Daniel Unsworth (M.Sc.)
Dr. Driver, Dr. Leijun Li
Concerns have been raised that current Canadian design standards overestimate the strength of welded girders (commonly used in bridges), bringing the safety of the standard into question. Though there is evidence to support the concerns, there is insufficient research on the subject to warrant a change in the standard; further work needs to be done to make an informed decision. If current standards are in fact unsafe, the resulting changes in girder designs will see costs increase significantly for steel fabricators and designers. This will be in addition to the time and money expended in assessing the safety of pre-existing bridges (to ensure their continued safe operation). The effect of welding on the internal (residual) stresses of girders will be assessed through advanced stress measurement techniques. This data will be used to gain a better understanding of how modern fabrication procedures affect the behaviour of welded Canadian bridge girders. Having more detailed internal stress data on these girders will provide a more complete understanding of girder failure mechanisms. This will not only enable proper assessment of the design standard, but will pave the way for future research on girder behaviour.