Search

Power transformers play a vital role in adjusting voltage levels during transmission. This study focuses on optimizing the structural design of power transformer tanks, particularly high-voltage (HV) tank walls, to enhance their mechanical robustness, performance, and operational reliability. This research investigates various stiffener designs and their impact on stress distribution and deformation through finite element analysis (FEA). Ten different configurations of stiffeners, including thickness, width, type, and position variations, were evaluated to identify the optimal design that minimizes stress and deflection while considering weight constraints. The results indicate that specific configurations, particularly those incorporating 16 mm thick H beams, significantly enhance structural integrity. Experimental validation through pressure testing corroborated the simulation findings, ensuring the practical applicability of the optimized designs. This study’s findings have implications for enhancing the longevity and reliability of power transformers, ultimately contributing to more efficient and resilient power transmission systems.

Power transformers play a vital role in adjusting voltage levels during transmission. This study focuses on optimizing the structural design of power transformer tanks, particularly high-voltage (HV) tank walls, to enhance their mechanical robustness, performance, and operational reliability. This research investigates various stiffener designs and their impact on stress distribution and deformation through finite element analysis (FEA). Ten different configurations of stiffeners, including thickness, width, type, and position variations, were evaluated to identify the optimal design that minimizes stress and deflection while considering weight constraints. The results indicate that specific configurations, particularly those incorporating 16 mm thick H beams, significantly enhance structural integrity. Experimental validation through pressure testing corroborated the simulation findings, ensuring the practical applicability of the optimized designs. This study's findings have implications for enhancing the longevity and reliability of power transformers, ultimately contributing to more efficient and resilient power transmission systems. [ABSTRACT FROM AUTHOR]

AbstractThis paper presents analytical analysis of the axial load behavior of a profiled composite wall (PCW) consisting of two profiled steel sheets (PSSs) filled with concrete and reinforced with/without embedded cold-formed steel tubes (CFSTs). This type of composite wall was designed to resist in-plane axial loading (bearing wall). Three experimental samples were tested and its results were presented in this research. The ultimate axial loads of 42 PCW FE models were calculated based on a published work done by the authors earlier. Comparisons between the results of the FE models via the proposed methods and those of Eurocode 4, BS5400, AISC, Hossain (2000), and Wright (1998) were made. Applied calculation formulas for the ultimate axial load were presented via regression analysis theory on the basis of the verified FE results. Comparisons were made between the developed formulas and existing experimental tests, such as those of Hossain (2000) and Wright (1998) and an experimental study performed by the author, and perfect accuracy was achieved. The results of this study proved that the effects of the embedded CFSTs reduced local buckling of the PSS and increased ductility with increasing axial load resistance of the PCW. The provided formulas accurately predict the axial load of the PCWs. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) sections, increasingly favored in the construction industry due to their numerous advantages over hot-rolled steel, have received limited attention in research concerning the flexural behavior of galvanized iron (GI)-based CFS at elevated temperatures. Understanding how these materials and structures behave under elevated temperatures is crucial for fire safety. The authors have performed experimental studies previously on GI-based CFS under elevated temperatures. In that study, CFS sections made of GI of grade E350 of 1.5 m long and 2 mm thickness were used. Built-up beam sections were tested under two-point loading after heating to 60 and 90 min durations and subsequently cooling them down using air and water. This study aims to uncover the influence of different stiffener configurations on the load carrying capacity of sections under elevated temperature parametrically. With the experimental study results from previous studies as a reference, authors used FEM analysis to comprehensively study the behavior of GI-based CFS sections under fire. Vertical, horizontal, and not providing a stiffener were the configurations selected to study the beams parametrically. Parametric analysis confirmed that different stiffener configurations did not alter the predominant failure mode, which remained distortional buckling across all specimens. Beams with vertical stiffeners demonstrated superior performance compared to those with horizontal stiffeners in parametric analysis. Lateral–torsional buckling was observed in the reference specimen, lacking stiffeners due to inadequate restraint at the supports. [ABSTRACT FROM AUTHOR]

The study presented the results of model experimental investigations on box structures made using additive manufacturing. The examined models had walls with reinforcements in the form of corrugations. An experiment was also conducted using a reference model without stiffeners. The aim of the study was to determine the influence of corrugation geometry on the shape and magnitude of structure deformations, as well as on the level of critical loads. The experiments were conducted using a dedicated research stand. Nonlinear numerical analyses of selected structure variations were also carried out using finite element method-based software. A comparison of the maximum displacement values obtained by experimental and numerical methods was made. [ABSTRACT FROM AUTHOR]

