 × t ₂ ) / (t ₁ ) 71.0 defined in the AIJ design standard is adopted, and this value is used as the design yield stress. Generalized using F, 1100 / √ (F).

Considering the flanges and webs that make up rolled H-section steel as plate elements, and examining their local elastic buckling strength σcr and the specified values in each country, the elastic local buckling theoretical value of the plate can be obtained by the following equation (2). It is done.
σcr = k × (π ² × E) / (12 × (1−ν ² )) × (t / b) ² (2)
Here, k is a buckling coefficient, E is a Young's modulus, ν is a Poisson's ratio, t is a plate thickness, and b is a plate width.

In rolled H-section steel, the flange is a simple plate with 3 sides and a single free rectangular plate (buckling coefficient k = 0.425), and the web is a rectangular plate with simple support around it (buckling coefficient k = 4.00). When idealized, in order not to cause local buckling until these plate elements reach the yield stress, the above equation (2) is simplified as follows with σcr = F.
In the case of three-side simple support and one-piece free (in the case of a flange), since t = t2 and b = B, (B / t2) = 281 / √ (F), which is described in Table 1 above. Of 18.3 can be obtained as a theoretical value.
Further, in the case of simple peripheral support (in the case of the web), since t = t1 and b = H, (H / t1) = 862 / √ (F). From this, 56. 2 can be obtained as a theoretical value.

  The rolled H-section steel has a cross-sectional shape in which lateral buckling and bending torsional buckling are likely to occur. In particular, the flange is the most important part for securing the strength of the beam. From this, it is set slightly stricter than the elastic local buckling, and in the case of three-side simple support and one piece free (in the case of a flange), it is 14.0 in the allowable stress design, and (B / t2 ) = X / √ (F) is obtained so that the value of X is 14.0, and (B / t2) = 215 / √ (F) and the design yield stress F are generally used. It has become.

Moreover, in the beam using rolled H-section steel, as long as the acting shear force does not exceed the total plastic shear strength of the web, it has been found that the decrease in the total plastic moment due to the shear force can be ignored. Therefore, the web is set as follows so as to be slightly looser than the elastic local buckling.
In the case of simple peripheral support (in the case of web), since the allowable stress design is 71.0, the value of (H / t1) = Y / √ (F) is 71.0. The value of Y is obtained and generalized using (H / t1) = 1100 / √ (F) and the design yield stress F (N / mm ² ).

Therefore, the relationship of the sides of the length dimension B and the flange thickness t ₂ is the width of the flange,
11.1 <B / (2 × t ₂ ) ≦ 215 / √ (F) (3)
In the countries that specify the flange width-thickness ratio B / (2 × t ₂ ), the required cross-section while reducing the steel weight of rolled H-section steel with a new cross-sectional shape. It is possible to provide a rolled H-section steel having a medium width and a narrow width equal to or higher than the performance and easy to set dimensions.

Also, in countries defining the web width-thickness ratio _(H-2 × t ₂₎ it is, as described above, the height (H) and the web thickness t _1, the relationship of the flange thickness t ₂ is, for design When the yield stress F (N / mm ² ) is 235 ≦ F ≦ 275,
56.6 <(H−2 × t ₂ ) / t ₁ ) ≦ 1100 / √ (F) (4)
It is said.

On the other hand, by increasing the flange width / thickness ratio B / (2 × t ₂ ) and the web width / thickness ratio (H−2 × t ₂ ) / (t 1), the cross section of the rolled H-section steel 1 is increased. Since the height dimension H and the side dimension B can be enlarged, even if the web thickness t ₁ is slightly less than the same thickness as the flange thickness t ₂ , the secondary moment of inertia per unit cross-sectional area (in order to resist bending stress) It is possible to improve the rigidity (particularly around the strong axis) by increasing I) and the section modulus (Z) as compared with the conventional case.
Therefore, the web thickness / flange thickness ratio (t ₁ / t ₂ ) can be larger than the numerical range indicated by JIS G 3192, that is, the upper limit value 0.75 of the web thickness / flange thickness ratio (t ₁ / t ₂ ). .
Therefore, in the present embodiment, the lower limit value of the web thickness / flange thickness ratio (t ₁ / t ₂ ) is set larger than 0.75.

