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Current study presents a novel hybrid approach combining finite element modeling and density functional theory calculations to investigate the mechanical properties of monolayer puckered arsenene. The multiscale analysis in this study leverages finite element analysis as a distinctive approach, complementing the nano‐scale capabilities of density functional theory and molecular dynamics by overcoming limitations faced by these two methods in representing complex scenarios. Furthermore, finite element analysis demonstrates computational efficiency for larger structures, making it suitable for systems where atomistic simulations may be impractical. This hybrid methodology offers a unique framework for accurately predicting key properties, including elastic modulus and buckling force, by synergistically integrating the strengths of both computational techniques. In addition to demonstrating the effectiveness of our approach in accurately capturing material behavior, our findings shed light on fundamental aspects of nanoscale mechanics, with implications for various applications in nanotechnology, materials science, and structural engineering. By providing a deeper understanding of the mechanical response of 2D materials, our research contributes to advancing the field of nanoscale materials engineering and informs the design of innovative nanostructures with tailored mechanical properties. [ABSTRACT FROM AUTHOR]

Summary: This study aims to analyze the buckling and post‐buckling behaviors of multilayer nanocomposite beams reinforced with graphene oxide powders (GOPs) at low concentrations. The GOPs are randomly oriented and evenly distributed throughout the composite layers, with their weight fraction varying in the thickness direction. The Halpin‐Tsai model is employed to estimate each layer's effective material properties. The nonlinear governing equations for the FG‐GOPRC beam are derived based on the first‐order shear deformation beam theory, and a nonlinear algebraic system is formulated using the principle of potential energy. In this research, a comprehensive parametric analysis is conducted to examine the influence of various factors on the buckling and post‐buckling behaviors of the composite beams. These factors include the distribution pattern and weight fraction of graphene platelets (GPLs) nanofillers, as well as the geometry, size, slenderness ratio, and boundary conditions of the beams. Through the analysis, the study highlights the significant strengthening effect of these factors on the buckling and post‐buckling performance of the composite beams. The findings from this investigation contribute to a deeper understanding of the behavior of multilayer nanocomposite beams reinforced with GOPs. This knowledge can be valuable in designing and optimizing of composite structures for enhanced buckling resistance and post‐buckling performance. [ABSTRACT FROM AUTHOR]

Translation abstract Investigations on bonded stiffeners in steel and composite bridgesNumerous bridges are in poor condition. In particular, resistance to plate buckling is a problem. Strengthening of buckling‐prone sections in steel bridges is often difficult due to non‐weldable steels and the additional notch effect from conventional joining techniques. The use of adhesives for fixing stiffeners allows material‐friendly reinforcement of buckling‐prone steel sections. Prior to practical application, numerous questions must be answered with regard to the detailing of the stiffeners, the stress on the adhesive layer due to inhibiting buckling, the load‐bearing capacity of the adhesive layer, the resistance to aging and fatigue. On the basis of numerical and experimental investigations, a simple fracture condition could be developed which allows a design of the adhesive layer‘s load‐bearing capacity. A sufficient stiffening effect of the bonded stiffener is given as long as the adhesive layer‘s load‐bearing capacity is sufficient. The aging and fatigue behaviour was investigated in basic tests. It was possible to define boundary conditions that enable resistance for a limited time, but there is still need for further research in this field. [ABSTRACT FROM AUTHOR]

The current study presents an experimental investigation devoted to the nano‐silica and cutout effects on the axial and lateral buckling responses of carbon/epoxy fiber‐reinforced composite laminates. To this end, specimens manufactured by vacuum bagging after hand layup technique were prepared at various amounts of nano‐silica (0.5%, 1.0%, 1.5%, 2.0%, and 3.0% by weight) incorporated into epoxy resin. Furthermore, semi‐circular and circular cutouts were opened on specimens to understand cutout effect on buckling characteristics of specimens. The results demonstrated that nano‐silica had a significant effect on buckling behaviors of the carbon fiber‐reinforced composites. Regardless of cutout presences, maximum critical axial (393.33 N, 361.67 N, 320 N for W, C and S) and lateral buckling loads (34.67 N, 33 N, 32.33 N for W, C and S), were achieved from the samples having 1.5 wt. % nano‐silica. In specimens having no cutout, maximum improvements of 72.26% in axial and 48.6% in lateral directions were achieved from the specimens having 1.5 wt. % nano‐silica content. A further amount of nano‐silica addition decreased the resistance to buckling of the specimens. Also, the presence of cutouts on the specimens led to decreases in critical loads. The decreases of 1.5 wt. % nano‐silica doped specimens without cutout in the axial and lateral critical buckling loads, respectively, were seen as 22.9% and 7.24% for circular cutout, 8.75% and 5.06% for semi‐circular cutout. It was concluded that cutout processing and nano‐silica additions should be taken into consideration in a material that may be exposed the buckling failures. Highlights: Nano‐silica impact on buckling behaviors of carbon fiber‐reinforced compositesCutout effects on buckling properties of carbon fiber‐reinforced compositesFailure modes of carbon fiber‐reinforced composites with nano‐silica particlesFindings showed that 1.5 wt. % nano‐silica inclusion exhibited the best values for buckling. [ABSTRACT FROM AUTHOR]

Artificial intelligence is increasingly used in various branches of engineering. In this article, artificial neural networks are used to predict the crush resistance of corrugated packaging. Among the analysed packages were boxes with ventilation openings, packages with perforations and typical flap boxes, which make the proposed estimation method very universal. Typical shallow feedforward networks were used, which are perfect for regression problems, mainly when the set of input and output parameters is small, so no complicated architecture or advanced learning techniques are required. The input parameters of the neural networks are selected so as to take into account not only the material used for the production of the packaging but also the dimensions of the box and the impact of ventilation holes and perforations on the load capacity of individual walls of the packaging. In order to maximize the effectiveness of neural network training process, the group of input parameters was changed so as to eliminate those to which the sensitivity of the model was the lowest. This allowed the selection of the optimal configuration of training pairs for which the estimation error was on the acceptable level. Finally, models of neural networks were selected, for which the training and testing error did not exceed 10%. The demonstrated effectiveness allows us to conclude that the proposed set of universal input parameters is suitable for efficient training of a single neural network model capable of predicting the compressive strength of various types of corrugated packaging. [ABSTRACT FROM AUTHOR]

