Patch Loading Resistance on Inclined steel Plate Girders with Stiffened Cell Flanges

Varsha Unni k.1 , Krishna M. M.2

1PG Student APJ Abdul Kalam Technological University, Universal Engineering College, Vallivattom, Kerala, India

2Assistant Professor APJ Abdul Kalam Technological University, Department of Civil Engineering, Universal Engineering College, Vallivattom, Kerala, India

Abstract - Stiffening is always an important factor in the case of steel girders. Stiffening with different flanges are more effective when it comes to increasing the capacity to withstand concentrated loads caused by support reactions in steel bridge girders incrementally launched. Steel box girders are widely used in bridges when heavy loads are acting. During the construction or launching time of steel bridges there will be a concentrated force acting perpendicular to the flange of girders, this concentrated force during erection time of construction is known as patch loading. This patch loading case causes web bulking and premature bridge failure. Box girders with inclined web and their patch loading behaviour is studied. This paper aims at investigating the patch loading resistance on steel girders with different hollow flange shapes. Here it is designed and analysed by using finite element analysis method by ANSYS 2022 R2. The model is deigned with parametric studies and conducted in order to investigate the effect of various geometric parameters such as angle of inclination, web thickness and patch loading length and different patch loading length. The results showed that the use of rectangular hollow shaped cell flanges enhances the resistance of steel plate girders to patch loading

Key Words: Patchloading,Inclinedsteelgirders,Hollowflanges,Finiteelementanalysis,Concentratedload,Triangular cellflange,rectangularcellflange,Trapezoidalcellflange

1.INTRODUCTION

SteelbridgesarewidelyusedinHighway,UrbanandRailwaynetworksaroundtheworld.Steelbridgesareoftenmadeusing girderswiththinwebswithgoodshearstrengthsandflexuraltocoverlengthyspansandtobeabletowithstandheavyvertical loads during service. This causes premature failure of steel bridges or webs. To prevent buckling related failures and to increasetheresistancetoconcentratedloadsthefollowingstrategiesareemployed:(a)toincreasethewebthickness,(b)to usehollowflangesasstiffener(c)toaddadequatelyspacedverticalorhorizontalstiffeners

EuroCasanovaresearchedonpatchloadingresistanceofsteelplategirdersstiffenedwithtriangularcellflanges[1].NavarroManso[5]developedasteelbridgelaunchingsystembasedonaself-supportingdoubledeck,inwhichthebottomflangeswere stiffenedwithatriangularcelltowithstandtheconcentratedloadreactionsintheendsupportsandconnections.Dissertation BalázskövesdI[6]patchloadingresistanceofgirderswithcorrugatedwebsshowedcorrugationonwebscanreducepatch loading.

This paper aims at investigating the patch loading resistance of inclined steel plate girders stiffened with cell flanges. to investigatetheinfluenceofvariousgeometricparameterssuchastheangleofinclination,differenthollowshapes.Herehollow shapesofrectangle,triangleandtrapezoidalshapesareusedforthehollowflangecases.Theinvestigationisfocusedona locallyloadedsinglepanelandthus,otherimportantinstabilityrelatedphenomenaareoutofthescopeofthispaper.Patch loadingresistanceoninclinedgirderswithvarioushollowflangesandcomparisonhavetobestudiedotherthanfromstraight girders.

Thispaperprovidesadetaileddescriptionoftheoptimizationprocess,includingthemethodologyused,theresultsobtained, andtheirsignificance.Overall,theprojecthassignificantimplicationsforthepatchloadinganditsresistance.

1.2. Parametric Analysis of Inclined Girder

Parametricanalysiswasdonetofindtheoptimuminclinedgirderwhichhashigherpatchloadingresistance.Theoptimization ofinclinedgirderwasdoneusingANSYSWorkbench2022R2.14modelswereanalysedtofindanoptimummodelwithhigher patchloadresistanceandpreventionofbucklingbehaviour.Themodelswerespecifiedwerespecifiedwithdifferentanglesto getoptimumangleofinclinationfrom50,100,150 ,200,and250 .Thicknessofwebfrom4to8mmarestudied.Modelswere analysedusingtrialanderrormethodinwhichlengthof750mm,patchloadinglengthof200mm.Fromtheoptimummodel hollowflangecasesweredonetogetbetterpatchloadingresistanceoninclinedgirders.

