PROVENCHER BRIDGE OVER THE RED RIVER WINNIpEG, MANITOBA. C.D. Stewart and B.D. Thompson Wardrop Engineering Inc. Winnipeg, Manitoba.

Transcription

1 PROVENCHER BRDGE OVER THE RED RVER WNNpEG, MANTOBA C.D. Stewa and B.D. Thmpsn Wardrp Engineering nc. Winnipeg, Manitba and S.H. Rizkalla Civil Engineering Depament University f Manitba Winnipeg, Manitba ABSTRACT Alternative design schemes t replace the 76-year-ld Prvencher Bridge ver the Red River in Winnipeg, Manitba are presented. Future lng-term bjectives and site cnstraints were the majr factrs affecting the chice f a precast prestressed cncrete system incrprating a unique pst-tensined cnnectin. Preliminary design indicated that this cncept is ecnmical and efficient. An erectin scheme fr cnstructin f the bridge is discussed. Stewa, Thmpsn and Rizkalla. Prvencher Bridge ver the Red River.

2 BACKGROUND Prvencher Bridge is a fur-lane undivided radway bridge ver the Red River, near the gegraphic cent re f Winnipeg, Manitba, as sho'-'n in Figure 1. The bridge links the cmmunity f St. Bniface with Winnipeg's central business district. The bridge carried apprximately 37 vehicles a day in 1987, and functined at a level f service F during the p.m. rush hur and D during the a.m. rush hur. Built in 1914, the bridge structure cnsists f seven spans with an verall length f 28.8 metres. The superstructure is cmprised f tw riveted steel plate half-thrugh girders with intercnnecting transverse flr beams. n 1987, the City f Winnipeg cmmissined Wardrp Engineering nc. t investigate the traffic capacity, the structural integrity f the existing bridge, and t prvide recmmendatins t address the fllwing lng-term bjectives: 1. Prvide a river crssing with a traffic capacity adequate fr the predicted future grwth. 2. mprve the hrizntal and veical radway and apprach alignments. 3. Upgrade lad-carrying capacity f the existing structure t the prpsed legal limits. 4. mprve the navigatin channel. 5. Maintain an acceptable level f service thrughut implementatin f the rehabilitatin r replacement f the existing structure. The investigatin cncluded that rehabilitatin f the existing structure, t meet the abve lng-term bjectives, wuld be unecnmical due t the type f superstructure and deteriratin f the bridge river piers. The study als recmmended an extensive strengthening and upgrading. The investigatin als required replacement f all bearings, expansin jints and high density cncrete verlay. The wrk culd require clsure f the bridge fr a six-mnth perid. PROPOSED ALTERNATVES Three upgrading alternatives were selected t achieve these specified demands: Alternative 1: New six-lane superstructure n the existing rehabilitated piers Alternative 2: New three-lane bridge and rehabilitatin f the existing bridge Alternative 3: Tw new three-lane twin structures Evaluatin f the abve three were based n functinal, structural and cst cnsideratins. Using a matrix methd f evaluatin with each area f cnsideratin assigned a relative impance weight ttalling 1 pints, it was fund that alternative 3 was fund t be the ptimum verall slutin. Based n this study it was recmmended t replace the 76-year-ld structure with tw new three-lane twin bridge structures. The prpsal included future provisin fr widening the bridge t fur lanes. The future expansin includes cnnecting the river piers t prvide supp fr the future additinal median lanes. Using the same bridge piers, tw alternative slutins fr the superstructures using precast cncrete and steel girders were prvided. Due t funding cnstraints, the prject is prpsed t be cnstructed in three phases with the fllowing milestne dates: Phase - cmpletin Nvember 1992, as shwn in Figure 2 - cnstructin f the first (eastbund) new three-lane bridge utilizing existing bridge as the westbund 3-1ane bridge with the apprpriate upgrading f the bridge deck Phase - cmpletin Nvember 1999 use f the cmplete bridge in the firs t phase as tw lanes, each way, as shwn in Figure 2 - demlitin f the ld bridge - cnstructin f the secnd three-lane (westbund) bridge Phase - cmpletin 22 (if resired) extensin f the tw cmpleted br idges int fur lanes each way by cnnecting the bridge piers and widening each superstructure with ne additinal lane. Final design fr the first phase is currently in prgress. Stewa, Thmpsn and Rizkalla. Prvencher Bridge ver the Red River. 2

