votonosi bridge - the structural engineer

18 September 2007 – The Structural Engineer|39

paper: ahmadi-kashani et al

Fig 1. Egnatia motorway and location of Votonosi Bridge / Fig 2. Elevation and plan / Fig 3. Cross section of the deck andpiers a) Deck over pier with lane widths b) Deck at mid-span c) Piers M1N, M1S and M2N d) Pier M2S

SynopsisThe recently constructed Votonosi Bridge situated in an areaof outstanding natural beauty and within a seismically activezone, forms part of the Egnatia motorway project in northernGreece. With a main span of 230m, this bridge has thelongest span for balanced cantilever bridges constructed inGreece to date. This paper provides general informationregarding the bridge and outlines its construction.

IntroductionThe Egnatia motorway in northern Greece is one of the prior-ity projects in the Trans-European Network for Transportwhich will provide Europe with a fast and safe access route toTurkey and the Middle East1. It will also provide links to theneighbouring Balkan countries and to the rest of mainlandGreece. Its main axis stretches from the port of Igoumenitsa onthe Ionian Sea to the town of Kipi at the Greek-Turkish border(Fig 1). This axis is 680km long and consists of a dual two-lanemotorway with hard shoulders and includes more than 600bridges with a total length of over 40km(ref.2). The design,construction, maintenance, operation and exploitation of themotorway is being managed by ‘Egnatia Odos AE’ (EOAE), acompany wholly owned by the Greek State which was estab-lished in 1995 by the Greek Ministry of Environment, Planningand Public Works. Kellogg Brown and Root (KBR) has acted asthe Project Manager since 1996, and Thales-Omek has beeninvolved in the construction management for its western regionsince 1997.

In north-west Greece, the Egnatia motorway crosses moun-tainous terrain demanding the construction of many majortunnels and bridges. Situated in this region, Votonosi Bridge islocated near the village of Votonosi, between Antochory andVotonosi Tunnels, and crosses a 500m wide river valley with adepth of over 100m (Fig 1). This location demanded a bridge

with minimum number of piers to be cost effective. To meet thisand all other project requirements, a three-span balancedcantilever bridge was selected for detail design and construc-tion. With a number of in situ balanced cantilever bridgesalready successfully completed by local contractors, this form ofconstruction is well established in Greece. However, with amain span of 230m, Votonosi Bridge by far exceeded the longestspan previously constructed by this method (140m), and itsconstruction was therefore a challenge for the constructionindustry.

This paper provides general information regarding VotonosiBridge, and outlines the design process and its construction.

General descriptionVotonosi Bridge consists of two independent 13.5m wide deckslocated at 27.5m centres with each deck carrying two 3.75mwide carriageways and a 2.5m wide hard shoulder overMetsovitikos River and a local road. The north and south decksare 478m and 490m long respectively, consisting of three spansof 127m–224m–127m and 130m–230m–130m (Fig 2). Thesuperstructure has an upward longitudinal slope of approxi-mately 5% eastwards. A 90m length of both decks at the east-end is on a transition curve joining a 1000m radius circularcurve which results in the highway super-elevation increasingfrom 2.5% to 5%.

The site investigation boreholes indicated that the groundconsists of thick/medium layers of sandstone inter-bedded withthin layers of siltstone. The piers are founded on circular 10mdiameter rock sockets with depths of up to 25m resisting up to140MN vertical load, 11MN shear force, and 300MN-m fixitymoment. The piers have heights varying from 45m to 53m andcomprise a 5m by 7m box section, except for the tallest pierwhich has a 6m by 7m box section (Fig 3).

The relatively tall piers are sufficiently flexible to be

The construction of Votonosi Bridge, Greece

K. Ahmadi-KashaniPhD, CEng,MIStructE, MIEITechnical Advisor, KBR,UK

I. RentzeperisPhD, TEEGeneral Manager,EOAE, Greece

C. BrunConstruction Manager,Thales-Omek, France

P. PapanikolasPhD, TEETechnical Manager,EOAE, Greece

V. TsebasTEESite Manager, MechanikiAE, Greece

C. MiltsakakisTEESite Engineer, MechanikiAE, Greece

Received: 10/06Modified: 02/07Accepted: 04/07Keywords: VotonosiBridge, Greece, Roadbridges, Balancedcantilever construction,Egnatia Motorway,Greece, Seismic design,Foundations, Concrete

© K. Ahmadi-Kashani, I. Rentzeperis, C. Brun, P. Papanikolas, V. Tsebas,& C. Miltsakakis

Your comments on thispaper are welcome andwill be published onlineas Correspondence.