Nowadays, thin-walled cylindrical tubes with stiffeners have been rapidly considered in crashworthiness applications owing to their outstanding energy absorption characteristics and comparatively light weight. This research article deals with the influence of the internal linear stiffeners with varying numbers on the lateral crushing characteristics and impact energy absorbing response of cylindrical tubes subjected to quasi-static loading through experimental approaches. Five different configurations were proposed and all the tubes were additively manufactured through Fusion Deposition Modeling (FDM)-based 3 D printing method. Eventually, the fabricated tubes were tested under quasi‐static lateral crushing force and their crashworthiness characteristics were determined. The obtained results revealed that the PLA-CF-based C6S tube exhibited Specific Energy Absorption of 4.99 kJ/g and attained Crush Force Efficiency is 98.68%. Overall outcomes reported that both the carbon fiber reinforced polymer composite tube structures presented better crushing behavior and enhanced energy absorbing capability. Therefore, the proposed linear stiffener induced cylindrical tubes could be employed as a crash box for absorbing energy under lateral impact. [ABSTRACT FROM AUTHOR]

Corrugated steel plate shear walls (CSPSWs) can be applied to high‐rise building structures to serve as lateral load‐bearing and energy‐dissipating members. Arranging stiffeners on corrugated steel plates shows substantial potential to further improve the seismic performance of ordinary CSPSWs. This study experimentally and numerically investigated the hysteretic behavior of unstiffened and stiffened CSPSWs. Cyclic quasi‐static tests were conducted on four, 1/2‐scale, two‐story, single‐bay specimens with different corrugation orientations, including two specimens with unstiffened corrugated steel plates and two specimens installed with stiffened corrugated steel plates equipped with two pairs of stiffeners. According to the hysteretic curves of different specimens, the effects of corrugation orientations and arrangement of stiffeners were revealed in terms of the skeleton curves, energy‐dissipating capacity, and stiffness degradation. Then, finite element (FE) models, which were applied to gain a deeper understanding of the experimental results, were established, and validated against the test results. This study demonstrated that the arrangement of stiffeners was effective in improving the seismic performance of CSPSWs regarding the ultimate shear strength and energy‐dissipating capacity, while the influence of corrugation orientations on the performance of the specimens involved in this study could be ignored. [ABSTRACT FROM AUTHOR]

In order to ascertain how explosive load influences orthotropic slabs with short span stiffeners partially positioned in the x-direction, the purpose of this study is to perform a numerical analysis. The maximum displacement of a floor surface with respect to the force of an explosive load and the angle of inclination. It is feasible to calculate the impact of the angle of inclination and the height of the blast load on the vertical deflection of the slab using the 6th order polynomial blast equation, as long as the local blast load is positioned in the center of the slab. An analysis reveals that the vertical deflection of the slab is affected by the timing of the explosion. Specifically, a more powerful explosion has a diminishing effect on the deflection of the slab. The inclination angle has no major impact on the outcomes of deflection.

Column base connections represent the support system of a structure, and they should be strong enough to sustain the transmitted demands between the columns and foundation. This study describes numerically the performance of strengthened column base plate connections under cyclic loading. Four types of stiffeners were considered in the analysis: bracket plates, angles, channels with vertical stiffeners, and built-up stiffeners. The efficiency of used stiffeners, the cyclic performance of the strengthened connections, and along with the failure modes were investigated. The numerical results showed that all the proposed strengthening methods have sufficient flexural strength and stiffness higher than the column. A pinched hysteretic response was observed for all strengthened connections under the applied cyclic loading. The built-up stiffener presented the maximum moment capacity and rotational stiffness among the other configurations. Using strengthened connections with more stiffeners made the anchor rods the fuse elements in the connection. [ABSTRACT FROM AUTHOR]

