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Thermal link is an important carrier used to transfer the cooling capacity and suppress the temperature fluctuation in cryostat. To balance these two points, it is usually necessary to find the optimum thermal link parameters. This paper establishes a model for the cryocooler cold head-thermal link-second flange based on a cryostat. Utilizing the response surface method, response equations correlating thermal link parameters with the temperature and its fluctuations of the second stage flange are developed at the lowest temperature of cryocooler. Through dual-objective optimization of cooling capacity transfer and temperature fluctuations at the second flange, the optimal thermal link parameters are determined and experimentally validated based on predicted results. The experimental and predicted values show good agreement with an error of 2 %. The optimized thermal link led a minor temperature increase and a significant temperature fluctuation reduction, decreasing from 230mK at the cold head to 2.900mK at the second flange, achieving a 98.74 % reduction. Furthermore, compared with non-optimization structure, the optimization one has further lowered the temperature fluctuation at the second flange from 4.000mK to 2.900mK with 27.5 % improvement. These results show that the present methods are reliable and useful to help to realize highly stable low-temperature environment in cryostat. [ABSTRACT FROM AUTHOR]

• Cold-formed steel (CFS) sigma-shaped sections in web crippling was studied. • A total of 29 new experiment results were reported. • A finite element modelling method was proposed and its accuracy was verified. • The existing design codes cannot accurately predict the strength of such members. Cold-formed steel (CFS) sigma-shaped sections used as flooring joists and bearers are commonly fabricated with web holes to accommodate building services. These sections featuring web stiffeners and curved lips exhibit lower web-bearing resistance than traditional lipped channel sections. However, the web-bearing resistance of CFS sigma-shaped sections with web holes has not been thoroughly investigated. To address this gap, a detailed experimental investigation was conducted, testing 29 CFS sigma-shaped sections with web holes under an interior-two-flange (ITF) loading case. For comparison, specimens without web holes were also tested. Variables such as hole diameter ratio, hole location, bearing length, and flange condition were examined. A finite element (FE) model was developed and validated against the test results. The results indicated that the web-bearing resistance for specimens with web holes was reduced by 24.0 % on average. To assess the accuracy of existing design specifications, the test results were compared against the design strengths predicted by the American Iron and Steel Institute (AISI) (2016), Australian and New Zealand Standards (AS/NZS) (2018), European Standard (EC3) (2006), and Uzzaman et al. (2012). The comparison revealed that the design strength predicted by Uzzaman et al. (2012) agreed well with the test results. [ABSTRACT FROM AUTHOR]

• Axial compression tests were performed on eighteen lattice CFS columns with lacings. • FE models were developed to simulate the axial compressive buckling behavior of lattice CFS columns. • Effects of various parameters on the axial compressive buckling behavior of lattice CFS columns were investigated. • A method was proposed for determining the axial compressive bearing capacity of lattice CFS columns. Extensive research has been undertaken on built-up cold-formed steel (CFS) column with I-shaped or box-shaped section. However, there has been little attention given to lattice CFS columns, particularly regarding their buckling performance and the design methods for determining buckling capacity. This paper proposes a latticed CFS column, formed by combining two G-shaped (complex edge stiffener) channels using lacings (LCCFS). Eighteen LCCFS columns were tested under axial compression, divided into two groups with web widths of 75 mm and 200 mm. The experimental results demonstrated that no distortional buckling failure occurred in the G-shaped channels of all specimens, mainly due to the constraint provided by lacings on the flanges. A general consistency in the ultimate bearing capacities and failure modes was observed among duplicate specimens. Specimens with a small slenderness ratio predominantly experienced local buckling failure, leading to a more abrupt failure. In contrast, specimens characterized by a large slenderness ratio primarily demonstrated failure due to global buckling. The specimens with larger web width-to-thickness ratios exhibited earlier and more pronounced local buckling, resulting in a reduction in axial compressive stiffness. Furthermore, FE models have been developed to analyze the effects of different parameters on the axial compressive buckling performance of LCCFS columns. The existing direct strength method exhibited notable deviations in predicting axial compressive buckling capacity of LCCFS column, which are deemed unsatisfactory. Based on direct strength method, a method was proposed for determining the axial compressive buckling capacity of LCCFS column. [ABSTRACT FROM AUTHOR]

To address the insufficient collapse resistance of the beam-column welded connection (BWC), this study proposes a strengthening beam-column welded connection with truss elements (BWCTE). A static test on a BWCTE specimen with a composite slab was conducted to investigate its failure pattern, final deflection, and the evolution of axial force, bending moment, and collapse resistance. The results indicate that the addition of truss elements increases the peak load and corresponding deformation of BWCTE by 108.6 % and 27.3 %, respectively, compared to BWC. Moreover, the axial force in the composite beam of the BWCTE specimen achieved the yield axial force, facilitating the complete development of catenary action and optimizing beam performance. Subsequently, primary parameters of the truss element were analyzed using refined numerical models. It is recommended that the projected length of the inside leaning limb is within 0.5 to 0.7 times the height of the steel beam, and the thickness of each limb is within 0.6 to 1.2 times the thickness of the beam flange. Then, the working mechanism of BWCTE was explored through theoretical analysis. The resistance process of BWCTE can be divided into elastic, elastic-plastic, plastic, transition, and catenary stages. The loading and deformation synergies between truss elements and composite beams enable the formation of double plastic zones and double strengthening zones at the beam root, effectively delaying the rupture of the stretched beam flange. Finally, a design method for BWCTE is proposed according to theoretical and numerical analysis. • A strengthening beam-column welded connection with truss elements (BWCTE) is proposed. • Failure pattern, final deflection, and the evolution of axial force, bending moment, and collapse resistance of BWCTE are investigated. • Compared to fully-welded connection, the addition of truss elements increases the peak load and corresponding deformation of BWCTE by 108.6 % and 27.3 %, respectively. • The working mechanism of BWCTE is explored through theoretical analysis. • A collapse resistance design method for BWCTE is given. [ABSTRACT FROM AUTHOR]

Wheel flange wear on curved tracks is a significant issue that poses a threat to the safety of rail vehicles and leads to increased maintenance costs for railway operators. This study aims to develop a numerical model to predict wheel flange wear on small radius curves. The model integrates an efficient wheel-rail conformal contact model with laboratory-tested wear coefficients. By using virtual penetration and influence coefficients for conformal geometries, the model accurately simulates the conformal contact between the wheel flange and the rail gauge corner. The validity of the wheel flange wear prediction model is confirmed through field tracking testing. Using the proposed model, the effects of track layout parameters and solid lubricants on wheel flange wear are investigated. This study provides theoretical guidance for the operation and maintenance of the wheel-rail system to reduce wear. • A fast calculation model of wheel-rail conformal contact is developed. • Wear coefficient for wheel materials under lubrication conditions is measured. • Wheel flange wear model considering conformal and lubricated contact is proposed. • Effect of track parameters and lubricants on wheel flange wear is analyzed. • The proposed model is validated through a railway field test. [ABSTRACT FROM AUTHOR]

A framework for fatigue assessment for tower bolts of floating offshore wind turbine (FOWT) taking into account the impact of preload loss due to ambient temperature creep and plastic deformation is proposed. The ambient temperature creep of high strength steel is modeled in terms of Norton's theory. The residual preload of tower bolt is predicted by a detailed finite element (FE) model of the threaded bolt connection. Subsequently, the residual preload is applied to the FE model of the entire tower segment to achieve the stress range of the bolts. Fatigue life prediction is finally conducted using the Palmgren-Miner's (PM) rule based on S-N curves, with corrections by effects of mean stress and bolt sizes. A fatigue assessment for tower bolts of a 5 MW FOWT is then performed to demonstrate the capability of the proposed framework. Moreover, impact of initial preload, thread friction coefficients and flange gap on preload loss and fatigue life of tower bolts are discussed. • A fatigue assessment framework for tower bolts of FOWT is proposed. • Preload loss on bolt connection due to ambient temperature creep is considered. • Impact of initial preload, thread friction coefficients and flange gap on preload loss and fatigue life of tower bolts are accounted for. • Effects of mean stress and bolt sizes are taken into account. [ABSTRACT FROM AUTHOR]

