Approximate critical load in analytic form of uniformly corroded shallow spherical shell under uniform external pressure

Oil storage tank roofs, which have been observed to undergo corrosion under service conditions, are usually designed as shallow spherical shells subjected to uniform external pressure, and it is necessary to determine the critical load of this locally thinned shallow spherical roof. We now present our approximate but very quick way of calculating this critical load. In this paper, we explain how to simplify the locally thinned spherical roof into a shallow spherical shell with elastic support.The fundamental equations, the solutions by modified iteration method, and contrastive analysis are proposed. Based on the above-mentioned simplification, we deduce a second-order algebraic equation to compute approximate critical deflection, thus obtaining the upper critical load of the shallow spherical shell. To examine the effectiveness of the method proposed, we do the contrastive analysis of two scenarios. The contrast results preliminarily show that the average error of the four upper critical loads calculated is less than 10%, indicating that the present method is effective.