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Editor - Publisher - AdvertisingRedacteur - Editeur - AnnoncesRedaktion - Herausgeber - InserateIABSE - AIPC - IVBHETH-HnggerbergCH-8093 Zrich, SwitzerlandTel.: (Int+ 41 1)377 26 47Telex: 822 186 IABS CHTelegr.: IABSE, CH-8093 Zrich

Papers published under the sole responsibility of the author(s).Les articles sont publies sous la seule responsabilite de (des) l'auteur(s).Die Artikel werden unter der alleinigen Verantwortung des oder der Autoren verffentlicht.

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IABSE PERIODICA 3/1988 IABSE STRUCTURES C-46/88 41

Repair and Rehabilitation of Bridges - Case Studies IReparation et restauration de ponts - Exemples concrets IInstandsetzung und Sanierung von Brcken - Fallstudien ITable of Contents - Table des matieres - Inhaltsverzeichnis

1. The Sioux Narrows Bridge, Ontario (Canada)2. Instandsetzung und Verbreiterung der Brcke ber die Grosse Erlauf

in Purgstall (sterreich)3. Steel Strip Reinforced Concrete Bridge (Denmark)4. Repairing Work of the Kyrjoki Bridge (Finland)5. La radioscopie pour l'auscultation des ouvrages d'art (France)6. Automatisation pour verinage de haute precision (France)7. Off Ramp of Hanshin Expressway in Osaka (Japan)8. Elevated Bridge in Hanshin Expressway in Osaka (Japan)9. The Bridge in the Radnicka Street in Beigrade (Yugoslavia)

10. Rehabilitation of Yamuna Bridge at Kairana (India)11. Rehabilitation of Girna Bridge (India)

Page42

44464850525456586062

IABSE STRUCTURES - Publication Programme in 1988 - 1989PublicationNovember 1988

February 1989

May 1989

August 1989

IABSE members are invited tocontribute to this series IABSESTRUCTURES. Guidelines for preparing contributions are available atthe IABSE Secretariat.

ThemeRepair and Rehabilitation of Bridges- Case Studies IIReparation et restauration de ponts- Exemples concrets IIInstandsetzung und Sanierung vonBrcken - Fallstudien IIStructures in PortugalConstructions au PortugalBauwerke in PortugalStructures in Sanitary EngineeringStructures en genie sanitaireTragwerke im SiedlungswasserbauRecent StructuresConstructions recentesNeuzeitliche BauwerkeLes membres de l'AIPC sont invites preparer une contribution pourcette sehe CONSTRUCTIONS AIPC.Des directives pour la preparationdes contributions peuvent etreobtenues au Secretariat de l'AIPC

Editorial Deadlinein IABSE SecretariatAugust 1, 1988

November 1, 1988

February 1, 1989

May 1, 1989

Die IVBH-Mitglieder sind eingeladen, einen Artikel fr diese ReiheIVBH BAUWERKE zu unterbreitenRichtlinien fr die Vorbereitung derBeitrge knnen beim Sekretariatder IVBH bezogen werden

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42 IABSE STRUCTURES C-46/88 IABSE PERIODICA 3/1988

1. The Sioux Narrows Bridge, Ontario (Canada)Owner: Ministry of Transportation of

OntarioDesign: Structural Office and Research andDevelopment BranchWork Duration: 6 monthsCompletion: 1982The Sioux Narrows Bridge is on Highway 71 linking FortFrances and Kenora in northwest Ontario. The bridgewas constructed in 1936 with a wooden Howe trussmain span of 64 m, Figure 1. It is believed to be thelongest Single span wood highway bridge in NorthAmerica.This bridge was one of the first to be listed under theHeritage Bridge Program of the Ontario Government,being an outstanding example of wood bridge construction, built of B. C. Douglas Fir in sizes no longer availableMost timber highway bridges have been replaced afterabout 40 years. Plans were prepared for the replacement of the Sioux Narrows bridge in 1975 when thedeck was showing signs of deterioration, and the vehicleloads greatly exceeded the design loads. A conditionsurvey showed the truss members to be in goodcondition, however, and studies were started to try torehabilitate and keep this heritage bridge in service.Analysis indicated adequate load capacity in the maintrusses, but a significant overstress in the transversefloor beam king post and tie bars, Figure 2. The floorsystem consisted of a traverse nailed laminated wooddeck on longitudinal wood stringers, which weresupported by transverse wood beams every 2.3 m.

At the time of these studies, the concept of a prestressed longitudinally laminated wood deck had beendeveloped by the Ministry. This prestressed deck typeacted like a homogeneous slab, and exhibited muchbetter load distributed characteristics than the old nailedlaminated decks. It was calculated that the longitudinaldistribution would be improved enough to reduce thestresses in the floor beams to acceptable levels. Thedecision was made to replace the old deck with a newwood deck, with 190 mm deep laminated prestressedtransversely with 25 mm bars at 1.525 m centres,tensioned by hydraulic jacks.The deck was replaced one lane at a time, Figure 3, sothe bridge could remain open to traffic. The prestressingbars were coupled together for construction of thesecond lane. A new asphalt wearing surface was thenapplied to the wood deck.Fll scale bridge testing using custom designed loadvehicles. Instrumentation and mobile laboratory for thecomputerized data acquisition System is a regulrfeature of the Mmistry's evaluation procedures. Loadtesting of the deck system was carried out before deckreplacement and after, Figure 4. Eight floor beams wereinstrumented by attaching strain gauges to the steel tiebars. The greatly improved longitudinal distributioncharacteristics of the prestressed deck was confirmedby a reduction of 35% in the truss bar strains for thesame tests as carried out on the old deck. No furtherstrengthening of the floor system is needed. The onlyother members that may need replacing are the maintruss hanger bars, which will be tested shortly.