Up to now, researches on the mobility–stretchability of semiconducting polymers are extensively investigated, but little attention was paid to their morphology and field‐effect transistor characteristics under compressive strains, which is equally crucial in wearable electronic applications. In this work, a contact film transfer method is applied to evaluate the mobility–compressibility properties of conjugated polymers. A series of isoindigo–bithiophene conjugated polymers with symmetric carbosilane side chains (P(SiSi)), siloxane‐terminated alkyl side chains (P(SiOSiO)), and combined asymmetric side chains (P(SiOSi)) are investigated. Accordingly, a compressed elastomer slab is used to transfer and compress the polymer films by releasing prestrain, and the morphology and mobility evolutions of these polymers are tracked. It is found that P(SiOSi) outperforms the other symmetric polymers including P(Si─Si) and P(SiO─SiO), having the ability to dissipate strain with its shortened lamellar spacing and orthogonal chain alignment. Notably, the mechanical durability of P(SiOSi) is also enhanced after consecutive compress–release cycles. In addition, the contact film transfer technique is demonstrated to be applicable to investigate the compressibility of different semiconducting polymers. These results demonstrate a comprehensive approach to understand the mobility–compressibility properties of semiconducting polymers under tensile and compressive strains. [ABSTRACT FROM AUTHOR]

Different scale of buckling patterns (1D ordered and 2D random) was employed for light extracting layer of top‐emission OLED. In the case of 2D random structure, thermal expansion and shrink of organic layers produced quasi‐periodicity. Improvement of TOLED efficiency as well as viewing angle behavior was analyzed in terms of the scale of periodic patterns and optical cavity effect. Methods in this work could be utilized as an effective tool for managing microcavity‐driven performance of TOLED. [ABSTRACT FROM AUTHOR]

Based on a large 3D seismic data set in the deep‐water domain of the Niger Delta, this study challenges previous interpretations involving the occurrence of multiple detachments and extensive thrust flats, illustrating timing and mode of shales flow at the toe of the gravity system. Five units of syn‐kinematic sediments, reaching a maximum thickness of ∼800 m, accumulated in the tectonically subsiding synclines during fold amplification between ∼9.5 and ∼1.4 Ma. The volumes of syn‐kinematic units roughly balance those of the shales accumulated in the thickened cores of WNW trending anticlines. This feature is consistent with folding resulting from buckling controlled by the competence contrast between isopach Cenozoic units and underlying overpressured shales of the Akata Formation. A dense network of NE‐SW striking oblique extensional faults offsets a prominent anticline characterized by a NE‐SW trend (which is almost perpendicular to the regional fold trend). These faults form a narrow, continuous deformation zone extending for tens of kilometers along and beyond the length of the anticline. The faults, rooting within the shales of the Akata Formation, formed since ∼5 Ma and deform the seabed. Displacement distribution suggests mechanical interaction between isolated fault segments within the deformation zone. The latter is interpreted as the shallow expression of a deep‐seated fault zone inherited from the segmented passive margin and marked by gravity and magnetic data. Our results, providing a comprehensive picture of active deformation features and their relationships with deep‐seated faults, shed new light into the modes of interaction between gravity systems and underlying basement structures. Plain Language Summary: The occurrence of thick successions of weak shales underlying sandy deltaic deposits control gravity‐driven deformation in deep‐water basins worldwide. In these conditions, large sedimentary bodies such as the Niger Delta of this study are characterized by (a) a spreading inner shallow‐water sector, which undergoes collapse due to the fast accumulation of deltaic sediments, and (b) a deep‐water domain characterized by shortening. Volume balancing in the latter domain points out that a 3D flow pattern must accommodate thickening of mobile shales into anticlinal cores as a result of flow of material from adjacent synclines. Folding occurred by buckling, a process characterized by mechanically active layering. This process was controlled by the strong viscosity contrast between the thick shales and the overlying sandy units, which tend to maintain a constant thickness in seismic lines. Fold nucleation was locally controlled by the occurrence of basement structures, which is revealed by magnetic and gravimetric data. These folds show "anomalous" trends that do not conform to the regional fold orientation. The interaction between the delta deposits and the underlying basement structures also led to the development of faults that display a clear morphology at the sea bottom and are therefore considered active. Key Points: Volume balancing indicates that mobile shales accumulated into anticlinal cores as a result of 3D flow from surrounding synclinesThe incompetent Akata shales thickened in the core of the anticlines during buckle folding accompanied by late‐stage thrustingThe detachment at the base of the shales interacted with basement structures, localizing deformation in overlying delta sediments [ABSTRACT FROM AUTHOR]

Composite cylindrical shell (CCS) structure are a number of engineering applications in aerospace, civil engineering, ordnance industry, sports equipment and other fields because of their excellent mechanical properties, low density and strong design. In this study, the classification, preparation technology and mechanical test of CCS are summarized. The research on the axial compression strength of CCS is reviewed. The theory of axial compression elasticity and the strength criterion of orthotropic composite materials are analyzed, and the strength criterion is compared. Finally, the basic theory of instability and buckling is deeply analyzed, and the stability theory of CCS is analyzed in detail. In order to provide a new reference for future scientific research and engineering application, the research difficulties are given in the conclusion, and the future research direction is predicted. Highlights: Comparing and analyzing the classification, preparation technology and mechanical properties of composite cylindrical shells (CCS) comprehensively.Summarizing and analyzing the axial compression strength of CCS in depth, and analyzing the theory of axial compression elasticity and the strength criterion of orthotropic composite materials thoroughly.Analyzing the basic theory of instability and buckling in depth, and analyzing the stability theory of CCS in detail.Giving the research difficulty of composite cylindrical shell, and predicting the future development direction of CCS. [ABSTRACT FROM AUTHOR]

The failure of steel cylindrical shells with carbon fiber‐reinforced polymers (CFRP) under hydrostatic pressure is studied in this article by experimental tests and the finite element method. Simulations were performed for 12 cylindrical shells with different dent numbers, dent depths, and two perfect models with and without CFRP. The finite element models are built to simulate the buckling behavior. The nonlinear stabilization method is preferred to simulate the buckling behavior. The finite element results agree well with the corresponding experimental tests and theories. A parametric study is conducted, and the number, depth, width of dents, and the effects of CFRPs on the critical buckling pressure are discussed. The dents are placed symmetrically around the cylinder with a thickness of tc (thickness of cylinder) and 2tc mm. The initial and overall buckling load decreased with increasing amplitude for dent numbers with different dent depths on all models. The results show that the number and depth of dents generally have a negative effect on the buckling strength, while CFRPs increase the critical buckling strength and are effective in repair as a retrofitting concept. [ABSTRACT FROM AUTHOR]

