b'STEEL BRIDGES AND BRITTLE FRACTUREEvaluation Methods for Fatigue Life and Toughness Assessment ofSteel BridgesBy Michelle Y.-X. Fan,BASc, University of Waterloo;Prof. Bertram Kuehn,PhD, TechnischeHochschule Mittelhessen, Germany ;Prof. Scott Walbridge,PhD, University of WaterlooAMONGTHECOMMONFAILUREMODESfor steel bridges, brittle fracture is a major concern to structural engineers as it has significant consequences in terms of safety and cost. Although occurrences are rare in the present day, it is well known that they occur without warning and may lead to the sudden closure of a bridge, loss of service, expensive repairs and/or loss of property or life. One special case of brittle fracture is known as constraint-induced fracture (CIF), which may occur under a tri-axial state of stress, when there are multiple intersecting welds, such as a web-flange-stiffener connection without a sufficiently wide web gap. In recent years, several cases of CIF in bridges, notably the US 422 Bridge (built 1965) and Hoan Bridge (built 1972), have demonstrated the need for a review of current practices in identifying CIF-prone details.In Canada, steel bridge fracture is a major concern due to our harsh climate, which, if the toughness properties are improperly specified,couldputmanysteelsonthelowershelfofthe toughness-temperature curve. Based on a review of recent research conducted in Europe and the United States, it is observed that more sophisticated approaches have been developed in terms of modelling and understanding brittle fracture in existing and new bridges than the ones currently in use in Canada. This project aims to increase the Canadian state of knowledge surrounding brittle fracture and CIF by assessing the reliability level of the current toughness provisions in the Canadian Highway Bridge Design Code (CSA S6) 1and developing improved assessment tools to evaluate the brittle fracture risk in bridges.The brittle fracture provisions within Eurocode 3: Design of steel structures (EN 1993-1-10) 2consist of two methods of analysis, a simplified method using design tables and a fracture-mechanics-based method. Both the Eurocode simplified method and CSA S6(Section10.23)designforbrittlefractureusetheminimum service temperature of the location of interest to determine the appropriate steel grade, subgrade and CVN test requirements: test temperature [C] and energy absorbed [J]. However, aside from the service temperature, the similarities end there. The Eurocode takes into account numerous other factors such as plate thickness, yield strength of the material, stresses on the component, radiation losses, member shape and dimension, safety allowances, strain rate and cold forming (if applicable). A very simplified summary of the Eurocode steps are as follows: ADVANTAGE STEEL SUMMER 2020|29'