Fatigue of welded tubular K-joints made up of circular hollow sections

This article deals with the fatigue behaviour of thick-walled welded K-joints made up of circular hollow sections (CHS). Two important aspects of the investigations were the extension of the application range to large CHS and the development of practice-oriented recommendations for fabrication and quality assurance for weld shape and weld quality. For this purpose, fatigue tests were conducted on large CHS joints and on single K-joints with specified weld irregularities. These studies were accompanied by systematic ultrasonic tests using the phased-array technique, which were also used for the development of an inspection method for these complex weld geometries. Based on the results achieved by these experimental studies and additional numerical and statistical investigations, a proposal for a German design guideline (DASt-Richtlinie 029) was finally elaborated to promote the practical implementation of trusses made up of CHS with thick-walled chords and also to take a first step towards standardization.