Stiffener Configurations Research Articles

Strengthening Transformer Tank Structural Integrity through Economic Stiffener Design Configurations Using Computational Analysis

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.

Enhancing cyclic performance of double steel plate shear walls with optimized stiffener configurations

Enhancing cyclic performance of double steel plate shear walls with optimized stiffener configurations

Investigation on Flexural Behavior of Galvanized Cold-Formed Steel Beams Exposed to Fire with Different Stiffener Configurations

Investigation on Flexural Behavior of Galvanized Cold-Formed Steel Beams Exposed to Fire with Different Stiffener Configurations

Effect of process parameters on the mechanical performance of fusion-joined additively manufactured segments

PurposeHerein, the authors report the effects of printing parameters, joining method, and annealing conditions on the structural performance of fusion-joined short-beam sections produced by additive manufacturing.Design/methodology/approachThe authors first identified appropriate printing parameters for joining segmented short beams and then used those parameters to print and fusion-join segments with different configurations of stiffeners to form a longer section of a wing or small wind turbine blade structure.FindingsIt was found that the beams with three lateral and three base stiffening ribs give the highest flexural strength among the three beams investigated. Results on joined beams annealed at different conditions showed that annealing at 70 °C for 0.5 h yields higher performance than annealing at the same temperature for longer times. It is also found that in the case of the hot-plate-welded three-dimensional (3D)-printed structures, no annealing is needed for reaching a high strength-to-weight ratio, but annealing is helpful for maximizing the modulus-to-weight ratio. Both thermal buckling and edge wrapping were observed under annealing at 70°C for 0.5 h for 3D-printed beams comprising two lateral and four base stiffening plates.Originality/valueFusion-joining of additively manufactured segments is needed owing to the constraint in building volume of a typical commercial 3D-printer. However, study of the effect of process parameters is needed to quantify their effect on mechanical performance. This investigation has therefore identified key printing parameters and annealing conditions for fusion-joining short segments to form larger structures, from multiple 3D-printed sections, such as wind blade structures.

Seismic performance of joint between steel H‐beam and rectangular concrete‐filled hot‐rolled‐steel tubular column

AbstractIn this paper, a new connection between the H‐beam and rectangular concrete‐filled hot‐rolled‐steel tubular column (CFHRSTC) was proposed to prevent the steel beam‐column joint protruded from the inside wall in residential buildings. The quasi‐static test and finite element analysis were conducted on four new joints to study the influence of the haunch stiffener configuration, internal steel plate thickness, and axial force on the failure mode, load‐carrying capacity, ductility, energy dissipating capacity, and stiffness degradation of the joint. The results revealed that the hysteretic curve of every joint was full. The damage to the joint was concentrated in the H‐beam, and the CFHRSTC remained elastic. The joint configuration could realize a weak beam‐strong column and joint core connection. Using the haunch stiffener on two sides of the H‐beam flange could effectively optimize load transfer at the end of the H‐beam and joint core. As the axial force increased, the ultimate load‐carrying capacity and ductility gradually decreased. Reducing the thickness of the internal steel plate did not significantly influence the seismic performance of the joint. Compared with the use of cover plate joints, the use of haunch stiffeners can effectively enhance the seismic performance of joints.

Experimental study on seismic performance of replaceable shear links with low-yield-point steel

Based on the design concept of controllable seismic damage during earthquakes and rapid functional recovery after earthquakes, a replaceable shear link with low-yield-point steel was proposed. Quasi-static cyclic loading tests and numerical analysis were conducted on six specimens. The failure mode, seismic performance, energy dissipation behavior, and shear distribution of each specimen were carefully considered to investigate the effects of web steel, web stiffening configuration and stiffener-plate stiffness ratio. The results showed that the stiffened specimens showed full-sectional shear yielding behavior, while the non-stiffened specimens exhibited coupling behavior of web yielding and buckling. Specimens with reasonable design parameters had excellent ductility and energy dissipation capacity, with the plastic shear angle exceeding 0.157 rad and the maximum equivalent viscous damping coefficients greater than 0.51 (80% of the theoretical maximum value). Owing to the cyclic strengthening of the low-yield-point steel web and the contributions of stiffeners and flanges, the specimens showed obvious overstrength behavior, with the overstrength factor ranging from 1.99 to 2.39. The cross-stiffening configuration was conducive to enhancing the seismic performance of shear links. Smaller web width-to-thickness ratios were recommended to match with smaller stiffener-plate stiffness ratios. Extended cross stiffeners and diagonal stiffeners resulted in earlier cracking of the web welds, which adversely affected the ductility of the specimens.