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2

3a 3c

3b

3d

IOANNINAN THESSALONIKI

BULGARIA

GREECE

Votonosi Bridge

NORTH DECK

SOUTH DECK

ANTHOCHORITUNNEL VOTONOSI

TUNNEL

3.00

130.00m

130.00m

126.60m

230.00m

223.90m

1.25 0.5 2.50 3.753.75 0.95 0.8

3.00

5.50

7.00

7.00

13.5

0

0.75

0.75

7.00

5.00

6.00

7.00

0.6

0.70

AON M1N M2N A3N

A3N

A3S

M2N

M2S

M1N

M1S

AON

AOS126.60m

SE18 Votonosi bridge :Layout 1 12/9/07 16:05 9

40|The Structural Engineer – 18 September 2007

Fig 4. Anti-uplift sliding bearing / Fig 5. Expansion joint detail / Fig 6. Bottom slab tendon anchorage

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monolithically connected to the superstructure, and to form a central frameto resist longitudinal loading and environmental effects including seismicforces. At the abutments the deck is free to rotate and move longitudinallyvia sliding pot bearings. Potential deck uplift during seismic events isrestricted by anti-uplift devices connected to the bearings (Fig 4). A guidedbearing at each abutment restricts the movement of the deck in the trans-verse direction. Two elastomeric bearings are provided with sufficient gapbetween the deck-ends and abutment cheek-walls to act as bumpers duringseismic events with intensities greater than the design earthquake. Theexpansion joints allow a total bridge movement of up to 400mm at each end(Fig 5).

Each superstructure consists of a box girder with a constant width of 7mand a depth varying from 13.5m at the piers to 5.5m at mid-span. The webthickness steps down from the piers towards mid-span taking values of0.60m, 0.50m and 0.45m over a transition length of 0.75m. The top slab hasa thickness of 0.3m increasing to 0.5m at the edges, and the thickness of thebottom slab varies from 1.3m at the piers to 0.3m at mid-span. The thick-ness of the side cantilever varies from 0.65m at the root to 0.25m at the tip(Fig 3).

Each pair of in situ concrete balanced cantilevers is connected to a 3m longconnecting in situ segment at mid-span: with approximately 16m long deck-ends supported from the ground during construction. The length of thecantilevers varies from 107m to 110m, each consisting of 26 in situ segments.In order to limit the weight of the segments, their lengths vary from 3m to4.5m for the first 13 segments, thereafter remaining constant at 5m. Thecantilever prestressing consists of 102 internal tendons made up of 19,15.7mm diameter superstrand (19T15) arranged in two rows over the pierswith a tendon length of up to 227m. The tendons run through the upper slaband are anchored at the segments’ end face within the slab thickeningwithout the need for blisters. Internal tendons are also placed in the bottomslab to provide the continuity prestressing which comprise 32, 19T15 in themain span and 12, 19T15 in the side spans. The continuity tendons areanchored in 2m long blisters constructed at the edges of the bottom slab(Fig 6).

Abutment galleries are provided to access the expansion joints and theinterior of the box girders for inspection and maintenance. Maintenance ordamage inspection of the inside of the hollow piers is by means of an accesshole at the pier top and then via ladders placed between permanent platformsthat are located at 5m intervals inside the piers. Inspection of the bearingscan be carried out from a platform situated in front of the abutments. Theprovision of jacking points allows the replacement of the bearings.

Parapets consist of standard metal posts and railings in accordance with

the Greek regulations. The main drainage pipes are made of fibre glass andrun on the outer face of each box girder with connections to the deck inletsvia transverse drainage pipes under the deck cantilevers. Motorway serviceducts are located under the outer footpaths and provision of ventilation anddrainage holes are made near the web tops and the bottom slab, respectively.A 1.0m by 1.5m opening in the bottom slab near abutment A0 is providedfor access in cases of emergency.

