PRECAST CONCRETE CONNECTIONS

1 PRECAST CONCRETE CONNECTIONSIES lecture 24 Oct 2018, Wed (750pm-830pm) Kian HauSENIOR LECTURER (CEE NUS) (Civil) (1stClass Hons., NUS), PhD ( structural Engineering), Chartered structural Engineer (UK), International PE (UK)Applied Research Area: structural Dynamics, structural Engineering Design, PRECAST CONCRETE Technology, structural Repair, Strengthening & Retrofitting, Advance CONCRETE Technology, Sustainable Building Materials & : E1-07-05 Telephone: (65) 660 17196 Email: CONCRETE ConnectionsSynopsis:Withtherapiddevelopm entofbuilding&constructionindustryworldw ideespeciallyindevelopedcountries,thereh asbeenasignificanttrendtopredominantlyus eprefabricationprefinished&precastconstr uctionmethodsduetoeconomyinconstructionc ost, ,Singaporeisalsonowre-knowngloballyasone oftheleading,reliable&reputablecountries inthecivil&structuralengineeringpractice s, (Thispartoneofseriesoflectureswillfocuso nEC2designsoitismorerelatedtolocal& sNAtoEC8mentionsprovisionsofEC2andEC3&EC 4issufficient)(Dr.)

2 Kong KH)*Slides are only for educational purposes for this IES Seminar. Detail references should be made to the Building Codes in actualdesign process and signing QP s calculation.(Dr. Kong KH)(Dr. Kong KH)Since 2000 till now in 2018, PRECAST CONCRETE elements and structures world wide have become:(i)Taller ( 36-storey skeletal PRECAST frame) and 54-storey wall frame (the Netherlands)(ii)Longer ( 50 m long prestressed CONCRETE beams)(iii)Deeper ( 1000mm deep prestressed hollow core floor units produced in Italy in 2014)(iv)Shallower ( span/depth ratio approaching 40 for prestressed composite and continuous beams)(v)Stronger ( grade C90/105 used in columns in buildings such as in 36-storey skeletal frame, Belgium)Theseadvancementshavebeencomplim entedbyanincreaseintheavailableliteratur es&researchreportsbutalsofromotherbooksf romNetherlands,Germany,Brazil,UnitedKing dom,andseveralbulletinsfromfibCommission 6onPrefabrication,togetherwith8 Europeanproductstandardscoveringawideran geprecastconcreteelements(hollowcorefloo rslabs,walls,stairs,etc.

3 ,theremaybeseveralload-transmittingjoint s,andsoitisfirstnecessarytodistinguishbe tweena joint anda connection .A joint istheactionofforces( ,shear,compression)thattakesplaceatthein terfacebetweentwo(ormore) connection istheactionofforces( ,shear,compression)and/ormoments(bending ,torsion)throughanassemblycomprisingone( ormore) (Dr. Kong KH)(Dr. Kong KH) , for the transfer of bearing joint, for the transfer of bearing forces and/or bending and/or torsional friction or shear wedging, for the transfer of shear with or without compression(Dr. Kong KH)The most commonly used methods of connection analysis in PRECAST are:(Dr. Kong KH)Strut-and-tie, for the transfer of bearing forcesOne of most commonly used methods of connection analysis (Dr. Kong KH)Column-Column Splice: A Coupled joint, for the transfer of bearing forces and/or bending and/or torsional momentsShear transmission through shear keys.

