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Diagrams and formulae for the buckling length factors β and for the critical forces Fcr of various frames. They are part of the large parametrical studies prepared for the Technical report Baláž, I., Snijder, H. H., Stroetmann, R.: CEN/TR 1993-1-103 Eurocode 3 – Design of Steel Structures – Part 1-103: Elastic Critical Buckling of Members. [ABSTRACT FROM AUTHOR]

In accordance with several studies, structural resistance of stainless steel members determined by utilizing flexural buckling curves for estimation of ultimate limit state, as proposed by current European standard, does not fulfill the required safety level of failure probability for some material grades and cross-sectional geometries. Several design provisions have been already recommended. The goal of this study is to verify and optimize certain provision suitable for analysis of circular hollow cross-section (CHS) members of various geometries and several stainless steel material grades. Numerical finite element simulations along with the first order reliability method (FORM) have been conducted utilizing the statistical values of input parameters (material, geometrical and initial imperfections) based on recent statistical research published in literature. The proposed design provisions of buckling curves are discussed. [ABSTRACT FROM AUTHOR]

Before 2020, buildings with steel structure in Indonesia was constructed based on Indonesian National Standard (SNI) 1729:2015. A year after that, new guideline of steel structure design, SNI 1729:2020 was published, replacing its predecessor. There are some new adjustments in this latest standard, which needs to be applied on the building going to be constructed. A 13-story apartment (11 upper ground floor with 2 basement), steel-concrete composite structure was designed in Aceh as a model from this latest standard. This building use buckling-restrained brace frame (BRBF) system which could solve the buckling problem that commonly happened in steel buildings triggered by earthquake and some other dynamic load. After modeling with the auxiliary program and doing the analytical study on the building design, it was found that in order to build this structure, the 2nd floor-roof floor used floor deck slab with 0,75 mm thickness, main beam's dimension on the 2nd floor-roof floor used Wide flange (WF) 700/300/13/24, on the basement-ground floor used reinforced concrete beams 400/600, main column's dimension on the 5th floor until roof floor used Concrete Filled Tube (CFT) 500/500, on the 2nd floor - 4th floor used CFT 600/600, on the ground floor used CFT 650/650, and on the basement-lower ground floor used 800/800 reinforced-concrete column. for the BRB frame used 300/300 HSS, and the dimension of steel core is 20.2 mm. the dimension of foundation design used Spun Pile D500 and 15 meters in depth, designed based on the local SPT result. [ABSTRACT FROM AUTHOR]

Grid shell structures are spreading in the last two decades thanks to their capacity to cover large span with light solutions. The peculiarity of these structures is to combine aesthetic/functional characteristics with optimal structural performances, which are completely merged since their shape and structural elements are the same thing. In this context, structural optimization techniques are increasingly adopted to support architects and structural engineers in the design of competitive constructions, usually in terms of structural weight, stiffness properties, cost and compliance specific requirements. In case of grid-shells, the optimal design process is strongly related to their susceptibility to global buckling phenomena, which are mainly related to the global stiffness of the structures. The main aspects that affect the susceptibility to global buckling are the rotational stiffness of joints, the boundary conditions and the presence of imperfections. In this framework, the paper presents a design optimization strategy that aims to minimize the weight by taking into accounts the rotational stiffness of the joints. In particular, the proposed approach pursues the objective to minimize the weight of the structure by specifically taking into account different levels of the rotational stiffness of the joints, while imposing specific structural requirements. The approach has been applied to case studies characterized by different boundary conditions, also considering the presence of imperfections. The results of the proposed design strategy highlight the beneficial effect of considering the rotational stiffness of the joints as a further parameter of the optimization, since it particularly influences the susceptibility of the grid shell to global buckling phenomena and the sensitivity to imperfections. [ABSTRACT FROM AUTHOR]

The aim of this work is to provide an extension of effective thickness method (ETM) in order to evaluate the ultimate response of aluminium members under uniform compression or in bending. It is well known that this approach is applied to evaluate the behaviour of aluminium slenderness sections affected by the local buckling phenomena in the elastic range. Starting from the original form, this approach has been extended for estimating the ultimate behaviour of aluminium members in the plastic region. [ABSTRACT FROM AUTHOR]

Metaheuristic optimization algorithms are increasingly applied to the solution of engineering problems. The current study focuses on the minimization of the CO2 emission associated with the production of a plate girder. Considering the tendency to lateral-torsional buckling in these structures, the critical buckling moment has been used as one of the optimization constraints. Furthermore, the flanges and the web of the plate girder are kept within the non-compact range throughout the optimization process. As the method of optimization, the metaheuristic Jaya algorithm has been modified using Lévy probability distributions for each design variable. The flange width and thickness, the web thickness and the clear distance between the flanges are chosen to be the variables of optimization. [ABSTRACT FROM AUTHOR]

