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| Supporting system solution – individually adapted  A huge inclined pier supports the motorway bridge on the Greek peninsula of Peloponnese. A team of Greek and German PERI engineers are supporting the site management team with project-specific system solutions. The 160-km long A7 motorway connects Kalamata in the south to Corinth in the northwest of the Peloponnese peninsula. The principle element being used to close the gap between Paradisia and Tsakona is the 390 m long arched bridge – known as "T4" – whose completion has been scheduled for early 2014. Two-thirds of the 22 m wide bridge superstructure will be suspended on a steel arch and realised using the steel composite construction method. For the northern bridge section, a pre-stressed concrete superstructure variant was selected which features a twin-cell hollow box cross-section. The supporting element of the motorway bridge is a huge, almost 30 m high inclined twin-pillar pier with an asymmetric V-shape. On the one hand, this serves as an intermediate support for the in-situ concreted carriageway and, on the other, as a support and starter section for the steel arch. For this, a team of Greek and German PERI engineers developed a comprehensive formwork and scaffolding solution – for the cost-effective construction of the pier structure and reinforced concrete superstructure as well as for the temporary support of the bridge during the entire building project which has been scheduled to take up to two years. Essentially, it is two modular construction systems combined with each other which transfer the high loads safely into the ground. With help of the PERI UP Rosett Flex modular scaffold system, forming a spatial load-bearing structure for the piers and superstructure formwork is formed, gradually increasing up to the total support height of over 20 m to the rear and upwards respectively. By means of 25, 50 and 75 cm long ledgers, the 150-cm basic grid can be adapted to suit the geometric and static requirements extremely flexibly. This allowed the polygonal 32° to 36° shallow pitched inclined piers on both sides of the bridge to be constructed in eight segments, each 4.50 m long. In addition to the PERI UP scaffold construction being used, the VARIOKIT engineering construction kit, in particular, offers standardized system solutions for tunnel, bridge and civil engineering projects. Thus, trusses consisting of rentable standard elements support the obliquely-positioned VARIO GT 24 girder formwork and transfer the formwork and concreting loads of the inclined piers safely into the scaffolding. The VARIOKIT modular construction system also forms the basis for the heavy-duty shoring. In the connecting area between the cast-in-place bridge and steel arch, two 17 m high, 42-leg VARIOKIT heavy-duty shoring towers are used to accommodate the high loads – throughout the entire construction period until the inherent load-bearing capacity is reached. Each of the two towers has to carry loads of 1,200 t and, due to the long utilization time, high earthquake as well as horizontal loads. Here, PERI engineers combined four standard towers, each with a 2.00 m by 2.00 m axis dimension, by means of several bundled 37.5 cm additional frames (number depended on the load concentration) to form two power packages – using only rentable system components and construction-compliant, type-tested connection means. write your comments about the article :: © 2012 Construction News :: home page |