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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]

The geometry and mechanical behavior of concrete bridge towers are complex. Hence, it is important to generate a rational mechanical analysis model for structural design. The method of strut‐and‐tie models (STMs) is an effective way to analyze disturbed regions (D‐regions) such as the anchorage zones of cables in bridge towers. This paper provides a detailed analysis of the elastic stress distribution on the bridge tower of a cable‐stayed bridge with two cable planes. The vertical component of the stay cable force was considered for the analysis. Additionally, two different STMs of the bridge tower were developed with the load path method using different horizontal spacings of the stay cables. Based on the minimum energy principle, the optimal STMs of the two different STMs were generated. A detailed calculation method for the configuration of the optimal STMs is presented. In the paper, computational expressions of the internal force for the tie members in the two STMs are also proposed. Overall, this study demonstrated the strong applicability of the proposed STMs for a bridge tower in a cable‐stayed bridge with two cable planes. This can be considered an effective simplified method in the structural design of bridge towers. Furthermore, the study established that the influence of the horizontal distance between stay cables on the mechanical response‐behavior of the structure should be considered in the design of concrete bridge towers. [ABSTRACT FROM AUTHOR]

The current paper resumes the design of a steel lattice transmission tower carried out in the framework of the RFCS‐funded research project ANGELHY. The scope of ANGELHY is the establishment of analysis methods for lattice towers and the development of design rules for steel and hybrid angle sections, as well as built‐up members composed of angles. In Europe, the design of transmission towers for overhead electrical lines can be carried out according to EN 1993‐3‐1: 2006 or for electrical lines exceeding 1 kV according to EN 50341‐1: 2012. Both standards prescribe linear elastic global analyses for the design of steel lattice towers. In the current paper, the linear elastic design of the suspension transmission tower according to the German National Annex of EN 50341‐1:2012 is presented. In a first step, common typologies of lattice transmission towers used in Europe are described. In a second step, the chosen tower typology is explained in detail. The Danube tower represents the widest spread tower typology in Europe. Finally, the detailed design procedure of the tower according to EN 50341‐1:2012 is presented. The design is carried out with the software TOWER – Version 15.0 from Power Line Systems. [ABSTRACT FROM AUTHOR]

The paper considers elastic anisotropic nano‐sheet with nanotopography and containing embedded nanocavities under time‐harmonic in‐plane wave motion. The mechanical model is based on the classical elastodynamic theory for the anisotropic bulk solid and the nonclassical boundary conditions along its boundary derived by Gurtin and Murdoch. A localized constitutive equation for the half‐plane boundary is considered in the frame of surface elasticity theory. The computational tool is an efficient direct displacement boundary element method (BEM) based on the frequency‐dependent elastodynamic fundamental solution for elastic generally anisotropic material. To show the versatility of the proposed methodology, wave propagation in an elastic anisotropic heterogeneous nano‐sheet with nanorelief presented by hill‐canyon nanotopography is studied. The simulations illustrate the dependence of the wave field on the material anisotropy, on the surface elasticity properties, on the nanorelief peculiarities, on the nanocavities existence and their dynamic interaction, and on the incident wave characteristics. The obtained results reveal the potential of the developed mechanical model based on the boundary integral equations in the frame of surface elasticity theory to produce highly accurate results by using strongly reduced discretization mesh in comparison with the domain‐based methods. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model for the elastic analysis of single floating piles subjected to axial dynamic loads, that is based on treating the soil surrounding the pile as a Tajimi‐type viscoelastic continuum. The pile and the soil column underlying the pile tip are modelled using one‐dimensional rod theory, and this allows obtaining an elegant solution that requires solving a system of linear equations, instead of complicated integral equations. Closed‐form expressions are derived for the dynamic stiffness at the pile head, and the frictional resistance along the pile shaft. The presentation concludes with a discussion on the main mechanisms that govern the inertial response of floating piles, and an investigation on the sensitivity of the dynamic stiffness and of the frictional resistance to the main geometrical and material problem parameters. [ABSTRACT FROM AUTHOR]

This article describes in detail the research on the elastic properties of carbon nanotube reinforced composite materials and graphene‐carbon nanotube (G‐C) reinforced composite materials. Several different composite material models were established using finite element software ABAQUS to study the influence of the inclination angle, quantity and volume fraction of carbon nanotubes and graphene on the elastic modulus of reinforced composites. The results show that as the volume fraction of graphene and carbon nanotubes increases, the Young's modulus and shear modulus of the reinforced composite material increase significantly. In addition, the tilt angle and quantity of graphene and carbon nanotubes will also affect the elastic properties of the composite material. The Young's modulus E and the shear modulus G decrease with the increase of the inclination angle, and increase with the increase of the number of graphene and carbon nanotubes. [ABSTRACT FROM AUTHOR]