The article presents a new approach to evaluation the ultimate load on existing trusses by tests. The main idea of the tests is to identify the "strain-load" and "load-deflection" dependencies to estimate the ultimate deflection corresponding to the ultimate strain of the weakest truss bars. It is proposed to use fuzzy membership functions for random variables in the tests due to the limited statistical data. Thus, statistical analysis of information turns out to be more reliable and free from normality tests and other statistical hypotheses. The technical result is achieved due to the fact that the strain-load functions for truss bars are substituted with the ultimate strain calculated for each bar separately: for compressed bars by the criterion of buckling and by the criterion of ultimate stress; for tensile bars by the criterion of ultimate stress. The approach also estimates an ultimate deflection of a truss which allows monitoring the structural safety level. The article also discusses a conceptual approach to the alarm system in the event of a dangerous situation: when the deflection reaches the lower limit value, the receiver stops obtaining a laser signal from the transmitter and the alarm system is automatically triggered. Such approach can be useful in buildings with permanent residence of people. [ABSTRACT FROM AUTHOR]

Structural steel design standards recognize elastic lateral-torsional buckling as a failure mode governing the capacity of steel beams with open cross-sections. Canadian standards provide critical moment solutions for laterally unsupported segments with idealized end conditions, full lateral and twist restraints but free warping and weak axis rotation. The Australian Standard and the Eurocode 3 Annex F have provisions to quantify for the elastic critical moment capacity when warping deformation or weak axis rotations are partially or fully prevented at member ends. The present study investigates the effect of end warping restraint and weak axis rotation at beam ends on the elastic critical moments based on thin-walled beam finite element models for loading conditions involving uniform moment, uniformly distributed load, mid-point load, a point load applied at the third span, two-point loads applied at third span, and linear moment gradients. The study shows that providing warping restraints at both ends increases the elastic critical moments of beam by 48% to 138% depending on the loading case and the type of warping restraint. Also, restraining the weak axis rotation at both ends increase the critical moment of the beam by 59% to 183%. Warping and weak axis rotation modification factors are then proposed based on the parametric runs and comparisons are then made against the Australian Standard and Eurocode 3 Annex F design provisions. [ABSTRACT FROM AUTHOR]

This research aims to examine numerically buckling of a rectangular plate with embedded stiffener under normal stresses using ABAQUS software. For this purpose, ninety-eight plate models were investigated under normal stresses. The major studied parameters were plate aspect ratio (a/b) ratio, (b/ t) aspect ratio stiffness height, shape and locations. The FEM results revealed that the stiffener location at the center of the plate is the best stiffener location for all plate's models, where it gives the highest bulking load where the increase ratio was from 15% to 140% if compared with the other location at the quarter and third of the plate where the ratio of increase at the third was 9% to 37% and 5% to 14% in the quarter, as well as with the increase in the stiffener's height a noticeable increase in the resistance to buckling from 8% to 140% with increasing in the stiffener height occurs, where the best case is achieved when the (stiffener height/plate length) ratio equal to 4% for most cases if compared with the plate without stiffeners. Regarding the shape of the stiffener, the best case that improves the structural behavior and performance of the plate was for the rectangular stiffener shape if compared with triangular, circular and trapezoidal stiffeners shapes where the ratio of increase was 130%. furthermore, it can be observed that there is a noticeable reduction from 5% to 1% in the resistance to buckling with the increase in the a/b ratio for all models, in addition to that for the (b/t) ratio, it can be concluded that with the increase in the mentioned parameter, a major decrease in the resistance to buckling occurs for all model specimens, where it's observed that the stiffened plate with a rectangular shape at the middle of the plate is the less affected shape with that decreasing lowest effected shape if compared with others shapes. [ABSTRACT FROM AUTHOR]

In this work, buckling behavior of nanocomposite plates with crack has investigated numerically under different types of buckling loads has been investigated numerically. Unsaturated polyester resin (UPR) matrix reinforced with fiberglass was fabricated incorporating (TiO2) and (SiO2) nanoparticles as fillers. (SiO2) and (TiO2) weight percentage used as 3% for. Finite element (FE) coded utilizing ANSYS 15 is used to work out the numerical model. A lot of design parameters had been varied for studying their influences on the buckling characteristics. The most important part of present work is the part which including the effect of crack parameters on the performance of buckling such as type of load, crack angle, position, and crack face direction. [ABSTRACT FROM AUTHOR]

This study investigates the stability response of pin ended complex angle sections subjected to axial compression. Eight different lipped angle sections (including plain and various stiffened) are considered. The thickness of the sections is adjusted such that the cross-sectional area of all sections is same. Based on the 'signature curve' obtained from preliminary finite strip analysis using CUFSM, height of the columns is considered to be 1m to ensure that flexural-torsional buckling mode governs their failure. Thereafter, linear and nonlinear finite element buckling analyses are carried out with the help of ABAQUS to determine the primary elastic buckling mode and column strengths, respectively. Nominal column strengths are quantified as per AISI S100-16 and are compared with the corresponding numerical column strengths obtained from finite element analysis. A good agreement between the numerical and nominal column strengths is noted. The findings of this numerical study indicate the superior performance of stiffened CFS angle sections over the plain angle section. [ABSTRACT FROM AUTHOR]

