DIN 18808

UDC 693.814.3 : 693.814.25 : 624.014.27.078.416 : 624.042.2 : 001.4 DEUTSCHE NORM October 1984

Steel structures Structures made from hollow sections subjected

to predominantly static loading

- DIN

18 808

Beuth Verlag GmbH Berlin 30. has exclusive sale rights for German Standards (DIN-Normen) 08.86

DIN 18808 Engl. Price group I l Sales No. O1 11

Stahlbauten; Tragwerke aus Hohlprofilen unter vorwiegend ruhender Beanspruchung

In keeping with current practice in standards published by the International Organization for Standardization .(lSO), a comma has been used throughout as the decimal marker.

This standard has been recommended to the Laender building inspectorates by the Institut für Bautechnik (Institute for Building Technology), Berlin, for inclusion in the Laender building regulations.

Contents

1 Field of application

Page

. 1

2 Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

3 Materials.. . . . . . . . . . . . . . . . . . . . . . . . . . . 1

4 Trusses.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4.1 General information on design . . . . . . . . . . . . 1 4.2 Nomenclature, quantities and symbols . . . . . . . 2 4.3 Truss members . . . . . . . . . . . . . . . . . . . . . . 4 4.4 Unstiffened truss junction points . . . . . . . . . . 5 4.4.1 Verification of wall thickness . . . . . . . . . . . 5 4.4.1.1 Actual wall thickness ratio . . . . . . . . . . . . 5 4.4.1.2 Required wall thickness ratio . . . . . . . . . . 5 4.4.2 Additional analysis when g exceeds 2 c

and y exceeds 0,7 . . . . . . . . . . . . . . . . . . . I O 4.4.3 Welded joints . . . . . . . . . . . . . . . . . . . . . . 1 1 4.4.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 4.4.3.2 Weld thickness . . . . . . . . . . . . . . . . . . . . 1 1 4.4.3.3 Weld types . . . . . . . . . . . . . . . . . . . . . . 1 1

Page

4.5 Truss junction points with stiffenings and indirect connections . . . . . . . . . . . . . . . . . . . 13

4.5.1

4.6 Load introduction points . . . . . . . . . . . . . . . 14 4.7 Three-dimensional truss junction points . . . . . . 14 5 Flexurally rigid frame corners made from

rectangular hollow sections . . . . . . . . . . . . . . . 15 6 Butt joints . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7 Requirements to be complied with by

the manufacturer and the welders . . . . . . . . . . . 17 7.1 Requirements to be complied with by

the manufacturer . . . . . . . . . . . . . . . . . . . . . 17 7.2 Requirements to be complied with by

the welders . . . . . . . . . . . . . . . . . . . . . . . . . 17 Standards and other documents referred to . . . . . . . 19 Other relevant standards and documents . . . . . . . . . 19 Explanatory notes . . . . . . . . . . . . . . . . . . . . . . . 20

Stiffened truss junction points . . . . . . . . . . . 13 4.5.2 Connections using gusset plates . . . . . . . . . . 14

1 Field of application This standard applies to structural components made from hollow steel sections subjected to predominantly static loading, and connected to one another without any change of cross section. Compliance with the specifications of this standard may be taken to signify that the design and construction of all junction points have been performed in a secure and workmanlike manner.

2 Concept For the purposes of this standard, hollow sections are members exhibiting a closed, circular or rectangular (including square) hollow cross section, in respect of which the wall thickness remains constant by design right around the entire periphery of the cross section, and also along the entire length of the member (see DIN 2448, DIN 2458, DIN 59410 and DIN 59411).

3 Materiais As a general rule, only steel grades St 37-2, St 37-3 and St 52-3 specified in DIN 17 100, DIN 17 119, DIN 17 120 and DIN 17 121 may be used, hereinafter referred to simply as St 37 or S t 52 steel. If different structural steels are used, DIN 18800 Part 1, March 1981 edition, subclause 2.1.1, second and third paragraphs are to be consulted.

