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Moderately thick perfect cylindrical shells under axial compression first exhibit an axisymmetric buckling mode, where a localization of buckling patterns, referred to as an elephant foot bulge, is caused by the first plastic bifurcation. However, the transition from the axisymmetric buckling mode to a nonaxisymmetric buckling mode, referred to as a diamond buckling mode, may occur due to the next bifurcation if we continue the loading under displacement control. Herein, this phenomenon is examined, based on a rigorous plastic bifurcation analysis. As a result, it is observed that the circumferential wave number of the diamond buckling mode increases with the decrease of the wall thickness. The boundary conditions also considerably influence the occurrence of diamond buckling. It is found that the strain concentration is intensified for the diamond buckling modes, compared with the axisymmetric modes.

This paper investigates the cyclic-localization behavior of axisymmetric plastic buckling patterns of cylindrical shells in terms of its influence on strength deterioration. Since localization occurs due to a plastic bifurcation in the postpeak range, we first present a rigorous method to analyze the plastic bifurcation under the two-axial stress state, which is characteristic of the axisymmetric buckling. In this analysis, we also use an accurate cyclic plasticity constitutive model. The validity of the proposed theoretical approach to localization behavior is confirmed by a cyclic loading test on thick cylindrical shells. Then, using the proposed method, we precisely examine the effects of structural parameters as well as boundary conditions on localization behavior.

Diagonal arrangement is a prerequisite for diagrid tube structures in preliminary design. Two scenarios made up of curved or varying-angle straight diagonals, all established by only two basic geometric variables, i.e. the bottom angle and the top angle of the control arc or straight diagonal, are evaluated under seismic and wind loads. Approaches to configuring diagrid tube structures of these two types are introduced graphically. A set of diagrid tube structures composed of curved and straight diagonals with various combinations of bottom and top angles, with height-to-width aspect ratios ranging from 3.6 to 9, are investigated focusing on the optimal geometries in terms of the material usage. By giving attention to both seismic and wind loads, the optimal values of bottom and top angles are suggested respectively for these two types of diagrid tube structures with different aspect ratios. Furthermore, the proposed method is validated by FEM analysis. Consequently, the structurally efficient use of diagrid tube structures with curved or varying-angle straight diagonals could be provided conveniently for both engineers and architects in preliminary design. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Diagrid tube structures have excellent lateral force resistance but poor structural ductility, which can be improved through buckling restrained brace. With respect to 30-story diagrid tube structures, nonlinear static analysis, i.e. pushover analysis was conducted respectively for the conventional diagrid tube structure and those with buckling restrained brace. The results show that the structural ductility is improved by utilizing buckling restrained brace. Furthermore, four schemes of diagrid tube structures partially with buckling restrained brace in different parts of the facades, including the corner and the middle, the bottom and the upper, were investigated for structural ductility. Diagrid tube structures partially with buckling restrained brace should be designed so that conventional brace remain in elastic state, while buckling restrained brace turn into plastic state in advance for energy dissipation. Diagrid tube structure with buckling restrained brace in the middle part of facade is recommended, which could effectively improve structural ductility to avoid brittle failure without decreasing shear load-bearing capacity. [ABSTRACT FROM AUTHOR]

This paper presents preliminary design guidelines specifically for diagrid tube structures composed of straight diagonals with gradually changing angles. A graphic approach to configurating a diagrid of this type is introduced, with two basic geometric variables involved, i.e. the bottom and top diagonal angles. In terms of both stiffness and strength design criteria, a methodology for calculating diagonal member sizes is developed and applied to a set of diagrid tube structures with height-to-width aspect ratios ranging from 3.6 to 9. The diagrid tube structures are designed with various combinations of bottom and top angles in order to investigate the effects of bottom and top angles on the material usage. Based on the results, the optimal values of bottom and top angles are suggested, then, the optimal geometries for diagrid tube structures with different aspect ratios are determined. This paper attempts to help the designer arrange the structurally efficient diagrid layout conveniently and perform approximate calculations of the diagonal member sizes. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]