The moiré effect arises from the superposition of periodic structures with differences in periods or angles. Although the moiré effect can be exploited as an intriguing tool to fabricate complex metastructures, reduction of the moiré effect can be an important issue in display technology that uses many optical films with periodic patterns. Because of the superposition, dark and bright regions can be seen by the naked eye, which is a reason for the degradation of the visual quality. In this work, the lateral deformation of shape edges of prism films is harnessed to reduce the moiré effect. After the preparation of a microprism array with hydrogel materials, the hydrogel microprism array is swelled via penetration of water molecules into the hydrogel networks. Due to the compressive stress applied by volume expansion with confinement, only the sharp edges laterally buckle randomly. The swollen hydrogel prism array is replicated by photopolymerization, and prism arrays with laterally buckled edges are obtained. The randomized edges help reduce the moiré effect of the optical film when the prism array is overlapped with other periodic devices, such as other prism arrays or display devices consisting of microscale pixels, without a significant decrease in the optical performance. [ABSTRACT FROM AUTHOR]

The buckling "General Method" of EN 1993‐1‐1 and EN 1993‐1‐5 can be applied to solve problems characterized by non‐uniform geometries and complex stress fields. A typical example occurs during the incremental launching of bridge girders with slender web panel subjected to patch loading. However, this method does not explicitly provide the most critical verification point of a structural element and does not allow to consider the mechanical interaction between instability modes. The objective of the study is the development of a novel methodology that can solve these important special design issues, using a completely automatic process by linear static and linear buckling analyses only. The procedure provides the definition of a slenderness parameter for each point of the structure, in order to avoid the nonlinear analyses with imperfections permutation (as described in Annex C of EN 1993‐1‐5) that require a high computational effort. This pointwise slenderness parameter indicates not only where the slenderness is maximum in each buckling mode, but also the slenderness in other points of the structural elements. This would allow to consider the interaction between global and local buckling, with the definition of an equivalent slenderness parameter for buckling modes coupling. [ABSTRACT FROM AUTHOR]

The newest version of shells buckling standard prEN 1993‐1‐6 (2021) adopts linear elastic buckling stress expressions for steel perfect cylinders under axial, circumferential, and torsional effects separately. However, there are no explicit detailed rules that cover the influence of two or more loading combinations on the cylinder buckling resistance, considering a full‐length domain and different boundary conditions. Consequently, this paper looks into such a topic, which will be a useful reference for future research extensions. The examined cylinders were subjected to three loading configurations: axial plus pressure, axial plus torsion, and axial, pressure, and torsion altogether. The finite element (FE) buckling capacities were compared with the prEN 1993‐1‐6 (2021) buckling strengths, from which several findings were obtained. Aspects such as the load configuration applied to a cylinder, the length domain in which a cylinder falls, and the boundary type of a cylinder's ends each led to distinctive and complex descriptions of buckling behavior. The outcomes of this study will in turn assist in developing the current standard prEN 1993‐1‐6 (2021) and its recommendation ECCS EDR5 (2013), particularly the chapter that is relevant to cylindrical shells of constant wall thickness under general loading. [ABSTRACT FROM AUTHOR]

A silo structure is usually constructed in the form of a cylindrical steel shell. It has the advantages of being lightweight, having a short construction period, and possessing a large storage space. It has been widely used in many fields of industry. Thin‐walled cylindrical shells often exhibit buckling failure and the experimental buckling load is usually lower than calculation results from classical theory and simulation without geometrical imperfection. Besides, test results with carefully conducted similar specimens still have substantial scatter due to imperfection sensitivity. The nonlinear analysis with FEM can obtain a high‐precision result comparing the experiment if the geometric parameters of the shell are fully known. However, this is almost impossible in practical engineering. The initial geometric imperfections and shell thickness of cylindrical shells are complex and random properties. Theoretically, these geometric imperfections can be described using a random field. This paper presents the experimental investigation of buckling analysis of cylindrical shells under axial compression considering the randomness of geometric imperfections and thickness. A total of 12 cylindrical shell specimens were fabricated and tested. Based on the test results, the optimal statistical distribution is obtained by the maximum entropy fitting method and the obtained results were compared with geometric imperfections based on laser scan measurements. [ABSTRACT FROM AUTHOR]

Steel braces are widely used to stabilize steel structures forming horizontal or vertical truss structures; however, their relatively poor buckling behaviour is often lead to overdesigned structures. Induction Heat (IH) treatment technology is a novel contactless material transformation process to effectively strengthen local areas of steel sections. Utilizing IH to increase the strength of the middle length of steel brace sections, buckling behaviour can be improved. The present study experimentally investigates the compression behaviour of the novel braces fabricated by IH‐treated circular hollow steel sections. A Digital Image Correlation (DIC) system is used to measure the experimental deformation quantities, such as axial displacements, out‐of‐plane deformations, and strain distributions along the brace length. Four specimens were tested with two set of different slenderness ratios (λ). Each set includes one conventional steel brace (CSB) and one IH‐treated steel brace (IHSB) with a stronger section at its mid‐length. The specimens were subjected to a monotonic displacement‐controlled loading history until reaching an axial compressive strain of 2.5%. It was found that buckling load can increase up to 20% in IHSBs. IH treatment was also beneficial in improving the post‐buckling behaviour of the brace. The compression strength was found to be more than double in IHSBs than in CSBs at a ductility level of 5 (ductility is defined as the ratio of the target axial displacement to the yielding axial displacement). Moreover, out‐of‐plane displacements were reduced by 28% for the IHSBs at an axial strain of 1% showing a more evenly distribution of strain demands along the brace length. [ABSTRACT FROM AUTHOR]

Lattice towers are extensively built in Europe and worldwide to serve power transmission purposes. Their members mainly consist of single angle profiles, while built‐up sections, such as star‐battened ones, are usually preferred for the strengthening of individual members or in case of very high compression loads. Recent upwards developments of the power grid requests also lead to the need to use high strength steels (HSS) for the design and construction of higher and heavier loaded steel lattice transmission towers. Within the present paper, investigations conducted on the bearing capacity of a star‐battened member made of two S460 L250×250×28 angles are presented, even if the conclusions may be extended to any angle size and steel grade. Firstly, a critical review of the current European normative documents (EN 50341, EN1993‐1‐3, prEN1993‐3) is made and the buckling resistance of the above‐mentioned member is evaluated. Secondly, the results of an experimental compression test performed on the studied member are presented; these results are complemented by a full non‐linear finite element numerical simulation. All the obtained results are finally compared and discussed. [ABSTRACT FROM AUTHOR]