Honeycomb crash absorbers have been widely studied as energy absorption devices for use in automotive industries. However, none of these investigations have studied the side impact of empty and foam-filled honeycomb absorbers and adding stiffeners between the different layers of the corrugated sheets which are composing the honeycomb structure to analyse the structure under transverse (L-direction) impacts. In this paper, the foam-filled and reinforced honeycomb crash absorbers are investigated under axial (T) and transverse (L) loading directions. Experimental results for both empty and foam-filled specimens under quasi-static and impact loads were implemented to validate the developed finite element model. Finite element analysis (FEA) was performed to find out the crashworthiness behaviour of the structure under axial and transverse impacts according to road conditions. Finally, a new design of stiffened honeycomb crash absorber was developed and investigated to reduce the level of acceleration experienced by the passengers during the crash event. In this regard, it is concluded that all the requirements related to the energy absorption capabilities and generated deceleration under impact loading can be met by introducing an advanced method to reinforce honeycomb absorbers using stiffeners. It is also proven that the thickness of these stiffeners will not significantly influence the force levels. Due to increase of wall thickness from 1 to 3 mm, the mean crushing force increased from 129 kN to 148 kN. This growth is not sufficient as the goal is to obtain a mean crushing force of 300 kN. Thickening the stiffeners would lead to a loss of efficiency of the structure, as the small increase in mean force would not make up for the gain in mass. Thus, increasing the corrugated sheet' thickness becomes necessary. [ABSTRACT FROM AUTHOR]

Conical shells and their panels are important elements of building structures, but have not been studied sufficiently. This paper explores buckling of truncated steel conical panels reinforced with an orthogonal grid of stiffener plates. The panels are simply supported and are subjected to external uniformly distributed transverse load acting normal to the surface. A geometrically nonlinear mathematical model that takes into account lateral shearing is used. Two options of describing the effect of stiffener plates are considered: the refined discrete method and the method of structural anisotropy (the stiffness of the plates is “smeared”). The computational algorithm is based on the Ritz method and the method of continuing the solution using the best parameter. The algorithm is implemented using Maple analytical computing software. The values of critical buckling loads were obtained for two cases of conical panels with different stiffener options. The load-deflection curves are presented. The convergence of the methods for describing the effect of stiffeners with the increase in their number is discussed. It was found that for conical panels, when choosing a small number of unknown coefficients in the approximation, the value of the critical load may be “overshot”, and it is necessary to select a larger number of unknowns compared to cylindrical panels or flat shells of double curvature.

The utilization and incorporation of glass fiber-reinforced plastics (GFRP) in structural applications and architectural constructions are progressively gaining prominence. Therefore, this paper experimentally and numerically investigates the use of GFRP I-beams in conjunction with concrete slabs to form composite beams. The experimental design incorporated 2600 mm long GFRP I-beams which were connected compositely to concrete slabs with a 500 mm width and 80 mm thickness. The concrete slabs are categorized into two groups: concrete slabs cast using normal-strength concrete (NSC), and concrete slabs prepared using high-strength concrete (HSC). Various parameters like the type of concrete (normal and high-strength concrete), type of stiffeners bonded to the composite section (bolt–epoxy or bolt only), and inclusion of corrugated metal sheets were investigated. To obtain the full shear connection between the GFRP I-sections and concrete slabs, two rows of shear connectors in the form of bolts were utilized. These shear connectors were erected to the top flange of the GFRP I-sections to compositely connect between the GFRP I-beams and the concrete slabs as well as the corrugated metal sheets. The strengthening of the shear webs of GFRP I-beams with GFRP T-section stiffeners resulted in an enhancement in the flexural and shear strength. The failure loads in the case of the bolt–epoxy connection for the stiffeners were 8.2% and 10.0% higher than those in the case of bolt only when the concrete compressive strengths were 20.1 MPa and 52.3 MPa, respectively. Moreover, the effect of the concrete compressive strength was vital where the failure loads increased by 79.9% and 77.1% when HSC was used instead of NSC for the cases of bolt–epoxy and bolt only, respectively. The epoxy adhesive used in conjunction with mechanical connectors, specifically bolts, resulted in sufficient composite action and delayed shear failure within the web of the GFRP beam. For the specimens with bolt–epoxy connection, strain levels in the concrete slabs were consistently higher than in the other specimens with bolts alone at the same loading level. The concrete slabs integrated with HSC registered strain levels that were 20.0% and 21.8% greater for bolt–epoxy and bolt-only connections, respectively, when compared to those using normal-strength concrete (NSC). This discrepancy can likely be credited to the enhanced composite interaction between the concrete slabs and the GFRP I-beams. In addition, ABAQUS software (version 6.2) was used to develop FE models to analyze the tested composite beams and provide a parametric study using the verified models. [ABSTRACT FROM AUTHOR]

