Creep buckling of imperfect thin-walled shallow concrete domes

The sensitivity of the nonlinear long-term creep behaviour of shallow concrete domes to geometric and material imperfections is investigated in this paper. A nonlinear incremental theoretical model is developed, which accounts for the effects of creep and shrinkage, considers the aging of the concrete material and the variation of the internal stresses and geometry in time, and is applicable for different and nonaxisymmetric imperfection scenarios and loading schemes. The model focuses only on shallow concrete domes, but the modelling concepts and solution techniques can be generated for the creep buckling analysis of different types of thin-walled concrete structures. The field equations are derived using the variational principles of virtual work and using integral-history-type constitutive relations that are based on the principle of superposition. A step-by-step procedure is used for the solution of the governing equations in time, while the solution of the incremental partial differential equations in space is achieved by a separation of variables and expansion into truncated Fourier series in the circumferential direction, along with the use of the multiple shooting method in the meridional direction. Numerical and parametric studies, which highlight the capabilities of the model and which provide insight into the nonlinear long-term behaviour of imperfect shallow concrete domes, are presented. The results show that the structural behaviour and the critical time to cause creep buckling are very sensitive to geometric and material imperfections.