With the rapid expansion of the installed offshore wind capacity around the world, it is essential to improve the structural integrity of these energy structures for reduced electricity cost and prolonged operational lifespans. An important part of the offshore wind turbine structures is the connection between the monopile foundation and the transition piece. Currently the dominant technology for connecting the monopile to transition piece is using L flanges held together with large-scale bolts. Threaded connections have emerged as a prevalent technology for linking sections of wind turbines, boasting commendable performance despite some inherent drawbacks. This study conducts a comprehensive review of the recommended fatigue design curves for threaded connections in international standards and compares them with the existing fatigue data on medium to large scale bolt sizes. Additionally, the fatigue behaviour of M72 threaded connections has been further analysed by performing new tests with two different values of mean stress. The obtained data from this study have been discussed in terms of the level of conservatism in the recommended fatigue design curves available in international standards for threaded connections. Moreover, the experimental analysis has been combined with numerical and analytical investigations to provide further insight into the life prediction of the threaded connections under fatigue loading conditions. [ABSTRACT FROM AUTHOR]

• The concrete in the hollow-core partially encased composite (HPEC) section effectively restrains the local buckling of the H-shape steel flange. • The failure mode and compressive bearing capacity of steel-hollow core partially encased composite spliced column (SHSC) are primarily influenced by changing the strength of the composite part and steel part. • The effective confined area of HPEC section concrete increases with the increase of flange thickness and the decrease of stirrup spacing. • The formulas for calculating the compressive bearing capacity of NSHSC are proposed. Steel-hollow core partially encased composite spliced frame beam (SHSFB) amalgamates the advantages of steel and composite structures, offering excellent deformation capacity, seismic performance, material savings, and reduced weight. These advantages are also essential for frame columns. Therefore, axial compression tests were conducted on four steel-hollow core partially encased composite spliced columns (SHSCs) and one steel comparison specimen to investigate their failure modes and compressive performance. The test results revealed that the SHSC does not fully utilize the compressive performance of the composite part under compression. Based on these experimental results, improvements were made to the configuration of SHSC, and a new type of SHSC (NSHSC) was further introduced. Finite element parameter analysis was conducted on the hollow-core partially encased composite (HPEC) short columns and NSHSCs, respectively, to investigate the confined effect on concrete in the HPEC section and the influence of different parameters on the compressive performance of NSHSC. The simulated results show that the effectively confined area of concrete in the HPEC section increases with thicker H-shaped steel flanges and narrower stirrup spacing. The compressive performance and failure modes of NSHSC are determined by the lower strength of either the steel part or the composite part. Finally, by integrating concrete confined area division and the compressive stability of variable stiffness column, the calculation method for the axial compressive bearing capacity of NSHSC was proposed. The calculated values exhibit good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

The use of corrugated web beams in civil buildings is gradually increasing. Therefore, the effects of web openings on the collapse resistance of corrugated web beam–column structures must be investigated. This study conducts static loading tests on standard corrugated web (SCW) and open corrugated web (OCW) specimens with a failed middle column. The web openings have minimal effect on the preliminary bearing capacity of the OCW specimen compared to that of the SCW specimen. The specimens show similar internal force development trends, deformation zones in the webs at 45° to the flange, and tensile flange ruptures near the failed column. The deformation of the web openings delays the formation of the deformation zone in the connection area. The maximum load-bearing capacity and failure displacement of the OCW specimen are 46.5% and 32% larger than those of the SCW specimen, respectively, which indicates that openings in the corrugated web can improve the collapse resistance of the substructure. A finite element model is used to analyze the effects of various opening parameters, such as the diameter-to-height ratio, margin, and opening eccentricity on the collapse resistance of the structure. The reasonableness of the numerical model is verified by comparing the results of numerical simulations and practical experiments. The diameter-to-height ratio is positively correlated with the collapse resistance of the substructure. To optimize the shear capacity of the beam, the diameter-to-height ratio should be <0.5. When the margin is <1.8 times the height of the beam, the collapse resistance of the structure increases with the increase of the distance between the opening edges. Therefore, a suitable margin is 1.3–1.8 times the beam height. Openings in the pressure zone negatively affect the collapse performance of the substructure. Therefore, openings should be eccentricity-free or located in the tensile zones. The results of this study can be used as a reference for future projects. • A half scale test is carried out on the beam-column substructure with corrugated web openings. • The continuous collapse behavior of the surrounding substructure under the failure of the middle column is investigated. • The finite element numerical model was established to verify its correctness. • Simulating the collapse resistance performance of corrugated web beam-column structures under different pore factors. [ABSTRACT FROM AUTHOR]

Composite structures made of concrete-filled steel tubular (CFST) columns and steel beams have gained widespread usage in high-rise and long-span structures, and beam-to-column joints strengthened by an internal diaphragm (ID) are expected to be efficient joint patterns. However, the thickness ratio (η bc) limit of beam-to-column flanges is not considered sufficiently in current design codes and existing studies. Moreover, the previous tests rarely included specimens with a beam flange thickness reaching 40 mm. Thus, three joint specimens were designed and tested under cyclic loadings to further investigate the mechanical properties of the ID-type joints and guide engineering applications. The effects of the thickness ratio of the beam-to-column flange were mainly considered in this study. All beam flange thicknesses were 40 mm. Two failure modes were observed, including excessive development of beam plasticity and failure of local connections. Specifically, as the thickness of column walls decreased, the seismic behaviour, such as the resistance, stiffness and ductility of the joints, deteriorated obviously. Two out of three joint specimens satisfied the AISC requirements for composite special moment frames (C-SMF). Based on the test results, the limit value of the thickness ratio of beam-to-column flange (η bc) has been proposed for design purposes. [Display omitted] • Cyclic tests were conducted on joints between thick-flange steel beams and CFST columns. • Effect of the ratio of beam-to-column flange thickness (η bc) was investigated. • Local connection failure was observed in the beam-to-column flange connection. • The design suggestion about the upper limit value of η bc was proposed. [ABSTRACT FROM AUTHOR]

An experimental study for investigating the delamination behaviour of 3D woven composite T-joints with weave variations and optimising weave architectures is carried out. This study involves 10 types of crossing warp architectures at the junction. Quasi-static tensile load is applied to two flanges of 3D woven composite T-joints to evaluate the in-plane mechanical performance. The crossing warp architecture effectively improves the in-plane mechanical performance. Results indicate a significant influence of crossing warp arrangements on failure modes of the 3D woven composite T-joints. The use of internal crossing warp architectures leads to severe delamination in the 3D woven composite T-joints while the composite T-joints with 3D woven external crossing warps primarily fail due to the debonding of fibres and matrix and fibre breakage. The optimal weave architecture for 3D woven composite T-joints is confirmed by analysing the in-plane mechanical behaviour with different crossing warp arrangements and proportions. Regardless of the crossing warp proportions, the external crossing warp architectures outperformed their internal counterparts in resisting delamination, resulting in a maximum increase of 68.75 %, 30.04 % and 116.81 % in modulus, strength and failure strain respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

A study into the mechanical behaviour and design of flanged cruciform section steel members subjected to axial compression is presented herein. The mechanical behaviour of flanged cruciform section columns is first described, with particular emphasis on the newly developed approach for determining the elastic local buckling load for full flanged cruciform cross-sections. Existing experimental data on flanged cruciform section steel columns collected from the literature are then employed to validate numerical models developed within the finite element package ABAQUS. A comprehensive parametric study is subsequently conducted that encompasses a broad spectrum of cross-sectional geometries and global slenderness values. The mechanical behaviour and ultimate resistance of flanged cruciform section columns are shown to be dependent on not only the global slenderness, but also on the ratio of the elastic torsional to flexural buckling loads. The existing experimental data alongside the numerical parametric study results are employed to evaluate the resistance predictions provided in the current Eurocode 3 design codes, revealing a high degree of conservatism. Finally, a new design approach for flanged cruciform section columns, suitable for incorporation into future revisions of Eurocode 3, is proposed which provides significantly improved accuracy and consistency in resistance predictions compared with the current provisions. A reliability analysis of the proposed design approach is conducted in accordance with the EN 1990 procedure, resulting in a recommended partial safety factor γ M1 = 1. 0. [Display omitted] • Description of critical and post-buckling behaviour of flanged cruciform section columns. • Formulae predicting cross-sectional elastic local buckling loads for flanged cruciform section columns are proposed. • Developed finite element models validated against existing test results and a parametric study is conducted. • Development of new design approach using collected experimental and generated numerical results. • Assessment and verification of reliability of the new design approach with EN 1990 procedure. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations on web crippling behavior of hot rolled rectangular hollow section (RHS) with web holes. A total of 20 rectangular hollow sections, subjected to interior-two-flange (ITF) and end-two-flange (ETF) loading conditions undergoing web crippling, were experimentally tested. The experimental program was designed to obtain web crippling of specimen having slenderness (h/t) value of 21.32, by varying size and offset distance of web holes under two flange loading conditions. Finite element models of experimentally tested beams were developed, and results of finite element analysis showed good agreement with experimental results. A parametric study was then conducted using finite element analysis on different cross section sizes, to demonstrate the effect of size and position of web holes on web crippling capacity of rectangular hollow sections. It was demonstrated that ratio of diameter of web hole to the depth of flat portion of web (a/h) and ratio of offset distance of web hole to the flat portion of web (x/h) are the primary parameters affecting the web crippling strength. Design recommendations in the form of reduction factors for both loading conditions are proposed, that are conservative to both experimental and finite element results. To assess the reliability level of design recommendations, reliability analyses were undertaken. • Web crippling tests on rectangular hollow section with web holes were performed. • Finite element models were developed and verified against experimental results. • Parametric study involving analyses of 360 finite element models was conducted. • The effects of size and position of web holes were evaluated. • Equations of strength reduction factors were proposed. [ABSTRACT FROM AUTHOR]

