Experimental study on ultimate strength of steel-welded ring-stiffened conical shell under external hydrostatic pressure

Abstract

This paper reports experimental and numerical investigations on the ultimate strength responses of steel-welded, ring-stiffened conical shells when subjected to external hydrostatic pressure. Four small-scale shell models were fabricated from general structural steel by cold bending and arc welding. First, hydrostatic pressure tests were performed to investigate the collapse behaviour of the models. The influences of different parameters were also studied experimentally. Before the experiments, quasi-static tensile tests were performed to obtain detailed characterisation of the test model material. In addition, the initial imperfection of the shell and other as-built geometry parameters were carefully measured. The test was conducted using compressed water in a small-sized chamber and loaded to collapse. Three models with heavy stiffeners were failed by local buckling at the shell between the ring frames. Another model failed by the overall buckling of the adjacent frames together with the shell. The numerical computations were performed on the finite element code of ABAQUS FEA. The imperfection due to fabrication, such as initial out-of-circularity, and residual stresses due to welding are simulated. The quasi-static response was compared with the experimental load and plastic deformation curves. The numerical results revealed a close agreement between the collapse pressure prediction and failure modes of the simulation and the experiment.