Experimental and numerical investigations on overall buckling of steel pipe truss with circular cutout on the compression element

Pitting corrosion, an extremely localized corrosion that leads to the creation of small holes in metal when a protective coating is damaged could trigger structural failure in platform structures. A single pit in a critical point, especially in compression element, can cause a great deal of reduction in overall buckling capacity of the structure. This study aims to indicate the effect of a circular cutout, representing a pitting corrosion on overall buckling capacity of steel pipe truss structure subject to static loading. Five models of truss structure having a circular cutout on their compression elements had been tested experimentally up to failure. The truss structures were made of steel pipes and contain only 2 elements as representation of part of real platform. The single cutout were located at 0.5L, 0.25L and 0.125L, where L is the length of the compression element. Two models without cutout had been used as control models. The overall buckling capacity of the truss were compared to similar truss based on the element buckling of compression element. The experimental test results, represented by nonlinear load deflection curves and their associated critical loads as well as buckling modes, had been verified numerically by eigenvalue and geometric nonlinear finite element analyses utilizing 3D solid elements on ABAQUS. The results showed that: (a) in the truss model with various hole positions, the overall buckling loads were slightly higher than that of element buckling loads: (b) the presence of cutout reduced the overall buckling capacity of the structure, (c) the capacity reduction factors depend on the cutout locations and (d) the lowest capacity reduction factor of 0.882 was associated with the presence of cutout at the middle of compression element.