The same type of calculations and evaluations as described above for butt welds were also carried out for cruciform joints.
This was done in order to maintain some consistency with the calculations for butt welds, and to assure that [k.sub.m,eff,min] did not become relevant in all cases.
The fatigue life predictions in Figure 13 to 15 confirm and reinforce the findings of section 4, valid for butt welds. For cruciform joints, it is again apparent that the various methods lead to significantly diverging fatigue life predictions.
In this paper, a study was presented in which two standard welded joints (butt welds between plates of equal and unequal thickness; T-joints with fillet welds) were analysed with the help of the structural stress and the effective notch stress approach, considering various levels of geometric imperfection up to the tolerance limits, and the resulting fatigue life predictions were compared to the nominal stress approach predictions.
Derivation of the IIW stress concentration factor [k.sub.m] for butt welds in plates of equal thickness
The residual stress increases with the increase of the width of the butt welds.
The residual stress data obtained by the hole-drilling method proved the distribution rule of the residual stress in wide butt welds. Particularly, the transverse residual stress errors between the simulation and measurement results are a little larger than the longitudinal residual stress errors.
The magnitude and distribution of residual stress in the wide butt welds have significant influences on the fatigue behaviors of the steel truss bridge .
It shows that after the ultrasonic peening the longitudinal residual stresses of the four different butt welds were reduced by 21%, 43%, 17%, and 33%, respectively.