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Transverse Stiffener Requirementsin Straight and Horizontally CurvedSteel I-GirdersYoon Duk Kim, Se-Kwon Jung andDonald W. WhiteGeorgia Institute of TechnologySchool of Civil and Environmental EngineeringAtlanta, GA2005 AASHTO Bridge Committee Agenda Item 38June 27, 2005 Problem Statement Identify the demands on transversestiffeners in curved and straightI-girders designed within theAASHTO (2004) limits: Transversely-stiffened I-girders with do/D < 3 D/tw< 150 Longitudinally-stiffened I-girders with do/D < 1.5 D/tw< 300 FEA Parametric Studies,Test Configuration Parametric Studies (Transversely-Stiffened I-Girders) D = 96 in (8 ft) do/D = 0.5, 1, 2 & 3 Straight & Curved with R = max(10do, 100 ft) D/tw= 150 (other D/twvalues considered for flat webs) Fyw= Fys= 70 ksi (other Fyvalues considered for flat webs) Fyf= 100 ksi (other Fyvalues considered for flat webs) bf/2tf= 6.47 (compact limit),except bf/2tf= 5 for do/D = 3 bfdetermined such that Mu~ 0.75Mnbased on theone-third rule bt/tp= 10 in primary studies (other bt/tpconsidered insupplementary studies) Various one- and two-sided stiffener sizes Parametric Studies (Longitudinally-Stiffened I-Girders) D = 96 in (8 ft) do/D = 0.5, 1 & 1.5 Straight & Curved with R = max(10do, 100 ft) D/tw= 300 (other D/twvalues considered for flat webs) Fyw= Fys= 70 ksi (other Fyvalues considered for flat webs) Fyf= 100 ksi (other Fyvalues considered for flat webs) bf/tf= 6.47 (compact limit) bfdetermined such that Mu~ 0.75Mnbased on theone-third rule bt/tp= 10 in primary studies (other bt/tpconsidered insupplementary studies) Various one- and two-sided stiffener sizes Longitudinal stiffener not included in models TFA Strength vs It/Itcrdo/D = 1, D/tw= 150Itcr= Itreq’d to develop Vn= VcrIt= ntpbt3/3It= nbt4/3/(bt/tp)It= As2(bt/tp)/3n TFA Strength vs It/Itcrdo/D = 1, D/tw= 150AASHTO (2004)area requirement,two-sided stiffenersAASHTO (2004)area requirement,one-sided stiffenersRecommended Shell Model - Perspective View ofDeformed Geometry at Max LoadIt= Itcr, do/D = 1, D/tw= 150, 1-sided stiffenerStraight I-girder (note: 18.5Itcris req’d to satisfy the AASHTO (2004) area reqmt)Undeformed geometryDeformed geometry(Scale Factor = 5.0) Shell Model – Mid-thickness Von MisesStress Distribution at Max LoadIt= Itcr, do/D = 1, D/tw= 150, 1-sided stiffenerStraight I-girder (note: 18.5Itcris req’d to satisfy the AASHTO (2004) area reqmt)(Scale Factor = 5.0) Perspective View of DeformedGeometry at Max LoadIt= 6Itcr, do/D = 1, D/tw= 150, 1-sided stiffenerCurved I-girder(Scale Factor = 5.0)Undeformed geometryDeformed geometry 123doc.vn