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1Fig. 1 General view of bridge

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Instandsetzung und Verbreiterung der Brcke ber die Grosse Erlaufin Purgstall (sterreich)

Eigentmer:Baujahr:Instandsetzung:Entwurf:Ausfhrende Firma:Bauaufsicht:Bauzeit:Verkehrfreigabe:

Land NiedersterreichLandesstrassenverwaltung,Brckenbau18721980Dipl. Ing. K. Koncki, Zivilingenieur fr Bauwesen, WienBau- und Zimmermeister Ing.K. Grillnberger, Purgstall ander ErlaufAbteilung BI2-D, Brckenbau,beim Amt der N Landesregierung7,5 Monate1980

Die Bogenbrucke, genannt Marktbrcke, berbrckt dietief in eine Schlucht eingeschnittene Grosse Erlauf undverbindet so die beidseits des Flusses gelegenen Ortsteile. Auf Grund des Ergebnisses einer routinemssigenBrckenkontrolle wurde eine allgemeine Instandsetzungvorgemerkt. Die sehr schmale Fahrbahn, der nur aufeiner Seite verfgbare Gehsteig und der sichtbarmangelhafte Zustand der Brstungsmauern veranlassteberdies die Gemeindevertretung von Purgstall bei derBrckenbauabteilung des Amtes der N Landesregierung einen Umbau des Objektes zu beantragen. Eswurde Zivilingenieur Dipl. Ing. K. Koncki mit der berprfung des Bestandes und der Ausarbeitung einesInstandsetzungs- und Verbreiterungsprojektes beauftragt.

berprfung und Naturaufnahmeber die im Jahre 1872 erbaute Marktbrcke lagenkeinerlei Aufzeichnungen vor, weil das Brckenarchivdes Landes Niedersterreich im Laufe des 2. Weltkrieges durch einen Brand zerstrt worden ist.Aufschlussbohrungen lieferten die ntigen Bohrkerneund Kenntnisse ber den Aufbau der Bogenbrucke.Ergebnisse/Abmessungen:Eingespannter kreisfrmiger BogenAchssttzweite 23,44 mBogenstick 5,19 mBreite des Bogens 6,88 mDicke des Gewlbes 1,25 mQuadermauerwerk:Porser Kalkstein (Rauhwacke), sehr guter Zustand,stark streuende Druckfestigkeiten von ca. 7 N/mm2 bisca. 20 N/mm2. Gewlbeoberseite verputzt, darber zurAbdichtung ein 5 cm starker Lehmschlag. Fugenmrtelteilweise ausgewittert, die Festigkeit war nicht feststellbar; in den Bereichen der Auswitterung starkerPflanzenwuchs.

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Bild 1 Brcke ber der Grossen Erlauf in Purgstall,1977Hinterfllung:Dicht gelagertes Gemenge aus Rundschotter, Kies undSand.Widerlager:Direkt an die steilen Felswnde der Schlucht angebaut.Vorhandes Kavernen waren bei der Erbauung mit einemGemenge aus Mrtel und Steinen ausgefllt worden.Fundierung:Die Fundamente sind unmittelbar auf die felsige Flusssohle aufgesetzt. rtliche Auswaschungen (Kolke) bedeuteten eine gewisse Gefhrdung. Eine eingehendeFlussgrundsondierung ergab die Stellen fr Sicherungs-massnahmen.Brstung:Aus Sandstein, an vielen Stellen rissig und abgewittert,nicht erhaltungswrdig.Zusammenfassend kann der Zustand der tragendenBauteile als zufriedenstellend bezeichnet werden. Auchdie sicherlich vorhandenen Tragreserven, ableitbar ausdem 107jhrigen weitgehend schadensfreien Bestand,rechtfertigten eine Instandsetzung und eine Adaptierungauf eine zeitgemsse Bentzbarkeit.Es konnte davon ausgegangen werden, dass eine Ver-grsserung der stndigen Last durch die Verbreiterungund die erhhten Verkehrslasten aus dem nunmehrmglichen Begegnungsverkehr noch gut vom Bauwerkaufgenommen werden knnen.

Statische BegutachtungDer statischen berprfung des Bestandes und derProjektierung der Verbreiterung wurden die erhobenenNaturmasse und Materialkennwerte sowie die geltenden NORMEN zu Grunde gelegt. Einzelne Masse unddie Bogenform wurden an grossformatigen Photos ermittelt. Die Berechnung wurde fr die Lastflle stndigeLast und Temperaturnderung, +/- 10C, durchgefhrt.

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Fr die Ermittlung der Verkehrslasteinflsse wurden dieentsprechenden Einflusslinien fr 3 reprsentativeStellen erstellt und nach Maxima und Minima ausgewertet. Im Scheitel und im Viertelpunkt traten maximale Druckspannungen von 1,33 N/mm2 und keine Zugspannungen auf. Im Kmpferbereich ergaben sich imExtremfall Randdruckspannungen von 2,38 N/mm2 undZugspannungen von 0,41 N/mm2. Bei Ausschluss vonZugspannungen eine maximale Randdruckspannungvon 2,48 N/mm2. Damit wurde im ungnstigsten Falleine Sicherheit von mindestens 3 erreicht. Wegen desAbbaues der Spannungsspitzen durch Kriecherscheinungen ber einen Zeitraum von 107 Jahren drfte dieSicherheit hher liegen.Die Ergebnisse der in sich genauen statischen Nachrechnung sind wegen der doch unprzisen Ausgangs-grssen diskussionswrdig Auch aus diesem Grundwurde die vor der Nachrechnung geschtzte Lastbeschrnkung fr LKW ber 20 t belassen.

