PRECAST CONCRETE CONNECTIONS IES lecture 24 Oct 2018, Wed (750pm-830pm)
Dr.. Kon Dr Kong g Kian Kian Hau
SENIOR LECTURER (CEE NUS) B.Eng B.E ng (Ci (Civil) vil) (1st Class 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 & Systems.
Office: E1-07-05 Telephone: (65) 660 17196 Email:
[email protected]
(Dr. Kong KH)
Precast Concrete Connections Synopsis: With the rapid development of building & construction industry worldwide especially in developed countries, there has been a significant trend to predominantly use prefabrication prefinished & precast construction methods due to economy in construction cost, manpower and time. Due to the dedication and diligence of all related stakeholders in C&S industry and Authorities, Singapore is also now re-known globally as one of the leading, reliable & reputable countries in the civil & structural engineering practices, standards and developments globally. With that there is an important need for C&S practitioners to keep up to date to the latest developments and advances especially in precast and prefabrication technologies worldwide. This presentation will explore and study on the recent the recent advances in precast connection systems adopted or researched for building structures in developed countries worldwide. (This part one of series of lectures will focus on EC2 design so it is more related to local & regional content exclude seismic design of precast connections i.e. not including ACI & EC8 design. In low sei seismi smicc reg region ion i.e i.e.. low duct ductili ility ty st struct ructure uress Sin Singap gapore ore’’s NA to EC8 men mentio tions ns provisions of EC2 and EC3 & EC4 is sufficient) *Slides are only for educational purposes for this IES Seminar. Seminar. Detail references references should be made to the Building Codes in actual design process and signing QP’s QP ’s calculation.
(Dr. Kong KH)
(Dr. Kong KH)
Since 2000Taller tillernow 2018, precast concrete elements and54structures world wide become: (i) all (e.g. (e.g.in36-st 36 -store orey y skele skeleta tall pr prec ecast ast fram fr ame) e) and 54-st stor orey ey wall wal l fram frame e (the (thhave e Net Nether herlan lands ds)) (ii (ii) Lo Long nge er ((e. e.g. g. 50 m lo lon ng pr prestressed sed con conccrete bea beam ms) (ii (iii) i) Deepe Deeperr (e.g (e.g.. 100 1000 0 mm deep deep pr prest estre resse ssed d hol hollow low core core flo floor or units units pr produ oduced ced in Italy Italy in 2014 2014)) (iv (iv)) Shall Shallow ower er ((e.g e.g.. sp span/ an/de dept pth h ratio ratio appro approach aching ing 40 40 for for pre prestr stress essed ed com compos posit ite ea and nd cont continu inuous ous beams beams)) (v) Strong Stronger er (e.g. (e.g. gra grade de C90 C90/10 /105 5 used used in in co colum lumns ns in in build building ingss su such ch as as in 36 36-st -store orey y sske kelet letal al fr fram ame, e, B Belg elgium ium)) The These adv dvan ance cem ments have be been en comp omplim limented by an incr increa easse in the avail ailab able le lit literatur tures & resear earch report orts but als also fr from om other books from Netherlands, Germany, Brazil, United Kingdom, and several bulletins from fib Commission 6 on Pr Pref efabr abrica icatio tion, n, toget togethe herr with with 8 Europe European an pr produ oduct ct st stand andar ards ds cove coverin ring g a wide wide rang range e pr preca ecast st con concre crete te eleme element ntss (h (holl ollow ow cor core e flo floor or slabs sla bs,, wall walls, s, stair stairs, s, et etc.) c.)..
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The design and construction of joints and connections is the most the most important consideration in precast concrete structures. Their purpose is to transmit forces between structural members and/or to provide stability and robustness. connection, there may be several load-transmitting Within a single connection, several load-transmitting joints joints,, and so it is first necessary to distinguish between a ‘joint’ and a ‘connection’ ‘connection’.. A ‘joint’ ‘joint’ is is the action of forces (e.g. tension, shear, compression) that takes place at the interface interfa ce b between etween two (or more) structural elements. ‘connection’ is is the action of forces (e.g. tension, shear, compression) The definition of a a ‘connection’ and/orr momen and/o moments ts (bending, torsi torsion) on) through an assem assembly bly comprising one (or more) interfaces. The design of the connection is therefore a function of both the structural elements and of the joints between them Rece Recent nt ad adva vance ncess in pr prec ecas astt co conne nnect ctio ion n sy syst stem emss ad adop opte ted d or re resea searc rched hed fo forr bui build ldin ing g structures in developed countries worldwide does not differ from basic fundamentals
(Dr. Kong KH)
(Dr. Kong KH)
The most commonly used methods of connection analysis in precast are:
1.
