In this paper, a database of the identically-distributed inherent strain within mechanical melting zone is developed and then applied for simplified distortion analysis in multi-layer and multi-pass welding of heavy section plate. First, numerical and experimental investigations of weld angular distortion were performed for multi-layer and multi-pass welding of heavy section plate to verify the simplified weld distortion analysis based on the theory of inherent strain. Next, the effect of

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... al stress due to precedent welding pass on inherent strain produced in current welding pass was investigated based on the fundamental bead-on-plate model to improve a database of the identically-distributed inherent strain within mechanical melting zone, which was already developed for single pass welding, for multi-layer and multi-pass welding. The usefulness of the developed database of inherent strain was validated for simplified distortion analysis in multi-layer and multi-pass welding of heavy section plate. Then, the simplified weld distortion analysis based on developed database of inherent strain was applied to quantify the effect of weld pass sequence on angular distortion in multi-layer and multi-pass welding of heavy section plate. Based on the results, the developed system can be expected to be a useful weld design support tool for accurately predicting weld distortion and managing construction quality in welded large structures.