Projektbeschreibung und BaudurchfhrungDie Vergrsserung der Nutzbreite von ca. 6,3 m auf9,0 m teilt sich 6,00 m fr die Fahrbahn und die beidseitsangeordneten Gehsteige von je 1,50 m.Nach den erforderlichen Abbrucharbeiten wurde dieGewlbehinterfllung unter geringem Druck (2 bar)durch Zementinjektionen weiter verfestigt, ca. 750 lfmBohrungen, D 5 cm, in einem Raster von 75 cm; verbraucht wurden fr die Injektionen ca. 47 t Zement.Quer ber die Bogenbrucke wurden auskragende Fertigteilbalken aus Stahlbeton der Gte B 400 verlegt, imAuskragungsbereich wurden Stahlbetonfertigteilplattenaufgelegt, auf die hernach im Verbund ein bewehrterAufbeton zur Erzielung einer Durchlaufwirkung aufgebracht wurde. Im Fahrbahnbereich wurde ber denFertigteilbalken eine durchlaufende und lastverteilendeStahlbetonplatte auf elastischer Bettung hergestellt. Dieneue Brstung aus Stahlbeton wurde dem Original mitgeringen Vereinfachungen nachgebildet. Die Pfeiler derBrstung bestehen aus profilierten Stahlbetonhlsen,die ber vertikal stehende verzinkte und ber Bodenplatten am Tragwerk befestigte I-Profile gestlpt undausbetoniert wurden. Eine dachfrmige Abdeckungbildete den Anschluss nach oben. Der ussere Gesims-abschluss besteht aus profilierten Stahlbetonfertigteilen. Alle Sichtflchen wurden zur Anpassung an denAltbestand sandgestrahlt und die Betonteile deshalb miteiner erhhten Betondeckung hergestellt.Die Brckenentwsserung war unzulnglich. Um strende Durchdringungen des Bogens zu vermeiden, wurdedie Fahrbahn kuppenfrmig ausgebildet und an denBrckenenden Einlaufschchte vorgesehen, die an diebestehende Strassenentwsserung angeschlossenwerden konnten. Auch die Entwsserung der Trag-werksabdichtung erfolgt ber diese Schchte.Besondere Schwierigkeiten bei der Baudurchfhrungergaben sich aus dem Bestand von verschiedenen Einbauten (Leitungen), die planlich nicht erfasst waren undim Zuge der berprfung auch nicht halbwegs exakterfassbar waren, ohne das Objekt weitgehend abzutragen.

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fhBild2 Auskragung von unten, 1988

Bild 3 Brcke ber der Grossen Erlauf in Purgstall,1988

Fr den Bau der Verbreiterung war eine Einrstung nichtntig, lediglich fr die Beseitigung des Bewuchses unddie Ausbesserung bzw. Herstellung der Verfugung desQuadermauerwerkes waren leichte Gerste erforderlich. Der Fussgnger- und Radfahrverkehr ber dieBrcke war immer mglichDieses Projekt, insbesondere die Wiederherstellung derBrstung, wurde dadurch gewrdigt, dass die Gemeinde Purgstall mit der Goldenen Kelle, einem Preisfr besondere gelungene Ortsbildpflege, ausgezeichnetwurde.

(P. Ortner)

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3. Steel Strip Reinforced Concrete Bridge (Denmark)Owner: The Danish Road Directo

rate by County of FrederiksborgDesign and supervision: Cowiconsult, ConsultingEngineers and PlannersAS, CopenhagenContractors: Armton AIS, CopenhagenWorks Duration: May 10 - Juny 22, 1985Closed for traffic: June 6-July 4, 1985Main Quantities of MaterialSteel plates st. 37 1931 kg (41 m2)Other Repair WorksWater proofing membrane: 320 m2Wearing course: 320 m2Expansion joints: 30 mIntroductionThe canal bridge at Frederiksvaerk was reinforced in1985 by glueing steel strips onto the underside of thebridge deck. This method is relatively unknown inDenmark, where similar cases of bridge strengtheninghave normally been solved by adding external prestressing cbles and additional reinforced concrete.The reinforced concrete bridge in question is an archbridge 45 m long, 13.5m wide, built in 1950 anddesigned by Cowiconsult. Above the 27.5 m span of thearch itself, the bridge deck is divided into sections. Ateither end of the arch there is a 7 m bay.

m ms*** imm

Canal Bridge at Frederiksvaerk.