Stru Strutt-a andd-ti tie e, ffo or tth he tr trans nsffer of beari earin ng fo force cess
2. Coup Couple led d joi join nt, for for the the tr tran anssfer of bea beari ring ng for orce cess and and//or ben bendi ding ng and/or torsional moments 3. Shea Shearr ffri rict ctio ion n or or she shear ar wed edgi ging ng,, ffor or the the ttrransf ansfer er of shea shearr w wit ith h or or without compres compression sion
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One of most commonly used methods of connection analysis
Strut-and-tie,, for the transfer of bearing forces Strut-and-tie
Two of most commonly used methods of connection analysis (Dr. Kong KH)
Column-Column Splice: A Coupled joint joint,, for the transfer transfer of bearing forces and/or bending and/or torsional moments
Shear transmission through shear keys. Shear friction or shear wedging, wedging , for the transfer transf er of shear with or without compression
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Compression Comp ive forc isetr tran smit betw prec conc comp onen eith ern by dire b earing, or thJoint. roughCo anmpre inress tessiv rm eedfo iarce teem diansm um sitte uted chd abe s itwee n een sitn u pr mecas orast tatr co orncre corete nte creco tempon . Th e ents dits stiei ncther tio is di mrect adct e depe de pend ndin ing g on to tole lera ranc nces es and and the the im impo port rtan ance ce of the the accu accura racy cy of th the e lo load ad tran transf sfer er loca locati tion on..
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Compression Joint.
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Compression Joint.
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Shear Joint.
Shear forces can be transferred between concrete elements by one, or more, of the following methods: 1. Shear adhesion and bonding (when cast in situ concrete is placed against a precast concrete surf surfac ace, e, ad adhe hesi siv ve bo bond nd de deve velo lops ps in th the e fr fres esh h ce ceme ment nt pa passte in th the e tin tiny crev crevic ices es an and d pore poress in the the ma matu ture re co conc ncrrete) ete)
2. 3. 4. 5.
Shear friction Shear keys Dowel action Mechanical devices
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Shear Joint.
Shear forces can be transferred between concrete elements by one, or mor ore e, of the following fol lowing method methods: s: Shear friction 2.
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Shear Joint.
Shear forces can be transferred between concrete elements by one,
o r owing more,method of ths:e following foll methods: Shear Ke Key 3.
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Shear Joint.
Shear forces can be transferred between concrete el elem emen ents ts by on one, e, or mo morre, of th the e fol ollo lowi wing ng me mettho hods ds:: Dowel Ac Action 4.
Shear Joint.
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Shear forces can be transferred between concrete elements by one, or more, of the following foll owing metho methods: ds: Mecchani niccal devices 4. Me The most common form of mechanical connection is the welded plate or bar shown in Figure.
Section
This may be cast into elements such as at the edge ed gess of do doub uble le-t -tee ee fl floo oorr un unit itss The ul The ulti tima matte shea shearr ca capa paci city ty of th the e welde elded d pl plat ate e jo join intt is th the e leas leastt of (a)T (a)The he pu pull ll-o -out ut re resi sist stan ance ce of the the em embe bedd dded ed pl plat ate e (b) (b) Th The e wel eld d ca capa paci city ty of th the e ho hold ldin ing g ba barrs to th the e em embe bedd dded ed pl plat ate, e, or (c)T (c)The he shea shearr ca capa paci city ty of th the e in intterme ermedi diat ate e pl plat ate e or bar
Plan
Tension Joint.
Plan
Elevation
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Tension Joint.
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Tension Joint.
By Bolting By Welding
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Brief Historical Developments of Precast Connections
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In ea earl rly y 19 1950 50ss in UK UK,, ad adop opti tion on of HH-fr fram ame e was do done ne,, wh wher ereb eby y pi pinn-jo join intted sit site co conn nnec ecti tion onss were ere ma made de near near the the positions of frame contraflexure; i.e. mid-column height and 0.2 × beam span. The solution removed one pr prob oble lem m by shif shifti ting ng th the e co conn nnec ecti tion onss to po poin ints ts of zero ero (o (orr sm smal all) l) be bend ndin ing g mo mome ment nt,, bu butt ca caus used ed ot othe herr di diff ffic icul ulti ties es elsew els ewher here e in man manuf ufact acturi uring ng and tr trans anspor porta tatio tion n by cr creat eating ing lar large ge,, tw two-d o-dime imensi nsiona onall uni units. ts.
