CEMP-E
TI 809-26
1 March 2000
groove angles and J-and U-groove details reduce the difference in weld width between the root and the
face of the weld, and therefore reduce the weld shrinkage.
3. DESIGN AND FABRICATION OF WELDED JOINTS.
a. Effective Weld Size / Throat. AWS D1.1 Section 2, Part A provides the details for the calculation of
effective weld size, also called effective throat, and effective weld length.
(1) Complete Joint Penetration (CJP) groove welds have an effective throat equal to the thickness
of the thinner part joined.
(2) Partial Joint Penetration (PJP) groove welds must have their size specified in the design, and
then be detailed to provide the throat required. AWS provides the required depth of preparation for PJP
groove welds in D1.1, Figure 3.3. AISC provides similar information in Table J2.1.
(3) For flat and convex fillet welds, the effective size is specified in terms of weld leg, but the
effective throat is the shortest distance from the root to a straight line drawn between the two weld toes.
Should the fillet weld be concave, the measurement of leg size is ineffective, and the throat must be
measured as the shortest distance from the root to the weld face.
b. Allowable Stresses / Design Strengths. Allowable weld stress, when using ASD, is provided in AWS
D1.1 Table 2.3, or in AISC Table J2.5 of the ASD Specification. Weld design strength (when using
LRFD) is provided in AISC Table J2.5 of the LRFD Specification. Both AWS and AISC tables are
similarly structured, with minor differences in certain sections. The following information is in terms of
LRFD, without consideration of the resistance factor phi. If ASD is used, see the appropriate
specification.
(1) For welds other than CJP groove welds loaded in transverse tension, the AWS D1.1 Code
permits the use of matching filler metal or a filler metal of lower strength. Overmatching is not permitted
in AWS D1.1. AISC permits the use of undermatching for the same conditions, and also overmatching
filler metal to the extent of one weld strength classification, nominally 70 MPa (10 ksi) more.
(2) For CJP groove welds that carry transverse tensile stress, the AWS D1.1 Code requires the use
of matching filler metal. Matching filler metal provides a weld with at least the strength of the base metal
in such an application. See AWS D1.1 Table 3.1 for matching filler metals. The strength of the weld is
treated the same as the strength of the base metal, as the base metal will be the weaker of the two
materials, with a phi of 0.9.
(2) Should the CJP groove weld be used in a T-joint or corner joint loaded in tension transverse to
its axis, with the backing bar remaining in place, AISC LRFD Specification Table J2.5, Note [d] requires
the use of filler metal with a designated CVN toughness of 27J @ +4oC (20 ft.-lbf @ +40oF).
Alternatively, the weld must be designed as a PJP groove weld, similarly loaded.
(3) For CJP groove welds in transverse compression, the AWS D1.1 Code requires the use of
either matching filler metal or a filler metal one strength classification less, nominally 70 MPa (10 ksi)
less. AISC places no limit on the undermatching strength. The strength of the weld is treated the same as
the strength of the base metal, with a phi of 0.9.
(4) CJP groove welds in shear may carry 0.60 times the classification strength of the filler metal,
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