Steel plate shear walls (SPSWs) often need to accommodate rectangular openings in their infill plates. When subjected to lateral loadings, such as wind and earthquake, unstiffened SPSWs with rectangular openings may experience large deformations around the openings. This paper presents a stiffener layout to limit the deformations around the rectangular openings in the SPSW system. The effectiveness of the proposed stiffener layout is investigated by conducting experimental tests on two one-third-scale single-story SPSWs with rectangular openings at the center of the infill plates. The two specimens have the same aspect ratio but have different rectangular opening sizes. To prevent deformations around the rectangular openings, the infill plates of the two test specimens are stiffened with the proposed stiffener layout. Quasi-static cyclic loading tests are performed on the specimens, and the deformations around the openings are measured at different loading stages. Tests showed that the proposed stiffener layout can successfully restrain the deformations around the rectangular openings. The specimens also showed stable hysteresis curves and good energy-dissipation capacity. To further examine the inelastic performance of the proposed stiffener layout, finite-element analysis of stiffened SPSWs is conducted. Seismic analyses are also performed for 4-story stiffened and unstiffened SPSWs with rectangular openings to investigate the seismic response of SPSWs with the proposed stiffener layout around the openings. Seismic analyses showed that the proposed stiffener layout around the rectangular openings can prevent the out-of-plane and in-plane deformations around the openings in the SPSW system. [ABSTRACT FROM AUTHOR]

This article presents the analytical and experimental study of Steel Plate Shear Walls (SPSW) with plate stiffeners, a variant that has been dormant within the development of SPSW walls due to the concepts that describe the steel plate behaviour before the application of shear loads parallel to the wall main plane, where the same theory allows to evaluate possible results when using stiffeners that increase the capacity of the plate before these load demands; to demonstrate these concepts, three samples of the wall with a stiffened plate, a sample of this with an unstiffened plate and a sample of the frame were created, reaching results where the walls with stiffeners presented a higher shear capacity than the unstiffened wall in a 27%, and the frame developed a good capacity of displacements, thus focusing the contribution of rigidity to the steel plate. [ABSTRACT FROM AUTHOR]

This paper presents a technical-economical optimization by maximizing the ratio between the critical buckling pressure (technical characteristic) and the production cost (economic characteristic) of stiffened cylindrical shells, a basic concept of value analysis. Critical buckling load values were determined using both the Finite Element Method (FEM) and analytical calculations to validate the accuracy of the results obtained. The maximum difference between the analytical and numerical results was 10%. Technicaleconomic optimization was carried out using the design of experiments method with MINITAB 19 and allowed to select the optimal input parameters, stiffener dimensional ratio 0.10, shell wall thickness 2.50 mm, and distance between circumferential stiffeners 400 mm, and identify the main factors that impact the output response. For the optimal constructive configuration, the ratio between the critical buckling load and the production cost of the stiffened cylindrical shells was maximized by 199%. [ABSTRACT FROM AUTHOR]

Abstract Circular hollow sections (CHS) have evolved as the primary choice for the tubular lattice structures, due to their excellent mechanical properties and aesthetic appearance. However, enhancing the joints capacities in such structures poses as challenge to structural designer. Recent research addressed several external reinforcing schemes that can be utilized for strengthening CHS X-joints. Although each of these schemes was studied thoroughly, no collective study was conducted to compare between their efficiencies in enhancing CHS X-joints strengths and stiffnesses. This study focuses on evaluating the structural performance of these techniques relative to each other. The results showed that CHS X-joints strengthened using outer flanged pipe to confine brace-chord intersection achieved the highest strength and stiffness enhancement among the examined joints. Also, it proved that joints strengthened with single or double outer stiffeners yielded acceptable capacity enhancement with the advantages of easy fabrication and acceptable aesthetically appearance.