(Dr. Kong KH)
The main cost elements are fabrication and material costs, and those rise steeply with increases in connector capacity. Pr Prec ecas astt de desi sign gner erss pref prefer er th the e co comp mpli lica catted as aspe pect ctss of th the e co conn nnec ecto torr to be under nder the the co cont ntro roll of the the facto actory ry,, re reduc ducing ing sit site e op oper erati ations ons to sim simple ple do dowe welli lling, ng, bol boltin ting g or we weldi lding. ng. Stanton et al. (1986) produced a special study for the PCI on moment-resistant and simple connections, and stated: The economic and functional success of a precast concrete structure depends to a great extent on the co confi nfigur gurat ation ion and pr prope operti rties es of its in inte ter-e r-elem lement ent con connec nectio tions. ns. Fle Flexib xibili ility ty of the con connec nectio tions ns af afffec ects ts the the di dist stri ribu buti tion on of cree creep, p, th ther erma mall and and shri shrink nkag age e stra strain inss and and de dete term rmin ines es join jointt perfo per forma rmance nce ov over er tim time. e. stre reng ngth th of th the e co conn nnec ecti tion onss re rema main inin ing g af afte terr th the e de dema mand ndss of volu volume me ch chan ange ge,, grav gravit ity y load loadss an and d di dime mens nsio iona nall or The st alig align nmen entt corr rre ect ctio ion ns have bee een n sa sattis isfi fied ed deter eterm min ines es wheth ther er the struct ructu ure will ill deform per erm man anen entl tly y und nder er acti action on of ex extr trem eme e wi wind nd or seis seismi micc fo forc rces es.. Ductility of the connections determines whether the permanent deformations will take place by a safe redi redist stri ribu buti tion on of lo load ad and and diss dissip ipat atio ion n of en ener ergy gy or by br brit ittl tle e co conn nnec ecti tion on fa fail ilur ure. e. This statement captures the essen encce of precast frame design in knowing which effects are to be considered in desi de sign gn,, an and d no nott si simp mply ly ca carr rryi ying ng ou outt th the e me mech chan anic icss of st stre ress ss eq equi uili libr briu ium m an and d st stra rain in co comp mpat atib ibil ilit ity y.
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For inst nstan ance ce fig figure ure belo elow sho how ws a bett etter so solu luti tio on: a ‘sc scar arff joi oin nt’, t’, ap app proxim ximately 0. 0.1 15L – sa say y, 60 600 0 to 750 mm fro from th the e co colu lumn mn – re redu duce cess th the e be bend ndin ing g mo mome ment nt in th the e be beam am by ar arou ound nd 40 per per ce cent nt,, resul esulti ting ng in a sh shal allo low wer be beam am.. Th The e scarf joint may be positioned at one end of the beam, or at both ends. This method of design has been used in mult mu ltii-st stor orey ey ca carr pa park rkss in or orde derr to save save he head adro room om.. The Th e mo most st ro robu bust st solu soluti tion on wa wass fo foun und d in a me mech chan anic ical al co conn nnec ecti tion on,, br brou ough ghtt ab abou outt by rely relyin ing g on th the e pr prec ecas astt co conc ncre rete te to firm firmly ly anch anchor or ro roll lled ed or fa fabr bric icat ated ed st stee eell sect sectio ions ns in po posi siti tion on so th that at a di dire rect ct stee steell-to to-s -ste teel el join jointt wa wass ma made de..
(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 foundations. The four rules for satisfactory joint design are that: (1) The components can resist ultimate design loads in a ductile manner manner.. (2)The precast members can be manufactured economically and be erected safely and speedily. (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 environmen environmental tal requirements.
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The Dywidag Ductile Connector Connector (DDC) system system was proposed by by Rockwin Corporation Corporation in 1995 The connection was usually applied at the junction between the precast column and the precast beam. It was reported that the DDC system was capable of providing suf suffic ficien iently hi high gh fle flexur ural al ca cap pac aciity, ty, an and d was also advantageous in fast erection and ex excell cellent ent seismic seismic resist resistance ance..