4 Trusses 4.1 General information on design In the case of members, trusses made from hollow sections shall be designed as described in subclause 4.3 and in the case of junction points, as described in subclauses 4.4 and 4.5.

Continued on pages 2 to 20

Copyright Deutsches Institut Fur Normung E.V. Provided by IHS under license with DIN

Not for ResaleNo reproduction or networking permitted without license from IHS

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Page2 DIN 18808

1

2

3

4

5

6

7 ~-

8

4.2 Nomenclature, quantities and symbols A distinction shall be made between hollow sections which pass through a junction point (continuous hollow sections) and hollow sections which terminate a t said junction point, as shown in figure 1. The hollow sections passing through the junction point shall be identified by the figure O, whilst the hollow sections terminating a t the junction point shall be identified consecutively by figures 1, 2, etc. in a clockwise direction. In addition, a distinction shall be made between topmounted and bottom-mounted hollow sections.

Hollow sections 1 and 2 terminating \.i. at the truss junction

3

rop-mounted hollow section

O -.

4 5 Hollow

Hollow section section passing through terminating junction point a t junction

i = O i = 1,2,. . . point

Figure 1

1

General

Hollow section O passing through the truss junction point Example of numbering hollow sections meeting a t a junction point

2

Bottom- mounted hollow

The main symbols required for the analyses specified are listed in table 1 and illustrated in table 2. In table 2, item 2, the following shall apply: - member O is a bottom-mounted hollow section in relation to members 1 and 2; - member 1 is a top-mounted hollow section in relation to members O and 2; - member 2 is a top-mounted hollow section in relation to member O, and a bottom-mounted hollow section in relation

to member 1 .

Table I . List of main symbols

ha ho hi

Yield strength

of the member at the junction point Normal stress in thedirection of the axis

I I section

ßs ßS"

U ull

Wa I I th ickness

Diameter

Width =dimension a t right angles to the plane of the structure

Height = dimension in the plane of the structure

Cross-sectional area ~~

Normal force in the member I N I N ,

Key to other symbols:

g e eccentricity (see figure 2)

gap width (see table 2, item No. 1)

c = 03. (bu - ba) I c = 0,5 . (du - da) I flank clearance

length of overlap (see table 2, item Nos. 2 and 3) lu



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DIN 18808 Page 3

d a y = -

d U

d a y=- bu

ratio of widths (see table 2)

bee figure 1 and tab1 Other symbols are explained in the standard when used for the first time.

Table 2. Nomenclature and parameters to be considered

:olumn ~

Item No.

1 2 3 4 1 5 1 6 1 7

Parameter to be considered for the analysis

Designation of junction

point

:onnec- tion

Thickness of

hollow section

Illustration Connec- tion

angle

8

Ratio of

widths

Y 1 Junction

point with ga P

o- 1 9.1

03 0-2

2

-

Junction point with overlap

0-1 t i

0-2 t 2

t 2 2- 1 -



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Page 4 DIN 18808

Table 2. (continued) - :olumn __

Item No.

- 3

-

2 3 4 1 5 1 6 1 7 1

Parameter to be considered for the analysis

Designation of junction

point Connec-

tion angle

ir

:onnec- tion

Thickness of

hollow section

Ratio of

widths

Y

I Ilustration

O - 1 t l Junction point with overlapping vertical member

0-3 t3

0-2 t2

3-2 t3 t2

1-2 t l t2

o: Note 1. The procedure i s similar for connections of rectangular hollow sections; depending on the circumstances,

Note 2. For the analysis of junction points with overlap, values 8 and y of columns 6 and 7 are not required. d should be replaced by b in column 7.

4.3 Truss members Members shall be verified as described in DIN 18800 Part 1, DIN 4114 Part 1 and Part 2 and, if applicable, as described in DASt-Richtlinie (DASt Code of practice) 012 and DASt-Richtlinie 013. The limits and specifications of table 3 shall be complied with in respect of the dimensions of the members. The analysis in respect of continuous chord members may be carried out without any consideration of the additional moments due to eccentricity e (see figure 2), on condition that:

or - 0.25 2 e/ho 5 + 0,25 - 0,25 5 e/do 5 + 0,25.

