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Abstract: This paper describes results of a dynamic analysis on partially concrete-filled steel columns, which are used for piers of the motorway viaduct. As a seismic loading the ground motion measured in the main shock and one of the post shocks of Chuetsu earthquake in 2004 are used. These two shocks have different vibration patterns and therefore the influence of the vibration pattern of the seismic load can be investigated. Through the analysis it is found that the main shock, which has smaller ground acceleration than the post shock, causes a larger displacement of the column because the frequency component of the main shock is similar to the natural frequency of the column. [Copyright &y& Elsevier]

With the aim of improving passive safety protection in subway vehicles, this paper investigates a cutting energy-absorbing structure by means of experiment and simulation. The proposed structure comprises a cutting knife, an energy-absorbing tube, and a support tool. The Johnson-Cook material model is used to study the coupled thermal–structural cutting energy-absorbing process, and a finite-element model of the cutting energy-absorbing structure is validated using data from a cutting collision experiment. The sensitivity of each factor is discussed using extreme difference analysis to identify the effects of the cutting depth, cutting width, and cutting knife rake angle on the energy absorbed (EA) and the peak cutting force (PCF). Based on sample points obtained from an optimal Latin-hypercube experimental design, a relationship between the crashworthiness index and the design variables is formulated using polynomial-response-surface and radial-basis-function surrogate models. Through comprehensive error analysis, the most accurate surrogate model is used to optimize the crashworthiness of the structure. The multi-objective particle swarm optimization algorithm is applied to multi-objective optimization to obtain the maximum EA and minimum PCF. The weighting factor plays an important role in selecting the ideal Pareto solution, and the optimal solution is determined using the minimum distance selection method. The results allow us to determine the structure with the best crashworthiness, for which EA = 991 kJ and PCF = 1441 kN. • Present a cutting energy absorption structure for used in subway vehicles. • The coupled thermal–structural method is used to analysis the crashperformance of the cutting absorption energy structure. • The results of simulations are in good agreement with the experimental results. • The multi-objective optimization of cutting energy absorption structure is carried out by two surrogate models. • The MOPSO algorithm is used to obtain the optimal parameters of the cutting energy absorption structure. [ABSTRACT FROM AUTHOR]

Foldcore sandwich structures have aroused considerable research interest in recent years. While foldcores made of metal or composite have been studied extensively, paper-based foldcore are relatively rare. In this paper, we focus on the flat-wise compression properties of foldcore sandwich paperboard with the Miura-ori pattern in the field of packaging and logistics engineering. The flat-wise compression properties and affecting factors of foldcore sandwich paperboard are identified experimentally. Among these factors, the side length ratio (a / b) of the Miura-ori unit significantly influences the deformation mode of the foldcore sandwich paperboard, thus affecting the load-carrying performance and energy-absorption properties. Moreover, the foldcore sandwich paperboard is compared with the conventional corrugated paperboard. The results indicated that although the specific peak stress of foldcore sandwich paperboard and conventional B-flute corrugated paperboard are approximately equal at the same profile angle, the specific energy absorption of the former was 2.06 times higher than the latter. What is more, the specific peak stress and specific energy absorption of the foldcore sandwich paperboard are 1.93 times and 3.24 times higher than those of B-flute corrugated paperboard by merely increasing the sector angle from 60° to 75°. These findings may provide the potential for practical application of paper-based foldcore sandwich panels, thus facilitating the structural design of multilayered cushioning paper pads. [Display omitted] • Flat-wise compression behaviors of paper-based foldcore sandwich structure were experimentally investigated. • Side lengths ratio a/b was the critical factor that affects the deformation mode of the foldcore sandwich paperboard. • Flat-wise compression performance of foldcore sandwich paperboard and conventional corrugated paperboard were compared. • Energy absorption of foldcore sandwich paperboard were 2.06 times higher than corrugated paperboard with same profile angle. • Load-carrying and energy-absorption properties of foldcore sandwich paperboard could be significantly improved with the increase of α. [ABSTRACT FROM AUTHOR]