(Dr. Kong KH)
HDB’s precast column is usually fabricated in a rectangular shap shape e re resu sult ltin ing g in larg larger er flex flexur ural al rigi rigidi dity ty in the the fr fram ame e di dire rect ctio ion. n. The cross-section length of column, h, usually varies from 200m 200mm m to 2000 2000mm mm an and d the the cr cros osss-se sect ctio ion n widt width, h, b, vari varies es from from 200mm to 400mm in practice. For the precast beam, a compo ompossite ite beam eam is usuall ally form ormed after fter the cast in pl plac ace e slab strip. The overall height of beam varies from 300mm to 1000mm and the width of beam varies from 200mm to 1000 1000mm mm in pr pract actice ice.. Due to cons constr train aints ts impos imposed ed on dimen dimensio sions ns by several fact ctor orss (c (cllear head ead room oom requ quiirement, low typ ypic ica al storey height, erection crane capacity, etc.), precast compon com ponen ents ts of signif signific ican antly tly larger larger dimens dimension ionss are are seldom seldom use used. d. The The ty typi pica call co colu lumn mn di dime mens nsio ions ns (h × b) ad adop opte ted d in HDB HDB pr prac acti tice ce is 1000mm×300mm and the precast beam of dimensions 300m 300mm m in wi widt dth h an and d 500m 500mm m in de dept pth h are are typi typica call lly y ad adop optted. ed. In addition, precast columns with a visible corbel are not ac acce cept ptab able le du due e to cl clea earr he head ad ro room om req equi uire reme ment nt for for re resi side dent ntia iall buildings. The clear span of the beam in HDB apartments comm common only ly rang ranged ed fr from om 4m to 6m 6m..
R&D at CEE NUS Ong KC KC et. al. (2013) (2013) on DfD Joints
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1. Th The e proposed osed Df DfD D M-R bea eam– m–ccolu lumn mn conne nect ctiion is sh sho own to be ca capa pabl ble e of prov provid idin ing g ad adeq equa uatte mo mome ment nt resi resisstanc tance e for us use e in mu mult ltiisto tore rey y RC ap apar artm tmen entt bl bloc ocks ks in Sing Singap apor ore. e. Th The e pr prop opos osed ed co conn nnec ecti tion on al also so sh sho owed goo ood d duc ucti tili litty whe hen n ass asses esse sed d based ased on the the CDF valu alues obtained. 2. Certain design adjustments was made to ensure that the
servi rviceability limit state of cracking can be satisfied through the pro provi visi sion on of a to topp ppin ing g wi with th co con ntinu tinuit ity y reb ebar arss (3 (3H1 H12) 2).. In gen ener eral al,, the the mome mo ment nt ca capa paci citi ties es co corr rres espo pond ndin ing g to wh when en a ma maxi ximu mum m crac crack k wi widt dth h of 0.3 mm was observed during testing reached about 50–65% of th the e ult ultima imate te mom moment ent cap capaci acitie ties. s. 3. Increasing the size of the specimen especially the depth is effective in increasing the ultimate moment capacity of the proposed connection. Under quasi static loading all the specimens tested performed similarly in terms of crack pr prop opag agati ation, on, fa failu ilure re mod mode e and th the e duc ductil tile e beh behav aviou iourr. Note: Other commercially marketed systems have also been proposed in the Netherlands, e.g. BESTCON 30, CD20 and MATRIXBOUW
Importance of Basics of Preca Precast st Connections Design Concepts acting as fundamentals of development of Advances in Precast Connections.