The out-of-plane buckling resistance of welded I-section columns and beam-columns is investigated using an extensive parametric study. Non-linear analyses of uniform and web-tapered doubly symmetric S275 and S355 welded members subjected to an axial force, or to a combined axial force and bending moment are performed. The ultimate resistances are determined for welded members with hot-rolled or flame-cut flanges. The numerical results point to the exceeding conservatism of the Eurocode 3 rules for welded members with flame-cut flanges. Thus, proposals are made to improve the prediction of the weak-axis buckling resistance of welded columns accounting for the flame-cut flanges. The current European rules prove somewhat conservative also for uniform welded columns with hot-rolled flanges having a medium or high slenderness. Thus, a proposal is made to improve the flexural buckling resistance for welded columns with hot-rolled flanges. The design methods proposed for welded members with flame-cut flanges in bending or in compression are used together for welded beam-columns with flame-cut flanges. The proposals are given in the format used in the framework of the Eurocode 3 interaction formulae and General Method. • Design method for flexural buckling of welded columns with flame-cut flanges using the Eurocode 3 buckling curves. • Design method for flexural buckling of welded columns depending on their geometry and flange fabrication process. • Design methods for the out-of-plane stability assessment of welded beam-columns with flame-cut flanges. [ABSTRACT FROM AUTHOR]

This paper explores the opportunities of digital fabrication with concrete (DFC) to improve structural efficiency and achieve sustainable construction. Efficient structural solutions that drastically reduce material consumption can be achieved by ensuring direct load flow and placing material where needed. More than 50 % of material savings can be achieved by using flanges or hollow sections, providing continuity in beams or slabs, reducing the span of structures or using structural systems such as arches, trusses or deep beams. These concepts are not fully exploited as they often require expensive and complex formwork. DFC tackles the latter point, as it promises to produce complex geometries, minimising extra effort, cost, or waste. The paper discusses the optimisation potential of DFC for several structural elements and presents existing applications that demonstrate this potential. Five case studies of different technological approaches are discussed in detail, highlighting advantages and disadvantages to be addressed for widespread adoption. [ABSTRACT FROM AUTHOR]

The non-uniformity of preload between bolts in flange often leads to problems such as loosening, fatigue, and even failure, which raises the safety risk of joint connection. In order to increase the accuracy of initial tightening and improve the uniformity of preload, more accurate tightening control methods are needed contrasted with conventional tightening control methods. This study introduces a multi-view network model for predicting the instant preload during tightening process based on hydraulic tightening system. First, a dataset about bolt tightening is established, and corresponding algorithm for extracting effective tightening time is created to obtain effective hydraulic pressure signals. Based on the operation of the hydraulic system and the transmission law of the wrench, an algorithm is designed to calculate the nut angle data from the raw pressure data. Then, based on the multi-view structure, several two-stream deep neural networks model with different feature extraction blocks and fusion strategies are developed to predict preload during the bolt tightening process. Finally, the suitable network models for preload control method and yield control preload monitoring are selected through comparison of all network structures, and the preload uniformity in test data of preload control method is further evaluated. All experimental results indicate that the two-stream deep learning model has achieved good prediction results in the allowable tightening process of hydraulic system. The preload control model can reduce the deviation of preload from 15% to 20% of conventional methods to about 10%. [ABSTRACT FROM AUTHOR]

• A novel general dynamic model for bolted composite cylindrical-cylindrical flanged shells is established. • The influence of the flange and the connection characteristics of the bolted joint are considered. • Sufficient modal tests are performed to prove the correctness of the model. • The effects of structural dimensions and bolted connection conditions are studied. • The phenomenon of coupling between different modes is analyzed. A semi-analytical model for bolted composite cylindrical-cylindrical flanged shells (BCCFS) considering the influence of the flange and the connection characteristics of the bolted flange joint is established. In the model, flanges are treated as annular plate structures and modeled using Kirchhoff plate theory. To simulate the connectivity performance of the bolted flange joint, a surface-spring model considering the pressure distribution characteristics is developed and applied to the model of the bolted structure. A method based on fractal contact theory is proposed to identify stiffness-related parameters of the surface-spring model, which avoids additional tensile experiments of the bolted joint. Sufficient modal tests are performed to validate the accuracy of the model. Furthermore, the effects of flange thickness, length ratio of two shells, and quantity of bolts on the free vibration characteristics of the structure are studied. The frequency veering phenomenon with the variation of size parameters is found and analyzed in depth. [Display omitted] [ABSTRACT FROM AUTHOR]

The vibration of underwater vehicles affects their instrumentation and acoustic stealth capabilities. Mechanical metamaterials offer an advanced alternative to conventional vibration control methods. This study develops metamaterial flanges consisting of rectangular star-shaped cells with horizontal ligaments and localized masses. The vibration attenuation performance of metamaterial flanges within the power cabin is validated through simulations and experiments. This research examines the correlation between the bandgaps of large radial span unit cells and the frequencies of vibration attenuation, using the bandgap superposition effect. The findings reveal that the metamaterial cell exhibits exceptional load-bearing capacity and directional bandgaps in the low- to mid-frequency domain. Notably, the vibration attenuation achieved via bandgap superposition reaches 5.1 dB within 823 Hz to 1359 Hz. Specifically, within the range of 1017 Hz to 1146 Hz, the attenuation peaks at an impressive 18.6 dB. The metamaterial structure significantly reduces weight, decreasing the power cabin mass by 36.5%. This research offers new insights and serves as a valuable reference for vibration suppression in small- to medium-sized underwater vehicles. • Advanced cells have bandgaps below 1500Hz and load-bearing capacity in a small size. • Variation of radial dimension widens bandgap to 835–1500 Hz by superposition effect. • Vibration suppression by metamaterial flanges is proved by experiment and simulation. • Metamaterial flanges reduce vibration by 5.1 dB while reducing mass by 36.5%. [ABSTRACT FROM AUTHOR]

[Display omitted] • A classification model of the contact between the profile's flange and the roller die was established for the stretch-bending process. • The maximum theoretical interference value was calculated to predict the extent of local deformation after contact. • Finite element software was used to analyze the changes in equivalent plastic strain of the deformation results. This study aims to investigate the influence of the roller dies' characteristics of shapes on the forming results in the roller-based flexible multi-point three-dimensional stretch bending forming (FSBRD) process for thin-walled profiles, as well as the prediction of mold-induced impressions during the FSBRD process. Considering the specific contact mode, an L-shaped section profile's flange was selected as the research object to analyze the impact of the roller dies' slot's geometric parameters on the product. A classification model of the contact between the profile's flange and the roller die was established for the vertical bending process, and the maximum theoretical interference value (i max) was calculated to predict the extent of local deformation after contact. Subsequently, finite element software was used to model the process and analyze the changes in equivalent plastic strain (PEEQ) of the deformation results when using roller dies with slots of different parameters, including straight, inclined, and arc-shaped slots. The analysis results indicate that the width of the straight slot has a significant influence on the forming quality of the product, as a smaller slot width leads to larger local dimples on the product surface. Replacing the straight slot with an inclined or arc-shaped slot improves the abrupt changes in local PEEQ, resulting in reduced macroscopic local dimples. The simulation results align with the analytical model's variation of i max. This study defined the theoretical contact angle γ and introduced the concept of the contact area and the local theoretical interference zone, providing a reasonable explanation for the observed PEEQ variations. Furthermore, based on the conclusions of the research above, modified experiments were designed, resulting in favorable forming effects. The validation of the simulation results was performed by comparing the local dimples in the contact zone of the actual experimental results. [ABSTRACT FROM AUTHOR]