Composite rod systems belong to the category of new structural systems, which allow (on condition of the rational designing) creating the effective engineering solutions for the load-bearing structures intended for various applications. These structures are adapted to the stress-strain behavior, possess improved bearing capacity, stiffness and at the same time provide reduced consumption of materials. However, for the designing of composite rod systems, it is necessary to generalize the traditional methods for thin-walled rods calculations, which allow taking into account anisotropic and layered structure of composites. Based on the analysis of the nature of the technological and temperature impacts on a composite rod with non-homogeneous cross-section, the method for determining the temperature stresses in the rod elements, leading to its complex flexural-torsional deformed state, has been developed. The method provides assessment of two-dimensional stress field in the section elements and local features of configuration of thin-walled rod. Using the example of angle section with the reinforcing plate, dependences of the internal stresses on the structural, technological and operational parameters are studied. Thickness and length of legs of the angle section were chosen as the geometric parameters; change in the temperature of the section during its manufacture served as the technological factor; angle of reinforcement of the regular part of the composite section was taken as the additional structural factor. It is concluded that in order to reduce stresses and, as a consequence, the subsequent buckling of the section, it is necessary to aim for using the lower curing temperature ranges and close values of angles of laying of the reinforcing plate and the basic section. Based on the parametric studies, practical recommendations have been developed for the designing and manufacture of thin-walled composite sections, and measures to reduce the magnitude of stresses and deformations arising at the stage of production of articles have been proposed. [ABSTRACT FROM AUTHOR]

The article is devoted to the lateral-torsional buckling of elastic beams loaded with a potential moment. Such problems were previously investigated in a linearized formulation. The prebuckling deformations of the beam is not considered in this setting. We use the nonlinear geometrically exact beam theory and an exact non-linear solution in our article. The exact spatial stability functional and stability equations are obtained by the variation calculus. The exact value of a critical moment for the cantilever beam was obtained. [ABSTRACT FROM AUTHOR]

The present study deals with the buckling phenomenon modeling in a dome-shaped dielectric elastomeric (DE) actuator used in different aerodynamic and fluid power system applications. The DE actuator is a circular membrane type of actuator, which shows a large out-of-plane axial-symmetric deformation with an electrically induced loading condition. A classical continuum mechanics-based analytical model is developed to predict the electrically induced buckling deformation in the actuator. A detailed parametric study has been performed to see the influence of standard Neo-Hookean and Mooney-Rivlin types of potential energies on the geometrical and physical parameters. The findings show that the present model successfully links the sensitivity of different potential energies concerning the actuator's initial dome height and radius. [ABSTRACT FROM AUTHOR]

Refer to the thin element of cold-formed steel elements, the phenomenon of local buckling and post-buckling be a serious concern on structures. Thin elements undergo local buckling before melting stress while receiving a bending load, tension/compression, or shear around the support. The instability of local buckling caused the post-buckling on structures. Unlike ordinary hot-rolled, cold-formed steel structures normally buckle before yielding but the compression elements do not collapse despite buckling. The additional load could be supported by the elements after buckle through the stress distribution. Post-buckling strength can be several times greater than the force caused by the local buckling critical stress. On the effectiveness width approach, it is assumed that the total loads are supported by the fictitious width bf experiencing at uniformly maximum stress. In this paper, the flexural buckling behavior of cold-formed steel is investigated by numerical modeling using a finite element analysis of software. A Thin element with a ratio of depth (h) to width (bf) great could cause a local buckling element. Local buckling of elements accumulates causing post-buckling structure, which works simultaneously with torque. The h/bf ratio of 3 has better resistance to buckling elements than it of 2. [ABSTRACT FROM AUTHOR]

The total potential theory and Lu's theory for cantilever beam to calculate critical loads considering various beam length and various cross sections of mono symmetric structures by above buckling theories and also predicting the critical loads of doubly symmetrical cantilevers and comparing with existing critical results from existing solutions and finite element analysis. Based on above buckling theories, am applying these theories to calculate critical loads for simply supported beams with two torsional loads and one torsional load on fixed beam of mono symmetric beam with dropped flanges. Explicit solutions, capable of considering various lengths and cross sections under various kinds of loads are predicting the critical loads of doubly symmetric simply supported beam and fixed beam. The obtained solutions are exploited through the comparisons of critical results with those from existing solutions and finite element analysis. [ABSTRACT FROM AUTHOR]

