Bending fatigue strength of slotted tubular joints in transmission steel tower members

Abstract

Slotted tubular joints are commonly used in transmission steel tower members. In these joints, fatigue cracks have been initiated at plate-end welds, tube-end welds and bolted connections due to bending loads. In this study, bending fatigue tests on slotted tubular joints were conducted to investigate fatigue strength based on nominal stress. As a result, cracks at tube-end welds were caused by in-plane bending of the slotted plate, and their fatigue strength satisfied Class H in the Specifications for Highway Bridges. On the other hand, cracks at plate-end welds were caused by out-of-plane bending, and their fatigue strength was higher than that of tube-end welds, while it was lower than that of bolted connections.