This paper investigates the shortcomings of the AISC 360–22 and Eurocode 3–22 provisions for calculating the plateau and lateral-torsional buckling (LTB) flexural resistance of thin-web singly-symmetric steel I-section members with the larger flange in compression. In addition, the paper proposes and evaluates corresponding newly recommended AISC 360 procedures, which eliminate the tension flange yielding (TFY) limit state check and implement a more mechanistically-based solution accounting for the inelastic reserve strength associated with flexural yielding in tension. The recommended procedures incorporate other recently proposed improvements to AISC 360, solving substantive LTB overprediction problems for certain types of built-up I-section members. The results from six large-scale experimental tests, associated finite element analysis (FEA) simulations, and parametric FEA simulation studies are considered. The results demonstrate improved accuracy and substantial gains in the predicted strengths by the recommended procedures relative to the AISC 360–22 and Eurocode 3–22 calculations for a significant range of geometries and loadings. In addition, the recommended methods address LTB overprediction problems exhibited by AISC 360–22 for a limited range of the member types studied. • Experimental evidence shows current flexure design codes can be overly conservative. • Accounting for tensile yield in flexure can result in substantial strength gains. • Codes do not calculate the true stain distribution for larger flanges in compression. • Experimental evidence shows current flexure design codes can overpredict capacity. • Improvements can be made to the design codes through simple modification. [ABSTRACT FROM AUTHOR]

This paper shows the results of full-scale tests conducted to investigate the mechanical behavior of flange joints for corrugated steel plate. The observed failure mode was local buckling of the flange plate. The moment-rotation response, deformation characteristic and strain distribution are presented and analyzed. A finite element model was established and verified with the test results, and used to perform a parametric study of key parameters. The influence of the bolt diameter, flange plate thickness and axial force on the initial stiffness, yield moment and failure mode are discussed. The failure mode can be classified into three types: flange plate buckling, bolt failure, and corrugated plate yielding. Additionally, an equation for the yield moment is proposed based on the yield line mechanism and numerical results. The proposed equation provides good accuracy, whereas the yield moment is conservatively estimated by Eurocode 3. • Full-scale tests of flange joints for corrugated steel plate were conducted. • The bending behavior and failure mode were investigated. • A finite element model was established and parametric study was performed. • An equation for yield moment is proposed using yield line mechanism. [ABSTRACT FROM AUTHOR]

• Buckling never governs resistance of a member under transverse load only. • The flanges provide sufficient fixity to the web. • Significant influence of axial load on resistance in transverse compression. This paper focuses on the problem of steel members of open double symmetrical cross-sections in transverse compression. First, the problem is introduced with examples of its application in steel structures of buildings and followed by the overview of selected substantial literature resources and current design codes provisions. The essential part of the paper is a presentation of results of experimental tests and advanced numerical analysis of members subjected to selected cases of transverse compression. Where possible, the results are compared with resistances obtained using provisions in currently valid design codes for steel structures. The influence of selected parameters on the resistance in transverse compression is quantified within the evaluation with specific attention paid to plate buckling of the web. Based on data obtained from the experimental and numerical investigations, the most notable findings are summarized. [ABSTRACT FROM AUTHOR]

• Shear was found to have significant impact on the LTB resistances. • 3344 cases were investigated with eigenvalue and large-displacement analyses. • Stiffened and unstiffened beams with a large variety of load were investigated. • Design equations were proposed for shear effects in singly-symmetric I-beams. • Proposed equations can achieve much better accuracy than Winter's approach. This paper presents an investigation on the negative effects of shear on the lateral torsional buckling (LTB) of singly-symmetric I-shaped beams due to web distortion associated with shear. Results from a parametric FEA study including eigenvalue buckling analyses and large-displacement analyses were utilized considering both stiffened and unstiffened webs to consider the impact of shear on the LTB resistance. Moment gradients caused by constant shear and a shear gradient were considered. The FEA solutions demonstrate that shear can significantly reduce the lateral-torsional buckling resistance. The FEA results were used to develop design equations that account for the reduction in the LTB capacity from shear. The solutions were compared with conventional methods proposed by Winter to account for the effects of web distortion on girders with slender webs. Results from the study show that (i) the average flange area should be used to account for the effects of shear of singly-symmetric beams; (ii) post-buckling strength has limited impact on the shear effects with regards to the LTB resistance; and, (iii) compared to Winter's approach, the proposed method can capture the variation of the moment reduction factor with the shear force in the unbraced length, and is able to predict moment resistances with reasonable accuracy compared to refined FEA solutions using both eigenvalue analysis and large-displacement analysis. Design examples are provided to demonstrate the calculation procedure. [ABSTRACT FROM AUTHOR]

In steel-bamboo composite beams, the debonding failure and slip behavior of steel-bamboo pure bonding interfaces at the flanges often lead to premature failure of beams and underutilization of material strengths. Therefore, a novel steel-bamboo composite I-beam with composite connections was presented in this study, in which the pure bonding interfaces at the beam's flanges were reinforced by self-tapping screws (STSs). 13 beams were designed and fabricated with interface type, shear span-to-depth ratio, height-to-thickness ratios of bamboo and steel at the web, and width-to-thickness ratio of steel at the flange as main parameters. Then, shear tests and theoretical analysis were performed to evaluate the beam's shear behavior. The results indicated that the debonding failure and slip behavior of the beams were effectively limited, and the shear resistance, deformation capacity, and ductility were significantly improved. The shear resistance of beams was improved by reducing the shear span-to-depth ratio, height-to-thickness ratios of the bamboo and steel at the web, and steel flange width-to-thickness ratio. Finally, the developed analytical models can be concluded to be used to accurately predict the interfacial shear stress at the beam flanges in the serviceability limit state (SLS) and ultimate shear capacity of the beams. • The shear behavior of a novel steel-bamboo composite I-beam with composite connections was investigated. • The debonding failure and slip behavior of beams were effectively limited. • The analytical models were developed to predict the interfacial shear stress and ultimate shear capacity of beams. [ABSTRACT FROM AUTHOR]

• A comprehensive case study is presented that studies curve squeal on a 213 m radius metro curve based on measurements performed both trackside and on-board passing vehicles. • Wayside noise measurements show squeal noise emission with an intermittent character that contains discrete jumps between dominating 1/3 octave bands with centre frequencies in the range between 6.3–15.8 kHz. This is significantly higher as compared to the main body of field measurements presented in literature. • On-board noise measurements taken close to the wheel–rail contacts of an instrumented wheelset show tonal squeal generated from the outer wheel with similar noise characteristics as typically related to inner wheel squeal. • Analysis of long-term on-board noise measurement data containing almost 2000 vehicle passages indicate squeal radiation from the inner and outer wheel of the instrumented wheelset for 65 % and 8 % of vehicle passages, respectively. Further, the occurrence of curve squeal radiated from the inner wheel was found to increase by 10 % after rail grinding. This case study is presented after observations were made that partially contrast the prevailing picture of railway curve squeal given in the literature. These are observations with significance both for modelling and condition monitoring. The current case study will be followed by a subsequent investigation focused on the validation and application of a simulation model to investigate root-causes for curve squeal at the Stockholm metro. Curve squeal in a 213 m radius curve on the Stockholm metro is studied. Data includes track characteristics (rail profile, rail roughness and gauge width) and noise measured at the trackside as well as by two vehicles equipped with an on-board mounted noise monitoring system. The current case study contrasts field measurements of curve squeal reported in the literature by a relative shift of emitted noise towards higher frequencies. Wayside noise measurements in the studied curve during a few hours showed squeal generation for all vehicle passages with dominating 1/3 octave band centre frequencies in the range between 6.3–15.8 kHz. Noise data measured during one year of regular traffic of two vehicles equipped with a monitoring system were obtained. The occurrence of curve squeal was analysed through an implementation of the curve squeal detection algorithm in operation at the Stockholm metro. This algorithm was also applied to search for events of squeal noise radiation from the outer wheel. Results show emissions of squeal noise from the inner and outer wheel for 65 % and 8 % of the vehicle passages through the studied curve, respectively. Further, the occurrence of curve squeal radiated from the inner wheel was found to increase by 10 % after rail grinding. In the literature, squeal radiated from the outer wheel is described as having an intermittent character with magnified spectral components in the frequency range between 5–10 kHz. In contrast, the current work presents sustained tonal squeal generated from the outer wheel with similar noise characteristics as typically related to ordinary curve squeal. [ABSTRACT FROM AUTHOR]