When the web thickness t ₁ is equal to or greater than the flange thickness t ₂ , the weight efficiency of the section secondary moment I and the section modulus Z deteriorates, so the web thickness / flange thickness ratio (t ₁ / t ₂ ) is , Less than 1.0.
Therefore, in the rolled H-section steel 1 of the present embodiment, the upper and lower limit values of the web thickness / flange thickness ratio (t ₁ / t ₂ )
0.75 <(t ₁ / t ₂ ) <1.0 (5)
It is said.

In consideration of the above points, various rolled H-section steels 1 of the present embodiment set to various dimensions are shown in Table 3 as Invention Examples A to H. Table 3 shows cross-sectional dimensions, side / height ratio (B / H), flange width / thickness ratio B / (2 × t ₂ ), and web width / thickness ratio (H−2 × t ₂ ) / (t ₁ ), web thickness / flange thickness ratio (t ₁ / t ₂ ), and cross-sectional performance. Table 3 shows various conventional rolled H-section steels 2 in Japan corresponding to Invention Examples A to H as Conventional Examples A to H in accordance with Table 3. Table 3 shows the cross-sectional area ratio, the cross-sectional secondary moment ratio around the strong axis, and the cross-sectional modulus ratio around the strong axis between the inventive examples A to H and the corresponding conventional examples A to H. .

  In addition, on the coordinate axis shown in FIG. 1 where the horizontal axis is the flange width / thickness ratio and the vertical axis is the web width / thickness ratio, the moving distance (unnamed) from the conventional example A (˜H) to the present invention example A (˜H). The number is calculated for each example as follows: Examples A and B of the present invention (horizontal axis: flange width-thickness ratio, vertical axis: movement distance on the coordinate axis in the web width-thickness ratio> 30 ) Is the amount by which the moving distance (anonymous number) becomes larger than C to H (the moving distance on the same coordinate axis <25), that is, the width and height of the H-shaped cross section are further increased, and the secondary moment of the cross section. The ratio was found to be large.

Example Travel Distance from Conventional Example to Example of the Present Invention Cross Section Second Moment Ratio A 33.3 1.61
B 31.8 1.39
C 23.6 1.17
D 21.3 1.23
E 18.4 1.18
F 23.1 1.21
G 22.0 1.14
H 19.7 1.14

As in the cross-sectional performance of this embodiment shown in Table 3, Invention Examples A to H are all rolled H-section steels for small beams, and the side-to-height ratio is 0.51 or less, and the flange width-thickness ratio is all. 11.8 or more and 13.8 or less, the web width thickness ratio is 64.6 or more and 69.8 or less, and the web thickness / flange thickness ratio is 0.77 or more and 0.95 or less.
Moreover, when the invention example AH which is the rolling H-section steel of this embodiment in Table 3 and the conventional examples AH which are the conventional rolling H-section steel corresponding to this are compared, compared with a prior art example, In the present invention examples A to H, which are rolled H-section steels of this embodiment in which the web thickness t1 and the flange thickness t2 are reduced and the height dimension H and the dimension B of the side that is the flange width are increased, the cross-sectional area A is 10 From 16% to 61%, the cross-sectional secondary moment (I) ratio around the strong axis can be improved from 14% to 61%, and the cross-section coefficient (Z) ratio around the strong axis can be improved from the same to 17%. Recognize.
In Tables 2-1 to 2-3, it can be seen that the minimum value of the side / height ratio (B / H) is 0.33.

