抄録
Hot dip galvanizing is considered to be effective for increasing corrosion resistance in steel bridges. The galvanizing makes possible to reduce the residual stress in the welded portion due to annealing effect, and stress concentration at the weld toe is reduced by the galvanizing if a part of stress is transmitted in the zinc layer. Therefore, it is considered that fatigue strength can be improved by hot dip galvanizing. These facts mean that the hot dip galvanizing is one of useful countermeasure against the fatigue and corrosion, which are regarded as weaknesses of a steel bridge. However, it has not been clear how the galvanizing influences the fatigue strength of a welded joint. This study aims at clarifying fatigue strength of welded joints galvanized. For this purpose, web-gusset welded joints that have especially low fatigue strength in the joint employed in steel bridges and are worried about occurrence of fatigue cracks are taken up, and model specimens were made of SM490YA and were galvanized under standard condition of hot dip galvanizing, then fatigue tests were carried out on these specimens.