The relatively high (12m) west abutments dictate that the backfill spillsthrough either abutment between its two tapering legs founded on a spreadfooting. The east abutments are of the bank seat type with spread footingfoundations located at two different levels due to the steep slope of the rockface.

DesignThe design of Votonosi Bridge was carried out in accordance with theperformance requirements set out in OSMEO3, the design guidelines devel-oped by EOAE. The loading and static design was based on German DINStandards including ZTVK 964 supplement for bridge design. To consider theeffect of deck plan curvature, a three dimensional computer model was devel-oped with measures to include soil structure interaction. The time depend-ent characteristic of the concrete was modelled in the analysis using anestimated construction programme.

The analysis and design covered all stages of construction and was carriedout using SOFISTIK computer program which automated part of the designprocess. A number of 3D finite element models were additionally developedand analysed to determine the intensity of stress concentration in the rocksockets, anchorage zones, and hammerheads. Camber analyses were carriedout during the balanced cantilever construction to determine the setting outgeometry of the segments using the time dependent properties of concreteand allowing for site temperature and humidity at the time of casting.

Votonosi Bridge is situated within Greek seismic zone II with peak groundacceleration (PGA) of 0.16g, upgraded by an importance factor of 1.35. Theseismic design of the bridge followed the Greek codes of practice EAK6 andE39/997. Its seismic integrity during construction was assessed for a PGAvalue of 0.104g. To allow for structural redundancy the ‘behaviour factor’ wasassumed as 3.0 for the completed bridge, thus allowing formation of plastichinges at the top and bottom of the piers during major seismic events. Thebehaviour factor was taken as 1.0 during the construction to prevent struc-tural damage before commencement of service.

During the construction, combinations of the following load cases wereconsidered in the design:• self weight of the form-travellers


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Fig 7. Construction programme / Fig 8. Mobile crane for construction of rock sockets / Fig 9. Rock socket excavation

• self weight of the newly cast segments • prestressing forces • an accidental drop of the newly cast segments• construction loading • temperature difference between the top and bottom of the deck• variation in the ambient temperature• differential settlement between adjacent substructures• wind loading with differential pressure• seismic loading

For the ‘in service’ design, combinations of the following load cases wereconsidered:• dead load and superimposed load• prestressing forces • SLW30/60 traffic loading in accordance with DIN 1072 • temperature difference between top and bottom of the deck• variation in the ambient temperature• differential settlement between adjacent substructures• wind loading • seismic loading

The following classes of material were specified in the design:• concrete (cube strength):

superstructure 45MPa piers 45MPa rock sockets (capping zone) 35MParock socket (shaft) 25MPaabutments 35MPaapproach slab 35MPa

• steel reinforcement BSt500 (St IV)• prestressing tendons 1550/1750MPa

The design and constructability of the bridge was reviewed by EOAE, anda category III check was carried out by an independent consultant. Thedetails of the analysis and the design are given in Ref (8).

Construction GeneralThe construction was carried out in accordance with TSY9, a materials andworkmanship specification produced by EOAE based on national and inter-national specifications. The works started in January 2000 and werecompleted in December 2005 with the outline construction program shown

in Fig 7. The bridge is situated in a mountainous region and the adversewinter weather dictated a stoppage of the works for approximately 2 monthsof the year.

The site was served by two tower cranes placed between piers M1 and M2with up to 100kN lifting capacity and 60m reach. Other major equipmentincluded a 300kN capacity mobile overhead gantry, two 125kVA generators,a 100m3/hr loader, two compressors with 850cfm and 335cfm capacities, six8m3 capacity concrete mixer trucks, four concrete 101bar capacity pumpswith 47m3/h output, a 10m3 truck, a 12hp gunite pump, a 8hp groutingpump, a mini-excavator, and a drilling machine.

Due to the relatively long distance between the site and quarries, aggre-gates were extracted from the nearby Metsovitikos River, crushed, screenedand washed for concrete production in a 50m3/hr batching plant situated onsite. The batching plant for the construction of the nearby MegaloremaViaduct2, situated within 2km of the site, was also used in cases of emergency.