PIN-JOINTED CONNECTIONS
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Pinn Pinned ed co conn nnec ecti tion onss ar are e used used ex exte tens nsiv ivel ely y in prec precas astt st stru ruct ctur ures es as they they ma may y be for orm med in the the simp simple lesst ma mann nner er by el elem emen entt to el elem emen entt be bear arin ing. g. Th The e very ery na natu turre of prec precas astt co cons nstr truc ucti tion on lend lendss itse itself lf to for ormi ming ng simp simply ly su supp ppor orte ted d co conn nnec ecti tion onss in or orde derr to avoi avoid d fl flex exur ural al co cont ntin inui uity ty acro across ss th the e en ends ds of in indi divi vidu dual al el elem emen ents ts.. this is re reas ason on,, th they ey ar are e of ofte ten n re reffer erre red d to as ‘j ‘joi oint nts’ s’ as th they ey te tend nd to in invo volv lve e on one e be bear arin ing g su surf rfac ace e on only ly.. For th
PIN-JOINTED CONNECTIONS
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Simply supported slabs on beams or walls
MOMENT-RESISTING (MR) CONNECTIONS
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MOMENT-RESISTING CONNECTIONS
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MOMENT-RESISTING CONNECTIONS Grouted joints for moment resistance
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MOMENT-RESISTING CONNECTIONS Eg. 7. 7.11 115 5
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MOMENT-RESISTING CONNECTIONS
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Example 7.115 Welded Plate Splice Design
Eurocode
BS8110
MOMENT-RESISTING CONNECTIONS Example 7.116 Grouted Sleeve Splice Design
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MOMENT-RESISTING CONNECTIONS
Example 7.116
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MOMENT-RESISTING CONNECTIONS Eg. 7.11 7.116 6 Grouted Sleeve Splice Design
BS8110
Floor connections at load-bearing walls (MR*)
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*Note MR denotes Moment Resisting Connections
Floor connections at load-bearing walls (MR)
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Floor connections at load-bearing walls (MR)
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Work Example 9.5 .57 7: Calcul lcula ate the ult ultima imate moment ent of resi esistanc nce e in the flo floor sl slab ab to wall all co conn nnec ecttion sho how wn below low. The ul ulti tim mat ate e axial xial for orce ce from from th the e uppe upperr wall wall is 500 500 kN/m kN/m ru run. n. Ch Chec eck k th the e co com mpr pres essi sion on lim limit of the the in infi fill ll co conc ncrrete ete in the the 50 mm gap be betw twee een n th the e ends ends of th the e floo floorr unit units. s. Chec Check k th the e lim limitin iting g mome moment nt of resis esisttanc nce e of the the floo floorr slab slab itse itself lf.. Us Use e f ck = 40 N/mm2, f cki = 25 N/ N/mm mm2, f yk = 500 N/m /mm m2 and μ = 0.7.
Floor connections at load-bearing walls (MR)
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Work Example 9.5 .57 7: Calcul lcula ate the ult ultima imate moment ent of resi esistanc nce e in the flo floor sl slab ab to wall all co conn nnec ecttion sho how wn below low. The ul ulti tim mat ate e axial xial for orce ce from from th the e uppe upperr wall wall is 500 500 kN/m kN/m ru run. n. Ch Chec eck k th the e co com mpr pres essi sion on lim limit of the the in infi fill ll co conc ncrrete ete in the the 50 mm gap be betw twee een n th the e ends ends of th the e floo floorr unit units. s. Chec Check k th the e lim limitin iting g mome moment nt of resis esisttanc nce e of the the floo floorr slab slab itse itself lf.. Us Use e f ck = 40 N/mm2, f cki = 25 N/ N/mm mm2, f yk = 500 N/m /mm m2 and μ = 0.7.
Floor connections at load-bearing walls (MR)
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Wor ork k Example 9.57: Ca Callcu cullate the ulti ltimate mome oment of resi sisstance ance in the floo floorr slab lab to wall all conn onnect ctiion sho how wn be belo low w. The The ulti ultim mat ate e ax axia iall force orce fr from om th the e uppe upperr wall wall is 500 kN/m kN/m ru run. n. Ch Chec eck k th the e co com mpr pres essi sion on lim limit of the the in infi fill ll co conc ncrrete ete in th the e 50 mm ga gap p 2 betw betwee een n th the e ends ends of th the e floo floorr un unit its. s. Ch Chec eck k th the e lim limit itin ing g momen omentt of re resi sist stan ance ce of the the floo floorr sl slab ab itse itself lf.. Us Use e f ck = 40 N/mm , f cki = 2 2 25 N/ N/mm mm , f yk = 500 N/ N/m mm and μ = 0.7.
Beam-to-column face connections (MR)
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Welded plate connector Thin Th in pl plat ate e is an anch chor ored ed to th the e be beam am usin using g la larrge ge-d -dia iame mete terr rebar ebars, s, typ ypic ical ally ly 25 mm hi high gh tens tensiile. le. Th The e pl plat ate e is site welded to a pr proj ojec ecti ting ng steel teel bi bill llet et.. Expa Expans nsiv ive e infi infill ll conc concrrete is used used to fil fill th the e gap (S (See ee left left si side de of co colu lum mn in Fi Figu gurre 9. 9.60 60a) a).. Prov Provid idin ing g that that are full fully y anch chor ore ed to the colum olumn n or ar are e con onttinuou ouss th thrrou ough gh the colum olumn, n, the tie steel bars ars are fu fullly stre tressed at the the bars are plate te is full fully y anch anchor ored ed such such th that at th the e weld at the bi bill lle et is also also fu full lly y eff effec ecti tive ve.. Th The e comp compre ress ssiv ive e ulti ultima mate te limi limitt st stat ate. e. Th The e beam beam pla str streng ength of th the e conc concrrete ete at th the e bot bottom of th the e be beam am is limi limite ted d by th the e stre streng ngth th f cki of the the in infi fill ll conc concre rete te.. Th The e cont contri ribu buti tion on of the the solid sol id steel steel bil bille lett is ignor ignored. ed.