The effect of warping bimoment in the analysis of thin-walled sections with restrained torsion is an essential concern and it creates the normal stresses in the cross-section which is related to the amount of resistance to warping. This paper presents the behavior of warping bimoment and its importance in the analysis of thin-walled structures with restrained torsion. The impact of warping bimoment of thin-walled sections is a main issue in the analysis of thin-walled structures as it associated with the external axial loads and torsion on the elastic torsional buckling of open cross section of thin-walled beams. Warping creates the normal stresses in the cross section which are clearly coupled to the amount of resistance to warping. The impact of section properties will change the bimoment effect and warping function so in this paper, the behavior of warping bimoment and its importance in in the analysis of thin-walled structures with restrained torsion is presented. [ABSTRACT FROM AUTHOR]

A safety assessment of the current EN 1993-1-1 buckling curve is performed in this paper using the first-order reliability method (FORM). A detailed numerical model is developed in OpenSees and validated against the experimental result. Safety assessment of the flexural buckling response of cold-formed square hollow section (SHS) was conducted, using reliability technique. Also, reliability sensitivity and importance measures are employed to identify the most influential sources of uncertainty on the flexural buckling of cold-formed SHS. The assessment shows a different buckling curve can be used for cold-formed sections. [ABSTRACT FROM AUTHOR]

The buckling action of I-beams under an axial load on a column is discussed in this paper. Buckling loads are critical loads under which some structure become unstable. The results are simple geometry curves and evaluating the impact of critical buckling load for different symmetrical rolled I sections such as Indian Standard Medium Beam (ISMB) are presented in graphical form are calculated by using finite element software (Abaqus). The critical buckling load results using Abaqus are compared with the theoretical calculation. [ABSTRACT FROM AUTHOR]

This paper aims to present the convergence behavior of triangular elements in buckling analysis under the mechanical and thermal load of square FGM plate problems. FGM is a new composite material with high-temperature and structural flexibility resistance. This material generally consists of ceramic and metal composition where the material properties change proportionally across the thickness. As a composite material, FGM is one of the most popular green materials used in many applications for high-temperature environments. It is essential to evaluate this material's critical buckling load or critical buckling temperature. For the performance of this material in buckling analysis, a numerical evaluation can be used to find the critical load or critical temperature. Three triangular elements (DKMT, DST, and MITC3) have been used in the study. These three elements give convergence results in static and free vibration analysis. For the buckling analysis, the results show that the three elements give good results in square FGM plate problems. The DKMT element shows superior results compared to the others. This phenomenon is due to the quadratic interpolation used in the DKMT element. [ABSTRACT FROM AUTHOR]

Buckling may occur during welding process and/or under loading of welded components. Real structures contain imperfection which may allow buckling. However, simulations are mostly done using geometrically perfect models. Therefore, imperfections are necessary to include in geometrically perfect models. In case of a simple geometrically perfect model, shape of resultant displacement is predictable, imperfection can by created in similar shap e. This work presents a novel numerical approach for creation of imperfection in finite element simulation of welding. Large temperature gradient is prescribed for calculation of shrinkage in welded structure to determinate load for linear buckling analysis. Buckling shapes obtained from linear buckling analysis are then used as imperfection shapes. The procedure presented in this work proposes method of calculating the weld-induced buckling in geometrical perfect model. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the buckling due to vacuum and its prevention for various locally manufactured thin-walled closed end cylindrical shells made of mild steel (MS). Length to diameter ratio (L/D) vary from 2.4 to 3.43 and corresponding diameter to thickness ratio (D/t) vary from 390.8 to 558.24 for unstiffened cylinders. While, for cylinders with various types of stiffener setups length to diameter ratio vary from 2.67 to 3.43 and corresponding diameter to thickness ratios vary from 390.8 to 502.42. Using an appropriate setup consisting of a vacuum pump, vacuum was developed within those cylinders, leading to buckling. The pressures at which the cylinders buckled was recorded using the calibrated vacuum gauge. Furthermore, the buckling pressures for cylinders modified with stiffeners were also recorded, and the differences in the buckling pressure between the stiffened and unstiffened cylinders were also investigated to estimate the effectiveness of the stiffeners in the prevention of buckling. In terms of thin-walled MS cylinders manufacturing process in Bangladesh, this paper provides knowledge on the effectiveness of the different types of stiffeners in increasing resistance to buckle. [ABSTRACT FROM AUTHOR]

Anisogrid structures made of high-modulus carbon fiber reinforced plastics have become widely employed as structural elements of spacecrafts. The unique mechanical behavior of anisogrid cylindrical shells determines the use of these structures in the development of new types of space technology. An example is a space telescope, whose main load-bearing component consists of a thin-walled lattice cylinder with massive equipment attached to its edges. The buckling of a telescope structure under thermal loading is an important issue to be addressed in design. The computational model for this problem is an anisogrid lattice cylindrical shell formed by composite helical and circumferential ribs experiencing a sudden temperature rise. This paper aims to numerically determine the temperature at which the two edges clamped lattice cylinder buckles. To simulate the anisogrid shell as a spatial frame, a beam-type finite element is used. A parametric study is performed to evaluate the influence of the number of helical ribs and their orientation angle on the critical buckling temperature. [ABSTRACT FROM AUTHOR]