2. Analysis and Design of Inclined Steel Girder Model (without Flange Case)

Anelastoplasticmaterialwithayoung’smodulusE=200GPaandPoisson’sratioν=0.3isconsideredtomodelthematerial nonlinearities.Takingoneside(oneweb) partofinclinedgirder(boxgirder)Forthestudy.

2.1 validation

Thematerialwithfy345MPasteelandthecomponentsofthegirdersaremodelledusingshellelementsSHELL181,afour-node elementwithsixdegreesoffreedomateachnode.Basejournaladoptedforvalidationwas‘Patchloadingresistanceofsteel plategirdersstiffenedwithtriangularcellflanges’byEuroCasanova,CarlosGraciano,RolandoChacon,2022.Forvalidation, patchloadingresistanceofsteelgirderswasanalysedusingANSYSWorkbenchR2andtheresultsobtainedwerecompared withthebasejournalresults.

2.2 The Effect of Angle of Inclination with Patch Loading

Theparametricstudyofangleofinclinationortheeffectofinclinationanglehavetobefixedinordertoknowfromwhichangle onwardsitreactstopatchloading,orstillbehavelikestraightgirdersratherthaninclined.Thetotalspan(a)ofgirdertakenis 750mmand patchloadinglengthof200mm(ss) forthestudies[1]asshowninfig.2. Anglesof50 ,100,150,200,250are observedtoselectthemodel.

Fig -1: Inclinedsteelgirder[7]

Table -1: ResultsofValidation

Meshsizeisacrucialfactorinfiniteelementanalysis(FEA),asitdeterminesthelevelofdetailandaccuracyofthesimulation. In this case, the mesh size of 20 mm was provided. The meshing process involves creating a finite element model of the structure,whichconsistsofsmallelementsthatareconnectedtoformamesh.

Table -2: GeometryandMaterialPropertiesUsedinParametricStudies

Fig -2: Patchloadinginstraightgirders[1]

Fig -5: BoundaryConditionFrontView Fig -6: BoundaryConditionIsometricView

Fig -3: Meshprovided(frontview)withangle50

Fig -4: Meshprovided(isometricview)

Boundaryconditionsrefertotherestrictionsimposedonastructureatitsedgesorboundaries.Theinclinedsteelgirderisa typeofstructuralmemberusedinbridgestotransferheavyloadstoprotectthestructurefromdamages.Here,fixedsupport wasprovided.Thefixedsupportsensurethatthestructureremainsstableanddoesnotundergosignificantdeformationunder theappliedloads

Thedeformationvaluesobservedfromtheanglesfrom5ºto25ºattheintervalof5º.Theangleoninclinationisanimportant partforinclinedgirdersandtheirbehaviourtopatchloadingisamajorconsideration(fig.7andfig.8).

2.3 Results and Discussions

Theloadvaluesofdifferentangleswithflatstraightgirders.Fromthis5oonwardsthedeflectionstartedtherefore5oinclined girderisselectedforhollowflangecasesforstiffening.Theresultsofvariousanglesasshownintable3.

And also, the web thickness (wt) of 4mm selected from the thickness of 4 to 8mm, as thickness increases load capacity increases,soselectedthelower(fig.9)valueitselfforthemodelforstiffeningmethods.Thatisangleof5o,wtof8mmandpatch loadlengthof200mmfortheoptimummodelforstiffening

Fig -7: TotalDeformationInclinedat5º Fig -8: TotalDeformationInclinedat25º

Table -3: LoadDeflectionValueofDifferentAngles

3. Design and Analysis of Inclined Girder with Stiffened Hollow Cell Flanges

Forthestiffeningofinclinedgirderforpatchloadresistanceofangleinclination50,andwtof4mmandthicknessofplatesused is4mmforflangecases.Thehollowshapesoftriangular,rectangularandtrapezoidalweremadeandcomparedforbetter resistanceiscomparedwithflatflange.Thetotaldeformationswerestudied.