The behaviour of the face-plate component under out-of-plane loading has been previously studied, and analytical formulations characterizing the initial stiffness have been proposed. However, research investigating the response of this component under simultaneous transverse loading is limited. This study examines the influence of in-plane transverse compression on the out-of-plane behaviour of the face-plate component in weak axis and tubular beam-to-column steel joints. An experimental test campaign was conducted, covering five representative joint configurations for connections to both I-section and tubular columns. Finite element models of the tested specimen were generated and validated based on the test results. Subsequently, these results were supplemented by two sets of numerical parametric studies, encompassing a total of 329 connections under different levels of transverse loads. The results indicate the detrimental effect of transverse compression on the stiffness and resistance of the face-plate component. Analytical expressions for the reduction of initial stiffness under compressive in-plane transverse loads were proposed and validated, facilitating easy incorporation into design standards. ● Experimental tests conducted on the face plate component under both out-of-plane and in-plane transverse loading conditions. ● Numerical models validated through test findings, which are then extended through a comprehensive parametric study. ● Influence of flange rotational restraint assessed regarding its effects on the initial stiffness of the face plate component. ● An analytical model proposed to evaluate in-plane transverse compression's impact on the initial stiffness of the face plate. [ABSTRACT FROM AUTHOR]

• An Auxiliary Measuring Tool (AMT) with elaborate structure is designed, which can represent the center, normal and in-plane rotation of the flange face in different styles and sizes. • A novel method for calibrating the AMT is proposed. • An efficient photogrammetry-based approach to attitude inspection of the flange faces on multi-branch welded tubes is put forward using the AMT. • Experiments demonstrate the high performance of the proposed method on real welded tubes. The attitudes (including positions and orientations) of flange faces on a multi-branch welded tube are critical to tube installation quality. However, it lacks appropriate approach for flange attitudes inspection. Given the inspection requirements, a novel Auxiliary Measuring Tool (AMT) is designed. A photogrammetry-based approach is put forward to inspect the attitude errors of the flange faces with the aid of the AMT. The specifically designed AMT can achieve flange face centering through a three-jaw chuck structure and establish in-plane rotation by employing a slider to locate the reference bolt hole. An ingenious calibration method is proposed to establish the AMT coordinate frame (ACF) and obtain the marker points' coordinates in ACF. With the calibrated AMTs attached to each flange, the flange attitude error can be efficiently evaluated by simply capturing a set of images of the tube. Experiments on two welded tubes demonstrate the high performance of the proposed method. [ABSTRACT FROM AUTHOR]

[Display omitted] • A semi-analytical method for dynamic modeling of variable stiffness composite flanged-cylindrical shells is proposed. • The correctness and efficiency of the proposed method are verified by finite element method. • The vibration test of a composite cylindrical shell with flange is carried out. • The effects of various design parameters on the variable stiffness composite cylindrical shell are analyzed. Variable stiffness composite structures show great application potential due to their flexible spatial stiffness adjustment ability. In this paper, the accurate and efficient dynamic models of variable stiffness composite cylindrical shells considering the effects of the flange are established based on a semi-analytic frame. Then, the finite element models of the corresponding structures are established by using the ANSYS commercial software. Through the comparison of the calculation results between models under two analytical frameworks, the correctness and efficiency of the proposed modeling method are well verified and reflected. In addition, an instant hammering test of a composite cylindrical shell with flange is carried out to verify the accuracy of the modeling method at the experimental level. Then, the influence of design parameters on frequency trajectories and modals of the variable stiffness composite cylindrical shell with flange is studied. The analysis results show rich and interesting phenomena, among which, the circumferential variable stiffness composite cylindrical shell with and without flange exhibits complex frequency veering behavior under continuous variations of design parameters. The research work has a certain guiding significance for the dynamic optimization design of the variable stiffness composite cylindrical shell with flange. [ABSTRACT FROM AUTHOR]

To enhance the anti-progressive collapse capacity of the conventional top-seat angle and web double-angle connection (TAWDC), this research proposes a novel top-seat angle and web double-bending-angle connection (NTAWDC). In contrast to the TAWDC, the NTAWDC incorporates four additional top and seat bending-angle steels (BSs) connecting the beam and column flanges, while concurrently substituting the web right-angle steels with web BSs. The validated numerical model is employed to perform a thorough analysis of the NTAWDC's progressive collapse resistance. The resistance behavior of the NTAWDC can be classified into three stages: elastic, first failure and second failure stages. In the second failure stage, the coordinated action of the tension-side BSs and the web BSs contributes to the development of an effective catenary mechanism of the structure. The simultaneous fracture of both the tension-side BSs and the web BSs leads to the maximum load-carrying capacity and deformation, thereby signifying a notable enhancement in the progressive collapse resistance of the NTAWDC due to the addition of BSs. A theoretical analysis describing the working mechanism of the NTAWDC under progressive collapse conditions is provided. Additionally, a predictive formula for determining the ultimate rotation and a design method for the NTAWDC are presented. The validity of the design method is validated through numerical model examples that encompass three different beam and column sections. The recommended thickness range for the web BS is 0.8 to 1.2 times the beam web thickness, while the suggested length range for the beam is 12 to 24 times its height. • A novel top-seat angle and web double-bending-angle connection (NTAWDC) is proposed. • The resistance development of NTAWDC experienced three stages: the elastic, first failure and second failure stages. • A geometric deformation relationship for NTAWDC is established. • The maximum resistance and corresponding displacement of NTAWDC increased by 123% and 32%, respectively. • An anti-progressive collapse design method for NTAWDC is proposed. [ABSTRACT FROM AUTHOR]

In recent years, single-layer spherical lattice shell structure has garnered extensive attention in the fields of spatial grid structures and prefabricated construction techniques. The design of joints constitutes an indispensable component of single-layer spherical lattice shell structures. In order to ensure that the joint design aligns with both mechanical performance and ease of construction, a comprehensive approach to joint design is imperative. This study introduces a novel intelligent design framework for rigid-jointed joints in single-layer spherical lattice shell structures. The architecture and loss function of this framework are specifically tailored to evaluate the performance of various joint design schemes. By integrating a multi-head attention mechanism, the Graph Attention Neural Network can extract global structural design parameters. In contrast to conventional design methods, the latter lacks consideration for the overall structural performance and optimization of joints. By incorporating the research group's enveloping tubular staggered flange spatial joint, this method not only addresses the stability of the overall structure but also accounts for the rigidity requirements of the joints. Numerical experiments demonstrate that the model loss value, when employing both multi-head attention mechanism and graph attention mechanism, decreases faster compared to the model loss value with only the graph attention mechanism, and it tends to plateau after approximately 70 iterations. The proposed intelligent design method for rigid joints in prefabricated single-layer spherical lattice shell structures offers a fresh perspective on the design of such structures and advances the development of spatial grid structures and prefabricated construction techniques. • Innovative Structural Design for Spherical Lattice Shells: Introduces a new flange joint to enhance node rigidity, with an automated design algorithm. • Graph Attention Networks (GAT) Utilization: Adopts GAT for processing graph-structured data, managing complex node relationships in designs. • Intelligent Design Architecture:Establishes a new method for lattice shell design using Graph Attention Networks and multi-head attention mechanisms. • Superior Performance of GAT-based Model: Validates effectiveness through analysis with Graph Convolutional Networks, showing lower model loss and higher efficiency. • Comprehensive Structure of the Paper: Covers the intelligent design process, automated sleeve design, Graph Attention Network workings, experimental analysis, and insights. [ABSTRACT FROM AUTHOR]

In high-pressure gas production environments, the reliability of wellhead flange connection is paramount for ensuring overall wellhead safety. Failure to meet stringent requirements regarding strength and stiffness under extreme conditions, can potentially lead to leakage and even catastrophic blowout incidents. To tackle these challenges head-on, a comprehensive performance analysis methodology is proposed for ultrahigh-pressure (UHP) wellhead flanges, integrating advanced simulation techniques with precise experimental measurements. Addressing the inherent difficulties in directly measuring moments under complex loading scenarios, an innovative approach is employed to estimate the ultimate moment using deflection angles. The study meticulously evaluates the strength and stiffness of pivotal components by leveraging a comprehensive finite element model of the flange. Detailed examination of valuation criteria and calculation procedures for determining the failure boundary conditions of strength and stiffness enriches the understanding of the flange's mechanical behavior under extreme operating conditions. Illustrating the practical applicability of the proposed methodology, a real-world case study of a UHP wellhead flange is presented, showcasing the efficacy of the approach through rigorous strength testing, resulting in the derivation of reliable mechanical performance parameters. Furthermore, the robustness of the proposed models is thoroughly validated through meticulous comparison of simulation results with empirical experimental data. • The mechanical property of UHP wellhead flange is determined by evaluating its strength. • The ultimate moment can be calculated from the upper limitation of deflection angle. • Critical conditions for strength and stiffness failure are identified. [ABSTRACT FROM AUTHOR]