\ /

a) Positive eccentricity . v ! ! b) Negative eccentricity

Figure 2. Ruling governing the plus or minus sign for eccentricity e in the case of a configuration of a truss junction point not true to the system line



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DIN 18808 Page 5

5

In the general stress analysis for web members in trusses, the structural component stresses to be complied with shall be thosespecified in DIN 18800 Part 1, March 1981 edition, table 11, lines 4 to 6. In the general stress analysis for chord members, the values specified in DIN 18800 Part 1, March 1981 edition, table 7, shall apply. In certain cases, additional analyses in accordance with subclause 4.4.2 may be required.

Table 3. Dimensions of members in trusses

For chord members in the case of

junction point d / t s 35

b / t < 35 analyses

item NO. I Limiting values

d 2 500 mm I

b 5 400 mm I 2 1 0,5 I h/b I 2.0

t > 1,5mm I 3 I St37: t g 30mm

St52: t < 25mm

St 37: d / t < 1 O0

St52: d / t < 67 For members in compression 4

St37: b / t< 43

St52: b / t < 36

4.4 Unstiffened truss junction points 4.4.1 Verification of wall thickness An adequate structural strength, and consequently an adequate loadbearing capacity of the junction point shall be deemed to exist if the actual ( = vorh) wall thickness ratio vorh ( tu / ta ) of two hollow sections connected to each other is greater than, or equal to, the required ( = erf) wall thickness ratio erf (tu&,):

vorh (::)- - > erf (?) 4.4.1 .I Actual wall thickness ratio The actual wall thickness ratio vorh (tu&) is the ratio of the wall thickness of the bottom-mounted section to that of the top-mounted section. If steels with differing values of yield strength, ,ßs, are used for top-mounted and bottom-mounted hollow sections, the actual wall thickness ratio, t,/t,, shall be replaced by the following relationship:

tu Bsu

t a ß s a -.-

If the permissible ( = zul) stress zu1 u as specified in DIN 18800 Part 1, March 1981 edition, table 11, lines 4 to 6 i s not fully utilized in the top-mounted hollow section, the actual wall thickness, t a , may be replaced by the reduced ( = red) wall thickness

vorh u, red t, = t, . -

zu1 a, (2)

4.4.1.2 Required wall thickness ratio The required wall thickness ratio erf, t,lt,, can be obtained from table 4 and from figures 3 to 8 for values of width ratio, y, not less than 0,35. In the case of thick-walled bottom-mounted hollow sections, with- I 20 or - I 20, it i s acceptable to have y 2 0,35 if

(3)

du b U

tU tu 1

vorh (:) 2 or erf (t) = 1 Y

In the case of junction points with a gap and with Bexceeding 60", factor f f i (see table 4) shall be taken into consideration. See relevant angles 8 in column 6 of table 2.



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Page 6 DIN 18808

O O a

* VI

V 8 W

h.

Al

e ? !2 5 '5

O

O

m

c C O Q C O o S

7

.-

.- U

a

Co Co

I- I-

d

m o

c O .- t L! Q

o o

a m e,

I o

't al

u i > L - W

o U)

o e '4 7

ai O z r



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DIN 18808 Page7

-

-

-

f

240

210

180 t N E E -150 2 C .-

St 3? St 52

-

-

-

HZ

120 s .- u> ln

90 g E

60 ; o

t "i

160

140

t 120- N E E 2 100-

z

-

-

.5 I

6 80- O .- v) v)

g 60- E o 1 4 0 -

b

HZ

I I I I I I I I I 1 1 1 1 I ' I I

St 52 1,33 1,6 2,O 2,4 2,8 3,2 3,6 4,O erf ít,lt,) -

Figure 3. Required wail thickness ratio as a function of ratio bu& 5 20 or du& 5 20