Wire‐and‐Arc Additive Manufacturing (WAAM) is based on the well‐known welding technique in which an electric arc is used as a heat source to melt a metal wire. The technology finds its application, among else, in the construction industry, where steel wire is the chosen feed material. Different scales of structural components and elements can be manufactured using WAAM, such as steel joints and pedestrian bridges. Robot‐assisted control of the layer build‐up allows for freedom in the design of structural elements. In this paper, the authors propose a hybrid manufacturing method to combine industrial serial processing with individualised additive manufacturing based on the local stress distributions and force‐flows. The method is validated on the set of five different demonstrators that tackle different local structural issues through different design solutions for local strengthening while exhibiting particular manufacturing constraints characteristic for a workspace confined by flanges of rolled I‐profiles. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a method of metal 3D printing which, when strategically combined with traditional methods of manufacture, has the potential to make a significant impact on the construction sector. To illustrate this potential, an experimental investigation into the flexural buckling response of 13 hot‐rolled I‐section columns, strengthened by WAAM, has been undertaken and is presented herein. The WAAM material was added at the flange tips and distributed non‐uniformly along the member length. Complementary material tests on the conventional and WAAM steels were also carried out. 3D laser scanning was employed to determine the geometry and global geometric imperfections of all specimens, while digital image correlation measurements were taken to provide a detailed insight into the surface deformation characteristics of the specimens during testing. The beneficial effects of the WAAM stiffeners were an increased cross‐sectional area and second moment of area, enhanced local buckling capacity and a more favourable residual stress pattern. Increases in axial capacity of between 17% and 54% for increases of mass between 2% and 26% were achieved, highlighting the tremendous potential in terms of structural efficiency and material savings that can be realised by the combination of WAAM with traditional manufacturing methods. [ABSTRACT FROM AUTHOR]

The Dielectric Elastomer-based Minimum Energy Structures (DEMES) pertain to an equilibrium configuration attained by the assembly of a pre-stretched electroactive polymer film and a compliant boundary frame. Because of their unique characteristics, such as fast response and a large reversible stroke; DEMES have been used widely in the development of soft robotic transducers. However, their utility is typically restricted because of the warping resulting from anticlastic curvature. The present investigation examines the effectiveness of stiffeners in controlling this warping, as well as their effect on the resulting electromechanical response when the DEMES is driven electrically. To this end, we devise an energy-based analytical model that predicts the initial equilibrium configuration of an elementary rectangular DEMES with a finite number of stiffeners adhered to the boundary frame. The proposed framework uses the neo-Hookean hyperelasticity model for the polymer film and the linear elastic constitutive model for both the frame and the stiffeners. Predictive capability of the proposed analytical model is established through comparisons with 3 D finite element simulations and experimental observations. The analytical model is then extended in the setting of the least-action principle to investigate the complex nonlinear dynamic behavior of the DEMES emanating from the interplay between material and geometric nonlinearities. The proposed dynamic model provides crucial insights into the role of varying levels of geometric and material parameters on the attainment of the initial equilibrium configuration of DEMES and its DC dynamic response when driven by a Heaviside electric load. In particular, we highlight the favorable impact of adding stiffeners in enhancing the stroke of the DEMES and an amplification in the attained equilibrium angle with an increasing spacing between the stiffeners. The analytical model and the results reported in this investigation can be of potential use in pre-designing the geometrical and material properties of DEMES for enhancing its electromechanical performance. [ABSTRACT FROM AUTHOR]

Abstract Steel plates are used as the main components of steel elements in many structures. Openings in steel elements may exist for maintenance or inspection purposes in addition to creating paths for different fixtures such as air conditioning, pipes, and facilities. The structural performance of plates with openings is different from that of solid plates when subjected to axial compressive load. Openings affect local buckling, lateral torsional buckling, and shear of plates. Adding stiffeners around openings is a common engineering practice to strengthen plates. However, different design codes and guides provide estimates of the flexural and shear capacity of beams with no clear formulas for the influence of such openings on axial buckling strength. In this study, a parametric study has been performed using general-purpose finite element software, ANSYS, in order to study the effect of using stiffeners around circular opening in simply supported axially loaded plates on the elastic buckling behavior. Different parameters were considered including the aspect ratio of the plate, opening diameter, opening position in both horizontal and vertical directions, and stiffener’s dimensions. The results of the extensive parametric study are used to propose an empirical design formula considering the different studied parameters.