• Structure design and DOF analysis of deployable unit. • Selection of actuation and identification of deployment continuity. • Surface fitting based on the hexagonal frustum unit. • Dividing analysis of antenna surface and verification of networking feasibility. • Prototype and deployment experiment were conducted to verify the mobility. With the development of space technology, deployable mechanism has been widely applied in large aperture space antennas. In this paper, a hexagonal frustum deployable antenna unit and an innovative modular assembling concept are proposed for large parabolic truss antenna. Screw topology diagram and screw constraint matrix are established to solve degree of freedom (DOF) of the antenna mechanism. By separating column vectors of screw constraint matrix, whole actuations of antenna mechanism are obtained according to unique solution condition. A new hexagon antenna network method based on hexagon frustum units and rotation transformation matrix is proposed, and correctness and efficiency of the modeling principle are proved by simulation. Finally, a prototype of the proposed hexagonal frustum truss deployable antenna mechanism is constructed, and a deployment experiment is conducted, which demonstrate the mobility and deployment performance of the mechanism. The mechanism proposed in this paper provides a theoretical reference for the parabolic truss deployable antenna mechanism, which is potentially valuable in the application of large aperture deployable antennas. [ABSTRACT FROM AUTHOR]

• A kind of laminated acoustic metamaterials for low-frequency broadband ultra-strong sound insulation is proposed. • The parallel coupling of in-plane gradient parameters and the series laminated in the thickness direction achieve bandwidth widening and amplitude improvement. • The working mechanisms of non-uniform mass distribution and non-consistent frame coupling are studied. • The efficient semi-analytical method based on dynamic surface mass density is successfully extended from periodic plate phonon crystal structures to frame-plate-mass type structures. In this paper, a kind of laminated acoustic metamaterials (LAMS), which can realize the bandwidth widening and amplitude improvement through the parallel coupling of in-plane gradient parameters and the series laminated design in the thickness direction of the local resonance units, is proposed. The designed LAMS consists of two different layers of single-layer acoustic metamaterials (SLAMs) laminated in series in the thickness direction. During the design process of the two layers of SLAMs, non-uniform mass distribution and non-consistent frame coupling layouts are respectively introduced to broaden the sound insulation frequency band of the acoustic metamaterials. Through careful design, the two layers of SLAMs have distinct working frequency bands, effectively preventing the occurrence of sound insulation valleys with low amplitude. Based on numerical analysis of two layers of SLAMs, this study discusses the results of transmission loss (TL) and the working mechanism of interlayer superposition coupling sound insulation. The analysis of TL for LAMS reveals its capability to achieve ultra-strong sound insulation effects across a low-frequency broadband range. The accuracy of the numerical analysis in this study is verified through semi-analytical methods and small-scale impedance tube experiments. The LAMS proposed in this paper holds significant potential for wide-band noise reduction control in various high-noise mechanical equipment or workplaces. [ABSTRACT FROM AUTHOR]

• The results of reference literature tests on tubular joints are summarized. • FE models are built and validated against the experiments. • Parametric studies examining a wide range of geometrical properties are performed. • A novel stiffness formulation for T-joints with CHS chord and branch-plate is provided. • A component model for stiffness and plastic strength of joints with CHS column and double-tee beam is suggested and verified. This paper focuses on predicting the flexural stiffness and strength of beam-to-column joints with Circular-Hollow-Section (CHS) columns and externally welded double-tee beams using the Component Method approach. Currently, Eurocode 3 Part 1.8 lacks guidelines for assessing the stiffness of these joints, resulting in their practical modelling using extreme assumptions like pin or full restraint. Nevertheless, the literature demonstrates that these joints can exhibit semi-rigid behaviour due to the relatively high local deformability of the tube in the joint area. Another concern relates to the strength of these joints. In fact, recent studies have shown that Eurocode 3 Part 1.8 formula for predicting the yield resistance of these joints is over-conservative. Within this framework, the purpose of this study is to fill the current knowledge gaps (over-conservative strength prediction and lack of rules for determining the stiffness) by undertaking a thorough investigation involving numerical and analytical activities. Specifically, the research presents a component-based modelling approach for predicting stiffness and strength of CHS to double-tee beam connections. In this regard, the work presented in this paper has involved the selection of experimental tests from literature to validate a Finite Element (FE) model, specifically focusing on X- and T-joints and internal and external beam-to-column joints. The validated numerical models have been then employed to simulate the response under monotonic loading conditions of additional sets comprising forty T-joints and thirty external beam-to-column joints, respectively. The currently available formulations for predicting the resistance of T-joints were applied to the forty cases simulated, evaluating their accuracy. This allowed the individuation of the most accurate literature formula for the strength prediction of T-joints, showing that the recent proposal of Voth and Packer (2012) yields sufficiently accurate results. Instead, analytical formulations for predicting the stiffness of T-joints were properly derived in a closed-form solution and were validated against the results of the parametric study. Finally, drawing upon knowledge regarding the stiffness and strength of T-joints, the flexural response of external beam-to-columns connections was evaluated proposing a component model, whose accuracy was verified against the cases simulated in the parametric analysis. [ABSTRACT FROM AUTHOR]