St 3 f St 52 HZ

.E I

I I I I I I I I 1 I I I 1 1 I I

St52 1,42 1,6 2,O 2,4 2,8 3,2 3,6 4,O erf ítu/t,) -

Figure 4. Required wail thickness ratio as a function of ratio bu& = 22.5 or d,/tu = 22,5

HZ 240

I .E 120 $

o .- u> o

90 h

60 U



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Page 8 DIN 18808

160

140

I 120- N E E 2 100- c .- r' 80- I

60- E

a 40-

O .-

o O

-

-

I I 1 I I I I I I , I I

St 52 1,s 1,6 2,O 2,4 2,8 3,2 3,6 4,O erf (tultal -

Figure 5. Required wall thickness ratio as a function of ratio bu& = 25 or d, / t , = 25

210

180 -

150 -

- 120

90

60

30

-

-

-.

S t 3 f

-240

210

t N E E 150 2 C .-

120 $

E

.- y!

90

60 8

160

140

I 120- hl E

z -E 100- c .- 6 80-

60-

O .- v> v)

E

o 40- t?

-

.-

St 52

-

-

-

-

- 33EU 4,O 4,4 4,8 1:

240

210

180 t rv E E -150 2 c .-

-120 $ .- v) v>

90 g E

60 2 8

I 1 1 1 1 1 1 1 1 1 1 1 1 1 ,

S t 52 1.59 2,o 2,4 2,a 12 3,6 &,o erf (tu /ta l -

Figure 6. Required wall thickness ratio as a function of ratio b,/t, = 27,5 or du& = 27.5



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DIN 18808 Page9

~

-

-

-

-

St 3f St 52

240

210

180 t (v

E -150 -$

c .- -120 c

90

O .- v> VI

E o 60 2

HZ

N E

z < 100- i 80-

60-

c .- O .- VI L.?

E 8 1 40-

b

140 ’“I E

100 z 120!

$ 80- .- Lo Lo

60- E 8 a 40- b

HZ 240

1210

c < -

-120 g < -

VI VI

- 90 g E o

60 2 -

I I I I I I I I I I I I I I l

St 52 1,67 2,O 2.4 2,8 3.2 3,6 4,O erf (tuka) -

Figure 7. Required wall thickness ratio as a function of ratio buhu = 30 or du/tu = 30

S t 37 St 52 HZ 160

140 1 t 120

I I I I I I I I I I , I I I

St 52 1,83 20 2,4 2,8 3,2 3,6 4,O erf (tultal

Figure 8. Required wall thickness ratio as a function of ratio bu/tu = 35 or du& = 35



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Page 10 DIN 18808

Section A-% Section C-D (alternatively)

B

Figure 9. Examples explaining the parameters which determine reduction coefficient k

4.4.2 Additional analysis wheng exceeds 2 c and y exceeds 0,7 i f the gap widthg exceeds twice the flank clearance c, ¡.e. if g exceeds 2 c, and if a t the same time the ratio of widths, y, exceeds 0,7, the permissible stress, zu1 u, for the topmounted hollow section (as specified in DIN 18800 Part 1, March 1981 edition, table 11, lines 4 to 6) shall be multiplied by coefficient k . Coefficient k need not however be entered a t a value lower than 0,7, ¡.e. 0,7 < k < 1.

For rectangular web members and rectangular chords, we have: g - 2 c bi

0.7 < k = 1 - 3. ~ e-' , i = l , 2 , . . . bo bi + hi

g - 2 c 0,7 < k = 1 - 1,5. -.

bo

For circular and square web members and for rectangular chords, we can use the simplified relationship below:

(5)

In the case of chords made from circular tubes, diameter do shall be entered in equations (41 and (51 in lieu of bo. In the case of square and circular web members, coefficient k can also be obtained from figure 10 as a function of y and of glbo or gfdo ,

(4)



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DIN 18808 Page 11

t

Y-

Figure 10. k values for square and circular web members

4.4.3 Welded joints 4.4.3.1 General Welded joints need not be verified if the specifications laid down in subclauses 4.4.3.2 and 4.4.3.3 are complied with.

