Löhning, ThomasThomasLöhningSchenk, JochenJochenSchenkStarossek, UweUweStarossek2024-09-262024-09-262007Proceedings of the 11th International Conference on Civil, Structural and Environmental Engineering Computing, Civil-Comp 2007978-1-905088-15-7978-1-905088-16-4978-1-905088-17-1978-1-874672-32-6https://hdl.handle.net/11420/49251For slender concrete structures material and geometrical nonlinearities have to be taken into account on grounds of safety and economy. The material nonlinearity of frame elements can be captured on the cross-sectional level. A nonlinear analysis provides the relation between the state of strain and the internal forces. For spatial frame elements six internal forces have to be considered. The sophisticated structural behaviour of an RC frame element under torsion is studied in detail with threedimensional finite elements. Taking into account existing models and the preliminary finite element analysis a new approach for reinforced and prestressed spatial frame elements with arbitrary cross sections is derived. The approach is based on a notional division of the cross section into two interacting systems. Bending moments and axial force act on the concrete section and the longitudinal reinforcement. The torsional moments and the shear forces are assigned to a assumed thin-walled hollow section assembled from membrane elementsenCross sectionFramesMembrane elementsNonlinear analysisReinforced concreteShear modelsTechnology::690: Building, ConstructionConference PaperConference Paper