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Abstract The ultimate strength of stiffened panels under compressive loads is assessed by numerical simulations, in order to compare with tests made to investigate the influence on the ultimate strength of varying pit location, pit diameter and pit depth. The validated model is them used for a numerical study on the influence of pitting on the residual ultimate strength of stiffened panels by a series of non-linear finite element analysis. The parameters of pit position, diameter, number, depth, and corroded volume loss will be investigated for the stiffened panels subjected to axial compressive load with initial deformations. It is found that the pits will induce the buckling failure of stiffened panels. All parameters discussed in this paper have significant influence on the residual ultimate strength of the pitting corroded stiffened panel. A formula was derived by introducing the reduction of plate slenderness and column slenderness. Highlights • The collapse mechanics of pitted stiffened plates are investigated numerically compared with tests. • A series of FEAs were conducted to study the influence of pit damage. • Pits can induce the buckling and reduction of ultimate strength of stiffened panel. • A formula is introduced considering the reduction of the plate slenderness ratio and column slenderness induced by pits. [ABSTRACT FROM AUTHOR]

In this paper, compressive behavior of tubular structures made of aluminum and multilayer carbon fiber reinforced plastic (CFRP) are studied experimentally and numerically. Results show that current evaluation of aluminum tubes using Johnson–Euler method overestimates the critical stress values of the tubular structure because local failure is ignored. A finite element analysis (FEA) model based on Riks method is proposed to re-evaluate compressive performance and failure modes of aluminum tubes. This model is modified for laminated composites by introducing damage model based on Hashin's theory, such as matrix tensile/compressive failure, and fiber tensile/compressive failure. Simulation results of CFRP tubular structure show close agreement with experimental results, but also sensitive to geometric constants. Material failure is primarily the failure mode of tubes with slenderness ratios under 21. A mixed failure mode can be found for slenderness ratios of tubes between 21 and 35. For tubes with slenderness ratios above 35, buckling failure is the primary failure mode. [Display omitted] • Establish evaluation criteria for load carrying capacity of tubular structures. • Analyze compressive behavior of tube by numerical and experimental methods. • Study the large-scale effect in metallic and composite tubular structure. • Design a new compression fixture to test composite tubular specimens. • Examine delamination of composite tubes under axial compressive load. [ABSTRACT FROM AUTHOR]

Thin-walled cylindrical shell is a fundamental engineering structure which has efficient load-carrying capacity. In practical application, this structure is more easily subjected to localized axial compression loads and is prone to buckling. However, until now there is only limited studies on the buckling problems of multi-region localized axial compression loaded cylindrical shells. To elucidate the buckling behaviors of cylindrical shell under such kind of non-uniform loading condition, experimental and numerical studies are carried out in this paper. Twenty cylindrical shell test specimens with different types of localized axial compression loads are fabricated and tested. The corresponding finite element model considering the measured initial geometric imperfections is established for buckling analysis, and good agreement between the numerical and experimental results is validated. Then the buckling failure mode and axial load-carrying capacity of cylindrical shells are investigated in details. Finally, the imperfection sensitivity of thin-walled cylindrical shell under multi-region localized axial compression is discussed. It is found that the number of loading regions and the total loading area have significant effects on buckling failure mode and axial load-carrying capacity of cylindrical shells. The results obtained from experimental and numerical studies can provide some important guidance or suggestions for the design of thin-walled cylindrical shell structures in actual engineering. • Buckling tests of 20 metallic thin-walled cylindrical shell specimens under multi-region localized axial compression loads were performed. • Finite element model for studying buckling behaviors of cylindrical shell were established. • Buckling failure mode and axial load-carrying capacity of cylindrical shell were systematically investigated for the first time. • Imperfection sensitivity of cylindrical shell under multi-region localized axial compression loads was discussed. [ABSTRACT FROM AUTHOR]

Buckling failure analysis of buried subsea pipeline under reverse fault displacement was investigated by the Vector Form Intrinsic Finite Element method in this paper, considering nonlinear soil–pipeline interaction in slit with sand and the multifold nonlinearities of nonlinear material, large deformation, large displacement and self-collision/contact. Two typical conditions discussed were the operation condition and the empty waiting state during installation, maintenance, and operation. Effects of soil properties, pressure loadings, diameter–thickness ratios and dip angles on local buckling formation, tensile strain and cross-sectional distortion were investigated. The results show that subsea pipelines obtain a large deformation capacity and the flexure curve shape is usually S-shape. The external pressure is more unfavorable than the internal pressure since it aggravates the compression strains but alleviates the tension strains. A small fault dip angle results in serious axial compression and can lead to local collapse in the empty waiting states. For big diameter–thickness ratios or great pressure level, external pressure will cause local collapse and even buckle propagation along the pipeline. Seven different modes of collapse and propagation are discovered in the empty waiting state. They can be classified by the first collapse location, buckle propagation direction and further propagation sustainability. The cross-sectional shapes after collapse and during propagation are mainly determined by the compression or tension state around the circum. These results can be used for the development of performance-based design methodologies for buried subsea pipelines. • Buckling failure analysis of buried subsea pipeline based on VFIFE thin shell element. • Practical solution for multifold nonlinearities, especially the self-collision/contact problem. • Performance assessment of the operation condition and the empty waiting state. • Effect analysis of the fault dip angles, the diameter–thickness ratios and the pressure loadings. • Seven different modes of collapse and propagation discovered in the empty waiting state. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose a new failure criterion for thin-walled steel frame structures based on the sum of the structural exponential strain energy density (ESED) parameters, by analyzing the whole behavior of thin-walled steel frame structures under static and seismic loads. Firstly, the strain energy variation of the thin-walled steel member and structures before and after buckling failure is studied theoretically by introducing the thin-walled theory, after this the ESED failure criterion is proposed to estimate the seismic failure loads of thin-walled steel frame structures. Secondly, a one-story thin-walled steel framework, a five-story thin-walled steel framework and a single-layer spherical reticulated shell separately subjected to different waves were selected on which to carry out the nonlinear time-history response analysis to obtain the ESED model to verify the new failure criterion. Finally, some discussions, comparison between the numerical solution and the analytical solution, the distinction of the ESED between pre- and post-structural failure and failure modes corresponding to the failure load, on the new failure criterion are conducted to a certain extent to prove its rationality. The research on the new failure criterion will provide a new approach to carrying out the structure failure mechanism analysis and contribute to the structural design with more overall confidence. • We proposed a new failure criterion for thin-walled steel frame structures based on the sum of the structural exponential strain energy density (ESED) parameters, by analyzing the whole behavior of thin-walled steel frame structures under static and seismic loads. • When buckling occurs in the bending model, the membrane strain energy will be converted into strain energy of bending. In a thin-walled structure, membrane stiffness is typically orders of magnitude greater than bending stiffness. Accordingly, the strain energy of a thin-walled structure can increase sharply when buckling occurs with small membrane deformations. [ABSTRACT FROM AUTHOR]