4.4.3.2 Weld thickness In the case of top-mounted hollow sections with wall thickness ta not exceeding 3 mm, the weld thickness shall be not less than the wall thickness of the top-mountedsection,viz. a 2 t a . In the case of top-mounted hollow sections with wall thickness ta exceeding 3 mm, the weld thickness shall be not less than the reduced wall thickness of the top-mounted section, viz. a 2 red ta, but a = 3 mm at least. In some cases, a greater weld thickness may be required for design reasons.

4.4.3.3 Weld types Where the connection of hollow sections is concerned, a distinction shall be made between zones A, B and C as illustrated in figure 11 a. When jointing rectangular hollow sections, the following specifications shall apply.

Zone A: the weld shall be made in the form of a single bevel butt weld for 8 less than 45" (see figure I l b), and in the case of 0 not less than 45", it may also be made in the form of a fillet weld (see figure 11 c). Zone B: for y I 0 , 8 : the welded joints may be made in the form of fillet welds (see figure 11 d); for y > 0.8: if perfect through-welding cannot be ensured in the case of small corner radii r , the edge shall be prepared

(see figure 11 e); in the case of large corner radii r (see figure 11 f), a check shall be carried out to determine whether welding i s possible.

Zone C: the welds inside the acute angle may be made in the form of fillet welds (see figures 11 g and 11 h).



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Page 12 DIN 18808

, -2 I

t

Detail A (section)

b)

Section B-B (magnified)

DIN 18800 Part 1, March 1981 edition, table 16 shall be consulted.

Detail C (section)

Figure 11. Examples of weld shapes adopted for the connection of rectangular hollow sections An analogous method shall be used for circular tubes.



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DIN 18808 Page 13

4 5 Truss junction points with stiffenings and indirect connections I f the requirements specified in subclause 4.4 cannot be complied with, then either the truss junction points shall be stiffened (see subclause 4.5.1 1 or the hollow sections shall be jointed indirectly via gusset plates (see subclause 4.5.2).

4.5.1 Stiffened truss junction points Truss junction points can, for example, be stiffened as shown in table 5.

Table 5. Examples of stiffened truss junction points

Designation of truss junction point

Junction point with partition plate

Juntion point with t ie plate and gap

Junction point with tie plate and overlap

I Ilustration

I I



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Page 14 DIN 18808

Table 5. (continued)

Item No.

4

Designation of truss junction point ~ ~

Junction point with tie plate and partition plate

I Ilustration

The thickness t, of the partition plates and stiffening plates shall be a t least twice the thickness of the largest reduced wall thickness of the terminating hollow sections:

tp22.red t i ( i=1,2 ,...) (6) The thickness ap of the welds for the connection of the partition plates and of the stiffening plates to the continuous hollow section, and for the connection of a partition plate to a stiffening plate shall be a t least equal to the thickness of the largest reduced wall thickness of the terminating hollow sections,

viz. ap 2 ti for ti < 3 mm (i = 1,2, . . .); (7) ap, however, shall not be less than red ti. As regards the parts of the hollow sections which are directly connected (as in table 5, connections 0-1 and 0-2 of item No. 1, and connection 1-2 of item No. 3). the specifications of subclause 4.4.1 shall apply. As regards hollow sections which are connected indirectly via a partition plate, no specifications have been given for the wall thickness ratio. As regards hollow sections which are connected indirectly via a t ie plate, the required wall thickness ratio shall be

erf (:) = í.

The specifications given in subclause 4.4.3.2 shall apply for the thickness a of the welds connecting terminating hollow sections.

4.5.2 Connections using gusset plates Hollow sections can be connected via gusset plates. The rules governing general structural steelwork shall apply for the analysis of such connections.