In addition, as can be seen from FIG. 1, on the graph of the flange width-thickness ratio-web width-thickness ratio, the present invention examples A to A satisfying the respective expressions (1) and (3) to (4) of the present embodiment. It can be seen that the rolled H-section steel 1 containing H is a rolled H-section steel in a region that can be clearly distinguished from a conventionally known rolled H-section steel region in Japan and abroad (see FIGS. 1, 6, 8, and 10). .)
Further, as can be seen from FIG. 2, on the graph of side / height ratio (B / H) −web thickness / flange thickness ratio (t ₁ / t ₂ ), the above formulas (1), (3 The rolled H-section steel 1 including Invention Examples A to H that satisfy the conditions of (4) to (4) is a rolled H-section steel in a region that can be clearly distinguished from the region of conventionally known rolled H-section steel in Japan and abroad. (See FIGS. 2, 7, 9, and 11).
Moreover, as can be seen from Table 3 and FIGS. 1 and 2, the rolled H-section steel 1 dimensioned as in this embodiment has much better cross-sectional performance than the conventionally known rolled H-section steel. Yes.

1 and Table 3 show the cross-sectional performance of the present embodiment example and the conventional example when the reference strength F of the steel material is 235 N / mm ^2. Next, as in the above-described embodiment, the reference strength F of the steel material is shown. The cross-sectional performance of the present embodiment when (N / mm ² ) is 235 ≦ F ≦ 275 and when the specific reference strength F is 275 N / mm ² will be described in comparison with the conventional example.

As described above, since the rolled H-section steel for small beams is used within the elastic range, the required plastic deformation capacity of the beam member is sufficient (zero plasticity factor 1.0). Therefore, the flange width-thickness ratio and web width-thickness ratio are the numerical ranges shown in JIS G 3192, Japanese Unexamined Patent Application Publication No. 2002-88974, EN standards and ASTM standards (upper limit of flange width thickness ratio 11.1, web width The upper limit of the thickness ratio can be larger than 63.5). As an upper limit value of the flange width-thickness ratio B / (2 × t ₂ ) and the web width-thickness ratio (H−2 × t ₂ ) / (t ₁ ) of the rolled H-section steel 1 in the present embodiment, the building standard method ( In addition to satisfying the limits set by the Ministry of Land, Infrastructure, Transport and Tourism Notification No. 596 on May 18, 2007, the AISC design standard, BS design standard, and EN design standard may be satisfied. That is, when the tensile strength is 400 to 510 N / mm ² (the standard strength F of the steel material is 235 N / mm ² ), the flange width-thickness ratio B / (2 × t ₂ ) is 215 / √ (F) or less ( That is, the web width-thickness ratio (H-2 × t ₂ ) / (t ₁ ) is 1100 / √ (F) or less (that is, 71.0 or less). When 400 to 510 N / mm ² (the standard strength F of the steel material is 235 ≦ F ≦ 275 N / mm ² ) and the design yield stress is F, the flange width-thickness ratio B / (2 × t ₂ ) is The web width / thickness ratio (H-2 × t ₂ ) / (t ₁ ) may be 1100 / √ (F) or less.
For example, when the design yield stress F is 275 N / mm ² , the flange width-thickness ratio B / (2 × t ₂ ) may be 215 / √ (275) or less (ie, 12.9 or less), The web width-thickness ratio (H−2 × t ₂ ) / (t ₁ ) may be 1100 / √ (275) or less (that is, 66.0 or less).

The rolled H-section steel of this embodiment, which is required to satisfy the following: 235 ≦ F ≦ 275N, the design yield stress F (N / mm ² ) of the steel material as described above is as follows. Is set.

The relationship between the height (H) of the rolled H-section steel and the side length (B) which is the flange width is
(B / H) ≦ 0.77 (6)
Tensile strength is is a rolled H-section steel 400~510N / mm ^2, the relationship between the length dimension B and the flange thickness _{t 2} of said sides,
11.1 <B / (2 × t ₂ ) ≦ 215 / √ (F) (7)
It may be a rolled H-section steel defined as follows. In some cases, it is intended to satisfy the above conditions, and the height dimension H and the web thickness dimension t _1, the relationship between the flange thickness t _2,
63.6 <((H−2 × t ₂ ) / t ₁ ) ≦ 1100 / √ (F) (8)
(However, F is a standard strength (N / mm ² ) of the steel material and may be a rolled H-section steel defined as 235 ≦ F ≦ 275).
In some cases, the above condition is satisfied, and the relationship between the web thickness dimension t ₁ and the flange thickness dimension t ₂ is
0.75 <(t ₁ / t ₂ ) <1.0 (9)
What is necessary is just to use the rolled H-section steel which is.

