Cross Sectional Adaption for Rod-Shaped Element in Compression

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The aim of the applied continuation phase is the optimisation of tubular shaped compression members which occur in constructions as columns. Columns carry the vertical loads of structures of the construction dead and live loads. Usual columns have rectangular or circular cross-sections. Depending on acting loads and the construction of the connection area between column and the adjacent members, different areas of the columns are more or less stressed and also the bearing behaviour of the adjacent members is influenced. It is aimed to develop optimised geometries for columns, for which the typical failure mechanisms of columns due to exceedance of stress or loss of stability can be excluded by an efficient material utilisation.In investigations during the first project period the factors influencing the bearing behaviour of columns have been determined and the transition points between the different failure types have been determined. At first the influence of the geometrical column form in longitudinal direction of centrically loaded columns has been investigated and optimised cross-sections and shapes in the column axis were found. Based on that the influence of additional bending moments acting on the column were analysed and the resulting principal optimum shapes for basic loading conditions developed. In reality columns are exposed to combinations of different actions, so that at first a characteristic loading scenario has to be chosen to develop an optimised column shape. For the design and construction columns are idealised as uniaxial trusses, but for the construction also the connection point to the slabs is important and was investigated. Thereby the positive influence of the developed column shape was found, because a haunching of the column ends improves the load transfer between slab and column and the overall behaviour of the structure.In the applied project period the developed column shapes for basic loading conditions are to be optimised for certain characteristic loading cases. Therefore numerical calculation will be done and the results verified by experimental investigations. As the result a column shape according to form follows force is developed which is also material- and resource-efficient. A separate focus lies on the connection point between column and slab under consideration of local problems, as e.g. the punching of slabs. Therefore a close cooperation with the project Lightweigth Ceiling Structures Made of Layered High-Performance Concrete, also applied for by the applicant, is planned. At the end the consolidation of form optimized members to a spatial structure is proven with the development and construction of a demonstrator.