ON SHAPE FINDING METHODS AND ULTIMATE LOAD ANALYSES OF REINFORCED-CONCRETE SHELLS

Due to considerable imperfection sensitivity the initial shape of a shell can play a dominant role for the quality of the load carrying behaviour. In particular, this is important if large deformation effects and material failure may interact unfavourably, as can be the case for thin reinforced concrete shells. The present contribution discusses different form-finding methods for the shape of free form shells. Among these are the well-known experiments with pressurized or dead-loaded membranes which can also be simulated by a nonlinear membrane analysis or the application of shape optimization schemes using stress levelling or strain energy minimization. The second part is devoted to ultimate load analyses of RC shells. After a brief review of the material models used, selected examples are described, for instance conical shaped cooling towers and a free form model shell which is also experimentally investigated.