Interactive plastic buckling of cones subjected to axial compression and external pressure

The paper discusses the results of buckling tests on carefully machined steel cones subjected to combined loading. Two cones were subjected to pure axial compression, further two were loaded by lateral pressure and the remaining six were tested under different combinations of axial load and external pressure. Cones were relatively thick with the radius, r2, at the base to wall thickness, t, being r2/t≈50. The ratio of height, h, to the base radius, h/r2=1.0, and the semi-vertex angle was β=14°. All numerical predictions of buckling load were found to be higher than the values obtained in experiments. Experimental results were also checked against values recommended by two design codes. Buckling loads recommended by codes show that five out of ten cones would have developed permanent, plastic straining at the recommended load level. Consequences of this, for repeated loading, are also highlighted in the paper. The paper also shows that a large portion of the interactive diagram is affected by plastic strains with the first yield envelope having bi-linear shape while the collapse envelope being quadratic.

► Combined stability of steel cones.
► Experimental and numerical results.
► Comparison with design codes.