A Tube with a Rectangular Cut-Out. Part 2: Subject to Axial Compression

Simply supported steel tubes with rectangular cut-outs of different sizes positioned at their mid-length were subject to axial compression to assess the effect of the cut-outs on the deformation behaviour. Experiments on 1000 mm long, 100 mm diameter, and 2.55 mm wall thickness DIN 2391 ST NBK supported steel tubes are described. The experimental tubes were relatively thick walled, with a thickness-to-diameter ratio typical of structural columns, rather than shell structures. The radial position of the cut-outs was such that the reduced cross-section was symmetric with respect to the direction of rotation of the pinned ends. Several permutations of the axial and circumferential dimensions of the cut-out were tested so that the effect of changing these dimensions could be assessed. Finite-element and semi-empirical analyses were carried out to predict the global load-deformation behaviour of the tubes. Both analyses gave good predictions of the experimental results for the majority of the cut-out parameters investigated. The motivation for the study was to investigate the feasibility of using cut-outs to initiate and control the toppling of offshore jacket structures.