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Page 1

ICS 77.140.70
H 44



NATIONAL STANDARD

OF THE PEOPLE’S REPUBLIC OF CHINA

中华人民共和国国家标准
P GB/T 706-2008

Replace: GB/T 706-1988;GB/T 707-1988;
GB/T 9787-1988;GB/T 9788-1988;GB/T 9946-1988




Hot rolled section steel






















Issued on Aug. 19, 2008 Implemented on April 1, 2009


Issued by PRC General Administration of Quality Supervision
Inspection and Quarantine PRC Standardization Administration

Page 14

8

Table 5 Method for calculation of sectional area
Type of section steel Calculation formula

I - steel hd+2t(b-d)+0.615(r2-r1
2)

Channel steel hd+2t(b-d)+0.349(r2-r1
2)

Equal angle steel d (2b-d)+0.215(r2-2r1
2)

Unequal angle steel d (B+b-d)+0.215(r2-2r1
2)

L shaped steel BD+d(b-D)+0.215(r2-r1
2)

4 Technical requirements

4.1 Steel grade and its chemical ingredients
The grade of steel and its chemical ingredients (heat analysis) shall be in accordance
with relevant requirements of GB/T 700 or GB/T 1591. The steel may be supplied per
other grade or chemical ingredients subject to the agreement by both the supplying
and requisitioning parties, depending on the request from the requisition party.
4.2 Mechanical performance
The mechanical performances of section steel shall be in accordance with the relevant
requirements of GB/T 700 or GB/T 1591. The steel may be supplied per other
mechanical performances subject to the agreement by both the supplying and
requisitioning parties, depending on the request from the requisition party.
4.3 Delivery status
The section steel shall be delivered as hot-rolled status.
4.4 Surface quality
4.4.1 The section steel surface shall be free of cracks, overlaps, seams, lamination and
inclusions.
4.4.2 The hairline, depressions, mechanical pitting, scratches and rolled-in scale are
locally allowed on the section steel surface, but shall not exceed the dimensional
tolerance for the section steel.
4.4.3 The defects on the surface of section steel are allowed to be removed when the
place after removal shall be smooth and free of sharp edges. But the removal in the
traverse direction shall not be carried out. The removed width shall not be five times
less than the removed depth. The dimension of the section steel due to removal shall
not exceed the dimensional tolerance.
4.4.4 The section steel shall be free of burrs of more than 5 mm.

5 Testing method

5.1 The inspection items, sample size and testing method for each steel batch shall be
in accordance with the requirements in the Table 6.

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9

Fig. 6 Inspection items, sample size and testing method
No. Inspection items Sample size (pc.) Sampling method Testing method
1 Chemical ingredient See the requirements of the standards for the corresponding grade.
2 Tensile strength 1 GB/T 228
3 Bending strength 1 GB/T 232
4 Impact strength at ambient T 3
5 Impact strength at low T 3


GB/T 2975

GB/T 229

6 Surface quality Piece by piece Visually or by means of measuring tool
7 Dimensions, profile Piece by piece By means of measuring tool

5.2 For I-steel, channel steel, the sample shall be taken from its web.

6. Inspection rule

6.1 The inspection and acceptance shall be carried out by the technical and quality
supervision departments from the supplier.
6.2 Lotting of section steel shall be carried out in accordance with GB/T 700, GB/T
1591 and other corresponding standards.
6.3 The regulation for retest and acceptance of section steel shall be in accordance
with the requirements of GB/T 2101.

7. Packing, identification and quality certificate

The packing, identification and quality certificate for section steel shall be in
accordance with the requirements of GB/T 2101.

Page 27

21

Table A4 (continued)


Sectional dimensions
mm Moment of inertia/

cm4 Radius of inertia cm
Radius of inertia

cm

Distance between
gravity center and

axis/
cm

Model


B b d r

Sectional
area/
(cm2)

Theoretic
weight/
(kg/m)

Surface
area/

(m2/m)

Ix Ix1 Iy Iy1 Iu ix iy Iu Wx Wy Wu

tga

X0 Y0

10 25.315 19.872 0.512 668.69 1362.89 205.03 336.59 121.74 5.14 2.85 2.19 62.13 26.56 21.92 0.390 2.28 5.24

12 30.054 23.592 0.511 784.91 1635.56 239.06 405.94 142.33 5.11 2.82 2.17 73.49 31.28 25.79 0.388 2.36 5.32

14 34.709 27.247 0.510 896.30 1908.50 271.20 476.42 162.23 5.08 2.80 2.16 84.56 35.83 29.56 0.385 0.43 5.40
16/10 160 100

16

13

29.281 30.835 0.510 1003.04 2181.79 301.60 548.22 182.57 5.05 2.77 2.16 95.33 40.24 33.44 0.382 2.51 5.48

10 28.373 22.273 0.571 956.25 1940.40 278.11 447.22 166.50 5.80 3.13 2.42 78.96 32.49 26.88 0.376 2.44 5.89

12 33.712 26.440 0.571 1124.72 2328.38 325.03 538.94 194.87 5.78 3.10 2.40 93.53 38.32 31.66 0.374 2.52 5.98

14 38.967 30.589 0.570 1286.91 2716.60 369.55 631.95 222.30 5.75 3.08 2.39 107.76 43.97 36.32 0.372 2.59 6.06
18/11 180 110

16 44.139 34.649 0.569 1443.06 3105.15 411.85 726.46 248.94 5.72 3.06 2.38 121.64 49.44 40.87 0.369 2.67 6.14

12 37.912 29.761 0.641 1570.90 3193.85 483.16 787.74 285.79 6.44 3.57 2.74 116.73 49.99 41.23 0.392 2.83 6.54

14 43.687 34.436 0.640 1800.97 3726.17 550.83 922.47 326.58 6.41 3.54 2.73 134.65 57.44 47.34 0.390 2.91 6.62

16 49.739 39.045 0.639 2023.35 4258.88 615.44 1058.86 366.21 6.38 3.52 2.71 152.18 64.89 53.32 0.388 2.99 6.70
20/12.5 200 125

18

14

55.526 43.588 0.639 2238.30 4792.00 677.19 1197.13 404.83 6.35 3.49 2.70 169.33 71.74 59.18 0.385 3.06 6.78

Note: r1 = 1/3 d in the sectional drawing and data on r in the table for grooving rather than as the terms of delivery.

Page 28

Tab.A.5 Sectional dimensions, area, theoretical weight

and sectional properties for L shaped steel


Sectional dimension/

mm
Model

B b D d r r1

Sectional

area/

cm2

Theoretic

weight/

kg/m

Moment

of

inertia Ix/

cm4

Distance between

gravity

center to axis Y0/

cm

L250×90×9× 13 9 13 33.4 26.2 2190 8.64
L250×90×10.5×15 10.5 15 38.5 30.3 2510 8.76
L250×90×11.5×16

250 90

11.5 16 41.7 32.7 2710 8.90

L300×100×10.5×15 10.5 15 45.3 35.6 4290 10.6
L300×100×11.5×16

300 100
11.5 16

15 7.5

49.0 38.5 4630 10.7

L350×120×10.5×16 10.5 16 54.9 43.1 7110 12.0
L350×120×11.5×18

350 120
11.5 18 60.4 47.4 7780 12.0

L400×120×11.5×23 400 120 11.5 23 71.6 56.2 11900 13.3
L450×120×11.5×25 450 120 11.5 25 79.5 62.4 16800 15.1
L500×120×12.5×33 12.5 33 98.6 77.4 25500 16.5
L500×120×13.5×35

500 120
13.5 35

20 10

105.0 82.8 27100 16.6

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