Structural Improvement in Crane Boom Rest

Crane boom rests are critical components that endure both static and dynamic loads, leading to deformation and a shortened lifespan. This paper addresses these issues by proposing a redesigned model with enhanced stiffness and load-bearing capacity. The new design incorporates gussets and Styrene-Butadiene Rubber (SBR) sheets. A series of trials were conducted to analyze various stiffener configurations, with results showing a significant reduction in deformation. The optimal configuration, consisting of three L-shaped stiffeners placed at specific intervals, reduced deformation from 17.2 mm to 2.2 mm. Additionally , the integration of SBR rubber sheets further minimized deformation to 0.15 mm. These modifications demonstrate the effectiveness of the proposed improvements in enhancing the durability and performance of crane boom rests. The findings provide a robust solution for extending the operational life of crane boom rests under dynamic loading conditions. Future research can explore different rubber materials and stiffener designs to further enhance structural integrity and load-bearing capacity.

Structural Improvement in Crane Boom Rest

Crane boom rests are critical components that endure both static and dynamic loads, leading to deformation and a shortened lifespan. This paper addresses these issues by proposing a redesigned model with enhanced stiffness and load-bearing capacity. The new design incorporates gussets and Styrene-Butadiene Rubber (SBR) sheets. A series of trials were conducted to analyze various stiffener configurations, with results showing a significant reduction in deformation. The optimal configuration, consisting of three L-shaped stiffeners placed at specific intervals, reduced deformation from 17.2 mm to 2.2 mm. Additionally , the integration of SBR rubber sheets further minimized deformation to 0.15 mm. These modifications demonstrate the effectiveness of the proposed improvements in enhancing the durability and performance of crane boom rests. The findings provide a robust solution for extending the operational life of crane boom rests under dynamic loading conditions. Future research can explore different rubber materials and stiffener designs to further enhance structural integrity and load-bearing capacity.

Improved Similarity Law for Scaling Dynamic Responses of Stiffened Plates with Distorted Stiffener Configurations

Experimental analysis on small-scale models is widely used to predict the dynamic responses of full-scale structures subjected to impact loads. However, due to manufacturing constraints, achieving a perfectly scaled model under a large scaling factor is challenging, leading to the use of distorted scaled models as a compromise. This paper introduces an improved similarity law that ensures distorted scaled models accurately replicate the dynamic responses of prototype stiffened plates under impact loads. The proposed similarity law meticulously considers both the distorted attached plate thickness and variations in stiffener configuration. Double input parameters involving the load case and geometry are formulated to govern the dynamic responses of integrated stiffeners. Additionally, an approximate method rooted in elastic–plastic theory is developed to assess the dominant behaviors of stiffened plates during impact. Consequently, the distorted stiffener configuration of scaled models is designed through a methodology primarily centered on capturing dominant behaviors. Comprehensive numerical simulations are conducted to evaluate the behavior of stiffened plates subjected to impact loads. The results compellingly demonstrate that the proposed similarity law adeptly compensates for geometric distortions, ensuring reliable predictions of dynamic responses in distorted scaled models.

Comparative Study of Castellated Steel Beams with Varying Compactness Ratios and different stiffener configurations

Comparative Study of Castellated Steel Beams with Varying Compactness Ratios and different stiffener configurations

