1、毕业设计（论文） 1 Long and light Bridge design & engineering Closure of the main span on the SundoyaBridge in Norway is expected to take place in the first week after Easter. This graceful crossing, the second longest of its type in the world, is being built in situ using high performance concrete SundoyaB
2、ridge is situated in one of Norways most scenic areas, only 100km south of the Arctic Circle. The 538m-long bridge spans Sundet, and when it is complete will provide a ferry-free road connection between Sundoya and the mainland. It is located some 35km west of the city of Mosjoen, close to highway 7
3、8 between Mosjoen and Sandnessjoen. It will be the second large bridge project connecting Alstenoya to the mainland, coming more than 12 years after the HelgelandBridge was opened. The region is no stranger to world-record scale bridges ?the Helgeland Bridges 425m long main span was the longest cabl
4、e-stayed span in the world when it opened in 1992. SundoyaBridge is divided into three spans； it has a main span of 298m and two side spans of 120m. The main span will be the second longest span in the world for a continuous post-tensioned cast in place box section concrete bridge. In terms of its d
5、esign, consultant DrIngAas-Jakobsen has followed a similar approach to that taken for the RaftsundetBridge, opened in 1998, to which the SundoyaBridge will almost be a twin. The two bridges have identical main spans, but Raftsundet has four spans as opposed to Sundoyas three. Contractor AS Anlegg, w
6、hich is part of the joint venture building Sundoya, was also the contractor on the RaftsundetBridge, and architect BoarchArkitekter has also worked on the two schemes. 毕业设计（论文） 2 In January 2001 the joint venture company AF Sundoybrua won the contract from client StatensVegvesen to build the Sundoya
7、Bridge. This joint venture consisted of the contractors ReinertsenAnlegg and NCC Construction. High performance concrete is central to the design of the bridge ?both normal weight HPC and lightweight HPC. Normal weight concrete, at approximately 2500kg/m3, is used for the 120m side spans, while ligh
8、tweight concrete, which weighs in at about 1970kg/m3, is used for construction of the 298m main span. This enables construction to proceed using the balanced cantilever method. Local rock from Norway is used as the aggregate for the normal weight concrete, but the lightweight concrete required an im
9、ported solution. Normally the aggregate used for lightweight concrete in Europe is expanded clay or shale, but this material has high levels of absorption and for this reason, regulations prevent such concrete from being pumped. In order to address this, the contractor adopted a similar solution to
10、that used on RaftsundetBridge ?importing Stalite aggregate from South Carolina in the USA. Stalite is produced through thermal expansion of high quality slate, and results in a lightweight aggregate that gives concrete of very high strength at low unit weights. Its low absorption of approximately 6%
11、 and high particle strength are two of the factors that allow Stalite to achieve high strength concrete in excess of 82.7MPa, the manufacturer says. The bondand compatibility of the aggregate with cement paste reduce micro-cracking and enhance durability, and its low absorption makes it easy to mix
12、and pump. According to AF Sundoybrua quality manager Jan-EirikNilsskog, this material has given a very good result. It produces concrete that is easy to pour into the formwork and it gives a good surface finish, he says. It is being pumped some 120m along the bridge deck to the concreting position.
13、Concrete is produced by a transportable mobile plant located only 1km from the bridge site. Constant monitoring of the concrete weight is necessary to ensure that the cantilevers are properly balanced. This is tested for each pour. 毕业设计（论文） 3 The project began in January 2001 at Aker Verdal with the
14、 production of caissons for the pier bases. In May 2001 the two caissons were towed 500km north to the bridge site. The bridge is being poured in situ using special mobile construction equipment developed by NRS. The cycle for construction of each 5m wide bridge segment is a week, and two mobile uni
15、ts are being used on the SundoyaBridge. These particular units were built for AS Anlegg to use on the VaroddenBridge in Kristiansand in Norway, and they have also been used by the same contractor on the RafsundetBridge. The design of the central part of the main span of the bridge is based on the us
16、e of lightweight concrete LC60 while other parts of the structure use the more standard type C65. Because of the aggressive marine environment, the quality of the concrete must be particularly good. The structure is a single cell, prestressed rectangular box girder, largely built using the travellin
17、g formwork system from NRS. The box width is 7m and its depth varies from 3m at the centre of the span to 14.5m over the piers. Close to the abutments, concrete of quality C25 will be used inside the box girder as ballast. In addition, the designers have included the necessary elements inside the bo
18、x girder in order to allow the possible addition of post-tensioning cables in the future. The long-term behaviour of such large spans is not fully known, so the possibility that the main span may sag over time has to be taken into account. The width of the road is a constant 7.5m from the barrier on
19、 one side to that on the other, and the total width of the bridge is some 10.3m. There is a 2m wide footway included in the width of the structure. The pier shaft is formed with twin legs, which are hollow inside. The pier shafts incorporate permanent prestressing cables and they have a constant wall thickness and a width that varies parabolically over their height. Temporary tie-down piers are used to construct the bridge - they are located 35m into each 120m-long side span from the main piers. Each consists of an I-shaped shaft, which is tied down to the ground using rock anchors and
