Nemetschek Engineering User Contest 2009 • Category 3: CAE Civil Works 141 3 of the other network arch. The longitudinal prestressing of the ramps is anchored in the end cross-beam of SO 201. The third layer of the prestressing is the transverse prestressing of the interchange part, which is necessary to mitigate the radial forces from the longitudinal prestressing of the ramps. The deck of the interchange part is 0,75 m thick in minimum. SO 203 – Bridge on the ramp No. 3 and SO 204 Bridges on the ramps No.3 (No.4) carry one traffic lane from (to) the interchange part.. The bridge decks of concrete C35/45-XF2 are 0.75 m high and are prestressed by 7 19-strand prestressing cables. The span lengths vary, from 12 to 16,5 m. Specifics of the construction method The network arches are built as simple beams. They are prestressed by one half of the prestressing cables anchored in the steel end cross-beam and are free to dismantle the scaffolding. Then, the interchange part together with the ramps is cast. The rest of the longitudinal prestressing cables of the network arches, the transverse prestressing of the interchange part and the longitudinal prestressing of the ramps follows. Due to the division of the grade-separated connection into four bridges, four sets of breaking and acceleration forces have to be considered in the design. It is not possible to assign such horizontal forces to one fixed bearing, so a unique configuration of bearings with no fixed bearing had to be developed. Bearings with lateral fixation are placed on all four ends of the bridge system – the system works as if it would have a fixed bearing in the intersection point of the laterally fixed bearings connection lines. Software and modules used in this project Such a complex task required development of a set of sophisticated 3D-models. The models were developed in IDA Nexis 32 3.90 then later exported and further developed in Scia Engineer and its predecessors. Many modules were used, among them: • Building phases, both 2D and 3D • Time dependent analysis • Stability frame – estimation of the critical buckling factor • Second order calculations • Non-linear elements • Dynamics – calculation of the Eigen frequencies • Graphical sections • Base • 3D Frame, 3D shell, 2D frame • Rib calculations • Free loads on 2D-model • Free input of cables on 2D objects • Check of prestressed concrete according to CSN 73 6207 Experience with the Nemetschek Engineering Group software Many functions of the used software were appreciated, among them the building phases which were necessary for the analysis of the construction sequence, the TDA which helped to quantify the losses in the prestressing cables due to creep and shrinkage and the construction sequence. The crucial function appeared to be the newly developed free input of cables on 2D objects, which enabled detailed check of the prestressing of the interchange part. Bridges on the grade-separated connection of the road II/468 and the industry area in Třinec-Baliny (CZ)
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