Circular hollow sections (CHS) have evolved as the primary choice for the tubular lattice structures, due to their excellent mechanical properties and aesthetic appearance. However, enhancing the joints capacities in such structures poses as challenge to structural designer. Recent research addressed several external reinforcing schemes that can be utilized for strengthening CHS X-joints. Although each of these schemes was studied thoroughly, no collective study was conducted to compare between their efficiencies in enhancing CHS X-joints strengths and stiffnesses. This study focuses on evaluating the structural performance of these techniques relative to each other. The results showed that CHS X-joints strengthened using outer flanged pipe to confine brace-chord intersection achieved the highest strength and stiffness enhancement among the examined joints. Also, it proved that joints strengthened with single or double outer stiffeners yielded acceptable capacity enhancement with the advantages of easy fabrication and acceptable aesthetically appearance. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing, employing conventional fusion welding processes, shows excellent versatility and can therefore be used for structural modifications of existing parts to create hybrid components. This study evaluates the modification of cold-formed AA2024 metal sheets with 2xxx filler metals to produce 2xxx hybrid structures. The alloys are investigated by thermodynamic simulations and the solidification crack susceptibility is assessed by calculating the index for hot cracking susceptibility. Using cold metal transfer, single-layer depositions are generated on profile sheets after which the specimens are characterised by three analysis procedures: metallographic analysis, chemical analysis, and hardness testing. Results indicate that AA2024 wire material, although generally considered difficult to weld, is more suitable for the additive modification of AA2024 sheets and profiles, as crack-free specimens can be deposited on cold-formed substrates. [ABSTRACT FROM AUTHOR]

A shear wall becomes weak when an opening is provided in it. It is important to provide some arrangement in the shear wall having an opening for recovering strength loss due to the opening. It may be recovered by providing some steel profiles around the opening or at weaker sections in the shear wall having an opening. At first, the identification of weaker sections in the shear wall having an opening is important and then, the wall can be made stronger as the shear wall without an opening by strengthening weaker sections. In the present study, the performance of a shear wall having an opening subjected to horizontal cyclic loading along the plane of the shear wall in the presence of concealed stiffeners is investigated. The reduced models of shear walls with openings were tested under axial and lateral load conditions. Load-carrying capacity, deformation behavior and strain behavior of shear walls were studied with experiments and the validation of the results was made with general-purpose finite element software ANSYS. Significant improvements were observed in strength, deformation and strain behavior of a shear wall having a central opening using concealed reinforced concrete (RC) stiffeners and steel tube stiffeners. [ABSTRACT FROM AUTHOR]

The Finite Strip Method (FSM) was employed to study the buckling behavior of laminated glass fiber-reinforced polymer (GFRP) stiffened plates with different boundary conditions under axial compression. The theoretical formulation was established based on the first-order shear deformation theory (FSDT) for the thin plate and the stiffener. In this formulation, the stiffeners are not required to be placed on the nodal lines. This feature is considered useful in modeling the stiffened plates in which the stiffener elements are placed arbitrarily in complex planforms. Experimental, numerical and analytical studies were conducted to investigate the effects of the plate width-to-thickness ratio, the stiffener thickness-to-width ratio, dimensions, angle, eccentricity, torsional stiffness and geometric configuration of stiffeners on axial buckling capacity. Furthermore, the obtained results of the analytical method were compared with experimental results and ANSYS code to show its accuracy and convergence. The advantages of the present are that number of elements is much less and the mesh refinement process is much more convenient than commercial finite element software and traditional finite element method (FEM). Therefore, time consumed for analysis is less than the codes which work based on the finite element method. [ABSTRACT FROM AUTHOR]

Long glass fiber-reinforced polypropylene (LGFR-PP) composite structures with stiffeners are important substitutes for metal parts for vehicle lightweighting; a good understanding of the buckling characteristics of LGFR-PP stiffeners would provide an important reference for engineering design. The current work is therefore intended to study the buckling characteristics of different cross-sectioned LGFR-PP stiffeners under axial compression via experimental and theoretical analysis. Firstly, LGFR-PP stiffeners with semicircular, rectangular, and trapeziform cross-sections were compressed at the axial direction using a universal testing machine to obtain the buckling process data. Then, the elasticity stability theory modified according to the experimental results was derived to estimate the buckling resistance of LGFR-PP stiffeners in different designs. The test results showed that the LGFR-PP stiffeners possessed a flexible–torsional bulking instability mode under axial compression, the LGFR-PP stiffeners with a semicircular cross-section had higher compression buckling resistance, and the rectangular and trapeziform cross-sectioned stiffeners had better rigidity. The theoretical analysis showed that the modified elasticity stability theory could generally predict the buckling resistance of LGFR-PP stiffeners under axial compression. [ABSTRACT FROM AUTHOR]