Mechanical Properties and Influence Factors of Ordinary Shear Links

The current specification requires the same limiting values of inelastic rotation and the overstrength factor for shear links with a length ratio less than 1.6. However, recent studies have shown that the mechanical properties of ordinary shear links with a length ratio ranging from 1.0 to 1.6 are obviously different from those of very short shear links with a length ratio less than 1.0. Additionally, shear links made of different steel materials have differences in mechanical properties. Based on Q345 steel, three ordinary shear links with a length ratio of 1.36 were designed to intensively explore the influence of stiffener configurations and spacing on mechanical properties. Under cyclic loading tests, the failure modes, hysteresis curves, skeleton curves, secant stiffness curves and energy dissipation capacities of shear link specimens were recorded. The results show that the overstrength factor and inelastic rotation of specimens SL-1 and SL-2, which had different stiffener configurations, reached 1.59 and 0.10, while those of specimen SL-3, which had wider stiffener spacing, reached 1.48 and 0.07, which showed that varying the stiffener configuration has no obvious effect, while relaxing stiffener spacing can result in severe buckling of the web. Additionally, its bearing capacity, inelastic rotation, secant stiffness and energy dissipation capacity reduced. Hence, the stiffener spacing should satisfy the requirements of the specification and not be too wide. Based on ABAQUS software, finite element models of ordinary shear links proved to be accurately consistent with test specimens in terms of mechanical properties. On this basis, 114 numerical models of ordinary shear links with different length ratios, stiffener spacings, flange-to-web area ratios, flange strengths, web depth-to-thickness ratios and stiffener thicknesses were designed to study the influence on the overstrength factor.

Seismic Performance of Iwf Flexural Link in Chevron Eccentrically Brace Frames (V-EBFs) with Different Stiffener Space

Eccentrically Braced Frames (EBFs) are the structural systems that are recommended to be constructed in Earthquake Hazard Areas. This system combines good characteristics in withstanding the seismic load, i.e., stiffness, ductility, and dissipation energy. Link is a component in EBFs that play the role of the seismic energy dissipator. As far, several studies have been conducted to enhance the link performance, but the information is still limited. This study observed the structural performance of the IWF flexural link, where this link will experience failure at the flange due to seismic energy dissipation. The investigation was conducted by establishing three Finite Element (FE) models of flexural link. Each link was designed with the same length, i.e. 1000 mm. Three-link models were distinguished by the differences in web stiffener configuration, i.e., non-stiffener link, 250 mmstiffener spacing link, and 100 mm-stiffener spacing link, respectively. All models were examined under cyclic loading with yield displacement controlled. The research discovered that adding the web stiffener on the IWF flexural link significantly escalated the EBFs’ seismic performance, i.e., strength, stiffness, ductility, and dissipation energy. The best seismic performance was presented by a 100 mm-stiffener spacing link. Accordingly, it is indicated that arranging the web stiffeners at the narrow space in the IWF link can be suggested to improve the seismic performance of EBFs.

Ultimate Load Behaviour of Castellated Beams with Stiffened Octagonal Openings

ctagonal castellated beam is fabricated by adding spacer plates between the web joints of the hexagonal castellated beam to further increase the beam depth. The resulted deep beam is advantageous to enhance the shear carrying capacity and moment resistance. However, large web openings are prone to Vierendeel mechanism in the deformation that lowers the overall beam performance due to formation of plastic hinges. The present paper is concerned with non-linear analysis to predict the ultimate load behaviour of octagonal castellated beams. Finite element models were developed by using a commercial programme LUSAS. The numerical models were first validated against the experimental results reported by other researchers. This study aims to propose the ideal configuration of web opening stiffeners and evaluate the effectiveness of the additional stiffening material for different beam span lengths. Provision of ring stiffeners is effective in short span beams in respect of resistance to Vierendeel failure. The stiffeners have increased the ultimate load to the extent of 73% in which the strength restoration is considerably near to the capacity of its parent universal beam. In long span beams, however, the stiffeners can only improve the performance up to 26.61% with larger additional steel materialthan that of shorter span. In all cases, the stiffener thickness is found to be the governing factor to restoring the loss of shear strength due to large web openings. The number of stiffeners contributes no appreciable variation of ultimate load particularly in long span beams where bending is prominent

