DNV-OS-C201 Structural Design of Offshore Units (WSD method)

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DNV-OS-C201 Structural Design of Offshore Units (WSD method)

Sec.9: Weld Connections

C: Weld Size

C600: Direct calculation of weld connections

Sec.9
C 600 Direct calculation of weld connections

Sec.9 C
601   The distribution of forces in a welded connection may be calculated on the assumption of either elastic or plastic behaviour.

Sec.9 C
602   Residual stresses and stresses not participating in the transfer of load need not be included when checking the capacity of a weld. This applies specifically to the normal stress parallel to the axis of a weld.

Sec.9 C
603   Welded connections shall be designed to have adequate deformation capacity.

Sec.9 C
604   In joints where plastic hinges may form, the welds shall be designed to provide at least the same capacity as the weakest of the connected parts.

Sec.9 C
605   In other joints where deformation capacity for joint rotation is required due to the possibility of excessive straining, the welds require sufficient strength not to rupture before general yielding in the adjacent parent material.

Guidance note:
In general this will be satisfied if the capacity of the weld is not less than 80% of the capacity of the weakest of the connected parts.

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Sec.9 C
606 The capacity of fillet welds is adequate if, at every point in its length, the resultant of all the forces per unit length transmitted by the weld does not exceed its capacity.

Sec.9 C
607 The capacity of the fillet weld will be sufficient if both the following conditions are satisfied:

raster

s_^	=	normal stress perpendicular to the throat
t_^	=	shear stress (in plane of the throat) perpendicular to the axis of the weld
t _\|\|	=	shear stress (in plane of the throat) parallel to the axis of the weld, see Table C3
f_u	=	nominal lowest ultimate tensile strength of the weaker part joined
b_w	=	appropriate correlation factor, see Table C3
h₀	=	basic usage factor, see Sec. 2 E

raster

Fig. 6 Stress components at a fillet weld

Sec.9 C
Table C3 The correlation factor b_w
Steel grade Lowest ultimate tensile strength
f_u Correlation factor
b_w
NV NS 400 0.83
NV 27 400 0.83
NV 32 440 0.86
NV 36 490 0.89
NV 40 510 0.9
NV 420 530 1.0
NV 460 570 1.0

Table C3 The correlation factor b_w
Steel grade	Lowest ultimate tensile strength f_u	Correlation factor b_w
NV NS	400	0.83
NV 27	400	0.83
NV 32	440	0.86
NV 36	490	0.89
NV 40	510	0.9
NV 420	530	1.0
NV 460	570	1.0

DNV-OS-C201 Structural Design of Offshore Units (WSD method)

Sec.9C 600 Direct calculation of weld connections

Sec.9
C 600 Direct calculation of weld connections