BalsaBridgeCompetitionOverviewTheBalsaBridgeCompetitionoffersparticipatingteamstheopportunitytodemonstrateknowledgeofstructuraldesignprinciplesintheconstructionofathree-dimensionalbalsabridgestructure.Studentswilldesignandbuildabridgestructureusingspecifiedbalsawood.Thestructurewillbeweighedandjudgedandthenloadeduntilfailure.ObjectiveTheobjectiveofthiscompetitionistodesignandbuilda3-Dbridgestructureconformingtospecificcriteria.Themodelwillbetestedviaaloadingplatformplacedonthedeckofthestructure.Theloadwillbeincreasedwithrespecttotimeuntilfailureoccursbythefractureofamemberorajoint.Pointswillbeawardedforthestrengthtoweightratioofthebridgeandforthequalityofthetechnicalpaper.EligibilityEachteammayconsistofuptofour(4)students,one(1)ofwhommaybeagraduatestudent.Eachteamwillhaveone(1)captain,whowillsubmitthebridgeandahardcopyofthetechnicalreportduringregistration.One(1)structureperuniversitywillbeallowed.Allcompetingbridgesmustmeetalldesignspecifications.Failuretomeetanyrequirementwillresultinadeductionofpointsordisqualification.SubmittalsAlltechnicalpapersandbridgestructuresmustbesubmittedwiththeregistrationoftheteamcaptainuponarrivalattheconference.Eachbridgemusthavethenameoftheuniversityprintedinpermanentblackinkalongthelengthofone(1)ormoreofthebridgemembers.MaterialsWoodOnlybalsamembersofA,B,orCgraintypesmaybeused.Drydensityofbalsamembersmaynotexceed15lbs/ft3.Nospecializedortreatedbalsawood,basswood,orothertypesofwoodareallowed.Thenominalcrosssectionofallmembersmustbe.25inx.25in±.025in.Structuralmembersmaynotextendbelowtheplanecreatedbytheloadingdeck.

GlueOnlyone(1)typeofglueperstructureisallowed.Thewoodglueusedmustbefromthefollowinglist:

o Elmer’sWoodGlueo TitebondOriginalI,II,orIIIWoodGlueso WeldbondGlueo GorillaWoodGlue

DesignParameters

o Nopaint,stain,orcoatingofbalsamembersisallowed.o Laminatingofmembersisnotallowed.o Gussetplatesareallowedtosupportjoints.o Excessiveglueassistingstrengthofbridgewillresultinpointdeduction.Alljoints

shouldbecleanofexcessglue.o Lengthofbridgeshallbestrictlybetween26”and30”.o Heightofbridgeshallnotexceed8”.o Widthofbridgeshallnotexceed6”.o A2x4blockofwood,(actualdimensions1.5”x3.5”)simulatingavehiclemustbe

abletopassthroughthebridgeacrossthebridgespan.Nodeckingsurfaceisrequired,simplyanopeningthatcanaccommodatetheblock,approximatelylevelwithspansupports.

o Thedeckofthebridgeisunderstoodtobeaplanarsurfacespanningtheentirelength.

o Numberofstructuralmembersintersectingatasinglejointmaynotexceedsix.o Allbridgestructuresmustaccommodatea1”x1”x9”barplaced

perpendicularlyonthecenterofthedeckspacefromwhichtheloadwillbeapplied.(SeeFigures1&2).

TestingTheorderoftestingwillbedeterminedbythejudges,andteamswillbenotifiedinadvanceoftestingorder.Theteamcaptainmustbepresentatthetimeoftesting;otherteammembersarenotrequiredbutmayattend.Theteamcaptainwillplacethebridgeacrossthe24”supportspan.Afterthebridgeisplacedonthespan,noadjustmentsmaybemadetothestructure.

Loadingwillbesuspendedbelowthebridge.Thesupportmechanismconsistsofanironbarwithdimensions1”x1”x9”thatwillbeplacedperpendicularlytothedecksurface.Chainswillbehungfromtheendsofthisbar.Abucketwillbesuspendedfromthechains.Bridgeswillbeloadeduntilfailurebyfillingthebucketwithsand.Therateofloadingwillbereducedatvisibledeformationorcrackingtoensuretheweightatcatastrophicfailureisexactlyrecorded.

JudgingTherewillbeaminimumofthree(3)judgesforthecompetition.Itwillbethejudges’dutyandresponsibilitytoevaluatetheteamsfairlyandconsistently.TheteamswillbeevaluatedbasedonthecriteriaoutlinedintheScoringsectionincludedbelow.Thejudges’rulingwillbefinalforallcompetitors.TechnicalPaperThetechnicalpapershallbe750-1000wordsinlengthandconsistof:

1. Introductiona. NameofUniversityb. Namesofteammembersc. Captainnameandcontactinformation

2. Documentationa. Allmaterialsusedforconstructionofbridge,including:

i. Balsawood,includingacountofallvertical,horizontal,andinclinemembers

ii. Thenameofadhesiveproductusedb. Purchaselocationofallmaterials,includingphotocopiesofreceiptsof

purchase.

3. Methodologya. Explanationofdesignprocessincluding:

i. Anyandallassumptionsmadeii. Alternatedesignsconsiderediii. Constructionprocess

b. Estimatedloadcapacitywithallcalculationsc. Hypothesisandtheoriessupportingchosendesign.

4. Figuresa. FullplanviewCADfigurewithallanglesanddimensionstoscale.All

anglesanddimensionsshouldbewithinareasonabletoleranceoftheactualstructure.FailuretomeettoleranceshallresultinpointdeductionfromtheTechnicalPaperScore.

b. Additionalscaledanddimensionviewsmaybesubmittedatthediscretionoftheteam.Pointswillbeawardedforclarityanddetail.

c. AllCADfiguresshallbesubmittedwiththetechnicalreporton8.5”x11”sheets.

ScoringScoresforthetechnicalpaperwillbebaseduponorganization,completeness,accuracy,andadherencetoallrequirements.Ascoringsummaryisprovidedonthefollowingpage.Aloadingcapacityscorewillbedeterminedbytheultimateloadcapacity(lbs)dividedbytheweight(grams)totwodecimalplaces.Thisvaluewillbemultipliedbyten(10)todeterminethetotalpointsawarded.Theteamwiththehighesttotalscorewillwinthecompetition,receivingthefullseven(7)pointsintheoverallscorebreakdownfortheconference.Intheeventofatie,thejudgesshallchoosethewinnerbasedonqualityofconstructionandaesthetics,whichshallbejudgedbeforeloadingbegins.

ScoringSummarySheet

ASCEStudentOrganization:_______________________________________

TechnicalPaperScoringRubric Score1.Introduction /152.Documentation /20

3.Methodology /40

4.Figures /25TechnicalPaperSub-Total /100

Infractions Deduction1.GlueViolation -10/instance2.MemberViolation -30/instance3.JointViolation -20/instance

4.BridgeViolatesLengthorHeightDimension Disqualification

5.LoadingDeckFailstoMeetSpecification Disqualification

StructuralDesignScore Sub-Total[LoadCapacity/TotalMass]x10-Deductions

TechnicalPaperSub-Total /100StructuralDesignSub-Total OverallScore