Enhancing the cyclic performance of shear links using longitudinal stiffeners

Shear links constitute the most crucial part of eccentrically braced frames. Their main responsibility is to dissipate the earthquake input energy away from the main structural members; therefore, keeping them responding within the elastic stage. However, the rotation capacity of vertical shear links directly influences the allowable interstorey drift of the eccentrically braced frame and the energy dissipation capacity. To enhance their rotation capacity and performance, transverse stiffeners in vertical shear links are proposed to be replaced with longitudinal stiffeners in this research. A numerical study is conducted, using Ansys Workbench, on fourteen shear links with different parameters to investigate their cyclic behaviour. The considered parameters are the stiffener configuration (transverse or longitudinal), web thickness, stiffeners number, stiffeners thickness, flanges width, and web aspect ratio. The influence of these parameters on the failure mode, hysteretic response, mechanical parameters (strength, rotation capacity, etc.), ductility, cyclic web shear buckling, and energy dissipation is analysed and discussed. The results demonstrate that longitudinally stiffened shear links surpass conventional transversely stiffened ones in terms of strength, overstrength, rotation capacity, ductility, web shear buckling resistance, and energy dissipation. Additionally, it is found that the current design provisions of EN 1998–1 cannot accurately predict the yield shear strength of longitudinally stiffened shear links. Moreover, numerous remarks involved with the influence of different parameters on the cyclic performance of longitudinally stiffened shear links are presented and discussed.

A Horizontal Stiffener Detailing for Shear Links at the Link-to-Column Connection in Eccentrically Braced Frames

This study investigates the performance and viability of a horizontal stiffener detailing (HSD) to (1) be used at the link-to-column connection in a D-braced eccentrically braced frame layout where conventional link-to-column connections show poor performance, (2) minimize the overstrength factor of shear links caused by the hardening of link flanges, and (3) mitigate an undesirable failure mechanism previously observed in shear links fabricated using ASTM A992 steel. HSD and conventional stiffener detailing (CSD) were tested using W460×60 sections under two loading protocols, including one simulating near-collapse excitation. While the flanges of CSD shear links are greatly stiffened by vertical stiffeners, webs of HSD shear links exhibit inelastic buckling at large rotation angles. This allows the flanges to freely deform, thereby reducing the likelihood of brittle fracture at the flange connections, as well as undesirable link overstrength induced by the flange contribution. This study shows that the horizontal stiffener configuration developed a ductile failure mechanism resulting from gradually increasing local buckling in the web. The strength degradation of links with horizontal stiffener detailing was much more gradual due to the ever-increasing web buckling, unlike the sudden brittle fracture at the flange-to-column face of links with CSD. This research shows that the HSD is a viable and economic alternative for shear links, which has the potential to decrease welding in the shear link while exhibiting adequate seismic performance. HSD also maintains a low overstrength factor and utilizes a simplistic design approach. Finally, the bolted extended end-plate connection and its details at the link ends used in the test experiment provided a viable solution for replaceable links.

Dynamic analysis of laminated composite cylindrical shells with stiffeners

The domain of engineering and structural mechanics has undergone a transformative shift, courtesy of composite materials, attributing to their remarkable strength-to-weight ratio and versatile design adaptability. Amid the diverse array of composite applications, significant attention has been directed towards composite shells fortified with stiffening elements. These configurations seamlessly amalgamate the merits of composite materials with the augmented load-bearing capabilities conferred by the incorporation of stiffeners. This research undertaking aims to dissect orthotropic multilayered shells manifesting distinct stiffening configurations. The analytical exploration is carried out through the utilization of the Finite Element Analysis (FEA) software ANSYS. The ensuing analysis embraces several stiffening patterns: no stiffener, edge beam, central stringer, three equidistant stringers, central ring, and ring with stringer. The inherent diversity in the natural frequencies is reflective of the variance in these stiffening arrangements. Keywords: Laminated Composite Shells, Finite Element Method, Stiffeners, ANSYS.

Thermal-mechanical buckling analysis and optimization of the stringer stiffened cylinder using smeared stiffener based reduced-order models

In this work, the thermal-mechanical buckling analysis and optimization of stringer stiffened cylindrical shells are achieved using the smeared stiffener based reduced-order models. A novel reduced-order modeling method is proposed for nonlinear buckling analysis of the stringer stiffened cylinder subjected to an axially compressive load and initial temperature field. The reduced-order model is constructed based on the improved Koiter perturbation theory and the smeared stiffener method. The axially compressive load, initial temperature field and perturbation loads are converted to be the degrees of freedom in the smeared stiffener based reduced-order model. The thermoelastic geometrically nonlinear response of the stringer stiffened cylinder can be obtained using the proposed method accurately and efficiently. Optimization problems are designed to achieve the optimal stiffening configuration for minimum weight and maximum buckling load, where the solutions of reduced-order models are selected as inputs. Stringer stiffened cylinders with various ratios of radius to thickness and length to radius are considered to illustrate the good performance of the proposed method. Compared to the fully nonlinear analysis based on the classical finite element method, the proposed method can achieve the nonlinear buckling load of the stringer stiffened cylinder much more efficiently and realize the optimization of the stiffening configuration at an affordable computational cost.