The buckling of thin cylinders is one in all the foremost-complicated phenomena in structural engineering. Buckling is a character study, which can be viewed due to sudden failure of engineering structure experienced by high compressive stress and it's a structural instability that may lead the engineering structure in a failure mode. One in all the main standard of thin cylinders structures that, encounters compressive loads and these are known to be the buckling load-limiting factor. Therefore, it's necessary to grasp the Buckling load factor. Complex designs are often uploaded from a CAD model and this project is anxious with the testing of mechanical behavior of plastic materials i.e.) ABS (Acrylonitrile Butadiene Styrene) and PLA (Polylactic Acid). It is often produced using additive manufacturing by a 3D printer machine. By varying the density of the material, mechanical behavior is often identified. The sturdiness and reliability of the ABS and PLA materials are high compared to the other material. This results in the manufacture of the merchandise of less cost and therefore the very best quality. Here the analysis for various percentage of infill is dole out in theoretically in ANSYS Software and experimentally, and similarity between the results is obtained. [ABSTRACT FROM AUTHOR]

A technique has been developed for the numerical solution of nonlinear problems of deformation and elastoplastic buckling of revolution shells with a filler under combined static and dynamic loadings in a two-dimensional formulation. The stability loss problem of steel cylindrical shells with and without elastic filler under linearly increasing external pressure in flat elastic and elastoplastic formulations is considered. When compressing a hollow cylindrical shell, a non-axisymmetric buckling occurs in the second mode in the circumferential direction. Until the stability of both the elastic and elastoplastic shells is lost, a linear increase in the circumferential force is observed until the pressure reaches a critical value, and then its sharp drop. It is established that for an elastic shell the value of the critical load does not depend on the amplitude of the initial imperfection of form. During elastoplastic deformation, a significant dependence of the critical load (up to 20 %) on the amplitude of the initial imperfection of form in the range from 10−5 to 10–2 thickness h was revealed for the first time. Similar patterns hold for shells with elastic aggregate, where the level of critical load is determined by the stiffness of the base. [ABSTRACT FROM AUTHOR]

This paper presents an experiment on the dove tail profiled steel concrete composite shear wall (DSCW) under axial compression. Four DSCWs specimens were designed and constructed in order to test and obtain the deformation behavior, failure modes, bearing capacity, stiffness changes, etc. The results indicate that the failure process of all 4 specimens is initialed from steel sheets local buckling to the final concrete crushing. The steel and concrete can work consistently because the dove-tail-shaped ribs of the sheets have a good anchoring effect on the concrete. Based on the experiment result and analysis, a simplified formula for DSCWs was suggested to calculate the axial compressive strength with consideration of the influence of local buckling of steel sheets. [ABSTRACT FROM AUTHOR]

Increasing world population and natural resource limitations has led to a growing demand for more efficient structural systems to achieve a sustainable economy and society. Cold-formed steel CFS) Structural systems are increasingly adopted as primary or secondary structural members in modern building construction because of their light weight, speed of construction, recyclability, and sustainability. However, the inherently low buckling resistance of thin sections results in relatively low strength and ductility in CFS elements, which limits their performance in tall buildings and under extreme loading events. The pre-engineered steel building system construction has great advantages to the single storey buildings, practical and efficient alternative to conventional buildings, the System representing one central model within multiple disciplines. Pre-engineered building creates and maintains in real time multidimensional, data rich views through a project support is currently being implemented by Staad pro software packages for design and engineering. In this research work we will design Industry using analysis tool Staad. pro and use novel cold formed steel structure and compare it with general steel available in Indian market. Here we will compare both in terms of strength and weight of structure with bolted and welded connections. [ABSTRACT FROM AUTHOR]

Analytical equation for critical buckling stress of metallic sandwich shell is derived based on well-known Nemeth's analytical solution for buckling stress of composite monocoque cylindrical shell incorporating the bending rigidity for the sandwich construction. A good agreement for the predicted critical buckling load with finite element analysis result for different geometric parameters is achieved for a rigid core sandwich. Once critical buckling stress of a monocoque shell is obtained based on Nemeth’s solution, then for the sandwich shell the buckling stress can be predicted following a factor of 0.9 (hc / tf). [ABSTRACT FROM AUTHOR]

This paper illustrates the optimal method for calculation of buckling load in thin cylindrical shell. In addition to experimental setup, the various imperfections of geometrical structures of specimen is discussed and analyzed using coordinate measuring machine. Different types of finite element models depending upon their complexity are used for simulation in an attempt to have good results when compared with experimental buckling loads. Parameters such as measuring the effect of initial geometric irregularities, eccentricity of load, as well as measuring eccentric load along circumferential direction of shell and arrangement, often influenced boundary condition strategies. Effects of measuring the initial geometric imperfections and load eccentricity often revere the experimental buckling load prediction when demonstrated with simplified rigid support conditions. This work also illustrates the dependency of eccentric load position and imperfection in geometry on circumferential direction while buckling load is applied. [ABSTRACT FROM AUTHOR]

