b'FEATUREAsteelsubgradeisthenselectedfrom theEurocodedesigntable,basedonthe referencetemperature,stressleveland plate thickness. Conversely, if the subgrade isknown,themaximumallowableplate thicknessforthecomponentcanbe determined. Whenthestressleveland/orreference temperaturefallinbetweentwocolumnsin the design table, interpolation may be used. Typically for rapid assessments, it is acceptable totakeamoreconservativeapproachby applyingthenext-higheststresslevelorthe next-lowesttemperatureonthechartand determiningthetoughnessrequirements based on this information. Although the Eurocode is more complex FIGURE 1 :CISC Steel Bridge Design Example 1. and takes more factors into consideration, a question of interest is whether the complexity takes a more or less conservative approach thanthecurrentCanadianprovisionsand, even if so, whether this increase complexity is justified. Toanswerthesequestions,abasic analysiswasperformedtocomparethe Eurocode with the CSA S6 brittle fracture provisions, using the CISC Straight Plate GirderBridgeDesignExample1asa common base case scenario (see Figure 1).Thisbridgehasfourxthreespan continuous girders (43 m / 53 m / 43 m) withflangeandwebplatethicknesses varyingalongthespan.Forcomparison purposes,thesteelgradeschosenare EuropeanS355andCanadianW350, which have similar yield strengths of 355 FIGURE 2 :Comparison of CSA S6 [1] and Eurocode [2] brittle fracture provisions. MPa and 350 MPa, respectively.Thefirstpartoftheanalysisinvolved varying plate thickness at the location of maximum positive stress along the girder (Span Reference 5), while holding all other parameters constant to study the effects A thickness-adjusted yield strength fy(t) isThe reference temperature is determinedofdifferentthicknessonthetoughness calculated from the nominal strength. fromtheminimumextremetemperaturerequirementsbetweenthetwocodes. The maximum stress on the component iswith a 50-year return period and radiationNote that instead of applying a minimum calculated using an SLS load combination. losses considered, along with temperaturemean daily temperature like CSA S6, the The maximum stress level is expressed as aadjustmentsformembershapeandEurocode requires the input of a minimum proportion of adjusted yield strength (e.g.dimension, safety allowance, strain rate andextremetemperaturewitha50-year 0.75 fy(t)) degree of cold forming.returnperiod.Historicalweatherdata References:1. CSA (Canadian Standards Association). (2019). Canadian highway bridge design code. CAN/CSA-S6-19.2. European Commission. (2006). Eurocode 3: Design of steel structures. EN 1993.3. Kuehn, B. (2005). Beitrag zur Vereinheitlichung der europischen Regelungen zur Vermeidung von Sprdbruch (Contribution to the standardization of the European regulations to avoid brittle fracture), PhD Dissertation, TU Aachen, Germany.30|SUMMER 2020 ADVANTAGE STEEL'