An offshore aluminum floor structure made from inverted T-shaped beams and a transversely stiffened deck was investigated experimentally and numerically. The deck assembly contained weld-connected extruded profiles with a closed trapezoidal stiffener and flat plating, which constituted the beams' top flange. A bending test was designed to produce a state of pure axial compression perpendicular to the stiffeners in the deck without the influence of transverse loading on the deck. The compressed floor deck developed buckling deformations where the deck profiles/stiffeners deflected elastically with alternating upward/downward buckling bows between the floor beams, occurring at an average membrane compression stress of 30 N/mm2 in the deck plate. Ultimately, the average membrane stress was 54 N/mm2, and the deck stiffener deflections were >10 mm. The compressive deck plate stresses gradually redistributed to the regions near the webs of the floor beams, where failure occurred by inelastic buckling of the deck plate. FE simulations accurately reproduced the bending resistance of the floor structure, the observed buckling forms and displacements in the deck, and the strain and stress distributions in the deck plate. The existing design provisions for compressed transversely stiffened plates are insufficient and provide capacities less than half of that from the experiment. • An experiment for a stiffened floor deck in transverse compression was presented. • Stiffener deflections and deck plate buckling occurred in the specimen. • Stress redistribution and post-buckling capacity were observed. • Modeling options for the stiffened deck and various capacity models were studied. • Capacity predictions by various methods were found conservative. [ABSTRACT FROM AUTHOR]

This paper developed a novel bolted connection of prefabricated partially encased composite (PEC) beam to concrete-filled steel tubular (CFST) column by end-plates or π-connectors, and two joints with varying design details were tested subjected to cyclic loading. The seismic performance of the developed connections was investigated by experimental and finite element (FE) analysis. It was observed that both the two type connections exhibited concrete crushing within the PEC beam, accompanied by localized buckling and eventual fracture of the flanges in the main steel component of the beam. At the same time, other components were essentially in the elastic phase, such as end-plates, π-connectors, high-strength bolts, and column steel tubes. The bolted end-plate connections demonstrated excellent hysteretic performance, exhibiting high ductility factors. The stiffness, ductility, and energy dissipation capacity of the bolted π-connector connections were significantly diminished due to the influence of relative slippage between the π-connectors and the beams, in stark contrast to the bolted end-plate connection. According to Eurocode 3, the suggested connection configurations exhibited semi-rigid behavior and full-strength characteristics for non-sway frames. • A novel connection of prefabricated partially encased composite (PEC) beam to CFST column was developed. • The seismic performance of the developed connections was investigated by experimental test and finite element (FE) model. • Bolt slippage has a significant effect on the stiffness, ductility, and energy dissipation capacity of the specimen. • The suggested connection configurations exhibited semi-rigid behavior and full-strength characteristics for non-sway frames. [ABSTRACT FROM AUTHOR]

Shear failure is a brittle type of failures, which should be avoided in any structure as it could cause property loss and human casualties. The shear behavior of thin-walled concrete-filled steel tubular (CFST) columns was hence investigated in this study, involving the tests of 24 thin-walled CFST columns and considering the following parameters: shear span-to-depth ratios = 0.15, 0.3, 0.5, 1, 1.5, and 2; confinement factor = 0.63, 1.27, 1.44, and 1.70; and axial load ratios = 0, 0.2, 0.4, and 0.6. The test results revealed the insights of the initial shear stiffness, failure modes, ultimate bearing capacity, load-deflection curves, load-strain curves, and ductility of the specimens. Based on the failure modes, a method is proposed to evaluate the load resistance, and explain the relationship between the shear span-to-depth ratio and the peak bearing capacity. A compression strut mechanism considering the confinement provided by the steel tube flange is also proposed. The effect of axial load on the shear strength of the concrete core is negligible when the axial load ratio doesn't exceed 0.4. The predicted results from using the proposed simple model agree generally well with the experimental results. • Monotonic tests are conducted to obtain the shear behavior of the thin-walled CFST columns designed with major parameters. • Steel tubes and concrete's contributions to shear capacity are clarified by experimental and analytical results. • The exact effects of some parameters on failure modes and shear capacity are explained based on the experimental data. • The formulas on the shear capacity of the thin-walled CFST columns are proposed based on the compression strut mechanism. [ABSTRACT FROM AUTHOR]

In an ideal flange joint configuration, the fatigue endurance of preloaded bolts is contingent upon factors such as the magnitude of preload, applied working load, and the geometric dimensions of the flange. However, real-world flanged joints often deviate from this ideal geometry, introducing imperfections that can markedly escalate the fatigue burden on bolts. This study endeavors to simulate the geometric imperfections inherent in a standard DN40 flange and ascertain their impact on bolt fatigue through a combination of empirical measurements and finite element (FE) analysis. The investigation reveals that even minor deviations in flange geometry, such as non-parallelism on the order of 0.03 mm, can exert a considerable influence on bolt fatigue, particularly when the flange gap aligns with the applied eccentric working load (same side). To mitigate the deleterious effects of these imperfections, the proposal and evaluation of employing filler material between the flanges are made. Specifically, it is demonstrated that a thin layer of liquid metal filler (KemisKit Fe21), substantially alleviates the fatigue burden on bolts. Empirical findings illustrate that this corrective measure enhances the fatigue life of bolts by a factor of more than 30 under the highest applied working load condition. • Geometrical imperfections of the flange drastically effects bolts fatigue life • The most critical part of the flange joint is the gap located on the load input side • The bolt load can be reduced by using a long – elastic bolt • Adding liquid metal to the joint can significantly increase fatigue life of bolts [ABSTRACT FROM AUTHOR]

A non-bottom mounted baffle is proposed in this paper to overcome the deficiencies of the traditional fixed baffles that can only effectively suppress the sloshing at a specified filling level, not always ensuring that the violent liquid sloshing triggered by the external excitation is prevented from causing damage to the tank structure. Based on a series of numerical experiments, one locally optimal baffle configuration is derived which can largely suppress the liquid sloshing by the synergistic effect of the web plate and bottom flange. Specifically speaking, the free surface is successfully separated into two parts by the web flange, effectively reducing the size of the region where the liquid can move freely in the upper part of the tank. The movement of the bottom flange can efficiently suppress the liquid sloshing by triggering vortex shedding to dissipate the kinetic energy of the fluid and by appropriately disturbing the flow state beneath the free surface to counteract the movement of liquid induced by external excitations. Thus, the maximum anti-sloshing effect can be maintained in most cases even though the filling level is changed, consequently exceeding the performance of various fixed baffles. • New floating baffle is used to efficiently suppress sloshing at any filling level. • Bottom flange limits vertical baffle movement to reduce collision with tank roof. • Three types of physical mechanisms can be identified for floating composite baffle. • Maximum suppression is caused by synergistic effect of web plate and bottom flange. • Second-order sloshing wave component is mainly induced by vertical baffle motion. [ABSTRACT FROM AUTHOR]

In order to solve the problems of complex construction process and long construction period in traditional embedded steel column base, this paper proposes a fully- assembled embedded steel column base joint. Two different constructions forms of specimens, high-strength bolt connection and anchor bolt connection, were designed and subjected to horizontal low cycle reciprocating loading tests to study the impact of different connection structures on their seismic performance.The numerical simulations of the tset was also carried out by using the software ABAQUS. The result shows that both connection structures of the specimens have safe and reliable connection capabilities and good seismic performance. The hysteresis curves and skeleton curves of the two connection forms basically overlap. Under large interlayer displace angles, the use of high-strength bolt connection joint has effectively delayed the stiffness degradation of the column base joint；Compared to the anchor bolt connection, its maximum ultimate bearing capacity has increased by 6.55%. At the same time, high-strength bolt connections can avoid the welding of the anchor bolt gaskets and the flange plate, to achieve green construction. In addition, the anchoring performance of anchor bolt connection is superior to high-strength bolt connection, which is suitable for cases where a small amount of welding is permitted on site. Therefore, two types of joints can be flexibly selected according to the engineering requirements in the actual design. • This paper innovatively proposes a fully-assembled embedded steel column base joint, which can achieve efficient assembly. • This study proposes two different constructive forms for this joints, both of which have good seismic performance. • Using high-strength bolts for connection has better ductility and allows for green construction. • The anchoring performance of anchor bolt connection is superior to high-strength bolt connection. [ABSTRACT FROM AUTHOR]