The details of the construction of the foundations, piers and superstruc-ture of the bridge are described as follows.

FoundationsAccess roads to the foundations were designed and constructed with theemphasis on minimising damage to the environment. 31 trial boreholes weredrilled at the pier and abutment locations. This was followed by levelling theground to install the mobile overhead gantry for the construction of the rocksockets. Due to the level difference between the south and north rock socketsat M2, an extended platform was built using a concrete enclosure filled withcompacted soil to allow the operation of the gantry over both sockets (Fig 8).The excavation for the rock sockets was carried out in depth intervals of 3mwith drilling at the perimeter followed by sequential firing of explosivecharges placed in a helical formation. With the available drilling machinesthe acceptable tolerance for vertical drilling could not be achieved for depthsof more than 15m. The drilling operation was, therefore, carried out in twostages: a larger diameter than the design diameter was first formed for theupper half of the socket, and the drilling machine was subsequently loweredand placed on the base of the upper half in order to drill for the design diam-eter lower half (Fig 9).

The excavated face was regularly inspected by a geologist to verify the geot-echnical parameters assumed in the design, and to optimize the measuresrequired to support the exposed face. The rock face was stabilised using rockanchors, steel beams, and corrugated metal sheets, followed by the installa-tion of mesh reinforcement and shotcreting. Concreting the sockets wascarried out in 5 or 6 lifts with the depth of each lift varying from 3m to 5musing up to 600m3 of concrete for each lift. Concrete temperature was


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controlled by means of early morning concerting in the summer months, andusing Portland cement type I. These measures reduced the risk of micro-crackformation in the concrete due to excessive heat of hydration.

The top 3m of the rock socket consisted of a heavily reinforced ‘cappingzone’. The lower 4 or 5 ‘shaft’ lifts contained mainly vertical reinforcementplaced at the perimeter of the socket. Reinforcement installation and concret-ing was carried out with the aid of the overhead gantry. A sump was providedon the top surface of each segment to remove any excess water. The construc-tion of each rock socket took between 3 and 4 months depending on thequality and type of rock mass encountered. The maximum settlement of thesockets after completion of the bridge was recorded as 4mm.

PiersThe piers were constructed using climbing formwork in 2.8m segments. Thereinforcement for the piers mainly comprised 7m prefabricated cages typi-cally formed with six longitudinal reinforcement bars connected by stirrups.The formwork and associated working platforms were fixed onto socketsembedded on the previously cast segment. The formwork panels were heldin the upright position and were fixed in place with through ties.Construction of a typical pier segment normally took 4 days to complete: 1.5days to place the reinforcement, 1.5 days to install the formwork and 1 dayfor concrete pouring and curing.

To avoid lapping reinforcement bars in the plastic hinge zones at the topand bottom of the piers, the reinforcement cages in this region were fabri-cated with14m/16m long rebars covering three segments, and were heldupright by steel framework that included three levels of working platforms(Fig 10). Additional horizontal reinforcement links were placed in this zoneto confine both the concrete and vertical reinforcement, and to allow the safeformation of plastic hinges during a major seismic event. In order for the piersof each superstructure to resist similar seismic forces, the stiffness of the piershad to be comparable; this meant that the M1 piers had to be extended downinto the ground (Fig 2). Concrete collars, 13m diameter and 10m deep, wereconstructed around these piers to allow the inspection and repair of theplastic hinge zones after a major earthquake (Fig 11).

Pier segments lower than 25m above ground level were concreted usinglorry mounted pumps. For higher levels, concrete was pumped through a150mm diameter steel pipe fixed to the pier by means of a pump with an 80mhead capacity. Suitable aggregate grading and admixtures were used toprovide the required slump and consistency for the pumped concrete.Temporary stairs and platforms were installed and used during the pierconstruction. The construction of each pier took approximately 4 months tocomplete.

