Consideration on fatigue durability of welded joints of existing I-girder highway bridges

Abstract

Fatigue cracks have recently been reported at out-of-plane gusset welded joints in main girders of old steel highway bridges on severe traffic routes constructed before adoption of fatigue design. In this paper, fatigue durability of those existing I-girders was discussed on the bases of current fatigue evaluation procedure from the viewpoint of preventive maintenance. Structural design by grillage analyses and fatigue evaluation were conducted for 22 cases of existing I-girders with various structural parameters, which were designed based on the past design specifications of highway bridges. As a result, relation of calculated stress range, cumulative damage due to fatigue design load and the structural parameters were examined in order to clarify structural characteristics of existing bridges susceptible to fatigue.