3 Figure 1. Overall view f existing Prvencher Bridge Phase ',.,, ", "" \ '." : Phase Figure 2, Mdels f the prpsed Phases and Stewa, Thmpsn and Rizkalla. Prvencher Bridge ver the Red River. 3

4 DESGN CONSDERATONS The fllwing cnsideratins were fund t be crucial t yield an efficient and ecnmical prject: 1. Pier lcatins were set t prvide equal spans fr the main girders f the tw precast and steel superstructure alternatives. This resulted in using tw abutments lcated n the east and west bank f the river and fur river piers. The fundatin types were caissns fr the piers and H-piles fr the abutments. 2. The veical alignment shuld match the existing intersectin at the east apprach which culd nt be ecnmically altered. 3. Elevatin f the bttm f the main girders shuld allw passage f 16-year fld predictins. 4. Central river spans shuld imprve the navigatinal channel in width and height. S. Alignment, length and lcatin f the bridge piers as well as the superstructures shuld accmmdate an additinal fuh lane expansin f the bridge. 6. The structural capacity f the bridge shuld be upgraded t the prpsed HSS3 City standard. 7. The verall structures n the Red River shuld be aesthetically pleasant, since the bridge is very clse t the histric "Frks" develpment in Winnipeg, where the Assinibine River flws int the Red River in the centre f Winnipeg. DESGN LOADS The bridge will be designed accrding t the AASHTO Standard Specificatin fr Highway Bridges, 14th Editin, The live lad will be based n the HS3 lane lad and HSS3 vehicle lad. The HS2S wheel lad will be used fr the deck design. The HS3 lane and HSS3 vehicle lading prvide a sufficient reserve capacity nt nly fr the current legal vehicle, but als fr the prpsed future legal vehicles, as designated by the City f Winnipeg. Due t the hrizntal curvature and skewed river piers shwn in Figure 1, an ANSYS finite element analysis prgram was used t determine the distributin f the mments, shears and trsinal frces in the superstructure. Thermal stresses were included in the analyses t determine the lateral lad and required expansin jints. The deck was liimulated using a plate element and the prelitreslied girder was mdelled using a beam element with specified height t the neutral axis t determine the trsinal stresses. The finite element mdel used fr the analysis is shwn in Figure 3. SUPERSTRUCTURE DESGN Based n the standard requirements f the City f Winnipeg fr large prjects such as the bridge under cnsideratin, tw alternative structural design cncepts were cnsidered. The first design cncept utilizes precalit cncrete girderli t prvide a cntinuus beam with cmpsite actin f the cncrete deck slab. The secnd design alternative uses trapezoidal steel bx girderli als with cmpsite actin f the cncrete deck slab. The bridge cnsists f five cnt inuus spans fr a ttal length f m, as shwn in Figure 4(a) and (b). The restricted elevatin f the bridge. cntrlled by the apprach rads and the 16-year fld level, impsed the need fr cnstant depth girders fr bth cncrete and steel design cncepts. Use f a haunched sectin fr the girders at the piers will reduce the navigatin channel and result in a very unecnmical design, since the girders shuld b dsigned t withstand the impact frces due t flating debris. Using cnstant d"pth girders will als have the advantage f using the same steel frm available frm lcal cntractrs and therefre prvide cnsiderable ecnmical advantage. The cnstant depth leads t the ptimizatin f the span length and the number f bridge river piers. The precast cncrete segmental cnstructin cncept was nt cnsidered due t the lack f experience f the lcal cntractrs in this field. Stewa, Thmpsn and Rizkalla. Prvencher Bridge ver the Red River. 4

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6 tj) P> g 't:l '" ::l P> ::l p :>: N :>; P> P> "" < f) :3 () f) t>: p <> CD CD f) :>: CD p :>: < CD 1 c: WEST ABUTMENT rxp. =---"-;::'''\.i!;: ; : : : ; r. \ j i t!1! ::::: ::: H ::::: ::: :: Hl H 51 -:. <t PER N. 1!:;!!-- 'j!i' EXP t. PER N.2 r.,;- t.rm-".; ::::: ii!u FXED NORMAL SUMMER WATER LEVEL <t PER N.3,.L_,-_, :rrrrrr;!iih! :.:.:.::.: EXP. NORMAL SUMMER Figure 4 (a). Elevatin f Phase f the Bridge 58 <t PER N.4 :;;';J :::!il U EXP <t EAST ABUTMENT EXP. '"