In this paper, an innovative metallic damper is proposed to improve the behavior of Concentrically Braced Frames (CBFs). Using vertical butterfly-flange plates connected to the two ends of the two rectangular web plates, the main plate provides the strength and stiffness as well as the energy dissipation capacity of the damper. The main plates are covered by boundary and middle plates as secondary plates to support the main plates. The damper is attached directly to the diagonal member of the CBF system. An experimental and numerical as well as parametrical study was carried out to evaluate the behavior of the damper. Experimental results revealed that the damper pertains a suitable hysteresis loops without any degradation in strength and stiffness. Also, numerical results indicated that by increasing the flange plate thickness, the ultimate strength and stiffness are enhanced, respectively, by 1.20 to 2.38 times, and 1.11 to 1.77 times. Likewise, with the flange plate angle of 30 o , the damper achieved the maximum ultimate strength. In the range of ρ < 0.15 , since a large reduction in ultimate strength and stiffness occurred by increasing the ρ , it was recommended to use the damper with ρ ≥ 0.15. Correspondingly, the required equations were presented for analysis, and design of the damper. • An innovative shear damper considering butter-fly flange plates is presented. • Required equations to design and analysis of the damper is proposed. • It pertains to a simple to construct and fabricate. • The geometric impact on the behavior of the damper as a parametric study was carried out. [ABSTRACT FROM AUTHOR]

• A general semi-analytical modeling method of bolted composite conical-conical shells with flanges is proposed. • A bolted joint model considering the non-uniform distribution of interface pressure is proposed. • The accuracy of the proposed modeling method is confirmed through incremental validation using finite element method and experimental testing. • The proposed modeling method can efficiently guide the dynamic design of bolted composite conical shell structures with flanges. This paper proposes a general semi-analytical modeling method of bolted composite conical-conical shells with flanges based on the first-order shear deformation theory. The coupling connections between conical shells and flanges are achieved by using the penalty function method. A bolted joint model that considers the non-uniform distribution of interface pressure is proposed, which can efficiently simulate any number of bolt connections between flanges and boundaries and between flanges and flanges. The correctness and effectiveness of the proposed modeling method are confirmed through step-by-step comparisons with finite element analysis and experimental testing. Then, the influence of various parameters on the frequency trajectories and modal shapes of bolted composite conical-conical shells with flanges is analyzed, with a particular focus on frequency veering and modal coupling vibration behaviors in these structures. The analyses indicate that the proposed modeling method can flexibly adjust structural geometric parameters, material parameters, bolt parameters, fiber layer parameters, and so on, which can efficiently guide the dynamic design of bolted composite conical shell structures with flanges. [ABSTRACT FROM AUTHOR]

The design resistance in shear of thin-walled I-sections has elicited numerous theories over the past decades. While there is a consensus on the post-buckling tension-field action that increases the ultimate resistance of thin webs in shear, the mechanism governing this tension-field action still remains debated. Presently, four constituent components for the shear resistance of I-sections are identified: (1) the resistance of the isolated web subject to a pure shear stress; (2) an increase in the web buckling stress due to flexural restraints provided by the flanges; (3) an increased web post-buckling resistance due to membrane restraint provided by the flanges; and (4) a direct contribution from the flanges to the shear resistance of the I-section. Each of these components is examined through parametric studies using finite element (FE) models analysed within Abaqus that are validated against published experimental results. A new design methodology for the resistance of I-sections in shear is presented, with closed-form expressions developed for each of the four component contributions. When compared with the current approach within EN 1993-1-5, the proposed formulae predict the shear resistance of the cross-section with greater accuracy and consistency. • Flange contributions to ultimate shear resistance of plate girders are identified. • Expressions for predicting flange contributions to shear resistance are presented. • Developed new model for calculating steel I-section girder ultimate shear resistance. • Enhanced predictions are obtained when compared to current EC3 provisions. • A practical worked example of the proposed design model is provided. [ABSTRACT FROM AUTHOR]

• Developed a highly efficient and convenient device for measuring the axial force of magnetic bolts. • Measured the axial force variation and plastic deformation of bolts as the internal pressure increased. • Established an empirical fitting model correlating bolt axial force with contact stress under different internal pressures. • Improved a leakage prediction model based on actual rough sealing surfaces. • Achieved the evaluation of flange sealing status based on bolt axial force. Under high-pressure conditions, flange sealing often fails due to inadequate bolt pre-tension, leading to unstable pressurization or leakage. Assessing the integrity of high-pressure flange sealing presents challenges, constrained by operational conditions, complex equipment integration, and associated costs. This study introduces a method to evaluate flange sealing using magnetic measurements of bolt axial forces. A novel device developed using the magnetoelastic method efficiently and conveniently measures these forces under various internal pressures. The results show a linear relationship between magnetic signals and bolt axial forces at nominal pressures, whereas excessively high pressures cause anomalous changes in magnetic signals, indicative of bolt plastic deformation. Finite element simulation analyzed the changes in bolt axial force and gasket contact stress due to internal pressures, leading to an empirical formula that correlates these variables under varying pressures. The study also explored the impact of uneven pre-tensioning and gasket material on sealing contact stress. A sealing contact surface model, established based on actual roughness profile parameters, enabled the simulation and formulation of an exponential relationship between contact stress and sealing clearance. This foundation facilitated the creation of a leakage prediction model that incorporates bolt axial force parameters, thus enabling a quantitative assessment of flange sealing performance. This research provides a practical approach to evaluating the sealing performance of operational high-pressure flanges. [ABSTRACT FROM AUTHOR]

• A thrust vector control test system with four-point support dynamometer is proposed. • The deflection flange structure is used to realize the large loading of vector force. • Three-way static calibration test of dynamometer was carried out on the test system. • Nonlinear/repeatability error and interphase interference all meet test requirements. The accurate measurement of thrust vector is very important to improve the life and safety of aircraft engine. In order to meet the requirements of thrust vector test of a solid rocket engine and overcome the contradiction between large thrust (>50 kN) and high-frequency response (≫30 Hz)/high precision measurement (<3%), a thrust vector control test system utilizing a four-point support piezoelectric dynamometer (FSPD) and a deflected flange structure was proposed. The test system mainly consists of a four-point support piezoelectric dynamometer and some vector force simulation loading devices. The theoretical mechanical model and the thrust vector control test system was set up to study the performance of solid rocket engine. Firstly, the piezoelectric elements and four-point support piezoelectric dynamometer were calibrated by the three-direction force calibration loading device. Secondly, the rationality and feasibility of the thrust vector control test system were proved by the simulated loading experiment. The research results show that the static and dynamic performance of the test system meet the test requirements, and it has good linearity and repeatability, errors are less than 1.00 %, and interphase interference is less than 2.00 %. The measuring system proposed in this paper provides a new idea for the accurate measurement of vector force with large load and high-frequency response. [ABSTRACT FROM AUTHOR]

The forging of hollow parts faces a great challenge as folding and buckling always occur during the forging process. To overcome these problems, a novel tube forging process combining upsetting and shear forging is developed to manufacture hollow parts with an inner flange at an arbitrary location. Firstly, two flow modes are introduced to analyze the deformation behavior of a hollow cylinder during internal thickening by upsetting, where the geometric limits associated with different deformation modes and the critical upsetting ratio with no folding defects are determined. The results clearly show the occurrence of a mode transition for some cylinders during the upsetting process; furthermore, the cylinder is less prone to folding in some cases due to the appearance of a third deformation zone located mid-way up the cylinder. Then, the forming mechanism of this novel process is analyzed, and its feasibility is demonstrated through finite element simulations and experiments. Results show that the flange can be moved to an arbitrary location on the inner wall in the height direction by controlling the stroke of the punch, and shear deformation can enhance the strength of the flange. Additionally, it is found that the shear depth, corner radius of the counter punch, and supporting force on the counter punch are the key parameters affecting the product quality. [Display omitted] • A new tube forging process combined upsetting and shear forging was proposed. • Two flow modes were introduced to analyze the deformation behavior in upsetting. • The deformation mode and critical folding limits during upsetting were determined. • Deformation characteristics in shear forging process were analyzed. [ABSTRACT FROM AUTHOR]

In this paper, the hydrodynamic performance of the comb-type breakwater-wave energy converter (CTB-WEC) system with a flange was investigated. Based on the linear potential flow theory, a semi-analytical model for wave interaction with the CTB-WEC system equipped with the flange was developed using matching eigenfunction method. In particular, Chebyshev polynomial was adopted to handle the singularity of velocity at the flange edge. Successful validation of the semi-analytical model was achieved by theoretical examination and comparing with the experimental data. The influence of wave resonance behavior in the confined water region (surrounded by caissons and the flange) was emphasized. It was found that: 1) the wave resonance behavior in the confined water region is modified due to the presence of the flange; 2) the hydrodynamic efficiency and wave attenuation performance of the CTB-WEC system is improved by properly configuring the flange; 3) the presence of piston and sloshing mode wave resonance in the gap between the WEC device and the flange led to the increment of hydrodynamic efficiency. • An analytical hydrodynamic model for the CTB-WEC system with a flange is developed. • The amplification of water waves of the CTB can be enhanced due to the presence of a flange. • The flange improves the efficiency and wave attenuation performance of the system significantly. • The piston and sloshing mode of water waves in the gap accompany the increment of efficiency. [ABSTRACT FROM AUTHOR]

