Fatigue behavior of reinforced welded hand-holes in aluminum light poles

Abstract

Hand-holes are used in the body of welded aluminum light poles to access electrical wiring for installation and maintenance of luminaires. Light poles are slender and subjected to cyclic loading due to the wind. Localized fatigue cracking around hand-holes has been observed in the field, but few studies have focused on the resistance of welded aluminum hand-holes. In this study, four-point bending fatigue tests were conducted on specimens with welded aluminum hand-hole details. Twenty welded aluminum specimens, each with two hand-holes, were tested under fatigue loading. Among the forty details, thirty-two failed as a result of fatigue cracking. Fatigue test results used to develop a design S-N curve revealed a resistance in reasonable agreement with the Category D design S-N curve of the Aluminum Design Manual. Fatigue cracking initially observed in the throat of fillet weld joining the reinforcement ring to the pole subsequently extended into the tube and/or through the reinforcement casting. Finite element analysis was used to augment the experimental studies in an effort to explain the observed cracking behavior.