StrengtheningThe reinforcement was necessary in Order to improvethe load-bearing capacity of the bridge to meet present-day load Standards. An assessment of the bearingcapacity of the intact bridge had shown that the structure of the 2 side bays did not comply with theseStandards. By adding in these bays some local reinforcement, a higher load-bearing Classification for the bridgecould be obtained.In each of the two end bays 9 steel plates(400 x 5850 x 6 mm, st. 37) were bonded to the concrete. When the bridge is subjected to the stipulatedmaximum load, the permissible tensile strength for thesteel will only be 50% utilized. In addition, the shearforce to be transferred by the glue Joint is only 10% ofthe permissible force. In other words, reinforcementwith plenty of built-in safety.The planning of the reinforcement work began in 1984.This involved some study of experience obtained abroadand some contact with experts from other countries,particularly in regard to the choice of bonding agent. Thisresulted in the choice of an epoxy bonder (Sikadur 31).Before the actual work on reinforcing commenced, testshad to be made of the tensile strength of the bridgeconcrete and the adhesive properties of the bondmgagent on the concrete surface. Altogether, tests weremade with six plates all of which were tested to breaking point.All ruptures occured either in the concrete itself or onthe surface between the concrete and the bondmgagent Based on the results, the compressive strengthof the concrete was assessed as minimum 25 N/mm2.To afford the best possible contact surface, extensivepreparation of the concrete surfaces had to be carriedoutFrom measurements taken in connection with a loadbearing test, it was established that the bondmg agentfully transferred the shear forces between the concreteand the steel plates. In addition, the distribution ofstresses in the steel plates as measured was in keepingwith the calculated stress-conditions for cracked anduncracked concrete cross-section.A load-bearing test carried out one year later producedlittle divergence in measurements from the year before.It is intended to repeat the load-bearing tests for sometime to come, to check whether the function of thereinforcing might alter in the course of time.

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G1 I l** I i

Bolts only at end of plateSteel plates bonded by epoxy

Cross section of bridge deck.

Other Repair WorksDuring the same period other repair works took place,such as replacement of water proofing membrane andwearing course The new water proofing membraneconsists of 2 layers of 3 mm fibre reinforced bitumensheetings glued on top of the repaired bridge deck. Aspecial 3 mm plastic/bitumen protection membranethen was applied. Then. a porous asphalt layer of10-15 mm was applied as a drain layer. Finally, 2 layersof wearing course were applied.New expansion joints at the bridge ends were alsocarried out (Thorma joint type). Besides. new trafficrailings were installed along the carriageway in Order toprevent heavy vehicles from entering the footwalks.

(J0rgen Birger Kragerup, Leif Jonsen)

tTensile stress at rupturecfT= (N/mm2)

1.941 81 1.74 1.74 1 811.67

Adhesion of the bonding measured by tests on 6 testslabs.

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Bridge deck reinforced with bonded steel plates. The strain gauges were used to verify the efficiency of thebonding. The bolts are removed after completion.

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4. Repairing Work of the Kyrjoki Bridge (Finland)

Main caracteristicsof the bridge: - arched span 26,50 m- overall length 54,00 m- width of theroadway 7,75 m- width of thewalkway 3,25 mOwner and contractor: Roads and WaterwaysA dministrationDistrict of KymiDesigner of therepairing works: Consulting EngineeringCompanyJorma Huura Ky, Tampere,FinlandDate of construction: 1963Date of repairing: 1983The Kyrjoki bridge (Fig. 1) is located in a dell whichcauses that water is flowing on to the bridge more thanotherwise. During wintertime the bridge is exposed tothe salt-frost action. The bridge was built in 1963 whenconcrete was not air entrained. Consequently the concrete in the edge beams was scaling very badly twentyyears after construction of the bridge.During designing of the repairing work, the wideningpossibilities of the bridge were also studied. The calculations proved that the bridge could be made wider by onemeter so that the total width of the walkway became3,25 m. The cantilever edge was designed to carry100 kN concentrated load which corresponds to the axleload of the vehicles used for road maintenance.

*mm' ..;Wm ~~~~~... -...iimFig. 1 The Kyrjoki bridge before repairing

The edge of the existing structure was stenghtened bytwo-meter-long steel plates which were clued by epoxyresin to the surface of the bridge deck (Fig. 2). Thethickness of the Joint between the plate and the concrete surface was 1 mm. Epoxy resin was injeeted intothe Joint. The shear strength requirement of the epoxyresin was 1.0 MN/m2. The injection was done beforeremoving the moulds and the scaffoldings. The workwas based on the research done by Technical ResearchCentre of Finland. The corresponding method has beenused afterwards successfully in various repairing works.It was calculated that the distance of the cracks in theslender cantilever would be 1,5 meters. On the otherhand, it was supposed that the cracking of the concrete

x 50 l i750 35 Y20002% iir-i tacadam OO M 'JL Ji,III1_ 0 750 ^^xisting structure

Steel plates - 160 x 5 c/c 680 Original edge beamFig. 2 The cross section of the cantilever edge with the clued steel plates

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could be avoided by over-dimensioning the reinforcement, by proper mix design and by careful planning andexecution of the concreting and curing works. Theseassumptions proved to be right.The reinforcement bars of the old structure wereexposed about one meter and the new bars wereanchored into the old concrete structure (Fig. 3). Thequantity of the cement in concrete was 300 kg/m3 andthe water-cement ratio was 0,50. The size of the aggregate was between 0 and 16 mm. Air entraining agent(aircontent 4,5-5,5%), plasticizer and retarder (retarda-tion 24 h) were used. The concreting work started atnoon and the work was finished the following morningat 6 o'clock. The air temperature was between +15 and+ 18C.

