Abstract
Recently, the discussion on prolonging life of steel bridges such as life cycle cost and long life bridge is widely done, and main factors of the prolonging life are countermeasures against fatigue and corrosion. As a countermeasure against corrosion, galvanizing is one of the effective methods, and many galvanizing steel bridges have been constructed until now. It is also considered that residual stress of welded portion is reduced by the annealing effect due to immersing welded member into hot dip galvanizing tank of about 450°C and the stress concentration at the weld toe as an origin of fatigue crack is reduced if a part of stress is transmitted in the galvanizing layer. These are correspondent to the two methods for increasing the fatigue strength. However, the effect of the galvanizing on the fatigue strength of welded joints has not been made clear sufficiently at the present. This study aims at investigating fatigue strength of welded joint with galvanizing. For this purpose, fatigue tests have been carried out on out-of-plane gusset welded joints which are made of 3 kinds of steel and are galvanized in several conditions. Residual stress measurements and three-dimensional finite element stress analyses for them are also carried out.