Longitudinal stiffeners are widely used in plated structures to prevent buckling of the slender plate elements and, therefore, to increase the load bearing capacity of these structures. There has been extensive research in the past regarding the shapes, sizes, and placement of these longitudinal stiffeners, however, there has been little research to make comparison between the different stiffener shapes across different numbers of stiffeners. The presented study compares the use of a single open stiffener, single closed stiffener, as well as the use of two open stiffeners. A numerical parametric study was conducted, considering different stiffener types, rigidities, and aspect ratios of the plates, for the cases of pure bending and compressions. The results of the study confirm that using a single closed stiffener or two open stiffeners is almost always more advantageous than the use of a single open stiffener. Furthermore, the study highlighted that it might be more advantageous to use two open stiffeners instead a single closed one. [ABSTRACT FROM AUTHOR]

The ultimate limit state of buckling is an important consideration for the design of wind turbine support towers (WTSTs) which is increasingly being done with the aid of advanced nonlinear finite element analysis according to EN 1993‐1‐6. As these towers are relatively slender thin‐walled metal shell structures, their response and buckling resistance is invariably affected by geometric imperfections. This paper presents a sensitivity study into the possible relative influences of four different types of realistic imperfections that are likely to arise in WTST construction on the elastic‐plastic buckling resistance as assessed by computational GMNIAs. These include idealised but realistic representations of axisymmetric circumferential weld depressions, unintended eccentricities at curved plate boundaries, a global out‐of‐roundness and corrected parallel flange interface gaps. The relative sensitivity is explored via a 'one‐at‐a‐time' (OAAT) study where all factors but one are kept at a constant intensity while the active factor is scaled, with the influence on the computed GMNIA under two load cases recorded. The OAAT study suggests that for shell structures representative of the geometric ranges typical for WTSTs, the weld depression has the most deleterious effect on the predicted buckling resistance. [ABSTRACT FROM AUTHOR]

Conventional I‐beam‐to‐SHS‐column moment resisting connections are generally stiffened with external diaphragms in order to limit excessive deformation of the tube‐wall. Passing through plates welded to the tube is an alternative solution that can develop significant strength and stiffness. This solution has been applied to CHS column and initial findings from RFCS project LASTEICON were encouraging. RHS columns are also widely used in practice due to simplicity of connections manufacturing. The new RFCS project LASTTS aims to investigate the application of this technique of passing through plates to SHS columns using laser cutting technology. The objective of this paper is to present the behaviour of I‐beam‐to‐SHS column moment resisting joints using passing‐through plates under equal hogging bending moments. A finite element model using brick elements is firstly presented. This model is used to perform a sensitivity analysis varying passing through plates thicknesses as well as SHS column dimensions. The failure mode is caused by the flange plate buckling inside the tube. Analytical models are developed to determine the bending resistance and initial rotational stiffness of these connections. [ABSTRACT FROM AUTHOR]

Hot‐rolled steel angles are utilized in various construction systems. This work presents an extensive numerical study on the behavior of hot‐rolled steel angles under concentric and eccentric compression. The numerical results were used for the evaluation of existing design procedures commonly applied in practice. In general, the analytical rules were on safe‐side in most analyzed cases. But in case of angle members in eccentric compression by two bolts, the codes presented very high values for ultimate compressive load capacity. Finally, the study extended the numerical data on the resistance available in the literature and promoted a critical discussion about the ongoing revision of design rules for angles concentrically and eccentrically loaded in compression. [ABSTRACT FROM AUTHOR]

Rack upright frames of conventional pallet racking systems are obtained by the assembly of uprights and braces or diagonals. Rack uprights are commonly mono‐symmetric open thin‐walled members with regular perforations along their length. These perforations are used to enable the connection with braces and beams by means of bolts or hooks. The structural behaviour of a rack upright frame under a pure compression load, in which the buckling phenomenon has a relevant influence, depends on several geometrical parameters, such as the column cross‐sectional dimensions, perforations characteristics, frame length, distance between braces, etc. Therefore, these particular issues should be considered to perform a proper structural analysis. In this paper, the structural behaviour of a pallet rack frame under a pure compression load is analysed by means of eigenbuckling and geometrically nonlinear Generalized Beam Theory (GBT) analyses. The influence of GBT deformation modes involved in the analysis is discussed. Moreover, different approaches to reproduce the connection between uprights and braces are presented and discussed. Finally, GBT results are compared with beam, shell finite element analysis and experimental values. [ABSTRACT FROM AUTHOR]

The stability evaluation of structures being lifted by cranes poses a challenger for the analysts from the inherent hypostaticity that the problem presents. Usual buckling evaluation for standard structures supported by foundations are not possible and alternative modelling strategies are required. Two strategies can be defined for buckling evaluation: The Linearized Buckling Check and The Direct Analysis Method. This paper states the problem and describes both strategies along with the presentation of modelling good practices and a clear framework of codes and standards which bring light into aspects such as load factors; weight contingency; Center of Gravity imprecision, etc. A comparative study for the results obtained from both methods for a typical truss being lifted is presented. [ABSTRACT FROM AUTHOR]

Wrought‐iron and mild‐steel riveted lattice beams are well‐represented in the metallic construction heritage of 1850‐1930. Many rafters and purlins of roof structures of train sheds or market halls are made of flat and angle bars assembled with single‐riveted joints. During retrofitting operations, those beams are often reinforced to prevent them from buckling. However, the assessment of the buckling risk depends strongly on the modelling assumptions regarding the out‐of‐plane rotational stiffness of the riveted joints. This paper therefore presents an experimental and numerical investigation aiming at quantifying this joint stiffness. A 3m‐long riveted lattice beam, dating from 1930, was collected from a demolition site. An experimental modal analysis was carried out and the measured natural frequencies and mode shapes were used to calibrate a finite‐element model of the beam. A parametric study suggests that the model with clamped connections, i.e. with high out‐of‐plane rotational stiffness, is in better agreement with the experimental results. This result could lead to a less conservative buckling risk assessment and less extensive strengthening measures. [ABSTRACT FROM AUTHOR]

Advanced structure design for energy absorption is a long‐lasting pursuit due to its fascinating scientific merit in mechanics and important engineering application. Curves, a type of mathematical variation in geometry, are widely adopted in the biological system and biomaterial structures after long‐time nature evolution toward optimization and adaption. Inspired by nature, a novel type of tubular structure is designed with golden spiral curvature. With the variations in the hierarchy of the supporting spirals and the number of arms, a maximum of 38.8% increase is demonstrated in performance over an uncurved counterpart structure. The computational modeling reveals that the additional added golden spiral arms within the tube enhance the rigidity and increase the energy dissipation via progress buckling involved by additional materials such that the energy absorption upon crushing is significantly improved. Theoretical models then provide intrinsic underlying mechanics analysis with more intuitive design guidance for such structures. Results develop an efficient yet simple design based on widely accepted tubular structure design for impact protection, enrich the mechanistic understanding of the nonlinear buckling behaviors, and provide applicable design guidance for engineering structures. [ABSTRACT FROM AUTHOR]

