Modelling active bent structures in a FE program for frameworks based on Excel is covered in this work. The question if it is possible to build an accurate model by using different linear-elastic calculation methods, like theory first or second order will be answered. After introducing some facts about active bending itself, especially two standard systems like the active bent column or the active bent bow, attention is payed on methods of form finding. To find an optimized form for frameworks, as well 3-dimensional ones, the force density method is presented. It is possible to find a configuration of a system with for example equal internal normal forces with this method. But of course also other arrangements of internal forces can be sought for. Secondary this work deals with different materials which are able to be used in active bent constructions. The most important property of such materials is the ability to get shaped in a low radius of curvature, that can be found particularly in construction materials like wood, aluminium or fibre reinforced polymers (FRP). Furthermore fundamental aspects of linear-elastic as well as non-linear calculation methods are explained as to evaluate results from the followed FE analysis example. By way of example an active bent footbridge in FRP is examined. It is constructed from two 32cm diameter FRP profiles with the original length of 45m bent on the building yard so that the span reaches 40m and the headroom of the bridge amounts to 9.2m. While being initial tensioned due to the bending process a bracing system is affixed slackly to special spots of the bridge. After this step the bending power is released and the system finds an equilibrium state dependent on geometric marginal conditions. These steps are implemented in FE as a construction progress and results are evaluated by using the facts which have already been introduced. The outcome of calculation using theory first order shows that it is impossible to generate correct values because important assumptions of linear-elastic approaches are hurt and necessary opportunities of modelling in non-linear theories are missing. By comparison to this the FE analysis applying theory second order is researched. The possibility to display the reality in this way cannot be confirmed without exceptions. After evaluating the results linear-elastic methods are not recommended to correctly calculate this example of a footbridge. Computing active bent structures like the spectated bowbridge needs to consider non-linear aspects from structural analysis in general.     «

Modelling active bent structures in a FE program for frameworks based on Excel is covered in this work. The question if it is possible to build an accurate model by using different linear-elastic calculation methods, like theory first or second order will be answered. After introducing some facts about active bending itself, especially two standard systems like the active bent column or the active bent bow, attention is payed on methods of form finding. To find an optimized form for frameworks, as...     »