Effect of the degree of restraint against thermal expansion and contraction on welding residual stress

Abstract

Steel bridges increased considerably since 1960's in Japan. That is due to the lightness and long trend in bridge construction. Bridges, which are damaged by an increase in vehicle load, corrosion, earthquake, and so on, need repairing or strengthening. Repair procedures of steel bridge generally include cutting, bolting and welding procedures. These procedures, cutting, bolting and welding, occasionally bring about a stress concentration within the limit range. So, a chain of confirmation against the safety of structure is necessary. A safety evaluation method, which has regard to heat effect, is necessary to repair damaged structure with welding. Generalized welding residual stress is useful employ, to estimate the safety of structure during the repair work with welding. This research investigates the features of thermal stress generated by welding. The pattern of welding residual stress distribution was classified according to the ratio between length and width of plate. With those results, the features of residual stress generated by welding were generalized.