Experimental investigations on high‐strength CHS for crane‐ and scaffolding construction So far, only a limited amount of experimental results is available for the derivation and verification of design principles for cold‐formed, high‐strength crane and scaffolding tubes up to S960. In this article, the authors present the conduction and results of buckling tests on centrally loaded scaffolding and crane tubes of steel grades up to S960. Measurements of residual stresses as structural imperfections using the sectioning method are discussed on ungalvanized and galvanized CHS in S960. Additionally, the geometric imperfections of the test specimens, which were captured by 3D scanning, are discussed and compared with the approaches of the European buckling curves. The deformations of the test specimens in the buckling tests were recorded using digital image correlation (DIC). The effects of galvanization and the buckling direction on the load‐bearing capacity are highlighted and elucidated. [ABSTRACT FROM AUTHOR]

Owing to excellent performance and a simple mechanism, stretchable piezoresistive strain sensors have been applied to human skin for monitoring physical activities, physiological activities, etc. However, it is still a challenge to simultaneously realize highly sensitive and stretchable piezoresistive strain sensors with high optical transparency. This study reports a transparent and stretchable piezoresistive strain sensor with 2D surface buckling by fabricating ultrathin indium tin oxide (ITO) film on the biaxially pre‐stretched polyacrylate (VHB) elastomer followed by pre‐stretch releasing. To the authors' knowledge, semiconductors are applied for a stretchable piezoresistive strain sensor for the first time. Furthermore, this strain sensor exhibits a high sensitivity of 569, a high transparency of 88% and a high biaxial stretchability of 110% at the same time. This device demonstrates the good long‐term stability over 500 stretching–relaxing cycles. The high sensitivity can be mainly attributed to the piezoresistive effect of the semiconductor where carrier mobility and the resulting resistivity can be significantly changed by the strain. The strain sensors attached to human skin are used to monitor many human motions such as chewing, swallowing, breathing, and walking. ITO‐based strain sensors pave the way toward the development of highly stretchable and sensitive wearable electronics. [ABSTRACT FROM AUTHOR]

Chiral metamaterials comprise a promising platform for advanced optoelectronic and biomedical applications. However, conventional fabrication via lithography is limited by its complexity and high cost. Herein, the lithography‐free fabrication of terahertz chiral metamaterials and their enhancement for sensing the chirality of biocrystal enantiomers is presented. Chiral Au microstrip patterns (CHAMs) in a saw‐tooth shape are fabricated by combining two‐step buckling processes and glancing‐angle deposition. Non‐superimposable geometric chirality is achieved by controlling the tilt angle between the asymmetric and biaxial strain axes and the selective area deposition of the Au layers by using the shadow effect. The manufactured chiral metamaterials show mirror‐shaped terahertz circular dichroism (TCD) signals in the range of 0.2–2.5 THz. Coupling of the induced electric and magnetic dipoles to the chiral‐shaped Au surfaces results in effective optical chirality enhancement. Finite‐difference time‐domain computational simulations reveal the homogeneous distribution of optical chirality with an absolute maximum of 2.24 in the near field. Summing the TCD signals for enantiomeric cystine biocrystals onto the chiral metamaterials shows an ≈7‐fold amplification in magnitude. This enhancement can be attributed to the synergistic effects of superchiral field enhancement and the electromagnetic resonance between the CHAMs and biocrystals. [ABSTRACT FROM AUTHOR]

Remotely controllable photoresponsive hydrogel actuators are promising for applications in multiple fields. However, simple deformation mechanisms, which rely on the general swelling/deswelling, limit their performance and application. Herein, we report a displacement amplification mechanism based on the buckling deformation of photoresponsive hydrogel film. The on‐chip buckled architecture of the hydrogel enables actuation between a flat 2D shape and tubular 3D buckled shape with remarkable performances, including high deformation ratio (height ratio: ≈360%), tunable cycle motion frequency (0.1—1 Hz) and high cyclic stability. Moreover, localized buckling deformation, such as tube opening and closing, can be controlled in response to photostimulation. Inspired by these biomorphic shapes and motions, an intestine‐mimetic device and demonstrate segmentation with substance crushing and peristalsis motion with substance propelling were further fabricated. This study will provide a useful design principle for hydrogel actuators and shed light on diverse applications in soft robotics, dynamic microfluidics and organs‐on‐chips. [ABSTRACT FROM AUTHOR]

One of the main hazards during tunnel boring machine (TBM) excavation in hard rock is related to the occurrence of unforeseen adverse conditions, leading to unfavourable rock mass behaviour during tunnel boring. In this respect, the continuous analyses of TBM excavation parameters may represent an interesting tool for a continuous monitoring of geotechnical conditions at the tunnel face and for early detection of changing ground conditions in the rock mass. This work provides a back‐analysis of TBM data recorded during the excavation of the Frejus Safety Tunnel, bored across the French‐Italian border in the Western Alps. It is a 13 km‐long tunnel excavated by a 9.4 m diameter, single‐shield TBM through strongly anisotropic calcareous schist, with cover up to 1800 m. Main problems faced during TBM excavation were related to the local occurrence of buckling‐related convergence and consequent asymmetrical loading on the precast segment rings. Correlating TBM performance parameters to the encountered geological and geomechanical conditions provides the possibility to identify which parameters are most affected by geomechanical properties of the rock mass at the tunnel face and by rock mass behaviour. Conversely, the analysis indicates which parameters can be adopted as monitoring tool of ground conditions during TBM advance. In addition, this work highlights how buckling phenomena can be distinguished, in terms of TBM operation and performance, from other adverse conditions as, e.g., blocky ground or squeezing. [ABSTRACT FROM AUTHOR]

Kirigami, the ancient art of paper cutting, has evolved into a design and fabrication framework to engineer multi‐functional materials and structures at vastly different scales. By slit cutting with carefully designed geometries, desirable mechanical behaviors—such as accurate shape morphing, tunable auxetics, super‐stretchability, buckling, and multistability—can be imparted to otherwise inflexible sheet materials. In addition, the kirigami sheet provides a versatile platform for embedding different electronic and responsive components, opening up avenues for building the next generations of metamaterials, sensors, and soft robotics. These promising potentials of kirigami‐based engineering have inspired vigorous research activities over the past few years, generating many academic publications. Therefore, this review aims to provide insights into the recent advance in this vibrant field. In particular, this paper offers the first comprehensive survey of unique mechanical properties induced by kirigami cutting, their underlying physical principles, and their corresponding applications. The synergies between design methodologies, mechanics modeling, advanced fabrication, and material science will continue to mature this promising discipline. [ABSTRACT FROM AUTHOR]