The galvanised steel maintenance inspection ladders and platforms wereinstalled inside the piers prior to the construction of the hammerheads. Dueto the height of the piers the formwork for the hammerhead was supportedfrom the pier tops. Each hammerhead, 13.5m high with two diaphragms, wasconstructed in five phases using a proprietary formwork system (Fig 12).Steel beams fixed to the inside walls of the piers supported the 2.5m thickbottom slab. The construction of the hammerhead required special formworkto include the various access openings to the interior of the piers and boxgirders. Once the hammerhead was constructed, a temporary lift wasinstalled for each pair of M1 and M2 piers which together with a high leveltruss spanning between the decks allowed access to both decks. The construc-tion of each hammerhead took approximately 3 months to complete.

Superstructure The superstructures were constructed using a proprietary form-travellerweighing 800kN with a capacity to support a segment weight of 2500kN, andwith its centre of gravity up to 2.5m beyond the end of the segment. Eachtraveller consisted of two main ‘A’ frames anchored to the deck and carrieda transverse truss from which the formwork for the webs and the upper andlower slab soffits were suspended using high strength hangers. The move-ment of each traveller was provided by two hydraulic rams. The top and sidesof the travellers were enclosed with a waterproofing tarpaulin to protect theoperatives from adverse weather. To meet the completion date, four pairs oftravellers were used during the construction (Fig 13).

The 6.6m length of the hammerheads was sufficient to place a pair of trav-ellers braced to each other (Fig 14). Once the first pair of segments had been

cast symmetrically on the opposite sides of the piers, the bracing wasremoved. The construction cycle for the next pair of segments consisted of thefollowing stages:

• moving the traveller to a new position• adjusting the formwork levels for the new segments• installing the reinforcement, prestressing ducts and tendons • concreting the new segments • prestressing the new segments

Each pair of segments was cast alternately in two stages: 1) The bottom slab and part of the webs, 2) The remainder of the webs andthe top slab. This sequence helped to reduce the unbalanced cantileverloading, and resulted in better scheduling for the teams of labour involved.Concreting each stage took about 3h and required up to 35m3 of concrete. Thedepth of the upper section was kept constant resulting in a similar rein-forcement arrangement. A number of surveys confirmed that the travellerwas sufficiently stiff to prevent separation of the first stage from the lastsegment when the second stage was poured and added its weight to the trav-eller. Casting the upper section at least 2 days after concreting the lowersection also helped in preventing crack formation at the construction jointby ensuring sufficient bonding between the concrete and reinforcement.

The transportation of the reinforcement beyond the reach of the towercrane was made possible by means of a light wagon driven by an electrictractor on rails. A specialist team were responsible for placing the 100mminternal diameter galvanized prestressing ducts, threading the tendons,placing spiral reinforcement, stressing the tendons and grouting the ducts.A grout test on a prestressed beam was successfully carried out prior to thegrouting the ducts. A steel template was used at the segment face to facili-tate accurate placement of the tendons. The strands were delivered on coildrums and were unrolled and pushed through the ducts by means of astrand pushing machine. The minimum clear distance of 100mm between theprestressing tendons specified in the design allowed for easy pouring andcompaction of the concrete and for placement of the traveller hangers.Temporary 1.0m by 1.5m openings were provided in the top slab to allow theequipment for prestressing the bottom slab tendons to be lowered into posi-tion.

Following the installation of reinforcement and tendons, the internal form-work for the box girder was placed in position, and preparation was madefor the concreting phase. For casting segments away from the pier, an addi-tional concrete pump was installed on the hammerhead to facilitate concretedelivery. The external formwork was backed with 50mm thick polystyrenepanels to insulate the concrete from the ambient temperature ranging from–15°C to 40°C during the construction period. Installation of fan heatersinside the box girder and radiant heaters on the deck during the wintermonths provided acceptable conditions for concreting. In the summer months,concreting was carried out early in the morning to avoid micro-cracking dueto excessive heat of hydration. Concrete samples were taken during castingto determine its properties such as creep, shrinkage and modulus of elastic-ity, which were then used in the camber analysis.

The average 28 days concrete strength achieved was 65MPa. Theprestressing was generally applied 3 days after concreting when the concretehad attained a minimum strength of 40MPa. The tendons were tensionedsymmetrically from both ends in sequence about the centreline of the boxgirder using a 3500kN capacity prestressing jack. The measured tendonextensions were within 5% of their theoretical values.

