The present paper discusses on ultimate strength of a shallow reinforced concrete domes supported at four corners. The loads for investigation are not only dead load but also approximate earthquake loads considering anti-symmetrical vertical loads caused by horizontal earthquake motions. The method is based on an elastic-plastic geometrically nonlinear analysis considering both effects of initial geometric imperfections and tensile strength of concrete. Based on the results, several important structural features are revealed. The geometric imperfection distribution similar to those caused by dead load reduces the ultimate strength, and the strength is much reduced if no tensile strength is assumed for concrete. If 40% of the shell thickness and no tensile strength are assumed respectively for the imperfections and for concrete, the ultimate strength is reduced by almost half from the perfect case. The ultimate strength interaction between dead load and earthquake loads shows the importance in design to include the anti-symmetrical load components of earthquake loads. The importance of not only stiffeners at free edges but also shell geometries of bending moment free are suggested.