7 t> n m > '1 " :f 'tl :: > :: Q ::<> N :;;- -. > EXSTNG RVER PER EXSTNG BRDGE '1 m :: ::" m '1 t:d '1 Q ()Q m < m '1 n ::" m ::<> m Q ::<> m '1 -- WEST ABUTMENT =-- NO.1 r ", \ \ -\ \ - ---:- - -"'; '\ \ \. / NO.4 RVER BANK Figure 4 (b). Plan view f the existing and Phase f the bridge.

8 Cncrete Alternative The design cncept challenge. t prvide a cnstant depth girder alng the entire bridge. was slved by using the fllwing special design cnfiguratin: - a duble cantilever pretensined precast cncrete -girder ver the piers. - centre drp-in precast pretensined cncrete -girder - unique arrangement f pst-tensined tendns t prvide cntinuity thrugh the end blck f the centre drp in girders. The prpsed design cncept eliminated the need fr haunched girders ver the piers and significantly reduced the length and cst f the pst-tensined tendns and cnsequently enhanced its efficiency. Using a cnstant depth girder significantly reduces nt nly the cst f fabricatin. but als the erectin cst. Based n a maximum capacity f the lcal precast plants in Manitba t handle a 42 m lng by 2.3 m deep -girder. a maximum length f the three intermediate spans was determined as 59.5 m. Nine rws f the precast cncrete 1- girders are prpsed t supp the superstructure. The selected spans als prvide an imprved length f the navigatin channel ver the Red River. The hrizntal curvature f the bridge and the skew lcatin f the piers will be accmmdated at the cnnectins f the precast girders. The lcatin f the river piers in Phase was designed t be in line with the river piers f Phase t facilitate cnnectin f the tw piers and supp the additinal girders fr the future deck expansin. The skew alignment f the river piers and hrizntal alignment f the secnd phase resulted in reductin in the span length f the first phase t an apprximate length f 58 m. The prpsed structural system cnsists f sh precast pretensined duble cantilever -girders with a length f 19.5 m at the bridge pier supping a centre drp-in precast pretensined -girder f apprximately 4 m in length. as shwn in Figure 5. The dapped ends f the duble cantilever girder at the piers will speed the erectin and eliminate the use f temprary river piers n each side f the pier. The dapped ends will als accmmdate the change in the girder alignments required t achieve the hrizntal curvature f the bridge. A ttal f nine rws f girders were required fr the 4-lane sectin f the bridge; The strage capacity f the turning lane at the end f the bridge required the turning lane t extend ver the last tw spans. Therefre. the spacing between the precast girder was varied t accmmdate the increase in the width f the bridge frm three lanes t fur lanes. The spacing between the girders in the first tw spans was designed t accmmdate the three lanes. The spacing between the girder in the third span was varied t accmmdate the changes frm a three lane t a fur lane width. The girder spacing in the fuh and fifth spans was designed t accmmdate a fur-lane bridge. Prestressing System The precast cncrete duble cantilever girder at the pier is pretensined t supp its wn weight. and weight f the drp-in girder. The duble cantilever sectin is als designed t accmmdate the pst-tensining ducts fr the cntinuity f the bridge required t supp the mments due t deck dead lad and t live lads acting n the cmpsite sectin f precast girders and cast-inplace deck slab. The precast cncrete drp-in girders are pretensined t resist their wn weight. the weight f the deck and the cntinuity mment due t the live lad as cmpsite sectins with the cast-in-place deck. The end blcks are als designed t prvide the anchrage fr the pst-tensining system f the duble cantilever sectin required fr the cntinuity. The dapped ends f the duble cantilever sectin are als used t prvide the curvature required fr the bridge in place. The resulting space due t the change f angles f the straight lines f the girders at the dapped end will be filled by cncrete cast mnlithically with the crss diaphragm at the same lcatin. This design cncept limits the need fr pst-tensining nly in the duble cantilever pin ver the piers. This significantly reduces the prestress lsses assciated with pst-tensining due t the reductin in length and Stewa. Thmpsn and Rizkalla. Prvencher Bridge ver the Red River. 8

