THICKNESS EFFECT CRITERION FOR FATIGUE EVALUATION OF WELDED STEEL STRUCTURES

In this study, the thickness effect was investigated by systematic experiments on welded steel joints with thicknesses ranging from 10 to 80 mm. Cruciform joints and Tee joints with improved weld by overall profiling or toe-grinding were tested under pulsating tension and under pulsating bending respectively. These experimental results were analysed together with previous results as-welded joints. It was concluded that the thickness effect exponents for various conditions may be classified into three categories according to the combination of joint type and loading mode. As-welded joints under bending stress have the greatest thickness effect exponent of -1/3, while as-welded joints under tension having an exponent of -1/5. If the weld profile is improved by grinding, the thickness effect becomes much milder to an exponent of -1/10. The as-welded joints with constant-sized attachments also have an exponent of -1/10. Furthermore, thickness effect dependency on fatigue life was investigated.