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| Bridge building with VST heavy-duty shoring tower as falsework  The new VARIOKIT heavy-duty shoring tower is currently being used as falsework for the building of a motorway bridge across the Rio Sordo – an impressive 30 m high and with leg loads of up to 600 kN. Through the use of rentable system components taken from the VARIOKIT engineering construction kit, PERI was able to develop a cost-effective solution for the superstructure formwork and shoring. The A4 motorway is situated in the north of Portugal and stretches eastwards from Porto on the Atlantic coast to Bragança on the Spanish border. The route through the Marão Mountains requires the building of a new motorway bridge for crossing the Sordo Valley near Vila Real. This is in the form of a 412 m long, five-section structure with two separate superstructures. The almost 20 m wide and 3.60 m high prestressed concrete hollow box girders are being realised using two different construction methods: the three middle bridge spans with the balanced cantilever method and the respective edge spans formed on PERI shoring.PERI's Portuguese engineers provided a comprehensive formwork and scaffolding solution for the construction of all structural components: VARIO elements and CB brackets formed the climbing formwork for the bridge piers; for the pier tables, suspended SB brace frames served as loadbearing scaffold whilst the VARIO girder wall formwork system was used for forming the starters for the balanced cantilever. The superstructure formwork and falsework for the four edge sections are based on the PERI VARIOKIT engineering construction kit. The fact that the superstructure width increases from 16 m to 19.40 m was taken into consideration during the planning phase. As falsework, the contractor is using VARIOKIT VST heavyduty shoring towers – 6 m to 30 m high, with loadbearing capacities of up to 2,500 kN each. The VST towers are erected as four-legged individual structures which support the 72 m long superstructure formwork at defined load application points with axis spacings of between 10 m and 24 m. Transversely, the tower measures 2.00 m in each case, longitudinally between 2.00 m and 7.50 m – depending on topographical and static requirements. In those areas which are subjected to particularly high loads, additional legs with axis spacings of 37.5 cm provide an increase in the loadbearing capacities. The partial adaptation to the loads which are to be carried considerably reduces material requirements along with minimizing the erection work needed for the falsework. Due to the modular design of the VST heavyduty shoring towers, it is possible to adapt the loadcarrying system to suit all construction site requirements. This has meant that lateral truss girder spacings and the distances of the supports in a longitudinal direction can be variably defined and has led to an optimization of the static system overall. In addition, all individual legs can be adapted to suit the different ground contact areas as well as the geometry of the superstructure formwork. Furthermore, adaptations due to the bridge piers has therefore been possible with system components. Assembly of the falsework was carried out using variable frame arrangements with heights ranging from 1.25 m to 10.25 m. These are delivered to the construction site as pre-assembled units and then further extended on the ground to form tower segments. A crane was used for erection of the towers and height extensions. Safe PERI UP working platforms are used to ensure accurate positioning along with fixing in place with bolts and pins. Together with the heavy-duty shoring towers, these are continuously added to as required. PERI engineers have combined VARIOKIT heavy-duty shoring towers with the PERI UP Rosett modular scaffold. Both modular construction systems are based on a metric grid pattern. Corresponding adapter elements ensure assembly-friendly connections – and hence for perfectly coordinated access technology as well as suitable working levels. This increases on-site safety and therefore allows a rapid assembly sequence and accelerated moving procedures throughout the four construction phases. The new VST heavy-duty shoring tower from PERI (VST = VARIOKIT Shoring Tower) serves as load-bearing scaffold in large bridge construction and civil engineering projects. The modular system can be assembled extremely flexibly for heights up to 40 m as frame arrangements, towers or shoring tower frames. As part of the VARIOKIT engineering construction kit, PERI also uses multi-purpose system components – which are completely rentable – for heavy-duty shoring towers. Bolts and pins as standardised connecting elements facilitate simple and fast assembly. Special parts and time-consuming welded structures carried out on site are no longer necessary. write your comments about the article :: © 2011 Construction News :: home page |