The geometry of the balanced cantilevers was monitored by surveying thecoordinates of three steel plate markers placed at the tip of each segment.One marker was installed at the centreline of the deck and the other twolocated 5.5m either side of the centreline. The survey was carried out earlyin the morning to avoid differential temperature effects. Measurements weremade on all the segments after three events: a) casting a pair of newsegments, b) prestressing the new segments and c) moving the travellers toa new position. The results were compared with the theoretical values, andafter allowing for adjustments to comply with the design, a set of coordinateswere calculated for setting out the formwork for the next segment. Theextension of hangers transferring the weight of a segment to the travellerwas measured as 11mm, and was taken into account when setting out the




Fig 10. Pier reinforcement in plastic hinge zone / Fig 11. Collar for inspection of plastic hinge zone / Fig 12. Hammerhead constructionFig 13. Utilisation of four pairs of form-travellers / Fig 14. Braced form-travellers / Fig 15. Support system for the deck-end at abutment A0 before backfilling / Fig 16. Restraining the tip of balanced cantilever adjacent to abutment A0

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Fig 17. Support system for the deck-end at abutment A3/ Fig 18. Construction of the deck-end at abutment A3Fig 19. Construction of the mid-span connecting segment/ Fig 20. Construction of central span connecting segment a) Elevation b) Cross-section/ Fig 21. Construction of the edge beams / Fig 22. Theoretical and as built road levels / Fig 23. Votonosi Bridge nearing completion

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formwork for the bottom slab. The construction of a new pair of segments wasplanned on a 10 day cycle which was generally achieved after the initiallearning curve. The construction of each pair of balanced cantilever deckstook approximately 12 months to complete. After completion of the balancedcantilever over pier M1, the travellers were removed and the deck levels weresurveyed. Subsequently, the construction of the 16m long deck-end next toabutment A0 commenced. The formwork for the deck-end was supported ona proprietary truss system which in turn was supported from the ground atthe two edges (Fig 15). The lateral and vertical movement of the cantilevertip was prevented during concreting by means of a braced frame and byanchoring the tip of the cantilever to the ground (Fig 16). The constructionof the deck-end consisted of the following sequence:

• concreting the bottom slab and part of the webs (stage 1 concreting)• stressing a third of bottom slab tendons • concreting the remainder of the webs and the top slab (stage 2 concreting)• curing the concrete • removal of the temporary truss• de-tensioning and stressing the bottom slab tendons

Partial stressing of the bottom slab enabled the lower section of the deck-end to carry the weight of stage 2 concreting and allowed the removal of thetemporary truss.

The 16m long deck-end next to abutment A3 was subsequently constructedby means of two pairs of right angle steel frames, pinned at the top andbottom, with horizontal extension arms anchored to the cantilever tip (Figs17 and 18). Before construction, the travellers were moved to pier M2 and adeck level survey was carried out. The formwork was then placed on scaf-folding supported on the steel frames. The construction of the A3 deck-endwas carried out in a sequence similar to that described for the A0 deck-end.The connection of the cantilever tip to the deck required a careful concret-ing procedure, including the use of a counterweight at mid-span and regularmonitoring. To minimise the effect of differential temperature, concreting wascarried out at night. The lower deck section constructed in the stage 1 concret-ing was designed with sufficient reinforcement to span between the bearingsand the cantilever end, allowing for the removal of scaffolding after comple-tion of the stage 1 concreting.

Prior to constructing the central connecting segment, a level survey wascarried out and the maximum level difference between the opposite cantilevertips was found to be 16mm and 20mm for the south and north decks respec-tively, both within the required tolerance. The external formwork from the trav-eller was anchored to the segments each side of the gap to provide theshuttering for the connecting segment. To correct the level difference betweenthe cable ducts in the bottom slab and to prevent relative vertical movementof the cantilever tips, the two pairs of 600mm deep base beams of the travellerswere placed over the gap and anchored down to the deck (Fig 19).