For example, in the case where the standard strength F of the steel material is 275 N / mm ² , various rolled H-section steels 1 of the present embodiment set to various dimensions under the above conditions are shown in Table 4 as Invention Examples A to H. Show. Table 4 shows cross-sectional dimensions, side / height ratio (B / H), flange width / thickness ratio B / (2 × t ₂ ), and web width / thickness ratio (H−2 × t ₂ ) / (t _1. ), Web thickness / flange thickness ratio (t ₁ / t ₂ ), and cross-sectional performance. Table 4 also shows various conventional rolled H-section steels 2 corresponding to the inventive examples A to H as conventional examples A to H. Table 4 shows the cross-sectional area ratio, the cross-sectional secondary moment ratio around the strong axis, and the cross-section coefficient ratio around the strong axis between the inventive examples A to H and the conventional examples A to H corresponding thereto.

  As in the cross-sectional performance of this embodiment example shown in Table 4, Invention Examples A to H are all rolled H-section steel for small beams, and the side-to-height ratio is 0.51 or less, and the flange width-thickness ratio. Is 11.3 or more and 12.5 or less, the web width-thickness ratio is 58.5 or more and 61.0 or less, and the web thickness / flange thickness ratio is 0.79 or more and 0.90 or less.

  Moreover, when the invention example AH which is the rolling H-section steel of this embodiment in Table 4 and the conventional examples AH which are the conventional rolled H-section steel corresponding to this are compared, compared with a prior art example. In the invention examples A to H of the rolled H-section steel of this embodiment in which the web thickness t1 and the flange thickness t2 are reduced and the height dimension H and the dimension B of the side which is the flange width are increased, the cross-sectional area A is 5 % To 10%, the secondary moment (I) ratio around the strong axis can be improved by 5% to 65%, and the sectional modulus (Z) ratio around the strong axis can be improved from the same to 20%. Recognize.

  The rolled H-section steel 1 of the present embodiment can be applied not only to narrow beams, but also to narrow beams, medium width beams, and beams.

  According to the present invention, the rolled H that is lighter for a small beam and does not deteriorate the cross-sectional performance than the rolled H-section steel standardized in major advanced countries including the United States, the United Kingdom, Europe, and Japan. Shape steel can be provided.

DESCRIPTION OF SYMBOLS 1 Rolled H-section steel of this embodiment 2 Conventional rolled H-section steel 3 Web 4 Flange

Claims (3)

A rolled H-section steel having a web and a flange,
When the height dimension is H and the width dimension of the flange is B, the following formula (1) is satisfied;
A tensile strength of 400-510 N / mm ² ;
Furthermore, when the plate thickness dimension of the flange is t ₂ and the design yield stress of the steel material of the rolled H-section steel is F (N / mm ² ), the following expressions (2) and (3) are satisfied;
A rolled H-section steel characterized by that.
(B / H) ≦ 0.77 (1)
11.1 <B / (2 × t ₂ ) ≦ 215 / √ (F) (2)
235 ≦ F ≦ 275 (3) It rolled H-section steel according to claim 1, characterized by satisfying the following equation (4) the plate thickness of the web when the t _1.
63.5 <((H−2 × t ₂ ) / t ₁ ) ≦ 1100 / √ (F) (4) _2. The rolled H-section steel according to claim 1, wherein a thickness t _{1 of the} web and a thickness t _{2 of the} flange satisfy the following expression (5):
0.75 <(t ₁ / t ₂ ) <1.0 (5)

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