9 CJ). '> 'i '" p- ' P '> P. N :>;" '> '> "1:1 'i ( p () p ( 'i t>: 'i. O<! ( ( 'i '" p- ( 'APHRAGM 1._ 8--. C!.tOSPAN,l""'- i! il J OUCTS FOR POST 'TENSONNG SYSlD C!.DAP PROPOSED POST TENSONNG SYSTEM FOR CONTNUTY OF THE BRDGE 'ANCHORAGE FOR POST TENSONNG SYSTEM 5 MD SPAN ( '". < ( 'i SEcnON A-A CANTll VER GRDER OlER 1llE PER SEcnON B-B END illock OF lhe PRE - TEN'!ENS1ONED DROP-N CtRlER SECTON C-C MDSPAN OF lhe PRE -TENSONED DROP-N GRDER \ 1iQf; AU. OMENSONS ARE N METERS. Figure 5. Prpsed pst-tensining system fr cntinuity

10 curvature f the tendns. This system eliminates the need fr haunched girders at the pier and results in a mre efficient and ecnmical design f the girders. The sh lengths f the tendns als reduces the lateral frces n the girders due t the hrizntal curvature f the bridge. Hwever, creep effect due t psttensining and its effect t increase the mment at the mid-span was cnsidered. Due t the sh length f the tendns, the pst-tensining will be jacked frm ne end nly, which will ceainly minimize the cst. The thickened end f bth the duble cantilever and the drp-in girder was fund t be large enugh t distribute the anchrage stress and allw easy access fr jacking. Erectin Scheme Erectin stas by placing the duble cantilever sectin n the river piers with temprary bracing frm ne side nly, as shwn in Figure 6(a). The temprary bracing will be used t balance the weight f the drp-in girder frm ne side supped by the abutment and the unsupped end f the duble cantilever sectin as shwn in Figure 6(b). The same scheme will be repeated fr the secnd river pier until the cmpletin f the bridge, as shwn in Figures 6(c) and (d). Casting f the crss diaphragms fllw cmpletin f each span. Pst-tensining will be applied after achieving strength f the cncrete f the diaphragms sufficient fr prestressing specified by the cde. During pst tensining, bridge bearings are designed t slide freely t prevent any stresses n the bridge piers and additinal secndary mments n the superstructure f the bridge. After cmpletin f the erectin, sme f the bearings are replaced t prvide the prper supp systems under service lading cnditins. The bridge deck slab will be 24 rm thick, cnsisting f a 1 rm thick nrmal cncrete layer and a 14 rm high density cncrete verlay. All reinfrcement bars fr the deck slab, traffic barriers, sidewalk and the reinfrcement prjecting frm the precast girders int the deck are epxy-cated. STEEL ALTERNATVE The steel alternative design cnsists als f five cntinuus spans based n the same arrangement f the bridge pier and abutments described fr the cncrete alternative. Based n the same limitatins f the hrizntal and veical elevatin cnstraints, the design cnsisted f three rws f 2.3 m deep trapezidal bx girders supping 24 rm slab deck in a cmpsite actin, as a cntinuus beam. Preliminary discussin with the steel febricatrs indicates that using a plate girder system culd be mre ecnmical, due t the hrizntal curvature f the bridge. Therefre, the design may be altered t six rws f 2.3 m deep steel plate -girder fr the superstructure. The erectin scheme fllws a similar cncept described befre fr the cncrete design cncept. Erectin will sta by placing a duble cantilever sectin ver the river pier and temprarily supp the tw drp-in girders frm bth sides. Cntinuity f the system will be prvided by field splices. After cmpletin f the girder erectin and installatin f the crss-bracing, the cncrete deck will be cast using the same design described befre. SUMMARY AND CONCLUSON Selected upgrading schemes fr a 76-year ld riveted steel plate halfthrugh girder bridge in Winnipeg, Nani tba are discussed. The design cnsideratin and limitatins f the site lead t the develpment f a ecnmical design apprach using precast pre tensined duble cantilever girders with dapped ends t supp drp-in precast prestress2d girders. The cntinuity f the bridge is prvided by a special design f the <,st-tensining tendns fr the sh duble cantilever pin ver the piers wit h an anchrage system int the end blck f the drp-in girders. An erectin h me fr the prpsed system is presented and prven t be ecnmical due t savings in temprary erectin supps and cnstructin time. Stewa, Thmpsn and Rizkalla. Prvencher Bridge ver the Red River. 1