• The proposed model only places the PD subdomain in the crack initiation region of porous material, which greatly improves the computational efficiency while ensuring the calculation accuracy. • The displacement vector and mass matrix are reconfigured to ensure the calculation consistency in the process of adaptive expansion of the PD subdomains. • The fracture phenomenon of porous materials based on this model is well reproduced and interesting results are obtained. Predicting the dynamic failure process of porous materials is a challenging task due to their complex structure. To minimize the use of time-consuming peridynamic (PD) models and to avoid surface effect issues in the dynamic failure of complex porous materials, this paper proposes a strength-induced PD model. The paper first presents the dynamic formula and relevant finite element discrete equation of the coupled PD and classical continuum mechanics (PD-CCM) model based on the Morphing method. The Morphing function is implemented to control the material parameters and enable the free transformation of PD and CCM models. Based on the coupled PD-CCM model, the strength-induced PD model is established to adaptively expand the PD subdomain in porous materials by controlling the Morphing function value through the strength state of the structure. This model enables the PD subdomain to appear automatically when the porous materials reach the critical stress state. The proposed model accurately predicts the location of crack initiation and path while minimizing computational costs and improving efficiency. Three two-dimensional numerical examples are used to verify the effectiveness, efficiency, and accuracy of the model. The results of the simulation suggest that the location where the crack initiates in the porous materials is strongly influenced by the amplitude of the dynamic load. Cracking is dependent on the pores and typically occurs through them. [ABSTRACT FROM AUTHOR]

• Compressive failure behaviors of stepped-scarf repaired composite honeycomb sandwich panels are analyzed experimentally and numerically. • Progressive failure analysis model, cohesive zone model and sandwich plate theory are utilized in the numerical models. • Failure modes of composite facesheets, adhesive film and honeycomb core are revealed. • Influence of repair parameters on the repair performance of composite honeycomb sandwich panels is investigated. Composite honeycomb sandwich panels (CHSPs) have been widely used in the aerospace industry owing to their lightweight and superior mechanical properties. However, these CHSPs are susceptible to impact damage, leading to a significant reduction in compressive strength and potentially jeopardize aircraft safety. It is crucial to investigate repair methods for CHSPs with impact damage. This paper aims to evaluate the repair performance of CHSPs with impact damage through an analysis of their compressive failure behaviors. To accomplish this, both experimental tests and advanced numerical models are employed. The numerical models for the intact, damaged and stepped-scarf repaired CHSPs are established using the progressive failure analysis model, cohesive zone model and sandwich plate theory. A good agreement is observed between the experimental results and numerical predictions of compressive failure behaviors. Moreover, the validated numerical models are successfully utilized for determining optimum repair parameters by parametric analysis of the repaired CHSPs. The establishment of these numerical models offers an accurate and cost-effective evaluation of repair performance for CHSPs with impact damage, highlighting the novelty and main contribution of this paper. [ABSTRACT FROM AUTHOR]

• CEL approach is employed to simulate the fluid-structure interaction. • CDP model considering the strain rate effect is adopted to this paper. • Damage evolution of prestressed thin-walled aqueducts to UNDEX. • The influence of the prestress on the dynamic response of aqueducts to UNDEX. To solve the problem of regional water resource shortage, water diversion projects have been built around the world. As an essential lifeline project, the prestressed aqueduct is commonly used in cross-regional water transfer and diversion projects. However, the prestressed aqueduct is inclined to damage and collapse under explosion loading due to its thin structure. The main purpose of this paper is to investigate the nonlinear dynamic performance and failure modes of the large prestressed U-shaped thin shell aqueduct to underwater contact explosion. The prestress application approach is validated by theoretical calculations. The reliability of the analysis method of underwater contact explosion for reinforced concrete structures is verified by the underwater contact explosion test. Damage cracking process and nonlinear dynamic response characteristics of prestressed aqueducts to the underwater contact explosion with different explosive weights are performed. Blast resistance performances of prestressed aqueducts are discussed in terms of the crack length, residual displacement, and prestressing force loss. The influence of prestress level on the damage modes of the prestressed aqueduct under the blast loading is discussed. The results indicate that thin-walled U-shaped structures are extremely vulnerable to localized damage from underwater contact explosions. The blast-resistance performance of the U-shaped thin shell aqueduct can be significantly improved by applying prestress. [ABSTRACT FROM AUTHOR]