Using the first‐principles method based on the density functional theory, hydrogen diffusion, electron structure, and mechanical properties of hydrogen impurity in W15V structure are investigated in this paper. It is found that in W‐V lattice the single H atom tends to be located in the tetrahedral interstitial site nearest to V atom with the solution energy of 0.614 eV. The calculation of energy barriers shows that the V doping can be helpful to trap H atoms near the V atom. The analysis of the elastic moduli shows that the V‐alloying can decrease the strength and improve the ductility of pure W. In addition, the H impurity further enhances this situation. Besides, the effect of H impurity on pure W is greater than W15V structure. The results of this study offer a useful database for the research of W‐based alloys for plasma facing materials (PFMs). [ABSTRACT FROM AUTHOR]

The stability of compression members is typically assessed through buckling curves, which include the influence of initial geometric imperfections and residual stresses. Alternatively, the capacity can be obtained more directly by carrying out a second order analysis using equivalent bow imperfections that account for both geometric imperfections and residual stresses. For design by second order elastic analysis, following EN 1993‐1‐1 recommendations, the magnitudes of the equivalent bow imperfections can either be back‐calculated for a given member to provide the same result as would be obtained from the member buckling curves or taken more simply as a fixed proportion of the member length. In both cases, a subsequent linear axial + bending cross‐section check is required. For design by second order inelastic analysis, there are currently no suitable recommendations for the magnitudes of equivalent bow imperfections and, as demonstrated herein, it is not generally appropriate to use equivalent bow imperfections developed on the basis of elastic analysis. Equivalent bow imperfections suitable for use in design by second order inelastic analysis are therefore established in the present paper and shown to yield reliable results when compared to benchmark results and current design guidance. [ABSTRACT FROM AUTHOR]

This paper addresses a linear elastic methodology for analysis of thin‐walled steel frames. The analysis is based on structural meaningful displacement modes that considerably reduce the number of degrees of freedom needed compared to a similar analysis using shell finite elements. The methodology allows the use of an adequate reduced number of higher order displacement modes. The methodology uses advanced beam elements to model the major structural elements within the frame and advanced joint elements to model the connections between the beam elements. Each joint element is a super element modeled by use of other finite elements such as shell elements. This allows the user to model virtually any geometry of the connection. Furthermore, the advanced beam element is formulated based on a linear combination of structural meaningful displacement modes belonging to each individual beam. Since the methodology is based on displacement modes of the (advanced) beams, it is possible to extract and identify critical displacement patterns for the frame as well as for each beam and joint within the frame. This gives the designer an in‐depth understanding of the behavior of the frame and hence a powerful tool to optimize its design. [ABSTRACT FROM AUTHOR]

Artificial intelligence is gaining increasing popularity in structural analysis. However, at the structural system level, the appropriateness of data representation, the paucity of data, and the physical interpretability of results are rarely studied and remain profound challenges. To fill such gaps, a physics‐informed model named StructGNN‐E (i.e., structural analysis based on graph neural network [GNN]–elastic) based on the GNN architecture, which is capable of implementing the elastic analysis of structural systems without labeled data, is proposed in this study. The systems with structural topologies and member configurations are organized as graph data and later processed by a modified graph isomorphism network. Moreover, to avoid dependence on big data, a novel physics‐informed paradigm is proposed to incorporate mechanics into deep learning (DL), ensuring the theoretical correctness of the results. Numerical experiments and ablation studies demonstrate the unique effectiveness of StructGNN‐E against common DL models, with an average accuracy of 99% and excellent computational efficiency. Due to its differentiability, StructGNN‐E is promising for bidirectionally linking structural parameters and analysis results, paving the way for a new end‐to‐end structural optimization method in the future. [ABSTRACT FROM AUTHOR]

