Nemetschek Structural User Contest 2013

138 X2 Category 2: Civil Structures The Bridge over Koberný lake and a wildlife corridor at the 87,500 km point of the D3 motorway section running from Tábor to Veselí nad Lužnicí, with a total length of 552.8 m (58.4 + 4 x 109.0 + 58.4), is located in a non-built-up area, within the meliorative area of Koberný lake, about 15.4 m above the terrain surface. It is located approximately two kilometres south-east of the town of Planá nad Lužnicí, and about one and half kilometres north of the village of Košice. The valley which is traversed by the bridge is used for agricultural and breeding purposes. The D 27.5/120 width configuration motorway bridge is set to a right-hand horizontal curve with the radius R = 1,750 m and in vertical alignment is on a vertical curve with the radius R = 35,000 m. Transversally, the roadway on the bridge is superelevated at 3.5 %. The C 30/37 XF4 concrete grade pillars, with the crosssection of 8.0 x 2.5 m, are founded on 19 thirty-metre piles 1.2 m in diameter. The piles are keyed into R3 and R4 paragneiss to the depth of about 1.5 m. Under abutments and in the transition area, the ground is reinforced with gravel piles, allowing for the effect of the settlement of adjacent embankments with the average height of 12 m. According to calculations, the aggregate settlement of the adjacent embankments reaches up to 0.6 m. The abutments are founded on 10 deep piles. Water encountered during drilling for the piles was pumped to settling tanks behind the abutment to be liquidated in an environmentally friendly way. Two pairs of casting carriages were used for the freecantilever-method construction of the load-bearing structure of the box girder with the variable depth ranging from 2.69 m to 5.89 m. Casting of the girder proceeded symmetrically from 16-metre long balance arms. The stub was cast at two stages, on a scaffold provided by PIŽMO supports. Four temporary reinforced concrete supports with the cross-sections of 1.3 x 1.3 m were tied for stabilising the balanced cantilevers on each foundation. The stub in the assembling condition was with the foundation for each temporary support in relation to a pair of pre-stressing rods 47 mm in diameter. After the joints of the neighbouring stubs were made monolithic, all the temporary supports were deactivated. Several mathematical models for apposite computational analysis of the structure during all the stages of the construction process were created in Scia Engineer. Calculations were realised with a global and local finite elements model using beam and (or) plate elements. Because of a great computational demand, or sometimes the poor relevancy of global models, some details of the structure and some phases of the construction have been modelled and calculated in separate models. Two global models were created. The first one - a 3D model, which consists of 1D members in proposed geometry - was made for clarification of the torque, for the assessment of inner forces from support settlement, the superimposed dead load and climatic effects, and for determination of the bearings load. The second one is a 2D flattened model which consists of 1D members. It was made for time dependent analysis. The model reflects the rheology and loading history for the assessment of inner forces and deformations in specific time. For the shape modelling, the 1D member modeller was used with a Variable crosssection, General cross-section and Planar 2D members. Concrete designer modules were used for better time dependent behaviour understanding e.g. Post-tensioned tendons, a Prestress check and Time dependent analysis. The global analysis model is a 3D frame TDA model with beam elements respecting the proposed geometry. Crosssections that are 1D member are defined as general cross-sections with a linear-variable connection. The piers are 1D members with a constant cross-section. The foundation details are calculated separately and in the global model are represented as an elastic support. The tendons are modelled using a Post-tensioned tendons module aid. Cantilever tendons in the upper plate of the deck and continuous tendons are applied as 1D member in real proposed geometry or in a flattened shape in a TDA model. The bearings are simulated as short 1D member with joints with specific material characteristics. In TDA a relevant displacement is released in a specific time. Temporary supports are rigidly connected to a balanced cantilever and in TDA they are also removed in specific time. The computation of inner forces is carried out with a standard linear calculation. Bridge over Koberný Pond and a Wildlife Corridor at km 87,500 of D3 Motorway - Soběslav, Czech Republic Software: Scia Engineer