4.6 Load introduction points Special measures may be required a t load introduction points, e.g. a t supports.

4.7 Threedimensional truss junction points Special measures may be required a t three-dimensional truss junction points.



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DIN 18808 Page 15

5 Flexurally rigid frame corners made from rectangular hollow sections 5.1 Flexurally rigid frame corners made from rectangular hollow sections with mitre cut, with or without stiffening plate (see figure 12),shall be dimensioned as specified in subclauses 5.2 to 5.5. The specifications given in the above-mentioned subclauses do not apply for values of Bof less than 90".

Item No.

1

Detail X (alternatives)

Limiting values for flexurally rigid frame corners with mitred joint

with without I stiffening plate

b c 400 mm bc300mm

h 5 400 mm h5300mm

--I?-

2

3

4

f2 = t*

a=t,

0,33 I h/b g 3,5

t 2 2,5mm

St37: t g 3 0 m m

St52: t125mm

St 37: blt 5 43, h/t 5 43

St 52: blt < 36, hlt g 36

Figure 12. Details of flexurally rigid frame corner weld



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Page 16 DIN 18808

35

3,o

t 2'5- 9 - E 2,o

I5

5.3 The thickness tp of a stiffening plate shall comply with the following conditions:

t , 2 1 , 5 . t i ( i = 1 or21 andt,>lOmm.

- o(

-

-

-

5.4 An adequate structural strength, and consequently an adequate loadbearing capacity of the frame corners shall be deemed to have been attained if the following relationships are complied with (see equations (9) and (10)):

N M vorh o = - +- < a zu1 o

A W -

where N i s the normal force M is the bending moment

] in the hollow section under consideration in the frame corner system point;

A W zu1 u i s the permissible stress as specified in DIN 18 800 Part 1, March 1981 edition, table 7; a

i s the cross-sectional area of the hollow section under consideration; i s the section modulus of the hollow section under consideration;

i s a stress concentration factor. a = 1 for frame corners with stiffening plates. For frame corners without stiffening plates, a shall be obtained from figures 13 and 14 as a function of the cross-sectional dimensions.

1

3 Q < - A ~ * Z U I Z

where

Q is the transverse force in the hollow section under consideration in the frame corner system point; A s i s t the cross-sectional area of the hollow section webs (As = 2 . h . t ) ; zu1 t is the permissible stress as specified in DIN 18800 Part 1, March 1981 edition, table 7. If the condition in accordance with equation (IO) is satisfied, then a comparison stress analysis may be dispensed with. Otherwise,ananalysis of the comparison stress shall b e carried out as described in DIN 18800 Part 1, multiplying the

1 normal stress by factor-.

a

5.5 The welds shall be verified as specified in DIN 18 800 Part 1. In this connection, the cross-sectional area of the hollow section shall be entered as weld area. The verification of the welds may be dispensed with in the case of unstiffened frame corners if factor a does not exceed the following values:

0,84 for St 37 and 0,71 for St 52.

The details iilustrated in figure 12 shall be complied with.

b l t - Figure 13. Stress Concentration factor a for rectangular hollow sections standing on edge



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DIN 18808 Page 17

Conditions

Welder with valid

b i t - Figure 14. Stress concentration factor Q for rectangular hollow sections lying on their side

zu1 u, as specified in

6 Butt joints 6.1 calculation.

In the case of butt joints, the cross-sectional area of the thinner hollow section shall be used as weld area for

Radiographic examination For rectangular of butt weld hollow sections For circular tubes

6.2 Butt welds subjected to compressive stress do not require verification.

DIN 18800 Part 1, March 1981 edit i on

6.3 In the case of butt welds subjected to tensile stress, the permissible stress depends on the quality of the weld. This stress can be obtained from table 7 below.

100% radiography, quality class BS as specified in DIN 8563 Part 3

Table 7. Permissible tensile stress for butt welds

Table 11, item No. 2

Item No.

