According to the constant amplitude fatigue test results of ST12 steel double-spot and three-spot tensile shear resistance spot welded specimens

the fatigue lives were predicted by using the notch stress method and equivalent structure stress method respectively. While using notch stress method

the three-dimensional solid finite element models for double-spot and three-spot tensile shear spot weld according to the actual specimen size and the recommendation of International institute of welding(IIW)

the von Mises maximum stress change regime were obtained from the finite element results

the fatigue lives were predicted according to the S-N curve in the IIW recommended standard and while using the structural stress method

a hybrid model for beam and shell stress analysis

then the fatigue lives were predicted according to the main S-N curve. The results showed that the results predicted by using the notch stress method and the equivalent structural stress method are well correlated relatively to the actual lives of the specimen within low cycle regime

where the results by using the equivalent structural stress method are closer to the experimental results.