Modelowanie i analiza mostu extradosed w fazie budowy i eksploatacji

This paper presents an example of modeling and analysis of an extradosed bridge structure which has been performed with the use of SOFiSTiK software. The input data for the development of models and execution of calculations was based on fragments of design documentation of a bridge over Vistula river in Kwidzyn, prepared by Transprojekt Gdańsk and made available to the authors in 2009. The main load bearing structure consists of a 6-span post-tensioned concrete girder, with cross-section of a 3.5m high 3-chamber box, additionally tensed with cables of extradosed type. The objective of the study was to develop computational models of the superstructure and their structural static analysis during two main phases, namely incremental launching and finally during operation of the bridge, when the target static scheme was achieved. The paper presents an analysis of the structure during incremental launching. The process of incremental launching has been modeled with the use of CSM module (Construction Stage Manager). The CSM is a part of the Sofistik environment which has been designed for modeling construction cycles and scenarios of structural systems which are to be built in stages. The methodology of development of numerical models has been described in detail, with regard to the capabilities of the used software. The paper presents the way that the geometry of the bridge has been generated, the method of simulating the incremental launching as well as the types of the loads which have been applied to the structure. The studies have been conducted on two separate numerical models. The numerical models consist of bar elements situated in a two-dimensional and three-dimensional spaces. The model created for the purpose of the operating stage analysis has been presented with regard to generation of the structure, division into finite elements, modeling of inner and outer tension cables, applied loads and the criteria assumed for analysis of the structure. Moreover, the authors present an alternative post-tensioning system, as compared to the one assumed in the building design, which ensures limited compression of the structure. Finally, the paper contains the conclusions and observations arising from the performed analysis.