1

2

3

B II R II

I Not required. I Table 11, item No. 5

B I R I Not required. 88 % of the values listed in table 11, item No. 5

7 Requirements to be complied with by the manufacturer and the welders 7.1 Requirements to be complied with by the manufacturer Manufacturers of structures made from hollow sections as specified in this standard shall comply with the requirements laid down in DIN 18 800 Part 7. In particular, the manufacturer shall possess suitable equipment for mounting hollow sections ready for welding.

7.2 Requirements to be complied with by the welders 7.2.1 Table 8 l is ts the welding qualifications required for different types of welded joints.

7.2.2 For joints illustrated in table 8, item No. 2, an additional test shall be carried out on a test piece as shown in figure 15 for proving the welder's competence. This test shall be carried out as described in DIN 8560. The test piece shall be prepared as shown in figure 16 and shall be broken open, so that an evaluation of the fracture of the weld can be made.



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Page 18 DIN 18808

Table 8. Welding qualifications required for different types of welded joints

1

5

~~

Type of joint Qualification required

R I , R II *)

R I plus additional test as

specified in subclause 7.2.2

BI , Bll’)

B I

B I

) The permissible tensile stress depends on the quality of the weld (see table 7).



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DIN 18808 Page 19

Figure 15. Test piece to be manufactured in the additional test

/ Break segments open

Figure 16. Preparation of test piece for evaluation

Standards and other documents referred to DIN 2448 DIN 2458 DIN 4114Part1 DIN 4114Part2

DIN 8560 DIN 8563 Part 3 DIN 17100 DIN 17 119

DIN 17120 DIN 17121 DIN 18800 Part 1 DIN 18800 Part 7 DIN 59410

DIN 5941 1

Seamless steel pipes and tubes; dimensions, masses per unit length Welded steel pipes and tubes; dimensions, masses per unit length Structural steelwork; stability cases (buckling, overturning, bulging); design principles, specifications Structural steelwork; stability cases (buckling, overturning, bulging); design principles; code of practice Qualification testing of welders for welding steel Quality assurance of welding operations; fusion welded joints in steel; requirements, classification Steels for general structural purposes; quality standard Welded cold formed square and rectangular steel tubes (hollow sections) for structural steelwork; technical delivery conditions Welded circular steel tubes for structural steelwork; technical delivery conditions Seamless circular steel tubes for structural steelwork; technical delivery conditions Steel structures; design and construction Steel structures; fabrication, verification of suitability for welding Hollow sections for structural steelwork; hot formed square and rectangular steel tubes; dimensions, masses, permissible deviations, static values Hollow sections for structural steelwork; cold formed welded square and rectangular steel tubes; dimensions, masses, permissible deviations

DASt-Richtlinie O12 Beulsicherheitsnachweis für Platten 1) (Verification of safety against bulging for plates) DASt-Richtlinie 013 Beulsicherheitsnachweis für Schalen 1) (Verification of safety against bulging for shells)

Other relevant standards and documents DIN 55 928 Part 1 DIN 55928 Part 2

DIN 55 928 Part 3

DIN 55928 Part 4

Corrosion protection of steel structures by organic and metallic coatings; general Corrosion protection of steel structures by organic and metallic coatings; proper design for the prevention of corrosion Corrosion protection of steel structures by organic and metallic coatings; planning of corrosion protection Corrosion protection of steel structures by organic and metallic coatings; preparation and testing of surfaces

1 ) Obtainable from Stahlbau-Verlags GmbH, Ebertplatz 1, D-5000 Köln 1



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Page 20 DIN 18808

DIN 55928 Part 5 Corrosion protection of steel structures by organic and metallic coatings; coating materials and protective systems

DIN 55928 Part 6 Corrosion Protection of steel structures by organic and metallic coatings; workmanship and in- spection of corrosion protective work

