Study On Stress Concentration Factors At Splice Welds Of Marine Steel Tubular Piles

Welded steel structures are widely used in marine structures because of itsadequate carrying capacity and the advantage of lighter weight, etc. However, it isdifficult to avoid the welding defect in the process of production, which may causestress concentration in the weld that can load fatigue cracks under alternating load. Thefatigue cracks may lead to fatigue damages.Thus, the study about the problem of stressconcentration of welding steel structure is significant to calculate the hot spot stress,which is helpful to evaluate the fatigue life of the welded steel structures.A lot of research on stress concentration factor of circumferential butt welds wascarried out. Nevertheless, most of these studies concerned with stress concentrationfactor of butt weld caused by axial force. It is far from enough to consider the axialtension situation only in marine structures. For more in-depth and accurateunderstanding, this paper researches the stress concentration at the butt-jointed weldbetween the steel pipe in identical wall thickness or the steel in different wall thicknessunder bending moments and the combination of axial tension and in-plane bendingmoment.Several practial approximations to the SCF is mathematically formulated onthe basis of a flat-plate configuration. To verify the effectiveness of the flat-platesolutions, this paper investigates the SCFs given equal wall thinkness and different wallthinkness with numerical examples.Finite element models are built by ANSYS tosimulate pipe splices for different pile diameters and wall thinkness. Axial tension andin-plane bending moment, as well as their combination are applied. The results ofapproximate calculation are compared with numerical results of SCFs. The results showthat the regular patterns of the result of approximate calculation are close to thenumerical results. The wall thickness and the transition between wall thickness are themain factors that influence the SCFs of butt weld, and the pipe diameters have a verylittle effect on SCFs.The findings will help in estimating the SCFs for splices welds ofsteel tubular members.In the end, the approximate calculations are used to get the SCFs of steel pipe pilesof wharf bents under different loading conditions. It is helpful to evaluate stressconcentration, which will provide references for similar projects.