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12 --...pments in Sh Medium Span Bridge Engineering' 9, Prvencher Bridge Over the Red River, Winnipeg, Manitba Fig. 4 King Gerge Flyver - Pier segments n Falsewrx C.D. Stewa Assciate Wardrp Engineering nc. Winnipeg, Manitba Canada B.D. Thmpsn Desifln Engineer Wardrp Engmeering nc. Winnipeg, Manitba Canada Saml Rlzka/1a Prfessr f Civil Engineering University f Manitba Winnipeg, Manitba Canada Fig. 5 King Gerge Flyver: r' '"" f:1. t Pier segments with Sffit Plates 5UO eurnu Summary Alternative design schemes t replace the 76 year ld Prvencher Bridge ver the Red River in Winnipeg, Manitba are presented and cmpared. Future lngterm bjectives and site cnstraints were the majr factrs affecting the eventual chice f a precast prestressed cncrete system incrprating a unique psttensined cnnectin. Preliminary design indicates that this cncept is ecnmical and efficient. An erectin scheme fr cnstructin f the bridge is discussed. :1 -'.--\ COlUMN' t ' ' ". "'US rlt-, tsp 1C [ east _N _ '1.&([ "'EL.O S'l.'C! USTN' fa"c "' m MO " '''.'LT!::r, u ::N::A::[tL 67 + i Fig_ 6 Cmmercial Drive Bridge 14 '"'"'" D'" 1 ; PA(CAST S;[GN("'TAl CONClCf( 8.1: "PO(R 141

13 " BACKG. Prvencher Bridge is a fur-lane undivided radway bridge ver the Red River, near the gegraphic centre f Winnipeg, Manitba, as shwn in Figure 1. The bridge links the cmmunity f St. Bnifece with Winnipeg's central business district. The bridge carried apprximately 37 vehicles a day in 1987, and functined at a level f service F during the p.m. rush hur and D during the a.m. rush hur. Built in 1914, the bridge structure cnsists f seven spans with an verall length f 28.8 metres. The superstructure is cmprised f tw riveted steel plate half-thrugh girders with intercnnecting transversa flr beams. n 1987, the City f Winnipeg cmmissined Wardrp Engineering nc. t invehigate the traffic capacity, the structural integrity f the existing bridge, and t prvide recmmendatins t address the fllwing lng-term bjectives: 1. Prvide a river crssing with a traffic capacity adequate fr the predicted future grwth. 2. mprve the hrizntal and veical radway and apprach alignments. 3. Upgrade lad-carrying capacity f the existing structure t the prpsed legal limits. 4. mprve the navigatin channel. 5. Maintain an acceptable level f service thrughut implementatin f the rehabilitatin r replacement f the existing structure. The investigatin cncluded that rehabilitatin f the existing structure, t meet the abve lng-term bjectives, wuld be unecnmical due t the type f superstructure and deteriratin f the bridge river piers. The study als recmmended an extensive strengthening and upgrading. The inve.tigatin ala required replacement f all bearings, expansin joints and high density cncrete verlay. The wrk culd require clsure f the bridge fr a.ix-mnth perid. Figure 1. Overall view f existing Prvencher Bridge PROPOSED ALTERNATVES Three upgrading alternatives were selected t achieve these specified demands: Alternative 1: New six-lane superstructure n the existing rehabilitated pieu Alternative 2: New three-lane bridge and rehabilitatin f the existing bridge Alternative 3: Tw new three-lane twin structures Evaluatin f the abve three were based n functinal, structural and cst cnsideratins. Using a matrix methd f evaluatin with each area f cnsideratin assigned a relative impance weight ttalling 1 pints, it was fund that alternative 3 was fund t be the ptimum verall slutin. Based n this study it was recmmended t replace the 76-year-ld structure with tw new three-lane twin bridge structures. The prpsal included future prvisin fr widening the bridge t fur lanes. The future expansin includes cnnecting the river piers t prvide supp fr the future additinal median lanes. Using the same bridge piers, tw alternative slutins fr the superstructures using precast cncrete and steel girders were prvided. Due t funding cnstraints, the prject is prpsed t be cnstructed in three phases with the fllwing milestne dates: Phase - cmpletin Nvember 1992, as shwn in Figure 2 - cnstructin f the first (eastbund) new three-lane bridge utilizing existing bridge as the westbund 3-lane bridge with the apprpriate upgrading f the bridge deck Phase - cmpletin Nvember 1999 use f the cmplete bridge in the first phase as tw lanes, each way, as shwn in Figure 2 - demlitin f the ld bridge - cnstructin f the secnd three-lane (westbund) bridge Phase - cmpletin 22 (if required) - extensin f the tw cmpleted bridges int fur lanes each way by cnnecting the bridge piers and widening each superstructure with ne additinal lane. Final design fr the first phase is currently in prgress..,,, Figure 2. Mdels f the prpsed Phases and ),