A Eurocode‐compliant design approach was developed for the design of thin‐walled cold‐formed steel sections which combines the AISI S100‐16‐Direct Strength Method (DSM) with the design provisions of EN 1993‐1‐3. The new design approach transfers the cross‐sectional resistance determined acc. to DSM based on numerical elastic buckling analyses on the gross cross‐section into the global member verification acc. to EN 1993‐1‐3. Additional factors were introduced to optimize the new approach, e.g., to account for the effects of the nonlinear stress distribution in cross‐sections subject to local and/or distortional buckling. Within the framework of the German research project FOSTA P1328/IGF 19964, an extensive series of tests on differently shaped, perforated, and unperforated cold‐formed sections in compression and bending were conducted which serve to analyze the buckling phenomena and the load‐bearing capacity and to validate the new design approach. In addition, a numerical model was developed, calibrated to the tests, and used for further parametric analyses on the load‐bearing capacity of cold‐formed sections. [ABSTRACT FROM AUTHOR]

Web holes are commonly seen in cold‐formed steel channel sections to accommodate the technical services. The presence of the web holes has resulted in the reduction of the sectional capacities of the cold‐formed steel sections and has been considered in the design according to the American Specification AISI S100‐16 using a new approach in the design called the Direct Strength Method (DSM). This article, therefore, will use this design method to investigate the sectional capacities of perforated channel sections under compression or bending with the variation of hole sizes in relation to those of gross channel sections. Elastic buckling analysis – a compulsory requirement for application of the DSM – can be conducted using a module CUFSM software program recently developed by the American Iron and Steel Institute. The investigated channel sections are taken from the availably commercial sections. The obtained sectional capacities are seen as the opposite trends for local and distortional buckling modes, although a downtrend of the sectional capacities is found in general with the increase of hole dimensions. It was found that perforated channel sections with smaller hole height and longer hole lengths were recommended to obtain the optimum section capacities in terms of the same web hole area, but the opposite trend was seen for these sections under bending with long hole lengths. [ABSTRACT FROM AUTHOR]

In United States practice, the strength of composite columns is assessed with available strengths that are computed considering member length effects. This approach has advantages; however, developing axial compression‐bending moment interaction diagrams that account for member length effects is not a straightforward task. Current methods result in unconservative error for highly slender members with large bending moments. While it is theoretically possible to develop more accurate interaction diagrams, a simpler approach, and one which more directly addresses the cause of the unconservative error, is to improve the accuracy of the stiffness used in the elastic analyses to determine required strengths. In this work, new recommendations are developed for this stiffness for steel‐concrete composite columns. The recommended stiffness is a function of required axial compression and bending moment, which increases accuracy and enables improved available strength calculations, resulting in more efficient designs. [ABSTRACT FROM AUTHOR]

The large fluctuation of uncertain parameters introduces a great challenge in the stability analysis of structures. To address this problem, a novel stochastic residual error based homotopy method is proposed in this article. This new method used the concept of homotopy to reconstruct a new governing equation for stochastic elastic buckling analysis, and the closed‐form solutions of the isolated buckling eigenvalues and eigenvectors are obtained by the stochastic homotopy analysis method. On this basis, a pth order origin moment of the stochastic residual error with respect to the elastic buckling equation is defined. Then, the optimal form of the homotopy series can be determined automatically by minimizing the pth order origin moment, which overcomes the disadvantage of highly relying on sample values of the existing homotopy stochastic finite element method. Moreover, the proposed method is developed to deal with the stochastic closely spaced buckling eigenvalue problem. Three mathematical examples and three buckling eigenvalue examples, including a variable cross‐section column, a 7‐story frame, and a Kiewitt single‐layer latticed spherical shell, are performed to illustrate the accuracy and effectiveness of the proposed method by comparing with the existing methods when dealing with large fluctuation of random parameters. [ABSTRACT FROM AUTHOR]

A series of Ni‐Mn‐Zn mixed spinel ferrite doped with Sm3+ ions is prepared by using sol‐gel auto‐combustion technique. Single phase cubic spinel structure of all the samples is confirmed by using XRD analysis. Incorporation of Sm3+ ions in Ni‐Mn‐Zn ferrites increases the lattice parameter from 8.4105 to 8.4134 Å. Williamson – Hall (W‐H) and strain size plot (SSP) analysis confirms the tensile‐type strain induced in the crystal lattice, which increases with the addition of Sm3+ ions. Average crystallite size estimated from Scherrer equation is found in the range 21.7–24.9 nm, which in good agreement with the results obtained from W‐H and SSP analysis. Infrared spectra recorded in the range 350–800 cm−1 reveals the characteristic features of spinel ferrites. Higher frequency band ν1 is observed near 580 cm−1 and lower frequency band ν2 is observed near 380 cm−1. By using the IR data, elastic constant (stiffness constant) and elastic moduli (Young's modulus, bulk modulus, and rigidity modulus) are estimated. Debye temperature obtained from Anderson formula ranging from 535 to 562 K and from Waldron equation ranging from 676 to 713 K with the substitution of Sm3+ ions. [ABSTRACT FROM AUTHOR]