The article is concerned with the development of recommendations for rationalization the measurement methodology of determining the total and residual deformation of the stiffeners, regulated by quality standard GOST 9135-2004 “Shoes. Method for determining the total and residual deformation of the toe puff and stiffeners”. This technique has a number of disadvantages, which are as follows: – the standard inserts in the stiffeners, as a rule, do not correspond to their internal shape and size; – the scale factor is not taken into account when applying the same deformation load for shoes that have different average sizes; The disadvantages mentioned above can be eliminated without making changes to the design of ZhNZO-2 device, but only to the testing procedure and the equipment used for this. The article also presents studies of the residual deformation of natural leathers, cardboards and stiffeners, which show that the use of new equipment and changes in the methodology regulated by GOST 9135-2004 can significantly improve the accuracy and reliability of the results. The objects of study are genuine leather “Elite”, cardboard for stiffeners “Ledtrret 22” and stiffeners. The results of the work can be used as recommendations for improving the methodology and equipment for assessing the overall and residual deformation of the stiffeners. Статья посвящена разработке рекомендаций по совершенствованию методики измерений при определении общей и остаточной деформации задника, изложенной в ГОСТ 9135-2004 «Обувь. Метод определения общей и остаточной деформации подноска и задника». Данная методика имеет ряд недостатков, которые заключаются в следующем: – стандартный вкладыш в пяточную часть обуви, как правило, не соответствует её внутренней форме и размерам; – не учитывается масштабный фактор при приложении одинаковой деформационной нагрузки для обуви, имеющей разные средние размеры: мужской, женской, мальчиковой, девичьей, обуви для школьников. Указанные выше недостатки можно исключить, не внося изменений в конструкцию прибора ЖНЗО-2, а только в методику проведения испытаний и оснастку, используемую для этого. В статье также приведены исследования остаточной деформации натуральных кож, картонов и задников, которые показывают, что применение новой оснастки и изменения в методике, регламентированной ГОСТ 9135-2004, позволяют существенно повысить точность и достоверность результатов. Объекты исследования – натуральная кожа «Элит», картон для задников Ledtrret 22, формованные задники из данного картона.

It is known that during long-term operation of crank machines for cold sheet stamping, which consists in cyclic loading of the structure with mechanical stresses, fatigue degradation of the metal occurs, leading to the occurrence and growth of cracks. Nevertheless, the main trend of modern Russian approaches to modernizing the park of forging and pressing machines is the desire to preserve large metal-consuming parts of stamping presses when replacing the control system and hydraulic and/or pneumatic components of additional actuators. Practice has shown that such approach is economically and technologically justified. For countries that do not have the capacity to manufacture stamping machines of their own brands, there is a need to purchase equipment abroad (including Russia), usually for economic reasons in the secondary market after a long period of operation. In this case, competent pre-sale preparation is required in order to avoid emergencies and equipment failures after its installation at the purchasing enterprise. Ensuring the durability of crank stamping machines after a period of long-term operation is an urgent task, both for the industry of developing countries and for the Russian one. Using the example of a powerful crank stamping press, during the pre-sale preparation of which cracks in the slider were revealed, a way to eliminate the causes of cracking during its further operation is shown.

The paper presents an approach to the strength analysis in steel cylindrical panels reinforced from the concave side with an orthogonal grid of stiffeners. A mathematical model of the Timoshenko (Mindlin – Reissner) type is used. Transverse shears and geometric nonlinearity are taken into account. The stiffeners are introduced in two ways: using the method of refined discrete introduction (proposed by author) and the method of structural anisotropy. Computational algorithm based on the Ritz method and the best parameter continuation method. For strength analysis von Mises criterion is used. The values of the maximum permissible strength loss loads are shown for several variants of structures made of steel S345. The extension of areas of non-fulfillment of strength conditions according to the Mises criterion for the stiffened and unstiffened structures are shown.

Many studies on structural topology optimization of steel plate shear walls have been conducted. However, research on topology optimization using the bidirectional evolutionary structural optimization method is limited. Accordingly, this study optimized the topology of the stiffening effect of steel plate shear walls (SPSWs) based on this method. A finite element model of the SPSW was established using Abaqus software through the "sandwich" modeling method. An optimization region was expanded into two optimization regions. As the optimization targets, SPSWs with different aspect ratios were selected. Elastoplastic optimization of a single-layer SPSW was performed through the horizontal displacement cyclic loading, and the distribution law of the stiffening effect was obtained. The stiffeners on the SPSW were arranged according to the SPSW-A075 scheme. Monotonic and reciprocating loading simulation tests were performed on the unstiffened SPSW and common transverse and longitudinal stiffeners to analyze their mechanical properties. The results show that the optimized layout of the stiffened SPSW demonstrated better seismic performance and energy dissipation capacity. The buckling bearing capacity increased by 2.17–2.61 times, and the stiffness and initial stiffness improved significantly. [ABSTRACT FROM AUTHOR]

