Fatigue tests and design of welded thin-walled RHS–Channel and Channel–Channel cross-beam connections under cyclic bending

Abstract

Research on fatigue strength of welded galvanized cross-beam connections has been carried out and reported. Previous research focused on cross-beams made up of rectangular hollow sections (RHS) and Angle sections; RHS–RHS as well as RHS–Angle cross-beam connections and was published in Thin-Walled Structures, 48 (2010) 159–168. This paper reports on the fatigue strength of cross-beam connections made up of rectangular hollow sections (RHS) and Channel sections; RHS–Channel and Channel–Channel cross-beam connections. Fatigue tests on RHS–Channel and Channel–Channel cross-beam connections were carried out under cyclic bending in the bottom member. The resultant failure modes during the fatigue tests are reported. The crack growth patterns that are observed leading to failure are studied in relation to the stress concentration factors (SCFs) from sample specimens. The stress concentration factors (SCFs) are determined from stress measurements around the hot spots of the sample specimens. The resultant RHS–Channel and Channel–Channel S–N data is compared to S–N data of cross-beam connections from previous research. A comparison of the S–N data with existing fatigue design curves in the Australian Standard, AS4600, gives an indication of the class that can be adopted for the fatigue design of RHS–Channel and Channel–Channel cross-beam connections under cyclic bending using deterministic methods. Statistical analyses of the S–N data are also carried out to determine recommended design curves for the RHS–Channel and Channel–Channel cross-beam connections for both the classification and hot spot stress method.