DIN 55928 Part 7 Corrosion protection of steel structures by organic and metallic coatings; control areas DIN 55 928 Part 8 Corrosion Protection of steel structures by organic and metallic coatings; corrosion protection of

thinwalled structural members DIN 55928 Part 9 Corrosion protection of steel structures by organic and metallic coatings; binders and pigments for

coating materials Supplement 1 to DIN 55 928 Part 4 Corrosion protection of steel structures by organic and metallic coatings; preparation and testing

of surfaces; reference photographs DASt-Richtlinie O09 Empfehlung zur Wahl der Stahlgütegruppen für geschweißte Stahlbauten 1 ) ( Recommendation

for the selection of steel quality groups for welded steel structures)

Explanatory notes The specifications of this standard are based on extensive research work and testing carried out at the Versuchsanstalt für Stahl, Holz und Stehe at Karlsruhe University, and abroad. The design rules relating to truss junction points have been elaborated taking account of the following criteria. - Stressing of the web members i s not to exceed the permissible stresses for fillet welds. As the area of the weld is a t

least as great as the cross-sectional area of the hollow section, and the permissible weld stresses are not exceeded, an analysis of the welds may be dispensed with.

- The permissible loadbearing capacity in the junction zone shall be deemed to have been attained when the maximum deformation in the connecting surface of the bottom-mounted member amounts to 1/100th of the width or diameter.

- In respect of the safety against rupture the factor of safety shall be at least 2.

If the d/ t and blt ratios specified in tables 3 and 6 for members in compression have been complied with, a verification of safety against bulging of the hollow sections may be dispensed with. The limits specified in the present standard deviate from those laid down in DIN 18800 Part 2 (at present a t the stage of draft) because the specifications relating to width b or to diameter d are defined in a different manner. The required wall thickness ratios have only been specified for width/wall thickness ratios b,/tu not exceeding 35 or du/tu not exceeding 35, because bottom-mounted members with even thinner walls are hardly ever used. However, should they be present in exceptional cases, it will be necessary to carry out special analyses. In figure 11 of the standard, weld shapes to be used when jointing rectangular hollow sections are illustrated. In detail C of figure 1 1, a distinction i s made between two different included angles. For an included angle Bof not less than 60", fusion of the theoretical root point i s always possible. On the other hand, for truss junction points with included angles 8;. 30°, in most cases complete fusion of the theoretical root point i s not possible. This does not however result in any diminution of the loadbearing capacity of the junction point, because there is only slight stress in these areas due to the stress distribution at the junction point. The value of the limit angle ensuring adequate fusion of the theoretical root point does not only depend on the welder's ability, but also, amongst other aspects, on the welding process adopted. In the case of included angles of less than 300, it i s not reasonable as a general rule to expect that the welds will be free of fusion defects. In exceptional cases; flawless welds a t included angles Bof less than 30' can be achieved by using specially trained welders, adopting special welding parameters and using special equipment (e.g. narrow gap nozzles). Different tu& ratios for St 37 and S t 52 steels make allowance for the different ratios of permissible weld stress to permissible structural component stress of these two steel grades. The design of a structure according to the ultimate load method or, by way of simplification, according to the plastic-hinge theory, which makes it possible to exploit load-carrying reserves in statically indeterminate structures, is contingent upon adequate rotational capacities, an accurate assessment of which for loadbearing structures made from hollow sections has as yet not proved possible. In respect of loadbearing capacity, truss junction points made from circular hollow sections are somewhat more suitable than truss junction points made from rectangular section hollow sections (shell structural conditions). For reasons of simplification, no attempt was made to include special diagrams relating to the exploitation of these load- carry i ng reserves. In the case of flexurally rigid frame corners with included angles Bexceeding 90'. the stress concentration factor Q may be used, because it i s situated on the safe side. The design method specified shall however not be used for frame corners of multistorey frames with continuous column. Special considerations concerning adequate strength shall be devoted to the design of flexurally rigid frame corners with stiffening plate, in respect of which a tensile stress in the direction of the material thickness of the stiffening plate cannot be avoided.

International Patent Classification

1) See page 19.

E 04 C 3-32



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Documents

DIN 18808