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Fig. 3 The reinforcement of the cantilever

Fig. 4 The new sidewalk after the repairing workThe protecting and surfacing layers of the repairedbridge deck were accomplished as follows (Fig. 2):1. The waterproofing was made of rubberbitumenmembrane, which was covered by ordinary bitumensheets.2. The levelling and drainage layer was made ofmacadam (without binder).3. The wearing course was layed of asphaltic concrete.The total costs of the repairing works wereUS $ 100000. Under these circumstances, the construction costs of a new pedestrian bridge would have beenUS$200000. This means that the savings wereUS$100000The repairing work was made five years ago and theconcrete structures are still in good condition. It isamazing that there are no cracks in the slender edgecantilever whatsoever. (Jorma Huura, Kalevi Falck)

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5. La radioscopie pour l'auscultation des ouvrages d'art (France)Coordination:Etudes-utilisationConception-fabrication:

Laboratoire Central desPonts et Chaussees, ParisLaboratoire regional desponts et chaussees de BloisCentre d'Etude et de Construction de Prototypes,Le Grand Quevilly

IntroductionLes methodes de gammagraphie sont encore actuellement les seules techniques d'auscultation non-destruc-tives des ouvrages d'art fournissant des informationsprecises sur la geometrie et l'etat de la structure internedes ponts en beton arme ou precontraint. Elles peuventpermettre, par exemple, de mettre en evidence tempsdes defauts indetectables par les methodes classiquesde surveillance et d'examen visuel, et qui risquentcependant de mettre en cause terme la perennite del'ouvrage.Cependant, la gammagraphie classique, qui utilise engeneral une source de Cobalt 60 et des films radio-graphiques, presente l'inconvenient d'etre lente et surtout ponctuelle. En effet, les films ne mesurent que 30sur 40 centimetres et un grand nombre de cliches estdone necessaire pour obtenir une information representative. En outre, la gammagraphie ne s'applique qu' desparois de beton d'epaisseur maximale de 60 centimetres, ce qui interdit l'examen de nombreuses partiesd'ouvrages.

Les Laboratoires des Ponts et Chausses frangais ontdone decide d'ameliorer ces Performances, et leursrecherches ont abouti la mise au point du SystemeSCORPION pour la radioscopie des ponts en betonarme ou precontraint.La radioscopieEn radioscopie, l'emetteur de rayonnement est ungenerateur electrique de rayons X et le detecteur unSysteme special capable de fournir en temps reel uneimage sur un moniteur TV, cette image pouvant etreenregistree sur bnde magnetique.Si cette technique est courante dans le domaine medical, o l'on utilise des rayonnements de faible energie,son application aux ouvrages d'art a necessite la conception d'un accelerateur lineaire de haute energie (4 Mega-electrovolts) utilisable sur chantier et la mise au pointd'un nouveau convertisseur rayons X-Iumiere visibleadapte cette energie (brevet L. P. C).Le rayonnement X emis par l'accelerateur lineaire (typeNeptune IV, fabrique par la societe CGR-MeV) possededone une energie nettement superieure celle desphotos gamma du Cobalt 60 et surtout le flux de cerayonnement est environ 60 fois plus eleve. Ces deuxcaracteristiques permettent d'examiner des epaisseursde beton deux fois plus importantes, avec des tempsd'exposition considerablement plus courts et une meil-leure definition de l'image. En outre, l'utilisation de

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Fig. 1 Deux exemples de resultats de radioscopie et leur interpretation

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J% IABSE PERIODICA 3/1988 IABSE STRUCTURES C-46/88 51

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i#***tf&0^^5* R S ?WQWwH.viriZm\l*\ ^>,

f/gj. 2 Systeme SCORPION pour la radioscopie d'un pont caissonl'accelerateur lineaire rend plus facile la protection radio-logique du personnel et du public: il n'est dangereux quelorsqu'il est sous tension, ce qui permet son transportsans contrainte particulierePour la radioscopie des ouvrages d'art, l'accelerateur etle detecteur sont deplaces simultanement par tele-commande de part et d'autre de la paroi en beton ausculter. II est ainsi possible, par exemple, dans le casd'un pont en beton precontraint, de suivre les cbles surpartiquement toute leur longueur, verifier leur position,examiner leur etat et celui des gaines (fils detendus ourompus, manque du coulis d'injection et etendue dudefaut, deformation des gaines observer lesancrages, l'homogeneite du beton, ete (figure 1).Les images etant obtenues en temps reel, la sensibilitede la radioscopie est plus faible que celle de la radio-graphie (qui permet d'utiliser des temps d'exposition deplusieurs minutes). Son application est done limitee des parois de 70 centimetres environ; pour desepaisseurs plus importantes (jusqu' 1,1 metre) il esttoujours possible de realiser des cliches radiographiquescomplementaires.Utilisation sur chantierL'accelerateur lineaire, dont la partie emettnee forme uncube de 75 centimetres d'arete environ pesant 240 kg,necessite pour etre utilise sur ouvrages d'art, un bras demanipulation concu specialement sous la forme d'unepasserelle qui peut etre aussi utilisee pour l'examenvisuel du pont.Pour des raisons de radioprotection, cette passerelledoit etre entierement telecommandee partir d'un

camion laboratoire situe environ 80 metres de la zoneauscultee. De plus, eile doit posseder des qualites derigidite et de stabilite sffisantes pour obtenir desimages de bonne qualite, ce qui interdit l'utilisation despasserelles de visite classiquesEtant donne la diversite des geometries des ouvrages examiner, il n'a pas ete possible de realiser des le departun appareil universell c'est pourquoi, le developpementdu Systeme SCORPION comprend plusieurs etapes.Dans un premier temps, un appareil a ete construit pourla radioscopie des ponts caissons (figure 2). Dans cecas, le detecteur est place l'interieur de l'ouvrage: ilpossede son propre Systeme de deplacement, sesmouvements telecommandes depuis le camion laboratoire etant synchronises avec ceux de l'accelerateursitue sur la passerelle. Cet appareil est operationneldepuis 1986.Au vu de la qualite des resultats obtenus, il a ete decided'etendre les possibilites de SCORPION d'autrestypes d'ouvrages et d'abord aux ponts poutres. Cetteadaptation sera terminee en Juin 1989.ConclusionSCORPION est le premier Systeme de radioscopietelevisee en haute energie utilise de fagon operation-nelle sur ouvrages d'art en beton arme et precontraint.Ses Performances, notablement superieures celles dela gammagraphie classique, devraient lui permettre undeveloppement rapide pour le contrle de fabricationd'ouvrages neufs et l'auscultation d'ouvrages anciens.