This article presents the detailed results of numerical investigation on the structural behaviour of a novel cold-formed steel (CFS) built-up beams composed of four plain channels arranged together as a closed I-beam, under simply supported end conditions. Finite element (FE) models were developed, validated against existing test results published in the literature. The parametric studies were conducted with main variables: (a) aspect ratio (b) thickness (c) compression flange plate slenderness (d) steel grades and (e) width of flange of flange channels. To analyze to effect of selected factors comprehensively, 168 FE models were studied. Additionally, numerical results were compared with the current DSM in the AISI-S100 Specification to observe the accuracy. The evaluation results reveal that the existing DSM is inadequate to predict the flexural capacity accurately of CFS built-up I-beams composed of four plain channels. Finally, suitable design modifications were proposed, which were also capable of having sufficiently realistic predictions of the flexural strength and behaviour of CFS built-up I-beams and the reliability of the design recommendations was confirmed by means of reliability analysis, which aids in predicting sufficiently realistic complex buckling behaviour of CFS built-up I-beams. • CFS built-up I beam composed of four plain channels under four-point bending were investigated. • Extensive FE parametric analysis on critical factors over a wider range was carried out on a validated FE model. • A novel method to determine the elastic critical buckling stress of CFS built-up I beam was proposed. • A new DSM design equation for accurate strength prediction of CFS built-up I beams was proposed • The reliability of the new proposed equation was verified through a reliability analysis. [ABSTRACT FROM AUTHOR]

Web openings facilitate the passage of pipes and enable plastic hinge transfer. However, because these openings reduce the ultimate load at certain values, reinforced flange plates are introduced into the beam–column connections with web openings. In this study, five experimental specimens were constructed and tested, including one base specimen with only web openings, one base specimen with only flange plates, and three specimens with both flange plates and web openings. The failure modes, load–displacement responses, deflection shapes, and deformation capacity were mainly considered. Subsequently, after experimental verification, the thickness and length of the flange plates, as well as the position and diameter of the web openings were studied by numerical simulation. The results indicate that the catenary contribution coefficients and internal energies of the specimens with reinforced flange plates were higher than those of the base specimens. We also concluded that the optimal thickness of the flange plate is equal to that of the beam flange, and the optimal diameter is the maximum web opening that meets the specification requirements. In addition, the mechanical properties gradually increased with an increase the distance a from the web opening to the beam end for a ≤ 190 mm and then decreased for a > 190 mm. • Beam–column connections with flange plates and web openings (FW) are prepared. • The catenary internal energies of FW specimens exceed those of base specimens. • The dimensions of flange plates affect the mechanical properties of FW specimens. • The deformation capacity of FW specimens increases with the web opening diameter. [ABSTRACT FROM AUTHOR]

• A novel general semi-analytical dynamic model for the bolted composite flanged cylindrical-cylindrical shell structure under arbitrary connection conditions is established. • The free vibration characteristics of locally loose structures are emphatically studied. • A spring surface model for the bolted joint and the corresponding parameter determination method based on fractal contact theory is developed. • Plenty of comparisons with the modal test results of the structure under different working conditions fully prove the accuracy of the model. • The influence of the number and degree of loosening bolts on the free vibration characteristics of the structure and the coupling phenomenon between different modes are discussed. The bolted composite coupled cylindrical shell is a common substructure in modern engineering, which may encounter the issue of local loosening conditions during service. Meanwhile, the influence of flanges on the structural vibration characteristics is often overlooked in dynamic numerical analysis. In this paper, a semi-analytical dynamic model for the bolted composite flanged cylindrical-cylindrical shell structure under arbitrary connection conditions is established, and the free vibration characteristics of locally loose structures are emphatically studied. In the model, the annular plate modeling method is developed to achieve the simulation of the flange part. To fully reflect the connection characteristics of the bolted joint, a spring surface model and the corresponding parameter determination method based on fractal contact theory are developed. The equations of motion of the structure are obtained utilizing the Lagrange equations. The accuracy of the model and its predictive ability for the vibration characteristics of the bolted composite flanged cylindrical-cylindrical shell under local loosening conditions are fully demonstrated through numerous comparisons with experimental results from other literature and modal test results obtained under various working conditions. Furthermore, the influence of the number and degree of loosening bolts on the free vibration characteristics of the structure and the coupling phenomenon between different modes are discussed. The research in this paper is expected to provide references for the design of bolted composite flanged cylindrical shell structures and the monitoring of bolt connection defects. [ABSTRACT FROM AUTHOR]

Bolted flanged joints play a crucial role in connecting pressure vessels and piping systems. The corrosion of the flange surface is one of the most common causes of leakage failure in bolted flanged joints. This research investigates the effect of three gasket materials on the corrosion behavior of 321 stainless steel flange material using a novel setup specially designed for corrosion quantification of such assemblies. The results show that graphite gaskets cause more corrosion to flange surfaces under the same working conditions compared to graphite gaskets with metal foil inserts and virgin polytetrafluoroethylene (PTFE) gaskets. The mechanism of flange face corrosion is that, for PTFE gaskets, corrosion propagation mainly occurs at the gasket inner diameter and propagates through the depth of the flange while, for graphite gaskets, corrosion occurs on the whole contact surface of the flange and the gasket. [Display omitted] • A developed test bench is employed to investigate the corrosion behavior of flanges. • Electrochemical techniques are deployed to study flange-gasket interface crevice corrosion. • The effect of three different gasket materials on the flange surface corrosion is investigated. • SEM and laser confocal microscopic images are used to characterize and visualize corroded areas. • Flange face corrosion mechanism is in the presence of gasket and fluid flow is explained. [ABSTRACT FROM AUTHOR]

Simulations on 192 concentrically braced frames with H-section steel (Q355B) are carried out to investigate their low-cycle fatigue performance. The fatigue life of a steel-braced frame is predicted using a multiaxial fatigue damage parametric model. To depict the fatigue failure sequence and the matching relationship of the fatigue life between the two components in the braced frame, the fatigue life ratio (β) is introduced. This ratio represents the gusset plate's fatigue life to the brace's fatigue life. Simulated results are analyzed, and β is found to be positively correlated with four influencing factors, the width-to-thickness ratio of the brace flange, connection coefficient, ratio of the column length to beam length, and slenderness ratio of the gusset plate. Also, β is found to be negatively correlated with the slenderness ratio of the brace. Based on the Bayesian updating method, a probabilistic model is formulated to predict β of a steel-braced frame. Accordingly, a fatigue design method is proposed, which contributes to avoiding the in-coordination of seismic capacity caused by the significant difference between the brace's and gusset plate's fatigue life within the steel braced frame. The proposed fatigue design method has the potential to serve as a reference for improving design specifications. • The low-cycle fatigue behavior of H-shaped steel braced frames is investigated. • The ratio of gusset plate's fatigue life to brace's fatigue life is proposed to represent their matching relationship. • The key influencing factors on the fatigue life ratio are obtained. • A probabilistic model is proposed to predict the fatigue life ratio. • A fatigue design method is proposed to avoid the in-coordination of components' seismic capacity within the braced frame. [ABSTRACT FROM AUTHOR]

Research on the seismic performance of eccentrically braced hybrid frames indicates that utilizing very short links can enhance structural stiffness and load capacity. However, there is limited investigation into their effectiveness within eccentrically braced substructures featuring flush end plate bolted connections. This study involves an experimental and numerical investigation to understand the behavior of very short shear links with flush endplates bolted connections in the substructure. An experimental study of 8 specimens was carried out, and the variables studied included loading protocol, links length ratio, flange thickness, and end plate thickness. The experimental results showed that the co-design methodology for flush endplates and bolts of very short links exhibited acceptable performance. Very short shear links bolted with flush endplates demonstrated an average overstrength coefficient of about 1.8 and an ultimate plastic rotation angle above 0.12 rad. Numerical analysis explored the effects of length ratio, web height-to-thickness ratio, and flange width-to-thickness ratio on overstrength behaviors and yield capacity of very short links. The analysis indicated that the length ratio was crucial in determining overstrength coefficients and the yield capacity of very short links. The study established modified formulas that consider the impact of different variables to more accurately determine overstrength behaviors and yield capacity based on formulas in the Chinese code. • Very short links with flush-end plate in eccentrically braced substructures was tested. • A co-design methodology for flush endplates and bolts was established. • A refined FEA model was developed for seismic performance investigation of very short links. • The overstrength coefficient and ultimate capacity of very short linkswas analyzed in detail. [ABSTRACT FROM AUTHOR]