• Both the uncertainties in elastic modulus and Poisson's ratio are firstly considered. • Multiple materials can be freely allocated during the optimization. • A non-intrusive method is adopted to quantify material uncertainties. • Multi-material structures possess smooth and clear boundaries. Multi-material structures have attracted more and more attention from scholars and engineers, because they usually have good composite performance. Uncertainty factors are ubiquitous in practice, especially for material uncertainties. Multi-material structures contain many materials with different properties, material uncertainties will affect the allocation of material usage, thereby affecting structural performance. Therefore, it is crucial to consider material uncertainties in the design of multi-material structures. This paper detailedly explores the impacts of elastic modulus uncertainty and Poisson's ratio uncertainty on the design of multi-material structures. The topology optimization is to minimize the compliance subjected to a mass constraint, where multiple materials can be freely allocated during the optimization. Floating projection topology optimization is adopted to search for the structural topologies, and robust sensitivity information is derived. For the quantification of material uncertainties, this paper introduces a non-intrusive polynomial chaos expansion (PCE) method to implicitly quantify them, the computational efficiency and accuracy in PCE is compared with the classical Monte Carlo method. Finally, topology optimization examples are provided to demonstrate the effects of elastic modulus uncertainty, Poisson's ratio uncertainty and hybrid uncertainty on the design of multi-material structures. [ABSTRACT FROM AUTHOR]

• The paper investigates rib-based reinforcement strategies for improving structural integrity of form-found shell structures. • The study introduces diverse stiffening patterns for shell structures, designed with geometric, biomimetic, and optimization-derived methodologies. • The paper demonstrates through mechanical testing and numerical simulations that these patterns significantly improve stiffness and buckling resistance of form-found shells. • The study validates that integrating form-finding with targeted rib-based reinforcements can lead to sustainable and structurally resilient solutions. This paper investigates innovative approaches for enhancing the structural integrity of form-found shell structures with a focus on rib-based reinforcements. It discusses the significance of ribs in enhancing stability and addressing the sensitivity of form-found structures to various loads. Traditional methods such as increasing shell thickness or introducing supports often compromise efficiency and aesthetics. A more intelligent approach involves reinforcing the shell with ribs and advanced materials. Diverse rib patterns are presented, including geometric, biomimetic, and topological optimization-inspired designs, each adhering to a 50 % volume constraint, when compared to the original shell. Physical testing and numerical simulations demonstrate that these rib patterns significantly increase stiffness and buckling resistance. The findings presented in the paper suggest that combining form-finding methodologies with well-designed rib patterns can create sustainable and resilient structures, contributing to a reduction in both the consumption of materials and the environmental impact of these structures. [ABSTRACT FROM AUTHOR]

• Cyclic tests on T-joints with CHS chord and passing-through plate are presented. • A FE model of the connection is built and validated against the experiments. • Parametric studies examining a wide range of geometrical properties are performed. • A GA tool is used to fit the simulated data with a phenomenological model. • A model predicting cyclic response from connection geometry is validated. This paper focuses on modelling the cyclic response of welded T-joints between Circular-Hollow-Section (CHS) chords and passing-through plates. Recent works have highlighted that, in practical applications, this specific joint typology can be regarded either as a standalone connection or as a component representing one of the main sources of deformability and energy dissipation capacity in more complex beam-to-column joints with CHS columns and passing-through I-beams. Currently, research efforts have primarily focused on predicting the strength and stiffness of this type of connection. However, there is a knowledge gap regarding the characterization of the cyclic response of joints with passing-through members, a crucial aspect for modelling steel structures with these connection types in seismic areas. In light of this, the paper aims to characterize the cyclic response of T-joints with CHS members and passing-through plates using a comprehensive approach that incorporates experimental, numerical, and analytical methods. Initially, the results of an experimental study examining the cyclic behaviour of T-joint specimens with passing-through plates are presented. Subsequently, models of the tested joints are implemented in Finite Element software and validated against the experimental outcomes. The validated models are used to conduct a parametric study, considering 44 different configurations to obtain their force-displacement cyclic responses. These responses are mathematically modelled using the hysteretic uniaxial material from the OpenSees library and a Genetic Algorithm based tool previously developed by the authors (MultiCal). Finally, regression analyses are performed to develop formulations for predicting the mathematical parameters of the hysteretic uniaxial material model starting directly from the geometrical and mechanical properties of the connection. This approach enables designers to model the cyclic response in structural analysis with a straightforward approach, without the need for new calibrations or tests, if the modelled joints fall within the proposed range of calibration. From the point of view of the component modelling, the approach presented aligns with the larger research strand devoted to the extension of the component method codified in Eurocode 3 part 1.8 to cyclic loading conditions. [ABSTRACT FROM AUTHOR]