14 ..t. " DESGN CONSDERATONS The fllwing cnsideratins were fund t be crucial t yield an efficient and ecnmical prject: 1. Pier lcatins were set t prvide equal spans fr the main girders f the tw precast and steel superstructure alternatives. This resulted in using tw abutment:s lcated n the east and west bank f the river and fur river piers. The fundatin types were caissns fr the piers and H-piles fr the abutments. 2. The veical alignment shuld match the existing intersectin at the east apprach which culd nt be ecnmically altered. 3. Elevatin f the bttm f the main girders shuld allw passage f 16-year fld predictins. 4. Central river spans shuld imprve the navigatinal channel in width and height. 5. Alignment. length and lcatin f the bridge piers as well as the superstruct:ures shuld accmmdate an additinal fuh lane expansin f the bridge. 6. The structural capacit:y f the bridge shuld be upgraded t the prpsed HSS3 City standard. 7. The verall structures n the Red River shuld be aesthetically pleasant. since the bridge is very clse t the histric "Frks" develpment in Winnipeg, where the Assinibine River flws int the Red River in the centre f Winnipeg. DESGN LOADS The bridge will be designed accrding t the AASHTO Standard Specificatin fr Highway Bridges. 14th Editin The live lad will be based n the HS3 lane lad and HS53 vehicle lad. The H525 wheel lad will be used fr the deck design. The H53 lane and HS53 vehicle lading prvide a sufficient reserve capacity nt nly fr the current legal vehicle, but als fr the prpsed future legal vehicles. as designated by the City f Winnipeg. Due t the hrizntal curvature and skewed river piers shwn in Figure 1, an ANSYS finite element analysis prgram was used t determine the distributin f the mments, shears and trsinal frces in the superstructure. Thermal stresses were included in the analyses t determine the lateral lad and required expansin jints. The deck was simulated using a plate element and the prestressed girder was mdelled using a beam element with specified height t the neutral axis t determine the trsinal stresses. The finite element mdel used fr the analysis is shwn in Figure 3. SUPERSTRUCTURE DESGN Based n the standard requirsments f the City f Winnipeg fr large prjects such as the bridge under cnsideratin, tw alternative structural design cncepts were cnsidered. The first design cncept utilizes precast cncrete girders t prvide a cntinuus beam with cmpsite actin f the cncrete deck slab. The secnd design alternative uses trapezidal steel bx girders als with cmpsite actin f the cncrete deck slab. The bridge cnsists f five cntinuus spans fr a ttal length f m, as shwn in Figure 4(a) and (b). The restricted elevatin f the bridge, cntrlled by the apprach rads and the 16-year fld level, impsed the need fr cnstant depth girders fr bth cncrete and steel design cncepts. Use f a haunched sectin fr the girders at the piers will reduce the navigatin channel and result in a very unecnmical design. since the girders shuld be designed t withstand the impact frces due t flating debris. Using cnstant depth girders will als have the advantage f using the same steel frm available frm lcal cntractrs and therefre prvide cnsiderable ecnmical advantage. The cnstant depth leads t the ptimizatin f the span length and the number f bridge river piers. The precast cncrete segmental cnstructin cncept was nt cnsidered due t the lack f experience f the lcal cntractrs in this field...,; Vl::l «X) "-1«q d :z a:: "- Cl. r<) ci :z a:: "- Cl. '" Ci :z a:: "- a: Ci z a:: "- 1-""; Vl:J "-1m -,, ft!,,'" <t Cl. <. > c ". " < a. " < (J). " < " 8. c " 8.. " c "" ", ""