Fig -9: Variousthicknessofwebwithselectedmodelofangleof50

Fig -10: HollowFlangeofTrapezoidal,Triangular,andRectangularHollowShapes

Fig -11: EquivalentStressofRectangularHollowFlange Fig -12: LoadDeformationCurveofFlangeCases

From the load deformation curve, it was observed that rectangular shaped hollow flanges showed better patch loading resistanceamongothertriangularandtrapezoidalshapes.Comparingwithdeformationvaluetakenandloadbearingcapacity, the rectangular shape has better patch loading resistance is due its rectangular shape. The max load of 608.86 kN with deformationof7.80mm

3. Conclusions

Thisstudycontributestotheadvancementofknowledgeinthefieldofsteelbridgesandothersteelstructuresandcanserveas avaluableresourceforresearchersandpractitionersinthefieldofstructuralengineering.Theinsightsgainedfromthisproject canbeusedtoinformthedesignofmoreresilientsteelstructures.Ithasprovidedvaluablesightsintotheeffectivenessofthis typeofrectangularhollowflangeininclinedsteelgirderswithloadbearingcapacity. Overall,thestudyprovidesvaluable insightsintothebehaviourofpatchloadingoninclinedgirdersanditsresistancemethods,suggestsapromisingmethodto enhancetheresistanceofpatchloadingactivities.

 Theresistanceisenhancedbyofhollowflangecasesoninclinedcasesandtheeffectofinclinationbeginsfrom5º onwards

 Rectangularhollowflangesshowedbetterpatchloadresistancewhencomparedwithothertriangularandtrapezoidal hollowflanges

 Hollowflangecanprovidelightweightandmaximumdelayinwebbuckling

 Therectanglehasequalwiderflanges,thereforetransferordistributionofpatchloadtowardstheflangesishigher, whilecomparingwithothertriangleortrapezoidalshape

 Thebucklingduetopatchloadingisreducedonwebduetoequalsharingofloadsonrectangularshapedflangeon inclinedsteelgirder

 Furtherstudyonthepatchloadingresistanceoninclinedsteelgirderswithcircularcellflangescases,whichisa specialcasetobecarriedout

ACKNOWLEDGEMENT

I wish to thank the Management, Principal and Head of Civil Engineering Department of Universal Engineering College, Thrissur,affiliatedbyKeralaTechnologicalUniversityfortheirsupport.Thispaperisbasedontheworkcarriedoutbyme (VarshaUnnik..),aspartofmyPGcourse,undertheguidanceofEr.KrishnaM.M.(Assistantprofessor,CivilDepartment, UniversalEngineeringCollege,Thrissur,Kerala).Iexpressmygratitudetowardshisforvaluableguidance.

REFERENCES

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[2]CarlosGracianoetal.(2021)Elasticbucklinganalysisofplategirdersstiffenedwithtriangularcellflangesunderpatch loading journal of structures 29373-992

[3]Matthewj.etal.(2020)Weldedsteelbeamwithnovelcross-sectionandwebopeningssubjecttoconcentratedflange loadingjournal of structures 24580-599

[4]FeiGaoetal.(2020)FlexuralbehaviourofhorizontallycurvedI-girderswithroundconcrete-filledtubularflange Journal of Constructional Steel Research 170106090

[5]RipaTetal.(2012)Designimprovementsforpatchloadingresistanceinbridgesduringlaunching.InProc.ofSteelbridge construction steel 054,2004

[6] Balazas kovesdi (2010) Patch loading resistance of girders with corrugated webs available: https://epito.bme.hu/sites/default/files/hirek/hsz/kovesdi_balazs_phd.pdf

[7]https://www.alamy.com/stock-photo/steel-box-girder.html?sortBy=relevant