Thin films may experience wrinkling instability when two clamped ends are stretched uniaxially. For a fiber-reinforced anisotropic thin film, the wrinkling distributions and evolutions can be significantly affected by the fiber orientation and the anisotropic parameters. In this paper, we study the stretch-induced wrinkling of anisotropic thin films based on a uniformly-valid asymptotic plate equation for anisotropic materials derived from the three-dimensional field equations. A numerical model is established in COMSOL Multiphysics by virtue of the weak form of plate equations and by employing the Holzapfel–Gasser–Ogden model. The effects of fiber orientations and anisotropic parameters on wrinkling evolutions are unraveled from various case studies. In particular, we find that there exists a critical fiber orientation interval where the usual isola-center bifurcation will give way to the pitchfork bifurcation, and the associated amplitude against strain curve presents an N shape. A phase diagram for different bifurcation types is characterized as well. Our numerical model is validated by three-dimensional numerical simulations. It is expected that the results in this paper will offer useful insight into pattern formation in anisotropic soft materials. • The wrinkling responses of anisotropic parameters and fiber orientation are analyzed. • Stretch-induced wrinkling could be an N-shaped pitchfork bifurcation. • A phase diagram for different bifurcation types is provided. • The numerical model is validated by 3D numerical simulations. [ABSTRACT FROM AUTHOR]

• A series of compression tests to investigate member buckling behaviour and ultimate strengths of cold-rolled aluminium alloy channel columns are performed. • The aluminium alloy 5052-H36 materials are used to fabricate the cold-rolled aluminium structural channel columns. • The observed failure modes are flexural, flexural-torsional and local-global interaction buckling failure modes. • The experimental results are compared with predictions by current Australian/New Zealand, North American and European design specifications. Cold-rolled aluminium alloy sections have been recently introduced in Australia as newly developed thin-walled products. To fabricate these sections, the roll-forming process used in cold-formed steel production has been employed, which has proven to be more cost-effective than the conventional extrusion process. This paper describes a series of compression tests to investigate member buckling behaviour and ultimate strengths of cold-rolled aluminium alloy 5052-36 channel columns. Twenty-eight specimens of three commercially available sections (C10030, C25025 and C40030) were tested at the University of Sydney. Two configurations of end boundary conditions were specially designed to capture flexural, flexural-torsional and local-global interaction buckling failure modes. Prior to testing, initial geometric imperfections were measured using a laser scanning method, and flat/corner coupons were tested to determine compressive and tensile strengths of the aluminium alloy material. The experimental results are compared with ultimate column strength predictions by current Australian/New Zealand, North American and European design specifications for aluminium structures. Additionally, the test results provide data for calibration of finite element models of cold-rolled aluminium structural members for use in parametric and similar studies. A companion paper describes such parametric study and the derivation of new design guidelines for member buckling of cold-rolled aluminium channel columns based on the numerical parametric data and the experimental data presented herein. [ABSTRACT FROM AUTHOR]

