Locally flattened or dented domes under external pressure

•Eigenmode imperfections may not represent the worst scenario.•Lower-bound, increased radius imperfections nearly always on safe side.•Force Induced Dimples offer alternative approach: safe and computationally superior.

The paper provides comparisons of sensitivity of buckling pressures to initial shape imperfections, for the case of externally pressurised steel domes. A priori defined deviations from perfect shape include: Legendre polynomials, increased-radius patch, and localised inward dimple. The latter is created by a concentrated force acting radially. In this case the effects of spring back and/or annealing of the dented patch and the surrounding area on the load carrying capacity are assessed. Some of the elastic solutions related to the lower-bound approach are compared with the available experimental data.