Two horizontal steel I-beams were installed in the connecting segmentgaps bearing onto steel angles cast into the cantilever ends, and the gapbetween the beams and the cantilevers tips were grouted. In order to preventrelative horizontal movement between the cantilevers during concreting anumber of the bottom tendons were partially stressed (Fig 20). The bottomslab and part of the webs were subsequently concreted and the steel beamswere removed. The remaining part of the webs and the top slab wereconcreted followed by de-stressing the partially stressed tendons and subse-quent stressing all the bottom slab tendons. As before, concreting was carriedout at night.

The construction of the deck-ends and the connecting segments werecarried out in the calm summer days in order to reduce the risk of any vibra-tion damage during concreting. It is interesting to note that before castingthe connecting segments the cantilever tips deflected upward by 150mm dueto the sun shining on the deck top. It is also noted that, after completion ofthe superstructure, the top of piers moved by 120mm laterally due to the plancurvature of the bridge, as anticipated in the design.

Other activities carried out to complete the construction of the bridgewere as follows:

• backfilling behind the west abutment• concreting the access holes in the top slab• constructing parapet edge beams using counter-balanced form-travellers

(Fig 21)• installing the parapets• installing the deck waterproofing• surfacing the deck• installing the expansion joints

• installing the electricity cables and lighting columns• installing the drainage system • installing the lighting inside the box girder and the hollow piers

As shown in Fig 22, the vertical profile of the main span is conservativelyconstructed above the theoretical profile in order to offset any uncertainties dueto the creep and shrinkage effects. The nearly completed Votonosi Bridge isshown in Fig 23.

ConclusionVotonosi Bridge, with a main span of 230m is the longest span for balancedcantilever bridges constructed in Greece to date. Situated in a seismicallyactive zone and in an area of outstanding natural beauty, the design andconstruction presented a new challenge to the client, designer, contractor andsupervisors. The successful and accident-free construction of this technicallydemanding bridge is the result of constant diligence in the workplace andteamwork from all the participants. The works were constructed through aquality management system developed by EOAE/KBR which is used on allprojects under EOAE management. The experience gained in the design andconstruction of Votonosi Bridge is being used in constructing a more chal-lenging and longer span balanced cantilever Metsovitikos Bridge currentlyunder construction as part of Egnatia motorway project.

General dataStructural concrete: 29 000m3;Steel reinforcement: 5400t;Post tensioning tendons: 1260t;Duration of construction: 58 months;Cost of construction: €20.7M

Credits and acknowledgmentThe design and construction of Votonosi Bridge is the combined effort of manyindividuals in the following organisations:

Client: EOAE, ThessalonikiStructural design: DOMI OE, AthensCategory III checker: VCE, ViennaDesigner of temporary works: Zografidis, AthensContractor: Mechaniki A.E, AthensProject manager: KBR (UK), LeathearheadConstruction manager: Thales-Omek, Paris/Athens Climbing formwork: DOKA, GermanyForm-travellers: NRS, Norway

The authors would like to thank Mr P Gibbons, KBR project manager, forreviewing the paper. The opinions expressed by the authors do not necessarilyexpress those of EOAE, KBR, Thales-Omek and Mechaniki AE.

1. Hindley, G., Gibbons, P., Agius, M., Carr, B., Game, R. and Kashani, K.:‘Linking past and present’, Civ. Eng., ASCE, 2004

2. Ahmadi-Kashani, K. and Gavaise, E.: ‘Bridges of Egnatia motorway’, Proc. 6thInt. Conf. Short and Medium Span Bridges, Vancouver, Canada, 2002

3. OSMEO: ‘Guidelines for conducting road works design’, EOAE InternalReport, 2000

4. ZTVK 96: ‘Zusätzliche Technische Vorschrift für Kunstwerke’, 1996 5. Ahmadi-Kashani, K.: Seismic design of Egnatia motorway bridges, Proc. Inst.

Civ. Eng., J. Bridge Eng., London, 2004 6. EAK: ‘National Greek anti-seismic regulations’, 20007. E39/99 – ‘National Greek directives on anti-seismic design of bridge’, 19998. Stathopoloulos, S., Kotsanopoulos, P., Stathopoloulos, E., Spyropolous, I.,

Stathopolous, K.: ‘Votonosi Bridge in Greece’, FIB Symp, New Delhi, 20049. TSY: ‘Specification for material and workmanship’, EOAE Internal Report,

2000

REFERENCES


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