In this paper the BEHAVIOUR of steel frames is investigated under an applicable range of initial rotational geometric imperfection in joints, which are mostly created during the manufacturing process. A nonlinear analysis is applied in both geometry and material BEHAVIOUR of steel frames. The results show considerable reduction in BUCKLING and ultimate load carrying capacity of portal frames, when they are affected by a rotational imperfection.

The spacecraft and space shuttles demand novel engineering materials to meet the required properties. This can be accomplished by altering the material properties in more than one direction. The introduction of inplane bidirectional functionally graded materials with porosity are expected to exhibit these properties. This paper presents the BUCKLING analses of inplane bidirectional (2-D) functionally graded porous plates (IBFGPPs) considering uniform porosity distribution in uni-axial and bi-axial compression. The effective modulus of elasticity of the material is varied in in x-and y-axes by employing the rule of mixtures. The higherorder theory used for the study of BUCKLING response meets the nullity requirements at plate’s upper and lower surface and derived the equations of motion thru Lagrange equations. The displacement functions are formulated in simple algebraic polynomials, incorporating admissible functions to satisfy the simply supported conditions in both axial and transverse directions. The components of admissible functions are derived by Pascal’s triangle. Accurateness of this theory is judged by comparing it to existing numerical data in the literature. The effect of thickness ratio’s (a/h), aspect ratio’s (b/a), exponents (ζ_1and ζ_2) in η_1 and η_2-direction, and the porosity on the BUCKLING response of IBFGPPs are examined comprehensively. The numerical findings provided here serve as reference solutions for evaluating diverse plate theories and for comparing them against results obtained through alternative analytical and finite element techniques. From the obtained results, it can be inferred that the proposed theory facilitates the assessing of BUCKLING tendencies of in-plane bi-directional porous FG plates produced through sintering process and could be deemed as a pivotal in the process of optimizing the design of the IBFGPPs.

The present paper investigates the BUCKLING BEHAVIOUR of single layer geodesic and reticulated dome form of space structures. For this purpose, three aims have been pursued. Initially, the results of linear and non-linear BUCKLING analysis have been compared by finite element method. Correctness of the utilized finite element method has been checked by results of previous articles, then with description of slenderness factor of dome as geometrical parameter of dome, by investigating the results of non-linear BUCKLING analysis that resulted for domes with different slenderness factors, the rage that general BUCKLING, dimple BUCKLING and member BUCKLING can occur have been determined. The ultimate aim is earning relations for estimating critical BUCKLING load of single layer geodesic and reticulated dome form of space structures. By using these relations, BUCKLING loads of domes could be estimated accurately without any need to time-consuming non-linear analysis and complicated mathematical calculations. In order to achieve to these three goals, the geometrical modelling of structures has been performed by programming at MatLab and coordinates of dome's joints have been determined.

For design purposes, the stability of any structure being designed is of paramount importance. The fact that it is possible to perform an analysis on a space structure which shows that the stresses in that structure are all below those permissible for the materials used in its construction, is, in itself, no guarantee that when the structure is loaded it will not collapse. In order to determine this, it is necessary to find out if the structure is stable under the action of the applied loads.The secondary paths, especially in unstable BUCKLING, can play the most important role in the collapse of the structure.In this paper, an attempt is made to automatically calculate the bifurcation path of shallow lattice domes. This calculation is performed in a two-stage analysis of the space structure, without introducing any geometrical imperfections. The method is implemented in a combined materially and geometrically nonlinear finite element analysis computer program, based on an incremental /iterative Newton-Raphson solution procedure. In the first stage analysis, the proportional live load factors, at which critical points occur, are determined and the primary path is obtained. In the second stage analysis, the perfect structure is led towards the lowest bifurcation path, using the technique described in the paper. The resulting theoretical predications are verified by existing experimental observations on a model dome.

The aim of the study is to investigate the distortional BUCKLING BEHAVIOUR of intermediate cold-formed lipped channel sectionunder pinned end condition subjected to axial compression. An extensive test and numerical investigation of cold-formedlipped channel column with various types of intermediate web stiffeners is presented. In this study, three types of intermediateweb stiffeners are chosen such as V, U and Σ . The entire cross-sectional dimensions meet with the pre-qualified columndimension given in Direct Strength Method for cold-formed steel structures. Totally, 12 columns are tested and results arecompared with the numerical analysis. Numerical analysis is carried out using software ABAQUS. Material and geometricimperfections are incorporated in the FE model. Selected section dimensions met with the distortional BUCKLING mode. Goodcorrelation is achieved between experiment and finite element analysis. All the results are compared with the Direct StrengthMethod specifications for cold-formed steel structures. Based on the comparison of results, a suitable design modification isproposed. Furthermore, results are verified with the existing results which are available from the literature.

Fish cell cellular metastructures have received wide interest from researchers due to their zero Poisson ratio BEHAVIOUR. However, their production, which is mainly based on additive manufacturing processes, is one of their limitations. Therefore, in this research, a new method based on the conventional manufacturing processes including laser cutting and metal forming was presented for the production of metallic cylindrical metastructures. Two samples were manufactured using this method and their quality was verified using mechanical and non-destructive tests. The samples’ mechanical and BUCKLING BEHAVIOUR under uniaxial compression were simulated using ABAQUS FEM package and experimentally validated. This was followed by the effects of the metastructures’ geometrical parameters including the cylinder diameter, height and thickness on their linear BUCKLING being investigated numerically, and the results compared with the outcome of classic theories for conventional cylinder BUCKLING. The results showed that these metastructures can be produced successfully with the conventional manufacturing processes, and t the BUCKLING BEHAVIOUR of these metastructures does not follow the classical BUCKLING theories of cylinders; their BUCKLING BEHAVIOUR shows much lower sensitivity to the thickness and radius changes in comparison with conventional cylinders.

To investigate BUCKLING/ultimate strength of ship bottom plates, a series of elastoplastic large deflection analyses is performed applying finite element method. To achieve this purpose, symmetrical conditions are imposed on the plate boundaries. Also a series of elastic large deflection analyses is done in order to assess BUCKLING BEHAVIOUR and strength of continuous plates under combined lateral pressure and inplane compression.