2015 CSCE Annual Conference Regina - Building on our Growth Opportunities

2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference

The effect of overload of a bolted connection on its fatigue life: A case study

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Dr. Shahin Shadlou, University of Saskatchewan
Dr. Leon Wegner, University of Saskatchewan (Presenter)
Dr. Timo Tikka, Stantec Consulting

In practice, many structures experience random and variable-amplitude loading during their service lives. On that account, the effects of overload on various components have been extensively studied since the 1960s. However, most of the research has focused on individual components and there is a lack of knowledge about the consequences of the overload on an assembled structure. This study investigates how overload of a bolted connection affects its fatigue life by using experimental and numerical methods. The structure chosen for this case study is a sub-assembly of the steelwork used to support the skips used in a potash mine shaft under simulated slam forces from payload skips. After exposing the structure to one million cycles at the design slam load and one million cycles at double the design load, it was subjected to one cycle at five times the design load. Then, the structure was carefully investigated for signs of damage, and slippage of bolts and other components on one another. In addition, the structure was dis-assembled to investigate the presence of local damage, especially in bolts and bolt holes. Moreover, changes to the distribution of load among the bolts and within each component from the intended design values due to slippage or plastic deformation was investigated using finite element analysis. The effect of the overload on the fatigue life of the bolted connection will be presented, discussed, and compared to the well-established fatigue performance of individual components where tensile overload is typically understood to retard crack growth.