(J. P. Chevrier, R. Guinez, J. Marignier)

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6. Automatisation pour verinage de haute precision (France)Maitre d'Ouvrage:Maitre d'CEuvre:Entreprises:Laboratoire:

Etat - Direction des RoutesDDE du Val de Marne et DRE del'ile de FranceSitraba, Savoure, CipecLREP (Bourget)

Description de l'ouvrageLe viaduc de la Bievre, qui permet le franchissement dela valiee de la Bievre par l'auroroute A6a Arcueil (94)est constitue de deux tabliers comportant chacun 6travees independantes de 36 m de portee.Chacune de ces travees est formee de 5 poutres sousChaussee en beton precontraint reliees par 5 entretoisesdont 2 sur appui. L'altitude du tablier par rapport auterrain naturel est variable de 10 18 m de hauteur.L'ouvrage a ete realise il y a une trentaine d'annees etnecessite actuellement des actions d'entretien specia-lise consistant notamment en l'echange des appareilsd'appuis et la refection de leurs bossages.Cet ouvrages, dont la conception est anterieure auxdirectives de SETRA, n'integrait par les dispositionsnecessaires un remplacement aise des appareilsd'appui, tant geometriquement pour la mise en place deverins que mecaniquement pour la resistance des entretoises sur appuis.II etait done indispensable, pour le verinage de chaqueligne d'appuis, de trouver des solutions innovantes auxproblemes poses.Respect des contraintes de circulationAfin de ne pas gener la circulation tout en laissant letemps necessaire la refection des bossages et desabouts de poutre, il a ete convenu de veriner les deux

1

**.

Fig. 1 Montage des palees au droit d'une pile

travees situees de part et d'autre d'une meme pile l'aide de palees metalliques speciales. De ce fait, lacirculation n'etait interrompue que le temps du verinagec'est--dire, quelques heures de la nuit.Pour le cas particulier des eulees il etait necessaire deredescendre le soir meme afin de ne pas creer demarche d'escalier sur la Chaussee et d'aeeepter la genedue au peu de hauteur disponible pour reconstituer lesdes d'appui.Precision du verinageLe probleme le plus important restait celui de laprecision du verinage. En effet, celui-ci consistait en unedenivellation de 2 x 5 poutres avec 0,3 m de precision,alors que les verins etaient positionnes sur des paleesde 15 m de hauteur qui risquaient elles meme de tasserpar adaptation et par deformation elastique inegale.Par ailleurs, la deformation elastique du chevetre del'ordre de 0,3 0,6 mm en le dechargeant du poids despoutres lors du verinage etait superieur la precision deia mesure souhaitee.Afin de tenir compte de ces problemes de deformation,il est necessaire de disposer d'une reference fixe demesure. A cet effet, des fils Invar equipes de capteursde deplacement sont descendus des poutres jusqu'ausol et permettent d'obtenir l'information absolue surles deplacements. Mais possedant cette information, iln'etait pas imaginable de la traiter manuellement: laprecisin souhaitee etant trop grande.L'asservissement des verins au deplacement apparais-sait comme la Solution adaptee car, apportant les avantages suivants:- regroupement de toute les informations sur unecentrale permettant une visualisation instantanee de

la position des poutres (sensibilite de lecture desappareils de contrle 0,1 mm).- rapidite et fiabilite des Operations de verinage.- possibilite d'interruption immediate en cas d'anoma-lies et possibilite de fonctionnement manuel.- standardisation d'un verinage de haute precision quiallait se repeter de nombreuses fois (28 verinages oudeverinages pour ce viaduc).Automatisation des verinagesL'asservissement realise est base sur un micro-ordinateur sur lequel sont transferees les valeurs des deplacements des poutres par l'intermediaire de capteurs etd'un interface approprie.Un logiciel special permet d'analyser les valeurs desdeplacements et d'en deduire les actions necessaires auniveau des verins. II a pour but d'empecher que deuxpoutres quelconques aient plus de 0,3 mm de denivel-iees ce qui revient creer une boucle o les verinseffectuent leur course en se rattrapant ou se depassantmais toujours avec moins de 0,3 mm d'ecart.Avant de passer au verinage de l'ouvrage, il fallait testerle bon fonctionnement de l'ensemble hydraulique,electnque et informatique.