• Experiments on the member buckling and ultimate strengths of cold-rolled aluminium alloy channel columns are performed. • The aluminium alloy 5052-H36 materials are used to fabricate the cold-rolled aluminium structural channel columns. • Non-linear FE models are developed using ABAQUS to simulate laboratory experiments and calibrated against the test results. • A parametric study based on FE models is performed to extend the data by varying cross-section dimensions and member lengths. • Experimental and numerical results are ued to calibrate the new design equations for cold-rolled aluminium alloy columns. The paper first presents the development of detailed finite element (FE) models for investigating the member capacity of cold-rolled aluminium alloy 5052-36 channel columns. The numerical non-linear FE models are developed using the commercial FE software package ABAQUS to simulate laboratory experiments and calibrated against the test results. The experimental program was performed by the authors at the University of Sydney and the detailed test results are fully described in a companion paper. The calibrated numerical FE models with actual mechanical properties and measured geometric imperfections in analyses accurately predict the experimental results and behaviours, including flexural and flexural-torsional buckling as well as local-global interaction buckling failure modes. A parametric study is subsequently performed to extend the data range by varying cross-section dimensions and member lengths. The effects of loading eccentricity positions and initial geometric imperfections are also considered in the parametric study. The experimental and numerical results are compared with design strength predictions from current Australian/New Zealand, American and European specifications for aluminium structures in the companion paper. In this paper, the Direct Strength Method (DSM) for the design of compression members as per the Australian/New Zealand standard AS/NZS 4600 for cold-formed steel structures is adopted for comparison. The DSM design rules for cold-formed steel compression members are found to provide more accurate predictions than those of current specifications for aluminium structures and therefore used to propose improved design equations for cold-rolled aluminium alloy columns. Finally, a reliability analysis is performed to evaluate the safety level of current design specifications and the proposed design rules. [ABSTRACT FROM AUTHOR]

The paper is devoted to the analysis of the influence of ambient temperature on the linear free and non-linear harmonic vibrations of laminate plates with viscoelastic layers. The Zener fractional material model is adopted. The plate kinematics is described using the refined zig-zag theory. The formulation of vibrations of the plate is based on the physical law with the separation of deviatoric and volumetric deformation. The temperature influence is included using the frequency-temperature superposition principle. The shift factor applied to modify the damping properties of the viscoelastic material is computed using the Willams-Landel-Ferry formula. The paper contains the results of several analyses of laminate plates with various viscoelastic materials for which the material data were available in the literature. In particular, the analyses focus on determination of the properties characteristic for the plates with Zener fractional model under the influence of the ambient temperature. • Frequency-temperature superposition for temperature influence on plates vibrations • Refined zig-zag theory applied to define the plate kinematics • Fractional Zener material with separated volumetric and deviatoric deformation • Numerous analyses of various viscoelastic materials • Explanation of non-monotonous character of temperature effects on damping [ABSTRACT FROM AUTHOR]

• Phononic crystals, elastic metamaterials, ABHs and elastic metasurfaces are considered. • The principles of suppressing vibration and sound radiation by these artificial structures are introduced. • The advances in suppressing vibration and sound radiation by wave manipulation are reviewed. • The further works of suppressing vibration and sound radiation by wave manipulation are prospected. The newly generated artificial structures, including phononic crystals, elastic metamaterials, acoustic black holes (ABHs) and elastic metasurfaces, can abnormally control wave propagations. In this paper, focusing on plate structures and from the perspective of the suppression of vibration and especially sound radiation by manipulating flexural waves, we give a thorough review of the advances of above-mentioned artificial structures, involving their extraordinary characteristics, corresponding mechanisms of vibration and sound radiation suppression, design methods of phase-gradient elastic metasurfaces, and some representative works on suppressing vibration and sound radiation of plates by flexural wave manipulations. Additionally, we compare the advantages and disadvantages of these artificial structures in vibration and sound radiation suppression. Finally, we look forward to the prospects on vibration and sound radiation suppression of plates based on wave manipulations. This paper will provide a timely and practical assistance to academic and technical researchers in the field of vibration and noise reduction. [ABSTRACT FROM AUTHOR]

• Twelve rack-to-spine-bracing shear connections were experimentally investigated. • Comprehensive test data were generated using digital image correlation technique. • A component-based analytical model is established for the shear connections. • Three-dimensional behavior of individual components are analytically determined. • Design and construction recommendations for the shear connections are provided. High-rise steel storage racks are cold-formed thin-walled steel frames, which achieve their lateral strength and stiffness by the use of a spine bracing system in the down-aisle direction commonly located at a short horizontal distance away from the main rack frames. The shear connections between the main rack frame and the spine bracing system play a dominant role in the effectiveness of the spine bracing system. This paper experimentally investigates the behavior of the shear connections used in industrial practice between a steel storage rack and the spine bracing system with posts using four groups of three nominally identical connection specimens. By employing a digital image correlation (DIC) system, the tests generate comprehensive data and establish the real-time deformation fields of individual components of such shear connections. Based on the component-based approach, a linear-elastic analytical model is developed for the type of shear connections under consideration. The proposed analytical model explicitly captures the behavior of the individual connection components, including the three-dimensional flexural bending of endplates, as well as the distortions of the open sections of the upright and the bracing post. Based on the proposed model, this paper quantifies the contribution of each component towards the total deformation of the shear connections. The investigation establishes that the cross-sectional distortion of the bracing post and the out-of-plane bending of the upright web are the most flexible components of such shear connections. Recommendations associated with the shear connections under consideration are proposed for the rack designers and manufacturers. [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]