The present study focuses on thermal buckling and post-buckling analysis of functionally graded material (FGM) rods for various uniform temperature rises under different sets of boundary condition. Only chemical gradient FGMs are analyzed and power law functions are considered for material gradient along the thickness of the rod. The governing equations are developed relative to the neutral plane, and displacement fields are considered to be of first order to coincide with the Timoshenko beam theory. The set of highly nonlinear equations are solved using a commercial software package, ANSYS based on finite element method (FEM). To tackle the problem of spatial variation of material properties along the thickness of the FGM rod, the entire geometry is divided into finite number of layers, each layer being homogeneous and material properties are assigned to the layers from the power function making the spatial variation of any material property a piecewise function across the thickness of the whole geometry. Variation of critical buckling temperature and post-buckled configurations for different material gradient under different thermal loading and rod end conditions are observed and presented. [ABSTRACT FROM AUTHOR]

The introduction of effective elastic moduli allows us to apply the classical nonlinear von Kármán theory for modeling the behavior of nanoplates with surface stresses taken into account according to the Gurtin–Murdoch model. In particular, this allows us to apply the known solutions and methods for macroplates to nanoplates. So, earlier the authors solved the problem of buckling an thin elastic annular plate stretched by two point loads. In this paper, we address buckling this annular plate having nanosize. In previous studies, the manifestation of the size effect under buckling of nanoplates was shown mainly in the case of a homogeneous stress field. Here, the size effect is considered when a nanoplate is buckling under an inhomogeneous stress field. [ABSTRACT FROM AUTHOR]

In this paper the calibration of a model for the evaluation of moment-rotation curves of I-shaped aluminium alloy beams by ABAQUS computer program is reported. Beams are subjected to non-uniform bending and effects of local buckling are accounted for. The calibration of the model is made on the bases of experimental tests performed by Moen et al. [ABSTRACT FROM AUTHOR]

EN 1999 Design of aluminium structures give guidance how to design and verify uniform built-up member under compression with hinged ends laterally supported only. The built-up members in Eurocodes are considered as the member with equivalent bending and shear stiffnesses with a local bow imperfection e0 = L / 500. This paper investigates a more general case. The second order analysis is used for analysis of the battened built-up member with two extruded I-sections under combined compression, bending and sway initial imperfection. The bottom member end is fixed and the upper end is free in the case of in-plane buckling. The member is restrained against out-of-plane buckling at both ends. [ABSTRACT FROM AUTHOR]

The bent beam may lose overall or local stability of the web or compression belt depending on the type and manner of load, shape and geometric features of the cross-section, length, support conditions or indirect spring constraints. The purpose of this article is to determine the critical moment of loosening for purlins using three sections, namely IPE 140, CE 140 and Z300×94×86×30×2.5, assuming their cross-sectional values are as close as possible to each other. In order to determine the bearing capacity of the cross-section of the beam, it is necessary to determine the critical moment of the deflection ie the loss of flat bending form with twisting with respect to the longitudinal axis. Only for the case of constant load torque is known an analytical solution in closed form [1–3]. Other waveforms of bending moments are included in the analytical formula by the factor C1 [5]. For complex support conditions, you can use numerical programs to calculate the finite element method. For more detailed description of the beam, you must model the shell elements. [ABSTRACT FROM AUTHOR]

The subject of the researches were rectangular plates with a rectangular hole subjected to uniform compression. Plates were simply supported on shorter edges, made of composite with high strength properties. The aim of the analysis was to choose a laminate layer configuration that ensures the lowest buckling form about bending-twisting character, ensuring stable construction work in the post-critical range. To ensure stable work of structure in post-critical range, used an asymmetrical configuration of composite layers, having Extension-Twisting and Extension-Bending couplings. The scope of the research included numerical FEM analysis of linear and non-linear stability. The numerical tool used to analysis was the ABAQUS program. [ABSTRACT FROM AUTHOR]

The bifurcation buckling load can be determine solving a linear eigenproblem of buckling. If the structure is not perfect, the effect of bifurcation doesn’t occur. So, how to estimate a value of the lowest buckling load of the real structure? A methodology for determination of the lowest buckling load of a real structure with initial imperfection using a post-buckling path is presented. The investigation is performed for a Z-column made of carbon-epoxy laminate. The amplitude of initial imperfection is small less than half of the walls thickness. The column is simply supported on both ends. All calculations are performed by the finite element method and Koiter’s method. A plate model of the thin-walled structure has been applied. First, an eigenvalue buckling problem is solved to determine bifurcation loads. Next, post-buckling equilibrium paths for the plate structures are determined to calculate the lowest approximate bifurcation loads by the P-w and P-w2 methods, the inflection point method and the Koiter’s method. The presented methodology is correct, when the uncoupled buckling is considered. The numerical results were verified in experimental tests. A Aramis system was applied. A static compression test was performed on a universal testing machine. Specimens were obtained with an autoclave technique. Tests were performed at a constant velocity of the cross-bar equal to 2 mm/min. The compressive load was less than 150% of the bifurcation load. [ABSTRACT FROM AUTHOR]