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7. Off Ramp of Hanshin Expressway in Osaka (Japan)

Owner:Consultant:Contractor:Work's duration(Field work):Repair date:

Hanshin Expressway Public CorporationProf. Dr. K. HorikawaTakara Giken Co. Ltd.4 months (2 weeks)1985

Reshape of End Part of Plate Girder BridgeCorrosion is one type of damages in steel bridges inservice and is apt to occur near expansion joints, bearingshoes and so on. In these parts, the thickness ofmembers decreases by corrosion. In an extreme case,the fillet welds between web and lower flange are lost,as shown in Fig. 1. The cause of this example wasconsidered to be the leakage of water with free limebeacuse Stalagmite was found on the lower surface ofslab and water dropped even on a fine day.For the repair of the bridge, following three procedureswere discussed as alternatives.1) Cutting off the corroded part, then a new memberwith T section is connected using H.T. bolts.2) Cutting off the corroded part, then a new memberwith T section is connected using welding at site.3) Cutting off the corroded part, then only a new lowerflange is connected using welding at site. As a result,the plate girder Is reshaped from uniform section tonon-uniform section.

Before the actual repair, a model plate girder wasreshaped from a uniform section to a non-uniform section by gas cutting and welding under loading. Thesafety of structure during the repair and the deformationafter the repair were studied and also the ultimatestrength after the repair was measured. Through theseexperiments the possibility of the repair and the cares tobe paid in the actual repair were examined.From the above results, the procedures for the repair tobe recommended are as shown in Fig. 2.1) Firstly, welding of vertical stiffener2) Secondly, welding of horizontal stiffeners

It is desirable that the stiffeners marked by * in Fig. 2is welded on the same level as the lower flange fixedin stage 5) and welded to the next vertical stiffener.3) Then drilling of a hole

4) And gas cutting5) Finally, welding of lower flangeAssuming an existing girder with the same proportion asthe model, the stresses on each stage are considered tobe as shown in Fig. 3.

(1) Welding of verticalstiffener

These procedures have both merits and dements. However, procedure 3) has merit for repair of bearing shoes,because the working space is secured after the reshapework, and the safety of structure is maintained duringthe repair.The safety of structure during the repair and the ultimatestrength after the repair should be examined in the caseof heating process under loading. w

(2) Welding of horizontalstiffeners divided intofour parts

'.Q:

s

(3) Drilling a hole(4) Gas cutting

(5) Welding of lower flange

Fig. 1 An example of corrosion Fig. 2 Recommended procedures

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IABSE PERIODICA 3 1988 IABSE STRUCTURES C-46/88 55

Stage I

Stage I Original sectionAssume the stresses due to the dead loadand the live load as shown in the figureStage II Welding of stiffenersThe live load is not considered, because thereis no traffic The stress due to the dead loaddoes not changeGas cuttingThe stress. that exists in the section to be cutoff. is redistnbuted Also, the force is sharedby horizontal stiffeners The stress afterredistribution can be calculated from thefollowing three conditions1) Difference of strains exists betweenstiffeners and web2) The integral of moment by the stressesequilibrates with the external moment3) The integral of the stresses is equal tozero

Stage IV Welding of lower flangeThe stress due to the dead load does notchange The entire section is effective toresist the live loadThe existing bridge after the repair is shown in Fig 4

(K. Horikawa, H. Suzuki)

Dead Live Totalload load load100 40 USLf. 7_ WAi SB W00 JLflOl-0* 126yA-

160 126 46.7Ai n i89 / 1 18w

Stage I

Stage U

Stage m

Stage IV32 Tr

Fig. 3 Schematic example of stress (MPa)

\-

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8. Elevated Bridge in Hanshin Expressway in Osaka (Japan)Owner:Consultant:Contractor:Work's duration(Field work):Repair date:

Hanshin Expressway Public CorporationProf. Dr. K. HorikawaTakara Giken Co. Ltd.6 months (2 weeks)1986

Replacement of Flange without Traffic InterruptionHeavy corrosion appeared at the lower flange plate, thelower end of web plate and one of the vertical stiffenersof a plate girder bridge (Fig. 1). It was caused by leakageof water through the timber plate used for a mold, whichhad been left in the concrete slab after completion. Thelocation of the corroded area was the main girder nearthe span center of a 2-span continuous girder bridge forhighway. The bridge was an elevated bridge in such aheavy traffic urban area (Fig. 2), that it was impossible touse any intermediate supports for the girder duringrepair and also impossible to suspend the traffic on thehighway. Thus, the corroded area had to be repairedunder loading and Vibration.Following alternatives were discussed.1) To remove rust from the surface of the corroded areaand paint it.2) To remove rust from the surface of the corroded areaand weld a reinforcing cover plate.3) To remove the corroded area and install newmembers.Thinking of the heavy corrosion, method 3) was adoptedin the repair using a by-pass member, which was to

carry the force that was carried by the part to beremoved, during the repair This repairing method isnamed By-pass Method. Connections of the new partwere of both welding and fastening with H.T. bolts, thelower flange was welded and the web was fastenedwith H.T. bolts.Before the repair at Site, experiments were conducted inthe laboratory under similar loading conditions to thecorroded part, containing all the repair process thatshould be done at site such as gas cutting and weldingto examme the validity of the by-pass method as well asthe workability of the field welding.According to the results of experiments, the by-passmember was applicable to the actual repair at site andalso the stress caused by the shrinkage due to weldingplayed a role of intentionally induced pre-stress.However, it was found that lack of fusion and cracks inthe first layer could not be avoided when welding wasconducted under Vibration. Therefore, to prevent thoseflaws, following procedures were considered asnecessary:1) To reduce the Vibration as much as possible2) To make the X type groove for welding and toremove the first layer by gougmg3) To keep the root gap from 1 mm to zero4) To make a scallop in the part of web plate where thewelding line crosses the web plate5) To set end tabs6) To adopt the relay welding process.The repaired girder is shown in Fig. 3. The TechnicalMerit of Kansai Branch of JSCE was awarded for thiswork.