15 f <t. WEST ABUTMENT 51 <t PER N. 1 1,,, ,. <t PER N.2 <t PER N. 3 <t PER N. 4 <t EAST ABUTMENT ,",r ), L A Ol 1.--1!=!! C::.r::l ihn! :::: :: illju "" C:.:.Cl il 1\ illlu NORMAL SUMMER WATER LEVEL Figure 4(a). Elevatin f Phase f the Bridge A. - -==----- EXSTNG BROGE \ V -. f' \ a /'-, ) /4--! ' p:s::::;: '\<O",\ -"\-'r-- _ \ \ - - 'i )VJ\,.s< -'-_4' WEST ABUTMENT NO.1 RVER BANK Figure 4(b). Plan view f the existing and Phase f the bridge

16 Cncrete Alternative The design cncept challenge, t prvide a cnstant depth girder alng the entire bridge, was slved by using the fllwing special design cnfiguratin: - a duble cantilever pretensined precast cncrete -girder ver the piers, - centre drp-in precast pretensined cncrete -girder - unique arrangement f pst-tensined tendns t prvide cntinuity thrugh the end blck f the centre drp in girders. The prpsed design cncept eliminated the need fr haunched girders ver the piers and significantly reduced the length and cst f the pst-tensined tendns and cnsequently enhanced its efficiency. Using a cnstant depth girder. significantly reduces nt nly the cst f fabricatin, but als the erectin cst. Based n a maximum capacity f the lcal precast plants in Manitba t handle a 42 m lng by 2.3 m deep -girder, a maximum length f the three intermediate spans was determined as 59.5 m. Nine rws f the precast cncrete 1- girders are prpsed t supp the superstructure. The selected spans als prvide an imprved length f the navigatin channel ver the Red River. The hrizntal curvature f the bridge and the skew lcatin f the piers will be accmmdated at the cnnectins f the precast girders. The lcatin f the river piers in Phase was designed t be in line with the river piers f Phase t facilitate cnnectin f the tw piers and supp the additinal girders fr the future deck expansin. The skew alignment f the river piers and hrizntal alignment f the secnd phase resulted in reductin in the span length f the first phase t an apprximate length f 58 m. The prpsed structural system cnsists f sh precast pre tensined duble cantilever -girders with a length f 19.5 m at the bridge pier supping a centre drp-in precast pretensined -girder f approximately 4 m in length, as shwn in Figure 5. The dapped ends f the duble cantilever girder at the piers will speed the erectin and eliminate the use f temprary river piers n each side f the pier. The dapped ends will als accmmdate the change in the girder alignments required t achieve the hrizntal curvature f the bridge. A ttal f nine rws f girders were required fr the 4-lane sectin f the bridge. The strage capacity f the turning lane at the end f the bridge required the turning lane t extend ver the last tw spans. Therefre, the spacing between the precast girder was varied t accmmdate the increase in the Width f the bridge frm three lanes t fur lanes. The spacing between the girders in the first tw spans was designed t accmmdate the three lanes. The spacing between the girder in the third span was varied t accmmdate the changes frm a three lane t a fur lane Width. The girder spacing in the fuh and fifth spans was designed t accmmdate a fur-lane bridge.. fj!1 U U n j '" - ('j a ; t5 " 5 )3 i '2 z'",,'" j!: i!; t; i fil OU 2s", mr g '" : 'i'i u il! U u '" "'" C " "'" u c ". u '" " a c: "'" c: C " < " u " a.." < " a. f "" 'l'1 '" < i, " d "'" "" Prestressing System The precast cncrete duble cantilever girder at the pier is pretensined t supp its wn weight, and weight f the drp-in girder. The duble cantilever sectin is als designed t accmmdate the pst-tensining ducts fr the cntinuity f the bridge required t supp the mments due t deck dead lad and t live lads acting n the cmpsite sectin f precast girders and cast-inplace deck slab. The precast cncrete drp-in girders are pretensined t resist their wn weight, the weight f the deck and the cntinuity mment due t the live lad as cmpsite sectins with the cast-in-place deck. The end blcks are als designed t prvide the anchrage fr the pst-tensining system f the duble cantilever sectin required fr the cntinuity. The dapped ends f the duble cantilever sectin are als used t prvide the curvature required fr the bridge in place. The resulting space due t the change f angles f the straight lines f the girders at the dapped end will be filled by cncrete cast mnlithically with the crss diaphragm at the same lcatin. This design cncept limits the need fr pst-tensining nly in the duble cantilever pin ver the piers. This significantly reduces the prestress lsses assciated with pst-tensining due t the reductin in length and toj Lr :z!.z "''' z ", 13 Vi "z!! 3; i 11 il!