Figure Figur e 9. 9.60 60(a) (a) Moment Moment-r -resi esist stin ing g beambeam-totocolumn connections for (a) negative moment
Left side
Beam-to-column face connections (MR)
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Steel billet connector A th thrrea eade ded d rod or do dowe well is site fix fixed throug ugh h a ho holle in the beam eam an and d supp suppor orti ting ng steel bil billet let and secu curred to a steel an angl gle e (or (or similar) lar) at the top of th the e beam (r (riigh ghtt side of co colu lum mn in Figu Figurre 9.60a 0a). ). The annu nulu luss aro aroun und d the bille llet is site ite gr gro out ute ed. If the tie steel is fu full lly y an anch chor ored ed as desc descri ribe bed d earl earlie ierr, the the ti tie e st stee eell bars bars ar are e full fully y stre stress ssed ed at the the ul ulti tima mate te limi limitt stat state. e. Th The e sh shea earr stre streng ngth th of vertica ticall dowe dowell is ig igno norred du due e to the negl neglig igib ible le st strrengt ength h of th the e bolt bolted ed angl angle e. The mome oment du due e to shear ear force in the the (sam same) the ver ve vert rtic ical al dowe dowell of area area is fairl airly y smal smalll owin owing g to th the e near nearne ness ss of th the e dowe dowell to the the co comp mprressi ession on zone. one. Th The e co com mpr pres essi sive ve str strengt ength h of the con oncr cre ete at the bo botttom of the be beam am is lim imiited by th the e streng ength f cki of the the na narr rrow ow gr grou oute ted d join joint. t. Th The e co cont ntri ribu buti tion on of the the ste steel el bill billet et is ignored ignored.. Tie Steel
Figure Figur e 9. 9.60 60(a) (a) Moment Moment-r -resi esist stin ing g beambeam-totocolumn connections for (a) negative moment
Right side
Beam-to-column face connections (MR)
Fi Figu gurre 9.60 9.60 Mome Moment nt-r -res esis isti ting ng beam beam-t -too-co colu lumn mn conne con necti ctions ons fo forr (a) nega negativ tive e momen momentt
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Figure 9.60 Moment-resisting connec con nectio tions ns for for (b) positi positive ve mo mome ment nt
beam-to-column
Beam-to-column face connections (MR)
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Work ork Exam Exampl ple e 9. 9.62 62:: Calc Calcul ulat ate e the the hoggi hogging ng mome moment nt of resis esista tanc nce e of the the be beam am–c –col olum umn n conn connec ecti tion onss sh show own n in Fi Figu gure re 9. 9.62 62a a an and d 9. 9.62 62b b fo forr the the weld welded ed plat plate e an and d bill billet et conn connec ecto tors rs.. In both both case cases, s, cont contin inui uity ty re rein info forc rcem emen entt is po posi siti tion oned ed in the the ga gap p be betw twee een n the the ends ends of floo floorr slabs abs and and abov above e the centr entre e line ine of the be beam am.. Trans ansverse tie steel woul ould be pr pre esent ent bu butt is not sho hown wn he herre. Use 2 2 2 2 grade e 8: 8:8 8 bolt boltss = 307 307 N/ N/mm mm , f ywd = 220 N/m N/mm an and d cove over to top steel = 50 mm. f cki = 40 N/mm , f yk = 500 N/m /mm m , shea shearr pbq for grad
Figure 9.62 (a) welded plate connector
9.62 (b) billet connector.