Architected metamaterials exhibit complex stress–strain responses, such as quasi‐zero stiffness (QZS) plateau response useful in vibration and energy absorption, by exploiting elastic instabilities such as buckling. However, the design of metamaterials with prescribed nonlinear mechanical properties is challenging due to the difficulty in accurately predicting nonlinear mechanical responses such as buckling and self‐contact, as well as geometric and material uncertainties. Herein, additive manufacturing (AM) with machine learning (ML) to demonstrate data‐driven modeling and the design of nonlinear elastomeric springs with a broad stress plateau is combined. 243 elastomer chi (χ) spring parts with different design parameters fabricated by AM are tested. A Gaussian process (GP) model is trained on key features of the measured mechanical response and predicts the mechanical response within a 3% error with as few as 97 parts. To account for the geometric and material uncertainties, the GP model to develop an uncertainty‐aware design optimization approach to tailor the mechanical response based on the covariance matrix adaptation evolution strategy (CMA‐ES) is utilized. Excellent agreement is demonstrated between the designed response and measured response over the range of plateau stress considered. The research illustrates the promise of experimental data‐driven approaches and AM in enabling complex material design. [ABSTRACT FROM AUTHOR]

Recent studies on isolated steel columns under combined axial load and cyclic lateral drift showed that the column response is affected by the boundary condition. To consider more realistic boundary conditions of first‐story columns in a frame, two‐and‐a‐half story beam‐column subassemblages were tested to investigate their behavior under reversed cyclic loading. The subassemblages, composed of a steel column with steel beams at two floor levels, used highly ductile I‐shaped sections with web slenderness of either 37 or 49. Two isolated fixed‐fixed columns were tested to facilitate a direct comparison with the subassemblage testing. An axial compression force corresponding to 20% of the yield force was applied. Test results showed that the realistic boundary condition at the top end of the first‐story column significantly alters the column plastic hinging, moment distribution, and out‐of‐plane deformation reported previously based on isolated column testing. Plastic hinging of the adjoining beams caused the inflection point of the first‐story column to move upward initially, then moved downward when plastic hinging developed at the column base. Out‐of‐plane deformation observed from isolated columns did not occur in the subassemblage column because hinging did not occur at the top end. Plastic components of the backbone curves for both the subassemblage column and isolated column were very similar; the former delivered a larger story drift angle rotation due to a larger yield rotation, dependent on the elastic lateral stiffness of the column. A closed‐form solution that calculates this stiffness for any boundary condition was developed and verified from test results. [ABSTRACT FROM AUTHOR]

Load‐carrying capability of corrugated cartons packaging fresh agriproducts must be significant enough. Collapse of the carton stacked on the pallet in an environment‐controlled container is commonly observed during the shipping trip. A homogenization approach of the corrugated paperboard is adopted to dramatically reduce the computational time in the present study. A creep model is further implemented into the numerical analysis to describe the stiffness decay of the carton over the relatively long period. A finite element analysis is conducted to investigate the mechanical performance of the carton locating at bottom of the stacked pile. Simulation results show that the carton performs local buckling deformations similar to the experimental observations. The vented carton based on the modified design exhibits rather smaller deformations after the transportation journey. Moreover, the modified design provides better uniformity of ventilation based on the computational fluid dynamics analysis. Current procedure is promising for the selection of liner and fluting that compose the corrugated paperboard and the assessment of the ventilation of cartons in the early design stage. [ABSTRACT FROM AUTHOR]

Frequent technology upgrades in telecommunications have led to an increase in wind load on the towers that hold this equipment. The legs of lattice towers are critical members to the structure's integrity as they transfer large portions of compressive load through to the foundations. Through the increasing amount of compressive load, these members could eventually fail due to insufficient strength, which has raised the need to reinforce existing structures. Currently within industry, retrofitting new members onto the existing legs is common, however there is currently little research that has been carried out to investigate the effectiveness of these methods. This research investigates the retrofit of a Circular Hollow Section (CHS) that has been strengthened with two steel rods and aims to provide greater clarity on the effectiveness of the design through numerical analysis. This was completed using ABAQUS 2021 by performing both linear and non‐linear buckling analysis. It has been found that the design can improve compressive strength by up to 277.3% for the short column which matches the predicted strength. For the long column, an increase of 130.2% was recorded which is significantly less then calculated values. The results obtained further stress the need for continued research in this field, with an emphasis on experimental results. [ABSTRACT FROM AUTHOR]

This paper discusses issues related to the modelling of so‐called "fork" supports using geometrically exact 3D thin‐walled beam finite elements whose rotations are parametrized using the rotation vector. This study is motivated by the fact that isolated members with "fork" supports are commonly employed in numerical and experimental studies, for the development of design rules for steel members. These supports are defined in the small displacement range, restraining the cross‐section in‐plane displacements and the torsional rotation of the beam (along the beam initial axis). This definition is usually extended to the large displacement case for beam finite element models, whereas in experimental tests and shell finite element models, a two‐axis gimbal‐type support is used instead. This paper thus aims at (i) showing how the two‐axis gimbal support may be modelled using beam elements which are based on a rotation vector parametrization of finite rotations and (ii) highlighting the differences between the two support types. Numerical examples are presented to illustrate the differences, which are quite significant for moderate‐to‐large displacements, but do not seem to affect the collapse load of standard steel members. [ABSTRACT FROM AUTHOR]

This paper presents a newly developed extension of the linear Generalised Beam Theory (GBT) formulation for members with circular axis, previously developed by the authors, to the linear stability analysis case. This extension incorporates the classic GBT kinematic assumptions, which ensure efficiency without sacrificing its accuracy. The finite element implementation of the proposed formulation makes it possible to calculate bifurcation loads and associated buckling mode shapes of members with circular axis and arbitrary flat‐walled cross‐sections, undergoing global‐distortional‐local deformation, with great accuracy and computational savings (with respect to refined shell finite element models). Moreover, it is shown that the remarkable GBT modal decomposition features, stemming from the fact that the kinematic description of the beam is based on a superposition of structurally meaningful cross‐section deformation modes, enable an in‐depth insight into the nature of the buckling modes in curved members. [ABSTRACT FROM AUTHOR]