4 Shear friction or shear wedging, for the transfer of shear with or without compressionTwo of most commonly used methods of connection analysis (Dr. Kong KH) , (Dr. Kong KH)CompressionJoint.(Dr. Kong KH)CompressionJoint.(Dr. Kong KH) forces can be transferred between CONCRETE elements by one, or more, of the following (whencastinsituconcreteisplacedagainstap recastconcretesurface,adhesivebonddevelo psinthefreshcementpasteinthetinycrevices andporesinthematureconcrete) devices(Dr. Kong KH) ,ormore, (Dr. Kong KH) ,ormore, (Dr. Kong KH) ,ormore, (Dr. Kong KH) ,ormore, (a)Thepull-outresistanceoftheembeddedpla te(b)Theweldcapacityoftheholdingbarstoth eembeddedplate,or(c)Theshearcapacityofth eintermediateplateorbarPlanSection(Dr. Kong KH) (Dr. Kong KH)TensionJoint.(Dr. Kong KH) BoltingBy Welding(Dr. Kong KH)Inearly1950sinUK,adoptionofH-framewas done,wherebypin-jointedsiteconnectionswe remadenearthepositionsofframecontraflexu re; (orsmall)bendingmoment,butcausedotherdif ficultieselsewhereinmanufacturingandtran sportationbycreatinglarge, Historical Developments of PRECAST CONNECTIONS (Dr.)

5 Kong KH)Themaincostelementsarefabricationandm aterialcosts, ,reducingsiteoperationstosimpledowelling , (1986)producedaspecialstudyforthePCIonmo ment-resistantandsimpleconnections, , , ,andnotsimplycarryingoutthemechanicsofst ressequilibriumandstraincompatibility.(D r. Kong KH)Forinstancefigurebelowshowsabettersol ution:a scarfjoint , say,600to750mmfromthecolumn reducesthebendingmomentinthebeambyaround 40percent, , ,broughtaboutbyrelyingontheprecastconcre tetofirmlyanchorrolledorfabricatedsteels ectionsinpositionsothatadirectsteel-to-s teeljointwasmade.(Dr. Kong KH)4 Types Of PRECAST CONNECTIONS :(1) beam-to-slab CONNECTIONS (2) beam-to-column CONNECTIONS (3) wall-to-frame CONNECTIONS (4)column splices, including to four rules for satisfactory joint design are that:(1) The components can resist ultimate design loads in a ductile manner.(2)The PRECAST members can be manufactured economically and be erected safely and speedily.

6 (3)The manufacturing and site erection tolerances do not adversely affect intended structural behaviour, or are catered for in a worst case situation.(4) The final appearance of the joint must satisfy visual, fire and environmental requirements.(Dr. Kong KH)(Dr. Kong KH)(Dr. Kong KH)(Dr. Kong KH)The DywidagDuctile Connector (DDC) system was proposed by RockwinCorporation in ,andwasalsoadvantageousinfasterectionand excellentseismicresistance.(Dr. Kong KH)HDB ,h,usuallyvariesfrom200mmto2000mmandthec ross-sectionwidth,b, , (clearheadroomrequirement,lowtypicalstor eyheight,erectioncranecapacity,etc.), (h b)adoptedinHDBpracticeis1000mm , (Dr. Kong KH)R&D at CEE NUS Ong KC et. al. (2013) on (3H12).Ingeneral, 65% , :Othercommerciallymarketedsystemshaveals obeenproposedintheNetherlands, ,CD20andMATRIXBOUWI mportance of Basics of PRECAST CONNECTIONS Design Concepts acting as fundamentals of development of Advances in PRECAST CONNECTIONS .

7 (Dr. Kong KH)PIN-JOINTED ,theyareoftenreferredtoas joints astheytendtoinvolveonebearingsurfaceonly .(Dr. Kong KH)PIN-JOINTED CONNECTIONSS imply supported slabs on beams or walls(Dr. Kong KH)MOMENT-RESISTING (MR) CONNECTIONS (Dr. Kong KH)MOMENT-RESISTING CONNECTIONS (Dr. Kong KH)MOMENT-RESISTING CONNECTIONSG routed joints for moment resistance(Dr. Kong KH)MOMENT-RESISTING (Dr. Kong KH)MOMENT-RESISTING CONNECTIONSE urocodeBS8110 Welded Plate Splice DesignExample (Dr. Kong KH)MOMENT-RESISTING CONNECTIONSG routed Sleeve Splice DesignExample (Dr. Kong KH)MOMENT-RESISTING CONNECTIONSE xample Sleeve Splice DesignBS8110(Dr. Kong KH)Floor CONNECTIONS at load-bearing walls (MR*)*Note MR denotes Moment Resisting CONNECTIONS (Dr. Kong KH)Floor CONNECTIONS at load-bearing walls (MR)(Dr. Kong KH) ,fcki=25N/mm2,fyk=500N/mm2and = CONNECTIONS at load-bearing walls (MR)(Dr.)