Beam-to-column face connections (MR)
(Dr. Kong KH)
Work ork Exam Exampl ple e 9. 9.6 62: Ca Calc lcul ulat ate e th the e hogg hoggin ing g mo mome ment nt of re resi sist stan ance ce of the the be beam am–c –col olum umn n co conn nnec ecti tion on sh show own n in Fi Figu gurre 9. 9.62 62a a an and d 9. 9.62 62b b fo forr the the weld welded ed plat plate e an and d bill billet et conn connec ecto tors rs.. In both both case cases, s, cont contin inui uity ty re rein info forc rcem emen entt is po posi siti tion oned ed in the the ga gap p be betw twee een n the the ends of flo floor slabs abs and and abo bov ve the ce cen ntre lin line of th the e be bea am. Trans ansverse tie tie steel woul uld d be pr pre esen sent but is not sho how wn he herre. Use grade e 8: 8:8 8 bo bolt ltss = 307 307 N/ N/mm mm2, f ywd = 220 N/m N/mm2 an and d co cov ver to top steel = 50 mm. f cki = 40 N/mm2, f yk = 500 N/ N/m mm2, shea shearr pbq for grad
See Fig. 9.62(a)
Beam-to-column face connections (MR)
(Dr. Kong KH)
Work ork Exam Exampl ple e 9. 9.6 62: Ca Calc lcul ulat ate e th the e hogg hoggin ing g mo mome ment nt of re resi sist stan ance ce of the the be beam am–c –col olum umn n co conn nnec ecti tion on sh show own n in Fi Figu gurre 9. 9.62 62a a an and d 9. 9.62 62b b fo forr the the weld welded ed plat plate e an and d bill billet et conn connec ecto tors rs.. In both both case cases, s, cont contin inui uity ty re rein info forc rcem emen entt is po posi siti tion oned ed in the the ga gap p be betw twee een n the the ends of flo floor slabs abs and and abo bov ve the ce cen ntre lin line of th the e be bea am. Trans ansverse tie tie steel woul uld d be pr pre esen sent but is not sho how wn he herre. Use 2 2 2 2 grade e 8: 8:8 8 bo bolt ltss = 307 307 N/ N/mm mm , f ywd = 220 N/m N/mm an and d co cov ver to top steel = 50 mm. f cki = 40 N/mm , f yk = 500 N/ N/m mm , shea shearr pbq for grad See Fig. 9.62(b)
As Assum sumpt ption ion:: We did did not consid consider er SemiSemi-rig rigid id beam-t beam-to-c o-colu olumn mn fa face ce conne connecti ctions ons.. Curr Curren entt calcul calculat ation ionss are are more more con conse serva rvativ tive. e. Note: Over the past 25 years (since 1990s) around 100 full- or small-scale tests have shown that many typical precast beam– column connections act as semi-rigid joints in flexure, reducing sagging moments in the beam due to imposed gravity load, as well as enhancing the frame action acti on by reducing the buckling height of columns.
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 Connections
Elevation showing 2 beams resting on column
(Dr. Kong KH)
Plan showing 2 beam ends and its interface
Beam-to-Column Connections
(Dr. Kong KH)
Beam-to-Column Connections
(Dr. Kong KH)
System Developed by Obayashi, Japan
Beam-to-Column Connections
(Dr. Kong KH)
Credit Acknowledgement: Obayashi, Japan
Beam-to-Column Connections
(Dr. Kong KH)
Elevation
Elevation
Plan
Beam-to-Column Connections
(Dr. Kong KH)
Beam-to-Column Connections Column Insert There are many types of inserts including: -Universal column or beam channel, angle or bent plate(RHS) --Rolled Rolled rectangular hollow section 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 Connections Column Insert
(Dr. Kong KH)
Beam-to-Column Connections Column Insert
(Dr. Kong KH)
Beam-to-Column Connections: Column Connections: Column Insert Work Example 5
(Dr. Kong KH)
Beam-to-Column Connections: Column Connections: Column Insert
(Dr. Kong KH)
Work Example 5
Sq is a biaxial (or often triaxial) confinement
Beam-to-Column Connections: Column Connections: Column Insert Work Example 5
(Dr. Kong KH)
Beam-to-Column Connections: Column Connections: Column Insert Work Example 5
(Dr. Kong KH)
Beam-to-Column Connections: Column Connections: Column Insert
(Dr. Kong KH)
Work Example 5
(to avoid overlapping stress)
(Lateral bursting force coefficient)
Beam-to-Column Connections: Column Connections: Column Insert
(Dr. Kong KH)
Work Example 5 (Area of confinement steel)
Beam-to-Column Connections: Column Connections: Column Insert Work Example 5
(Dr. Kong KH)
Beam-to-Column Connections: Column Connections: Column Insert Work Example 6 (related to Work Example 5)
(Dr. Kong KH)
Determine the area of bursting reinforcement beneath the billet. Assume:
b p = insert breath
Beam-to-Column Connections: Corbels Connections: Corbels
Shallow corbels: Strut-and-tie analogy used in the design of corbels according to PD 6687,
(Dr. Kong KH)
Deep corbels are usually around H = 600-750 mm, and so the inclination of the strut
Annex B.4
tan β is
2.5.
