BRANDANGERSUNDET BRO. Entreprenørens utfordringer ved bygging av broa Presentasjon på Brodagen 10.november 2009 Ved Torbjørn Kjoberg, Skanska

Transkript

1 BRANDANGERSUNDET BRO Entreprenørens utfordringer ved bygging av broa Presentasjon på Brodagen 10.november 2009 Ved Torbjørn Kjoberg, Skanska

2 Brandangersundet network arch bridge Free span: 220 meter Skanska offer: 105 mill NOK

3 Location of Brandangersundet bridge: The bridge location is in Gulen community, South of Sognefjorden and North of Bergen at the West coast of Norway The bridge is a part of county road 4 connecting the island of Sandøyna with the main land. The bridge location is in an area sheltered from the open sea, at the inside of Sandøyna

4 Bridge location and bridge fabrication sites: Bridge location The bridge location is about 5 km North of the construction site for the large main span element at Sløvågen. The Brandangersundet strait has sufficient water depth for the transport. At the bridge location, the strait is somewhat narrow. Bridge fabrication

5 Bridge location. The road access to the bridge location has been prepared in a previous contract (not by Skanska):

6 Location of bridge fabrication site at Sløvågen

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9 Alternative installation methods considered: Singel lift, 3.000t crane: Barge transport and lifting towers:

10 Status steel works at HSM: Cast in footings for support of steel arches are under production at HSM. To be delivered at Sløvågen Oct. 8. Steel arches are under fabrication at EEW in Germany

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14 Lifting pad eyes at arch footings lifting frame: Input from Smit: Lifting pad eyes and frame design:

15 Construction activities at the bridge location: At location, the foundations, columns, side spans and abutments will be constructed using conventional and well known technology.

16 Construction activities in Sløvågen: Main work: Fabrication and post tensioning of the concrete slab Installation of prefabricated steel arches, 3 or 4 pieces

17 Construction activities in Sløvågen, cont Main work, cont: Tensioning of net work cables Weighing of bridge element Removal of scaffolding Ready for lifting! Tensioning using 4 jacks at the same time to obtain balanced loading Included for tensioning in 2 steps

18 DEFORMASJON FRA EGENVEKT AV BUE Max opp 80mm Max ned 185mm Deformert stålbue etter at buen er sveist sammen og understøttelse er fjernet

19 SÅ STARTER VI KABELMONTASJE.. Max last 53 kn i stag for denne tilstanden 1. Det monteres kabler symmetrisk om senterlinjen, 2 på hver side samtidig (totalt 4) 2. For de første må vi ha hjelp av jekketaljer for å hale inn buen som har sklidd ut pga egenvekt 3. Justeringsmuligheter på stag (+/- 120mm) er en begrensende faktor for hvor mye vi kan jekke 4. Buen løftes tilbake til riktig høyde

20 VI FORTSETTER MED KABELMONTASJE.. Stag fase 2 montert. Stagene gis en liten forspenning på ca. 15 kn Stag fase 3 montert. Stagene forspenning ca. 20 kn. Maks. nedbøyning på midten er 130mm.

21 VI FORTSETTER MED KABELMONTASJE.. Stag fase 4 montert. Stagene forspennes ca. 20 kn. Deformasjonene i buen er nå relativt små, innenfor 55mm fra teoretisk linje Stag fase 6 montert. Stagforspenning ca. 20 kn. Maks. avvik i stålbuen fra teoretisk linje er ca. 60mm. PS: Alle faser ikke vist

22 KABELMONTASJE, ALLE STAG MONTERT 1. Alle stag montert, max deformasjon ca 70mm 2. Stålbuen har en relativt jevn bue, med større diameter enn teoretisk bue

23 Lift installation by two shear legs from Smit Tak in Holland, Taklift 6 & 7: Taklift 6&7 are sister vessel with a lift capacity of tones in main A-frame. They are operating out of Rotterdam for markets in Europe, Mediterranean, East coast of America and West coast of Africa

24 Special lifting considerations: Lifting frame included to getfixpointfor slings above bridge c.o.g. 360 degree rotating hook for easy positioning of shear leg

25 Lifting of bridge element from shore at Sløvågen: Critical parameters: Max outreach of crane vessel for position of bridge Inclination of slope of towards sea and required depth for crane vessel Geotechnical stability

26 Sløvågen Lifting by crane vessels from shore

27 Transport of the bridge element from Sløvågen to bridge location in Brandangersundet: Done before by Smit Transport of bridge element hangig in the hooks of the two shear legs and assisted by two tugs

28 Installation of the bridge: Gateshead Millenium bridge Done before by Smit Installation at Brandangersundet using the two shear leg vessels

29 Installation view from South