In recent years, the use of Wire-and-Arc Additive Manufacturing (WAAM) for strengthening standardized steel elements received significant interest within the research community. The reason for this lies in the theoretical potential of WAAM to improve the economic and environmental aspects of contemporary steel construction through efficient material consumption. As efficiency is often obtained through detailed design study, the paper presents a design exploration of suitable stiffener geometries under the assumption of infinite geometrical freedom. The assumption is eventually invalidated as process constraints specific to the generated geometries emerge from test trials. Once identified, process constraints are documented and overcome through adequate and precise path planning. Feasibility analysis is an important step between design and fabrication, especially in the case of large-scale or geometrically complex components. With reference to the case of stiffeners, a feasibility analysis is necessary to take into account the specific geometrical limits of the build volume, which is not typically the case for conventional WAAM fabrication. The current research provides the first investigation to understand the means for future on-site WAAM strengthening of existing steel structural elements. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tube (CFST) columns are used in tall buildings and bridges, and they provide more rigidity and higher bearing capacity, but buckling affects their behavior. There is an exceptional need to study the behavior of these columns under various conditions. The numerical method is beneficial in supplementing the experimental works and is used to explore the effects of various parameters because of the limitations in cost, apparatus, and time of the experimental program. The various parameters, such as the different slenderness ratios, i.e., column-height-to-cross-section-dimension (H/D), different steel-tube-thickness-to-column-dimension (D/t), and different compressive strength of concrete to yield strength of steel tube ratio (fc/fy) under concentric axial loading are considered in this current study. Firstly, a finite element model used the "ANSYS" software program and was constructed to validate the results of the experimental works. The extensive numerical models were carried out to extensively widen the study in this field. The numerical work was conducted on sixty-four specimens. Moreover, the analytical calculations from the different international codes/standards were compared with the numerical results to test their reliability in predicting the ultimate carrying loads. The study provided results that show the improvement effect of CFST columns with the high compressive strength of infilled concrete, while no remarkable enhancement effect with the high yield strength of steel tube was observed. Increasing the columns' diameter is more effective in enhancing the load capacity (about three times more) than increasing the tube thickness (about 1.3 times). Ring stiffeners for long CFST columns (H/D > 12) do not lead to any enhancement of the column behavior due to yielding occurring firstly at the location of the rings. ECP205-2007 is the most conservative design code in predicting the load capacity of CFST columns, while the AIJ design code is good at predicting the ultimate load failure compared to the other codes/standards. Eurocode 4 provides underestimation values of the load-carrying capacity of CFST columns. [ABSTRACT FROM AUTHOR]

The aim of the research is to assess and analyze the physical and mechanical properties of cardboards for stiffeners, as well as to develop an integral quality indicator that allows determining the best sample of materials. The object of research is modern leather cartons used for the production of stiffeners. The subject of research is their physical and mechanical properties. The article describes a set of indicators selected to evaluate the physical and mechanical properties of cardboard for stiffeners. Their characteristics and methods of assessment are given, the obtained data are presented. The results of assessing the quality of materials for stiffeners as a complex of their property indicators are discussed. The method used is an integral quality assessment method. As the result of the work the best article of cardboard for using in the production stiffeners is determined. The application area of the results is the footwear industry. Целью исследования является оценка и анализ физико-механических свойств картонов для задников, а также разработка комплексного показателя качества, позволяющего определить наилучший образец материалов. Объектом исследования являются современные кожкартоны, применяемые для производства задников обуви. Предмет исследования – их физико-механические свойства. В статье выбран комплекс показателей для оценки физико-механических свойств картонов для задников, приведена их характеристика и методики оценки, проведены исследования свойств и анализ полученных данных, представлены результаты оценки качества материалов для задников обуви в комплексе их показателей свойств. Использованный метод – метод комплексной оценки качества. Результаты работы – определён наилучший из используемых в производстве с точки зрения изготовления и эксплуатации артикул картона для задников обуви. Область применения результатов – обувная промышленность.