An analysis of pre-fatigued TIG-treated welded structures

Artikel i vetenskaplig tidskrift, 2021

Many existing steel bridges are approaching, or they have already exceeded their design fatigue life. Assessing and repairing these structures presents a challenge for the construction industry. In this paper, previous studies, which emphasised treating existing (pre-fatigued) structures by TIG dressing, are reviewed and analysed. In total, 109 fatigue test results have been studied which employ various steel qualities, welded details (longitudinal, transverse, and cover plate) and plate thicknesses. A plot and investigation of the S-N curves were carried out. In addition, a sensitivity analysis of the treated crack depth and the TIG dressing penetration depth was used to establish the extended fatigue life. The performance of TIG dressing in treating existing structures was examined by simulating a gain factor. It was found that the extension in fatigue life reached 3.4 times the as-welded fatigue life. This was particularly in cases in which TIG dressing completely removed the initial cracks or missed cracks less than 1 mm deep. Based on the findings, recommendations on treating existing welded steel structures by TIG dressing have been made.