(K. Horikawa, H. Suzuki)

iHsJf'Ti%&*.:.,,&**

-^E< 5H%(4j~~~f-

Fig. 1 Corrosion in a bridge

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-) ~?*L7

0m.,s

Fig. 2 Elevated bridge

~

Fig. 3 Girder after remedy at site

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9. The Bridge in the Radnicka Street in Beigrade (Yugoslavia)

The City of BeigradeConstruction: Directorate forBridges, Bei gradeRehabilitation: University ofBeigrade, Department ofCivil EngineeringConstruction and rehabilitation: Mostogradnja, Beigrade1968

Owner:Designer:

Contractor:Date of construction:Date of rehabilitation: 1984In order to increase capacity of the primary traffic route,a one-way road bridge at the Radnicka street in Beigradewas constructed in 1968. The bridge was built acrossthe five-gauge very busy railway line and the existingstreet, a temporary structure as the removal of therailway line from the location was antieipated. However,due to postponement of the railway network reconstruction, it appeared to be necessary to keep the bridge inexploitation for a significantly longer period.The bridge is skewed, in vertical curvature withthe biggest slope of 6%, the length being9 x 36 +10 334 m and the useful width 6 m, (Fig. 1).The main box girder, lateral Compound I beams, horizontal bracing and box columns are made of steel. Theconnection between the main and lateral steel girders ispresented in Fig. 2.Rectangular prefabricated reinforced concrete deckslabs were supported by lateral girders perpendicular tomain girders, their mutual distance being 2 m. The widthof the slabs corresponded to the width of the bridge.The slabs were 15 cm thick with haunches of 9 cm onboth supporting edges.As the direction of lateral girders did not coincide withthe skew position of the columns, unequal deflections ofthe lateral girders ends used to take place whenever avehicle crossed the bridge and those girders were thesupports of reinforced concrete deck slabs, Fig. 3.

The permitted movement of heavy vehicles by the rightmain girder only, still increased the unequal deflectionsof the lateral girders ends causing torsion and additionalinconvenient stressing of reinforced concrete deckslabs.Those slabs were connected to the upper chord of thelateral steel girders by tins anchored into the mass ofconcrete with four skrews on both supporting edges. Inthe course of time, the connection was weakened andpermanent damages of bridge decks above lateralgirders took place. The lateral joints in asphaltic bridgedeck, placed on each 2 m along the length of the bridgecaused, beside uncomfortable drive, constant unforseendynamic impacts to the structure of the bndge. Therepair of the bridge deck was practically impossible.REINFORCED CONCRETEBRIDGE DECK

THE MAIN GIRDER AI lO I IYX'&

mo rHE MAIN GIRDER Bn x 2.0010.00MAIN GIRDERDEFLECTIONS

Fig. 2 The connection between main and lateralsteel girders

9x36,00 324,000,00GANGES pR|MARY TRAFFIC ROUTE9X 38>o r 3' /

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JK IABSE PERIODICA 3/1988 IABSE STRUCTURES C-46/88 61- -

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F/ff. 2 Position of segmental roller bearingsThe well cap was also strengthened. Six numbers steelsupports were erected from the well cap for lifting of thebox girder. Each box girder was provided with two liftingpoints. one on either side of the pier. The large diameterHydraulic Jacks of 200 tonnes capacity with safety nutarrangement were used for lifting the weight of 800tonnes. In addition to the jacks stand-by support pointswere provided. Steel packing was provided over thesesupport points continuously during lifting Operation.Before commencement of lifting Operation, all thecracks were injeeted with epoxy resins. The slopingsuspended spans were properly held with the cantilevertips to prevent any undesirable movement during liftingOperation. To achieve uniform reaction at all the liftingpoints. all the jacks were connected to a commonhydraulic cireuit. The soffit of box girder was sloping.Therefore, wedge shaped steel boxes were fixed to thesoffit for getting level surface at lifting points. Liftingarrangement is shown in Fig. 3. Packing boxes of different heights were planned so as to have a minimumnumber of them in position at any given time.Tapered steel shims were used to cater for change ininclination of span over supports, during lifting Operation.After bringing the span to the level position, thesuspended spans were shifted longitudinally to theiroriginal position by use of Freyssinet flat jacks at theexpansion Joint positions.The main Operation of alignment of structure wascompleted in 12 days. While keeping the span sup-

Fig. 3 Lifting arrangementported, the new pier cap was concreted at the newhigher level. Twin fll roller bearings were provided fortransfer of load of the span.Experience gainedExcessive waterway should not be provided whileplanning the bridges. Proper guidebunds and other rivertraining works shall be arranged to confine the flow ofriver in the desired direction.

(P. Y. Man jure, M. R. Rohra)

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llllll mUn nt. itiii ' Li .11

- -.-.- .-

ftp. 2 Lifting arrangement for suspended span

f/ff. 3 Cantilever tip is broken and additional reinforcement is provided

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iyZZ:..L mSlHIX

jm RESTON Load Measuring Bearinss

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REPAIR AND REHABILITATIONOF BRIDGES

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peyssinetFREYSSINET INTERNATIONAL (S.T.U.P.) - S.N.C. AU CAPITAL DE 22 000 000 DE FRANCS

ZA DES MARAIS - 28 RUE DES OSIERS78310 COIGNIERES (FRANCE) - TELEPHONE : (1) 34 61 89 89TELEX FREISIA 699762 F - TELEFAX : (1)34 61 80 61

bse-pe-002_1988_12_c-46_s_d

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