In the present article the two‐dimensional hybrid equilibrium element formulation is initially developed, with quadratic, cubic, and quartic stress fields, for static analysis of compressible and quasi‐incompressible elastic solids in the variational framework of the minimum complementary energy principle. Thereafter, the high‐order hybrid equilibrium formulation is developed for dynamic analysis of elastic solids in the variational framework of the Toupin principle, which is the complementary form of the Hamilton principle. The Newmark time integration scheme is introduced for discretization of the stress fields in the time domain and dynamic analysis of both the compressible solid and quasi‐incompressible ones. The hybrid equilibrium element formulation provides very accurate solutions with a high‐order stress field and the results of the static and dynamic analyses are compared with the solution of the classic displacement‐based quadratic formulation, showing the convergence of the two formulations to the exact solution and the very satisfying performance of the proposed formulation, especially for analysis of quasi‐incompressible elastic solids. [ABSTRACT FROM AUTHOR]

Seismic events in recent years have underlined the need to quickly classify the built heritage in terms of seismic performances. The capacity of a structure can be assessed by means of inelastic analyses, requiring sophisticated numerical procedures. The simplified method herein proposed only requires use of common analyses such as the elastic structural analysis and the rigid‐plastic analysis. For this reason, it lends itself well to be used in the immediate aftermath of an earthquake, not requiring any static or dynamic non‐linear analyses. The proposed methodology has been set up by means of a large parametric analysis, carried out on 420 frames designed according to 3 different approaches: the first one is the Theory of Plastic Mechanism Control (TPMC), ensuring the design of structures showing global collapse mechanism (GMRFs), the second one is based on the Eurocode 8 design requirements (SMRFs) while the third is a non‐seismic design, based on design for vertical loads (OMRFs). [ABSTRACT FROM AUTHOR]

Hydroelectric power plants usually have penstock manifolds near the powerhouse, including individual bifurcations to provide several turbines. These steel constructions have numerous vertical supports and are designed based on linear elastic behaviour, leading to very small allowable settlements at the supports. For a representative built manifold, with five bifurcations (six branch pipes), the elastic‐plastic load capacity was studied in detail, assuming dead load, internal pressure and increasing settlements at the supports. Different settlement patterns were studied. The development of plastic zones was analyzed, depending on the rate of settlement. Due to the high bending stiffness of the penstock manifold, the penstock detaches from the single supports due to the settlement, leading to a significant redistribution of the vertical reaction forces at the supports. The comprehensive calculations show adequate robustness of the penstock manifolds, even though in case of very high settlements at the supports. Due to the significant redistribution of the reaction forces at the supports, these vertical supports must have an increased bearing capacity, in comparison to the reaction forces due to dead load and internal pressure based on linear elastic analyses. [ABSTRACT FROM AUTHOR]

The aim of the work is to make a comparison between the European and Japanese approaches to design Seismic‐Resistant Steel Frames (MRFs) in high seismicity areas. Therefore, the design rules for both the seismic codes are analyzed and compared. These design rules are applied to design a benchmark structure in DC3 ductility class (according to the new prEN1998) and following the Route 3 procedure (according to the Building Standard Law in Japan, BSL). The examined structural typology is a Spatial Moment Resisting Frames with regularity in plan and elevation configuration. The Japanese approach is divided in two stages. The first one regards the Allowable Stress Design (Elastic analysis) in which all the parts of the structure must be kept elastic; service and damage limitation requirements are in demand. The second stage regards the Ultimate Strength Design (Plastic Analysis) in which no‐collapse requirement and the protection of the human life are in demand. The seismic performance of the designed structures is evaluated by means of pushover analyses. [ABSTRACT FROM AUTHOR]

A new, Eurocode‐compliant design approach based on the Direct Strength Method (DSM) combined with EN 1993‐1‐3 was developed for the design of thin‐walled cold‐formed steel sections. The new design approach transfers cross‐sectional resistance according to DSM, based on numerical elastic buckling analyses on the gross cross‐section, into the global stability check according to EN 1993‐1‐3. Experimental investigations on various perforated and unperforated cold‐formed sections in compression and bending serve to verify the new design approach. In addition, a numerical model was developed, it was calibrated on the test results and used for further parametric analyses on the load‐carrying capacity of cold‐formed sections. [ABSTRACT FROM AUTHOR]