Numerical simulation of initial geometric imperfections of steel cylindrical tanks

The critical loads of shell structures can be properly approximated only through including randomness in geometries. As it is difficult and expensive to measure the initial structure imperfections in situ or in laboratory a methodology of identification and description of the available data should be provided. The presented procedure provides an opportunity for the reproduction of the measured maps of steel cylindrical tank geometric imperfections. Simulations of the nonhomogeneous random fields of imperfections, based on the original conditional-rejection method of simulation are applied. Using the measured data an envelope of the imperfections is also estimated. It allows for simulation of extreme but still possible fields of imperfections. Additionally, nonlinear numerical analyses of tanks with and without initial geometric imperfections are performed. Soil parameter randomness is also included in the calculations. The results indicate that the initial imperfections influence the solutions.