The paper concerns first order sensitivity analysis of flexural and torsional buckling loads of axially compressed thin-walled columns with bisymmetric or axisymmetric cross-section made of unidirectional fibre-reinforced laminate. The first variation of critical loads versus some variations of the column material properties and cross-sectional dimensions is derived. Numerical examples dealing with simply supported I-columns are presented. The distributions of sensitivity functions of critical loads are presented with respect to variations of the parameters assumed along the column axis are shown. Some differences between sensitivity functions of both kinds of buckling are described and accuracy of sensitivity analysis in assessment of the critical buckling load changes due to some variations of the column parameters is discussed. [ABSTRACT FROM AUTHOR]

In this study we give a geometrical model which employs the smoothness of nerve fibers as differentiable curves. We show that a nerve fiber may encounter large curvature due to the possible helicial bending and hence it could cause the fiber to buckle. However, its membrane structure provides a mechanism, entirely geometrical to avoid it. To overcome the challenge of emerging helix we project it into a plane. [ABSTRACT FROM AUTHOR]

Aiming at the problem that it is difficult to accurately calculate the critical load of the overall stability of the folding combined lattice boom crane in theory, in accordance with the national crane design specifications and based on the classical theory, a method for calculating the critical load of the folding combined lattice boom based on equivalent rotation and equivalent translation length conversion is proposed, and through ANSYS comparison and verification, the error results meet the requirements of engineering application, indicating that the method is scientific and applicable [ABSTRACT FROM AUTHOR]

The object of analysis is the casing of F124 turbofan engine. Analysis of load conditions indicates that a dimensioning load case is crash landing, while an axial component of inertial load is about 30g. The casing is a thin-walled ribbed shell made of titanium alloy. The aim of the paper is mass analysis of the casing subjected to axial compression. Comparative analysis of selected materials, i.a., a sandwich structure (metal-fibre laminate) made of titanium alloy faces and flax fibre core, is performed using a finite element method. In the case of a sandwich structure, a shift of titanium layers from a neutral surface of the shell is significant since it causes a decrease in titanium overall thickness compared to a reference plain model (without decreasing bending stiffness). The best material mass efficiency were obtained for a sandwich structure and it is over 40% higher compared to a plain isotropic structure, whereas, in the case of the original ribbed structure the efficiency is about 26% higher. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental program into buckling, ultimate and post-ultimate behaviour of thin-walled cold-formed steel lipped channel members subjected to eccentric compression about minor axis. Tested specimens are subjected to compression with a wide range of both positive and negative eccentricities. Thus the evolution of the plastic mechanisms and the use of them to characterise the ultimate strength is examined by the experimental tests. [ABSTRACT FROM AUTHOR]

Within the presented research rods exhibiting the maximum buckling resistance are looked for. It was assumed that they have to possess the same mass and the same length as a solid cylindrical bar treated as the reference one. Nonprismatic rods of circular hollow cross-section and of variable wall thickness were only included into considerations. It was assumed that the external and internal surfaces of revolution were defined by some assumed in advance smooth functions. Three different classes of functions were used in the research, and namely: polynomial of the second order, sine and hyperbolic cosine functions. The classical optimization problem was defined by the objective function which was the buckling force, being maximized with appropriate constraints. Design variables were three independent geometrical parameters defining uniquely the sought bar shape. All derivations were carried out analytically by means of MathematicaTM system. The presented procedure was illustrated by two examples. The obtained increase of the critical force was dependent on the slenderness of the reference bar and reached the value 40 in the case of the longer, considered reference bar. [ABSTRACT FROM AUTHOR]