17 curvature f the tendns. This system eliminates the need fr haunched girders at the pier and results in a mre efficient and ecnmical design f the girders. The sh lengths f the tendns als reduces the lateral frces n the girders due t the hrizntal curvature f the bridge. Hwever, creep effect due t psttensining and its effect t increase the mment at the mid-span was cnsidered. Due t the sh length f the tendns, the pst-tensining will be jacked frm ne end nly, which will ceainly minimize the cst. The thickened end f bth the duble cantilever and the drp-in girder was fund t be large enugh t discribute the anchrage scress and allw easy access fr jacking. H-+ [!::::::J H-+'1 C::::::l " Ereccin Scheme Erectin stas by placing the duble cantilever sectin n the river piers with temprary bracing frm ne side nly, as shwn in Figure 6(a). The cemprary bracing will be used t balance the weight f the drp-in girder frm ne side supprced by the abutment and che unsupped end f the duble cantilever sectin as shwn in Figure 6(b). The same scheme will be repeated fr the secnd river pier until the cmpletin f the bridge, as shwn in Figures 6(c) and (d). Casting f the crss diaphragms fllw cmpletin f each span. Pst-tensining will b3 applied after achieving strength f the cncrete f the diaphragms sufficient fr prestressing specified by the cde. During pst tensining, bridge bearings are designed t slide freely t prevent any stresses n the bridge piers and additinal secndary mments n the superstructure f the bridge. After cmpletin f the erectin, sme f the bearings are replaced t prvide the prper supp systems under service lading cnditins. The bridge deck slab will be 24 rm thick, cnsisting f a 1 rm thick nrmal cncrete layer and a 14 rm high density cncrete verlay. All reinfrcement bars fr che deck slab, traffic barriers, sidewalk and the reinfrcement prjecting frm the precast girders int the deck are epxy-cated. STEEL ALTERNATVE The steel alternative design cnsiscs als f five cntinuus spans based n the same arrangement f the bridge pier and abucments described fr the cncrete alternative. Based n the same limitatins f the hrizntal and veical elevatin cnstraints, the design cnsisted f three rws f 2.3 m deep trapezidal bx girders supping 24 rm slab deck in a cmpsite actin, as a cntinuus beam. Preliminary discussin with the steel fabricatrs indicates that using a plate girder system culd be mre ecnmical, due t the hrizntal curvature f the bridge. Therefre, the design may be altered t six rws f 2.3 m deep steel plate -girder fr the superstructure. The ereccin scheme fllws a similar cncept described befre fr the cncrete design cncept. Erectin will sta by placing a duble cantilever sectin ver the river pier and temprarily supp the tw drp-in girders frm bth sides. Cntinuity f the system will be prvided by field splices. After cmpletin f che girder erectin and installatin f the crss-bracing, the cncrete deck will be casc using the same design described befre. SUMMARY AND CONCLUSON Selected upgrading schemes fr a 76-year ld riveted steel plate halfchrugh girder bridge in Winnipeg, Manitba are discussed. The design cnsideratin and limicatins f che sice lead t che develpment f a ecnmical design apprach using precast pretensined duble cancilever girders with dapped ends c supp drp-in precasc prescressed girders. The cntinuity f the bridge is prvided by a special design f the psc-censining cendns fr the sh duble cantilever pin ver the piers with an anchrage system int the end blck f the drp-in girders. An erectin scheme fr the prpsed system is presented and prven t be ecnmical due t savings in temprary erectin supprcs and cnstructin time. f5 2 w iil J=:! 3D: Z g5 5 Z ffi a: }.... '._._J1::::::::::: : : H-+-{!::::::J f-++- C::::::l H-/---;\. - ' H 11::::::1 n::::::::::: r---j::::::::::: V-. - H----! -- l H'+-U::::::l H./ -f!::::::l H----11::::::1 " -ft. : ",,5 11 ".' r- Y::::::::::: v -'U' H +-! _J H-+ C::::::l " H ;'- --J t--t. -F:::::J.....<ft" :J ". v:::::::::::.." - V 8 V c:., c:., " Cl Q.. '" > :3 a fa<