Residual Stress Reduction through Thermo-mechanical Tensioning for an Orthotropic Steel Bridge Deck

Residual stresses from welding in orthotropic steel decks with closed ribs accelerate cracking and fatigue failure in the rib-to-deck weld root region. It considerably influences the structural integrity of the orthotropic steel deck sections. This study employs a residual stress reduction technique through a tensioning process called thermo-mechanical tensioning (TMT) by applying lugs to a rib-to-deck welded section. The process was developed and applied in a shipyard as a distortion mitigation technique for large welded stiffened panels. The developments of stress distribution are discussed here through finite element modelling by commercially available software for different deck thicknesses considering varying TMT parameters. The findings demonstrate that an adequate TMT process can significantly reduce the welding residual stresses even if the deck thickness increases. After validating it with the literature, the reduction in welding residual stresses is compared for an orthotropic steel deck section of the Jiangyin Yangtze River Bridge with and without TMT. In this case, the reduction of welding residual stress (Von-Mises) obtained in percentage was 46.86% in the mid-length section. The results demonstrate the effectiveness of TMT in reducing the welding residual stresses. This study also investigated the maximum limit of the TMT process for different deck thicknesses.