8 Kong KH) ,fcki=25N/mm2,fyk=500N/mm2and = CONNECTIONS at load-bearing walls (MR)(Dr. Kong KH) ,fcki=25N/mm2,fyk=500N/mm2and = CONNECTIONS at load-bearing walls (MR)(Dr. Kong KH)Beam-to-column face CONNECTIONS (MR)Welded plate connectorThinplateisanchoredtothebeamusi nglarge-diameterrebars, ( ).Providingthatthebarsarefullyanchoredto thecolumnorarecontinuousthroughthecolumn , (a)Moment-resistingbeam-to-columnconnect ionsfor(a)negativemomentLeft side(Dr. Kong KH)Beam-to-column face CONNECTIONS (MR)Steel billet connectorAthreadedrodordowelissitefixedt hroughaholeinthebeamandsupportingsteelbi lletandsecuredtoasteelangle(orsimilar)at thetopofthebeam( ). , (same) (a)Moment-resistingbeam-to-columnconnect ionsfor(a)negativemomentTie SteelRight side(Dr. Kong KH)Beam-to-column face CONNECTIONS (MR) (a) (b)positivemoment(Dr. Kong KH)Beam-to-column face CONNECTIONS (MR) :Calculatethehoggingmomentofresistanceof thebeam , ,fyk=500N/mm2,shearpbqforgrade8:8bolts=3 07N/mm2,fywd=220N/mm2andcovertotopsteel= (a) welded plate connector (b) billet connector.

9 (Dr. Kong KH)Beam-to-column face CONNECTIONS (MR) :Calculatethehoggingmomentofresistanceof thebeam , ,fyk=500N/mm2,shearpbqforgrade8:8bolts=3 07N/mm2,fywd=220N/mm2andcovertotopsteel= Fig. (a)(Dr. Kong KH)Beam-to-column face CONNECTIONS (MR) :Calculatethehoggingmomentofresistanceof thebeam , ,fyk=500N/mm2,shearpbqforgrade8:8bolts=3 07N/mm2,fywd=220N/mm2andcovertotopsteel= :Overthepast25years(since1990s)around100 full-orsmall-scaletestshaveshownthatmany typicalprecastbeam columnconnectionsactassemi-rigidjointsin flexure,reducingsaggingmomentsinthebeamd uetoimposedgravityload, Fig. (b)(Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column ConnectionsElevation showing 2 beams resting on columnPlan showing 2 beam ends and its interface(Dr.)

10 Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column ConnectionsSystem Developed by Obayashi, Japan(Dr. Kong KH)Beam-to-Column ConnectionsCredit Acknowledgement: Obayashi, Japan(Dr. Kong KH)Beam-to-Column ConnectionsPlanElevationElevation(Dr. Kong KH)Beam-to-Column CONNECTIONS (Dr. Kong KH)Beam-to-Column ConnectionsColumn InsertThere are many types of inserts including:-Universal column or beam-Rolled channel, angle or bent plate-Rolled rectangular hollow section (RHS) or square hollow section (SHS)-Narrow plate-Threaded dowels or bolts in steel or plastic tubes-Bolts in cast-in steel sockets(Dr. Kong KH)Beam-to-Column ConnectionsColumn Insert(Dr. Kong KH)Beam-to-Column ConnectionsColumn Insert(Dr. Kong KH)Beam-to-Column CONNECTIONS :Column InsertWork Example 5(Dr. Kong KH)Beam-to-Column CONNECTIONS :Column InsertSqis a biaxial (or often triaxial) confinementWork Example 5(Dr.