Since the real structure is not perfect, the geometric imperfections are present. In this case, the bifurcation buckling load overestimates the buckling load. This problem is particularly interesting in experimental studies, because the amplitude of imperfection and its mode can differ for each sample. In this paper, a methodology for determination of the lowest buckling load of a thin-walled plate structure with imperfection using a load–axial shortening plot was presented. The proposed approach can be applied, when the post-buckling path is stable, only. It was shown that the load corresponding to an alternation in rigidity of the real structure on the load-axial shortening plot determines the buckling load with high accuracy. The P-w² method and the inflection point method were applied, as well, to verify the obtained results. First, numerical calculations were performed by the finite element method and Koiter’s method using Byskov-Hutchinson’s formulation. The imperfections were defined explicitly. Other parameters of the system, such as boundary conditions, loads, geometrical dimensions were free from inaccuracies. A plate model of the thin-walled structure was applied. An eigenvalue buckling problem of perfect structures was solved to determine bifurcation loads and their eigenmodes. Then nonlinear problem of buckling was solved by Koiter’s perturbation method for one mode approach or the finite element method employing Newton-Rawson’s method. The load - axial shortening plots were made to analyse an influence of the imperfection amplitude on an approximate value of the lowest buckling load. The uncoupled local buckling was considered. Detailed computations were conducted for short Z-column made of general carbon-epoxy laminate under uniform compression. The Z-column was simply supported on both ends. Finally, the numerical results were verified in experimental tests using Aramis system. A static compression test was performed on a universal testing machine. Tests were performed at a constant velocity of the cross-bar equal to 2 mm/min. The compressive load was less than 150% of the bifurcation load. A very good agreement between the results attained with both the methods for solving the nonlinear problem was obtained. [ABSTRACT FROM AUTHOR]

The paper deals with buckling and post-buckling behaviour of thin-walled glass reinforced aluminium laminate (GLARE) members subjected to axial loading. Different open cross-section profiles were prepared by autoclave technique that provided a high-quality manufacturing. Symmetrical 3/2 lay-ups were analysed wherein 7 stacking sequences were distinguished based on the fibres alignment in the composite layer. Composite specimens were axially compressed in laboratory tests by means of static testing unit that provided displacement control loading. The behaviour of thin-walled GLARE members was investigated with main focus on post-buckling response together with various failure modes. First Ply Failure (FPF) analysis was carried out simultaneously by Tsai-Wu, Hashin and Puck failure criteria in order to detect a first failure occurrence. Numerical analysis included also an attempt to estimate particular regions of laminate’s damage in post-buckling state. Predicted collapsed mode shapes of GLARE members were found to be in a good agreement with experimental results. [ABSTRACT FROM AUTHOR]

The buckling mode of an edge cracks' surfaces contained in a PZT/Metal/PZT rectangular thick plate is studied and this study is made within the scope of the 3D linearized theory of stability loss with utilizing the piecewise homogeneous body model. It is supposed that there is an interface edge crack between the face and core layers and this plate is loaded with the uniformly-distributed compressive forces acting on two opposite end planes. it is assumed that the surfaces of the considered edge cracks have infinitesimal initial imperfections and investigated the evolution of these initial imperfections under compressive forces. The values of the critical buckling forces for the local bucklingdelamination of the considered PZT plate around the edge cracks are determined from the initial imperfection's criteria. Under some values of the problem parameters, the cracks' edge surfaces have surface wrinkles. The aim of this study is to investigate and analyze that. [ABSTRACT FROM AUTHOR]

The mechanical behavior such as bending, buckling and vibration describe a different impact on physical and material properties of structures at the nano scales. In the present paper the buckling behavior of boron nitride nanotube is analyzed with the use of non-local elasticity theory of Eringen. The system of governing equations is formed according to Timoshenko beam model and analytical method is applied to determine the critical buckling strain. Effect of various parameters such as size of nanotube and nonlocal parameter on buckling load is observed for simply supported nanotube. Moreover, to understand the impact of these parameters, outputs are plotted graphically and the obtained solutions are verified with those reported in literature. Analysis performed in this study is a forward step to understand the nature of small scale structures that are being used in several MEMS and NEMS systems and efficient electronic devices. [ABSTRACT FROM AUTHOR]

In this article, twist-bend buckling analysis of a cantilever beam subjected to a concentrated end load is conducted using Homotopy Perturbation Method (HPM). Even in the linear stability analysis, obtaining an exact solution for some cases is not an easy task. However, by the use of HPM this difficulty can be overcome easily. This issue is presented with a case study and the results show that HPM can be used successfully in the analysis of twist-bend buckling of beams. [ABSTRACT FROM AUTHOR]

In this article, flexural-torsional buckling analysis of a beam is conducted using both power series and Ritz methods. Even in the linear stability analysis, extracting a characteristic value from an exact solution for some cases is not an easy task. However, by the use of presented approaches this difficulty can be overcome easily. This issue is presented with case studies and the results show that presented techniques can be used successfully in the analysis of flexural-torsional buckling of beams. [ABSTRACT FROM AUTHOR]

The load carrying capacity of a hot-rolled steel beam IPN 200 under compression is analyzed. Computational models were created with the Ansys software, using the 3D element SOLID185. Load carrying capacity is determined using the geometrically and materially non-linear solution with consideration to the effects of initial random imperfections and residual stress. Latin Hypercube Sampling algorithm is used to generate samples of imperfections. The mesh convergence study is presented and a comparison how different variants with finer mesh influent the load-carrying capacity is carried out. [ABSTRACT FROM AUTHOR]