Experimental behaviour of plate girders in steel – Internal forces in intermediate transverse stiffeners

Economical design of steel plate girders usually adopts slender web panels sometimes combined with large panel aspect ratio, which determines the elastic stability of the web panel. The adoption of transverse stiffeners is one efficient strategy to retard the web buckling due to shear. The primary role of intermediate transverse stiffener is clear: divide the web into panels providing lateral support to the web plate along the span – This increases the shear strength of the web. However, FprEN 1993-1-5: 2022 [1] stiffener design approach is based mainly on direct compressive forces resulting from the tension filed action in post buckling phase. According to multiple investigations, this area requirement is much higher than that found in laboratory testing and numerical simulations. The findings of experimental testing on eight plate girders with thin webs and two configurations of transverse stiffeners under ultimate load are presented. Using the web and stiffener measure strains, the internal stiffener forces are calculated past the shear failure of the plate girders. These results show that the axial compression and bending moment measured in the intermediate transverse stiffeners are considerably lower than those specified for the design by the FprEN 1993-1-5: 2022 [1].

Effects of ring stiffeners on the underwater collapse behavior of carbon/epoxy composite tubes

An experimental study was performed to analyze the dynamic buckling behavior of stiffened composite tubes. The structures analyzed were filament-wound carbon-fiber/epoxy composite tubes with press-fitted compliant and rigid aluminum ring stiffeners. The ring thicknesses were chosen for a consistent buckling pressure for equally spaced one, two, and three compliant stiffener configurations. The composite structures were submerged inside a pressure vessel and then subjected to increasing hydrostatic pressure until buckle initiation. High-speed photography and Digital Image Correlation were used to acquire full-field displacements and velocities of the collapse event. In addition, piezoelectric transducers were used to concurrently record the local dynamic pressure histories along the length of the tube. The results show that increasing the number of stiffeners for the same collapse pressure decreases the overall energy emission from the implosion event by more than 16%. However, the energy mitigation effects are also influenced by the location of the stiffeners in relation to the buckling initiation point.

Development and testing of knife-plate connected steel panel dampers

Steel panel dampers (SPDs), consisting of the inelastic panel and elastic connecting segments, have been widely used in steel building structures commonly with brace- or stub-column-type configurations, especially in high seismic regions. The elastic connecting segments of stub-column-type SPDs were usually significantly enlarged to ensure their elasticity under the associated extreme loads of the inelastic panel. With the aim of improving the structural efficiency and ductility capability of SPDs, a novel design, named as knife-plate-connected SPD (KSPD), was proposed in the study. The proposed KSPD consisted of one steel panel and two boundary-columns on the horizontal sides with pinned column ends, which were achieved by knife-plate details, connecting to the framing systems. The designed configuration of KSPDs potentially reduced the aspect ratio of the steel panels for easily achieving shear yielding while remaining the stud-column appearance, and mitigated the deformation amplification of the steel panels usually occurred in conventional stub-column-type SPDs. Five full-scale KSPD specimens with various configurations of the panel stiffeners have been experimentally examined and compared under cyclic loadings including fatigue cycles. The feasibility of the KSPD design was experimentally validated, and the developed KSPDs were verified to achieve stable energy dissipation and significant ductility of approximate ten and cumulative plastic deformation (CPD) value up to 796. For the design purpose of the members, the width-to-thickness limits of the steel panel were established to prevent panel buckling and the sub-panel edge fracture upon the test results, respectively, and a design inequality of the knife plates upon strengths was developed to prevent the fracture of the knife plate. Finally, the design suggestions of the proposed KSPD were summarized upon the experimental results and findings of the study.