|
contents | technologies | |||||||||
| PERI launches self-climbing formwork in Hungary  This new bridge construction in Budapest is part of the northern section of the M0 motorway. The impressive bridge design with two highly visible reinforced concrete pylons will connect the M3 motorway with the main artery road 11 and in future will lead the new route safely across the Danube. The 1862 metre long bridge is divided into 5 sections on a total of 28 supports. The central element is the 590 m long cable-stayed bridge over the River Danube with spans of 145 m, 300 m, 145 m respectively. This type of construction had never been used before on Hungary´s motorway bridges. For the construction of two abutments, 4 joint supports, 7 floodplain piers and the two A-shaped pylons in the major distributary of the river, the experience and know-how of the PERI formwork and scaffolding experts proved to be of great benefit to the consortium of contractors, Hídépítö Zrt. und Strabag Zrt.The superstructure of the cable-stayed bridge consists of a steel slab with hollow box girders under the suspension points. A total of 88 inclined cables in two cable planes - with 4x11 cables in each plane - transfer the loads from the roadway into the two centrally-positioned pylons which serve as main support members. For the construction of the A-shaped reinforced concrete pylons with pre-stressed hollow beam cross-sections, the crane-independent PERI ACS (Automatic Climbing System) self-climbing technology in connection with PERI girder wall formwork is being used. The overall height of the pylons on the Danube Bridge is 100 metres. Up to the concrete tip, a total of 29 casting segments with variable concreting heights between 2.55 m and 4.07 m are to be mastered. The pylon supporting members are inclined towards to the centre of the roadway at an angle of under 13.3° and have a range of different cross-sections. Beginning with external dimensions of 5.00m x 4.11m on the bottom plate, the members taper up to 3.50m x 4.11m in the area of the cable stay connections. The internal dimensions are also reduced in the longitudinal direction by 0.80m. For the forward and reverse-inclined external walls, PERI ACS is used as climbing scaffold. Advantage: due to the continuously adjustable brackets, the working platforms are always in horizontal position which means work can be carried out safely and ergonomically. For the remaining external wall surfaces, ACS brackets were selected, which have proved their suitability once again on this construction site for laterally inclined climbing. As the internal scaffolding is only required for up to a height of 60 m – intermediate slabs are installed after this point – crane-climbed internal platforms are used here as most cost-effective solution. Guardrails and weather-resistant sheeting have been installed to totally enclose the five working levels, positioned one on top of each other, resulting in optimal working safety conditions and providing ideal protection against the weather. A connecting bridge is suspended from and is climbed together with the ACS scaffold, and provides construction site personnel the possibility of easily moving from one pylon member to the other. An elevator for moving personnel up to the working levels is therefore only necessary on one of the pylon legs. The solution developed by PERI guarantees that the bridge always proceeds horizontally regardless of the position of the climbing scaffold. The tailored girder wall formwork has been designed for a concrete pressure of 50kN/m_ and was accurately planned in advance by PERI engineers for each concreting section. All adjustment work required on the formwork, inevitable due to the structure´s cross-section with rounded outside edges, can be carried out on the platforms without any problems. In order to achieve the specified surface quality and the required number of uses, the rounded corner elements, with radii of 30cm, were covered with steel sheeting. To complicate matters further, massive intermediate slabs are being installed from the 15th concreting cycle onwards for the installation of the cable stay sleeves. By using a combination of panel formwork and girder wall formwork, simple adjustment of the internal formwork at the piercing points and angles of the cable stays, which vary in each concreting section, is possible in these areas. Pylon walls and intermediate slabs are constructed in one pour. In addition, special requirements had to be taken into consideration regarding the concrete surface structure during the formwork planning: this means the top section of the pylon is ribbed with depths of up to 50 cm beginning with the 26th concreting cycle. This relief is produced by formwork units which are attached the elements. write your comments about the article :: © 2007 Construction News :: home page |