Beam-to-Column Connections: Corbels Connections: Corbels
(Dr. Kong KH)
Fu Furt rthe herr dev develop elopm ment ent in th the e desi design gn of cor orbe bells with with high high shea shearr capa capaci citty or sh shea earr-wi with th-n -neg ega ative tive mo mom ment ent ca cap pac acit ity y ha hass us used ed mecha me chanic nical al connec connectio tions, ns, such such as st stee eell shoes, shoes, or armour armour the concr concret ete e corbel corbel heavil heavily y wit with h steel steel
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels
(Dr. Kong KH)
Work Example 7
next Figure as
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections: Corbels Connections: Corbels Work Example 7
(Dr. Kong KH)
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Design 1. Shallow recess is where a compressive strut resists the total beam end reaction 2.Deep reces recess, s, is where the depth of the nib above the bearing surface is insufficient to enable the strut to resist VEd, and so bent-up bars resist up to 50% VEd an and d th the e co comp mpre ress ssiv ive e strut strut an and d ve vert rtic ical al link linkss th the e re rema main inde derr. In some instances, a prefabricated shear box partially or wholly replaces the stirrup cage.
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Design: Design: Shallow recess
Although codes do not give an explicit definition of a shallow recess, it is found that where ae ≤ 0.6dh trus trusss ac acti tion on de deve velo lops ps by pr prov ovid idin ing g ad adeq equa uate te com co mpr pre essi sion on and and tens nsiile memb embers ins nsiide the beam eam wi with tho out the ne nee ed for bent bent-u -up p ba barrs. Anot Anothe herr ru rule le of thum thumb b is tha that the the heig heigh ht of a sh shal allo low w rec eces esss is ⅓ to ½ the beam depth, but it is dh tha thatt is more more criti critical cal..
Beam-to-Column Connections: Beam End Design: Design: Deep Recess
Where the depth of the recess is more than 2d/3, or where av>0.6dh, or where dh is less than about 2 200 00 mm
(Dr. Kong KH)
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Design: Steel Shear Box Concept A prefabricated shear box partially or wholly replaces the stirrup cage.
(a) strut and tie model (b) general arran arrangement gement of shear box with holding down rebars (c) general arrangement of shear box with holding down strap.
Beam-to-Column Connections: Design Concepts for beam end shear
(Dr. Kong KH)
Beam-to-Column Connections: Beam End Shear Design. Work Example 8
(Dr. Kong KH)
Beam-to-Column Connections: Beam End Shear Design. Work Example 8
(Dr. Kong KH)
Beam-to-Column Connections: Beam End Shear Design. Work Example 8
Eurocode
(Dr. Kong KH)
BS8110
Beam-to-Column Connections: Beam End Shear Design. Work Example 8
Eurocode
(Dr. Kong KH)
BS8110
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Shear Design. Work Example 8
Eurocode
BS8110
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Shear Design. Work Example 8
BS8110
Eurocode
Beam-to-Column Connections:
(Dr. Kong KH)
Beam End Shear Design. Work Example 8 2H12
Eurocode
BS8110
H12
Figures 4.39
Beam-to-Column Connections: Beam End Shear Design. Work Example 8
(Dr. Kong KH)
Column in Pocket Connection to Foundations
(Dr. Kong KH)
Column in Pocket connection to foundations
(Dr. Kong KH)
Eurocode 2 Design
Column in Pocket connection to foundations
(Dr. Kong KH)
Eg. 7. 7.12 126 6
N=950kN, M=95kNm
N=1000kN, M=100kNm
Column in Pocket connection to foundations Eg. 7.126 7.126
(Dr. Kong KH)
Eurocode
BS8110
Column in Pocket connection to foundations
(Dr. Kong KH)
Eg. 7.126 7.126
Eurocode
BS8110
Column in Pocket connection to foundations Eg. 7.126 7.126
(Dr. Kong KH)
Column Base Plate- Connections to Foundation
(Dr. Kong KH)
Eurocode
BS8110
Credit Acknowledgements of References BCA Structural Precast Handbook , 2nd Ed. 1999. 1999.
Obayashi Corporation, Japan. 2018. LRV Precast Installation Method
(Dr. Kong KH)
Credit Acknowledgements of References
Elliott, K.S. 2017. Precast Concrete Structures, 2nd ed., Taylor & Francis, USA. USA .
(Dr. Kong KH)