Buckling is a complex phenomenon, influenced by the non‐linear material properties, as yielding of steel, cracking of concrete as well as, slenderness, geometrical imperfection and residual stresses. The design codes provide essential rules for mechanical resistance, stability and safety aspects. However, the current Eurocodes essentially stipulates engineering models that can easily be transferred to classical structural analysis, but often do not guide sufficiently the application and evaluation of advanced numerical analysis. The present study investigates the buckling analysis of steel and partial encased composite columns. Different definitions for geometrical imperfections and residual stresses are considered. The geometrical imperfections are taken into account in accordance with prEN1993‐1‐14 [2]and EN1090‐2 alternatively. The residual stresses are based on prEN1993‐1‐14 [2] and ECCS – Pub. No.33. In addition, analysis without the consideration of residual stresses are investigated. The scope is to assess the non‐linear finite element analysis (GMNIA), comparing the behavior of hot‐rolled and welded steel cross‐section as well as the impact of additional reinforced concrete encasement. Guidance for the numerical analysis for steel and composite columns is developed. [ABSTRACT FROM AUTHOR]

A former study on wind turbine tower collapse incidences throughout the past 40 years revealed that among the various types the buckling failure was the most catastrophic as led to collapse of tubular tower shell structures. As the modern harvesting of wind energy is usually performed by wind turbine towers being cylindrical shells of thin walls, the need of thorough investigation of the buckling behaviour of shell structures operating under extreme environmental actions is obvious. The present paper addresses such knowledge gap through the study of a series of 100 numerical models underpinned by the well‐established Riks Method for buckling analysis. The method enables the scrutiny of tower shell elements under axial load and bending moment. Within the proposed framework of curvature–energy analysis, the energy stored within an imperfect shell structure is expressed and quantified through cross‐section diaphragms and symbolic lines, covering pre‐buckling, transient stage, and post‐buckling performance close to the bifurcation point. The analysis unveils changes of local surface curvature and energy flows with multiple longitudinal and circumferential wavenumbers taking place during the pre‐buckling process. Wavenumbers and curvature changes induce the energy magnitude jumping over to the adjacent buckling eigenmodes. Furthermore, the mode jumping sees a faster and more convergence result with higher bending moments. The diversity of the final buckling mode largely determined by the variance of shell geometry, compression–bending ratio and boundary conditions. [ABSTRACT FROM AUTHOR]

This work presents an accurate and efficient numerical tool for geometrically nonlinear thermoelastic analyses of thin‐walled structures. The structure is discretized by an isogeometric solid‐shell model with an accurate approximation of geometry and kinematics avoiding the parameterization of finite rotations. An efficient modeling of thermal strains, temperature‐dependent materials and general temperature profiles based on a numerical pre‐integration through the shell thickness is proposed. Then, a generalized path‐following method is developed for solving the discrete equations with the temperature amplifier as additional unknown, in order to trace the temperature‐displacement nonlinear curve also in case of limit points and unstable paths. A consistent definition of the tangent operators and a mixed integration point strategy give a robust and efficient analysis. Finally, a reduction technique is derived for a quick estimate of the nonlinear thermal buckling point. The reduced model consists of the initial path tangent, the first linearized buckling modes and their second order corrections. Numerical applications are given. [ABSTRACT FROM AUTHOR]

Thin‐walled cylindrical shells often exhibit buckling failure and the experimental buckling load is usually lower than calculation results from classical theory and simulation without geometrical imperfection. Besides, test results with carefully conducted similar specimens still have substantial scatter due to imperfection sensitivity. The nonlinear analysis with FEM can obtain a high‐precision result comparing the experiment. However, this is almost impossible in practical engineering. The initial geometric imperfections of cylindrical shells are complex and random properties. Theoretically, these geometric imperfections can be described using a random field or a Fourier series representation. After that a random sample of the buckling bearing capacity of the cylindrical shell can be obtained using the stochastic finite element method within the subsequent analysis. This paper presents the investigation of buckling analysis of cylindrical shells under axial compression considering the randomness of initial geometric imperfections, and the stochastic FEM is employed to calculate the statistical sample of the shell‐buckling load based on a series of random fields and Fourier series representation of geometric imperfections. [ABSTRACT FROM AUTHOR]

One of the benefits of using corrugated web girders is the increase of lateral‐torsional buckling resistance. Different approaches have been presented to obtain the value of the critical moment as a function of the cross‐section geometry. Previous research works consider that the increase in buckling resistance must be accredited to a higher warping constant. The paper presents a systematic finite element numerical analysis of girders with different corrugated web shapes. Bending with respect to the weak axis shows that corrugated web implies higher moment of inertia. Torsion analysis results clearly demonstrate that the increase of torsion resistance is mainly due to higher torsional constant. The paper compares the elastic critical moment values obtained by using finite element elastic buckling analysis with the values provided by theoretical expressions introducing equivalent section properties. Results show that the equivalent section properties approach provides values very close to those obtained using finite elements. Finally, the paper presents closed form expressions to directly compute approximate equivalent section properties of any girder with corrugated web, which compare very satisfactory with those values obtained with finite element buckling analysis. [ABSTRACT FROM AUTHOR]

A generalized path‐following method is proposed for the direct evaluation of the critical point sensitivity to geometrical imperfections expressed as combination of given shapes. After a finite element discretization, the critical point is defined by a system of nonlinear algebraic equations imposing equilibrium and critical condition according to the null vector method. An arc‐length equation is added to follow a path of critical points in the imperfection space. The solution of the extended system by a Newton scheme requires a Jacobian involving also the derivatives of the critical condition with respect to the FE DOFs and the derivatives of all the problem equations with respect to the imperfection parameters. An analytical and efficient computation of the Jacobian is achieved by a solid‐shell model and a strain‐based model of the imperfection. In addition, a mixed stress‐displacement iterative scheme is devised for a highly efficient and robust solution. Finally, the derivatives of the critical point with respect to the imperfection parameters are also obtained analytically and can be used to generate a gradient‐based critical path for a quick search of the worst‐case imperfection. A compressed cold‐formed lipped channel beam is analyzed as a case study. [ABSTRACT FROM AUTHOR]

A general and efficient approach to model thin‐walled members and frames with complex geometries (including tapered and perforated members) is proposed, combining standard shell and GBT‐based (beam) finite elements. Each element type is employed where it is most effective: (i) shell elements in plastic and geometrically complex zones, and (ii) GBT elements in prismatic and elastic zones. After providing a brief overview of the finite elements employed, several illustrative numerical examples are presented and discussed, in order to show the capabilities and potential of the proposed approach – they concern linear static, bifurcation (linear stability – calculation of buckling loadings and mode shapes), vibration (calculation of natural frequencies and vibration mode shapes), dynamic and first‐order plastic zone analyses. These numerical examples involve members with tapered segments and/or perforations and frames with complex joint geometries. For validation and comparison purposes, full shell finite element results are provided – in all cases, an excellent match is obtained. [ABSTRACT FROM AUTHOR]

Herein, an experimental investigation into the occurrence of "pinching" defects during cold‐rolling of thin metal sheets is presented. Pinched strips are typically characterized by repetitive ripples and local ruptures, which can cause strip breaks. Even though pinches are a widely experienced phenomenon in both hot‐ and cold‐rolling of steel strips, no previous studies are known that have investigated the underlying mechanism for pinching during continuous rolling processes. Therefore, a set of rolling experiments is performed in a single‐stand pilot mill to create pinches by applying sudden perturbations in the process conditions. For the rolling settings chosen in the performed experiments, it is found that disruptions in the lubrication state are a powerful approach to induce shape defects, which develop as pinches. Herein, a first extensive description of the pinching mechanism is provided, as observed during the trials, by monitoring the strip's behavior and analyzing the damaged sheets. It is shown that ripples in these pinched strips are the result of folds, which form in the roll bite. The folds originate from the waviness of the strip upstream of the bite, being created by nonuniform conditions over the width of the strip. [ABSTRACT FROM AUTHOR]

The importance of appropriate offshore wind turbine (OWT) monopile structural modelling technique cannot be overstated in the successful design and installation of a new generation of larger and heavier structures to deliver the increasing capacity demand. The lack of clear design guidance and acceptable structural modelling techniques across the industry results in a range of conservative but expensive design and installation techniques. Most of the OWT monopile modelling efforts lie in the substructure (foundation) and interaction with the supporting soil which is highly nonlinear along the length of the embedment depth of the monopile structure. Typically, monopile offshore wind turbine structural modelling can be completed using, amongst others, one of the following techniques: 3D finite element modelling with mass soil foundation, API p‐y curve soil springs, JeanJean soil springs, and the newly developed PISA modelling approach. The study presented in this paper considers the application of the 3D finite element modelling with mass soil, API p‐y soil springs, and the JeanJean soil springs technique. By comparing the structural response, the 3D finite element modelling with mass soil results in an improved natural frequency and harmonic response. Furthermore, a reduced displacement was observed in the 3D finite element model with mass soil which will ultimately result in a corresponding improvement in the structure's useful operational design life. The application of the API p‐y soil springs, JeanJean soil springs, and other modelling techniques requires extensive calibration to ensure the correct structural response and behaviour are achieved. This becomes a key factor as the boundaries of the size of the structure and turbine capacity are pushed even further for the new concept generation offshore wind turbines, which are required to deliver a higher capacity of 12 to 15 MW with the aim of achieving 20 MW, whilst achieving an efficient cost‐effective engineering design and installation process. [ABSTRACT FROM AUTHOR]

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 the main observations were presented qualitatively. Part 3, the final part of the paper, presents the statistical evaluation of the numerical investigations and the determination of the buckling curves. Two different approaches are conceivable for these buckling curves: conventional buckling curves with explicitly specified imperfection factor and plateau length parameters, and a modified Ayrton‐Perry approach with interpolated parameters. Both approaches are compared with the results of the numerical investigations and with test results. [ABSTRACT FROM AUTHOR]

Application of fiber‐reinforced polymer (FRP) for retrofitting and rehabilitation of concrete structures is a common method. The main role of FRP confinement for reinforced concrete (RC) columns is to increase the ultimate strength and strain of confined concrete core and therefore improve in the load carrying capacity of the columns. However, it is possible that a previously short column fails due to buckling after the application of FRP confinement. In other words, the enhanced compressive strength of a retrofitted column may go beyond its buckling load. Therefore, a design criterion to predict this condition is necessary for the designers in the preliminary and final stages of the design. In this paper, a predictive model is proposed to determine the slenderness limit of FRP‐confined circular RC columns. The suggested relation was derived using one of the accurate design‐oriented strength models for FRP‐confined concrete columns as well as analytically derived buckling equations. The effect of hybrid FRP confinement is also incorporated in the suggested slenderness limit. Moreover, a parametric study was performed on the suggested model to specify most influential parameters. The accuracy of the proposed relation was evaluated using a database of experimental results collected from previous studies. The results of the evaluations demonstrated acceptable accuracy of the proposed relation in predicting behavior and failure mode of FRP‐confined RC columns. [ABSTRACT FROM AUTHOR]

Dimensioning tools for stiffened and unstiffened buckling plates according to DIN EN 1993‐1‐5 – part 1: unstiffened buckling plates In Germany, stiffened buckling plates in bridge construction must be verified using the reduced stress method (MRS) according to DIN EN 1993‐1‐5. Unstiffened buckling panels, on the other hand, may be verified either according to the method of effective widths or according to the method of reduced stresses. To shorten the time‐consuming verification of the standardised verification formats for pre‐dimensioning, which is particularly prevalent for stiffened buckling fields, part 1 of this paper develops and presents diagrams for unstiffened buckling fields based on the MRS by reformulating the buckling verification, which enable fast pre‐dimensioning. With the diagrams, the dimensioning of plate thicknesses or stiffener spacings can be carried out in a few simple and comprehensible steps. The diagrams are selected based on the geometry parameters a, b and t or the applicable boundary conditions. For stiffened buckling panels, the maximum permissible distances of the longitudinal stiffeners or the required main plate thickness can be determined. In the second part of this paper, diagrams for the dimensioning of longitudinal stiffeners via the determination of minimum stiffnesses are presented. The minimum stiffnesses are derived from the geometry of the linear buckling shapes of simply stiffened buckling fields. [ABSTRACT FROM AUTHOR]

Nominated for Eurosteel 2021 Best Paper Award The paper addresses the instability of large angle columns in high‐strength steel subjected to compression loads. It presents a number of compression tests on such columns with different eccentricities and slenderness and the resulting different buckling failure modes observed. The experimental campaign is intended to widen our understanding of the behaviour of high‐strength steel columns with large angle sections in compression and bending and so to complement previous experimental studies. The tests were accompanied by numerical analyses and calculations of the load carrying capacities based on current Eurocode 3 design recommendations. The numerical simulations were conducted using the FEM software FINELG, which takes into account the influence of geometrical and material non‐linearities. The numerical and analytical results are compared with the corresponding experimental ones. The experimental campaign and the numerical simulations were conducted as part of the ANGELHY project funded by the European Commission's Research Fund for Coal and Steel (RFCS). [ABSTRACT FROM AUTHOR]

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 of the paper, the main observations are presented in qualitative terms. Those observations are: the influence of the allocation of the materials to buckling classes, the influence of the imperfections plus the cross‐section geometry including the position and size of the HAZ within the cross‐section. Part 3 will conclude this paper by discussing the proposed design approaches in detail. [ABSTRACT FROM AUTHOR]