• Experimental tests of CFDSST columns is presented in detail in this paper. • Using ABAQUS, 3D finite element CFFSST column models under axial compression are developed. • The fundamental behaviour of the CFDSST columns is discussed in detail. • The feasibility of current design codes to design the CFDSST columns is evaluated. • The proposed design model is shown to predict well the strengths of CFDSST columns. This paper explores the performance of concrete-filled double-skin (square stiffened hollow sections (SHS) outer and circular hollow sections (CHS) inner) steel tubular (CFDSST) stub columns under axial compression through experimental research and finite element analysis. The static axial compression experiments of six concrete-filled stiffened steel tubular (CFST) stub columns and fifteen CFDSST stub columns were conducted. The test method, process, phenomena and results are introduced in detail. The results indicated that compared with conventional CFST stub columns, CFDSST stub columns with reasonable hollow ratio can maintain load-carrying capacity, increase ductility and reduce self-weight. Increasing the strength of concrete is the most effective way to increase the load-carrying capacities of specimens when other variables remain constant. Finite element (FE) software was then utilised to generate the models of current specimens. The simulation results showed reasonableness and accuracy compared to the experimental results. Based on the validated models, parameter analysis was performed to reveal the influence of concrete strength, width-to-thickness ratio of the outer steel tube, stiffener depth, hollow ratio and yield strength of the outer steel tube on the ultimate strengths of the specimens. In addition, compared with test and FE strengths, the ultimate strengths predicted by available international codes were found to be quite conservative. Consequently, a formula was proposed to predict the load-carrying capacity of CFDSST stub columns considering the effective cross-sectional areas of the outer steel tubes and the strength of the confined concrete. The formula has been shown to provide the best prediction with acceptable reliability. [ABSTRACT FROM AUTHOR]

• The paper deals with ultimate of thin-walled, open cross section PC beams. • An approach to determine the interaction diagrams for axial force, bending and torsion is suggested. • The limits of this method are described. • Some examples show the effectiveness of this approach. Thin-walled, open cross section PC (prestressed concrete) beams are widely used in precast structures. Nevertheless, the analytical computation of their load carrying capacity under bending and torsion is still an unsolved problem. This is because of the markedly non-linear behaviour of both steel and concrete and of the asymmetry of the behaviour of concrete in tension and compression. This involves a search for the correct solution from a physical point of view (among those mathematically admissible) based on trial-and-error methods of numerical analysis. This paper suggests a method to evaluate the interaction diagrams under bending and torsion. According to this method the solving system is made by two equilibrium plus two compatibility equations. Some examples show the outcomes of this approach. [ABSTRACT FROM AUTHOR]

• A vertically oriented double corrugated steel plate shear wall is proposed. • The elastic buckling behavior of the wall is affected by the bolt spacing. • The compressive and shear stability coefficients are established. • The stability of the wall affects the correlation curve of N/N u - V / V u. As a novel structural component, the Double Corrugated Steel Plate Shear Wall (DCSPSW) is formed by interlocking two corrugated steel plates using high-strength bolts. This paper investigates the global stability design methods for DCSPSWs under combined shear and compression loads. Firstly, this paper examines the elastic buckling performance of DCSPSWs under horizontal shear loads and vertical compression loads separately. A bolt spacing factor (η) is introduced to reflect the influence of bolt spacing on the elastic buckling stress of DCSPSWs. Then, based on extensive finite element analysis (FEA), this paper investigates the elastoplastic buckling behavior of DCSPSWs under shear loads and compression loads and establishes the corresponding stability curves to predict ultimate load-bearing capacity. It is found that the stability coefficients (φ s and φ c) are closely related to the normalized slenderness ratios (λ ns and λ nc). A smaller bolt spacing allows the DCSPSWs to exhibit improved elastic and elastoplastic stability. Finally, this study investigates the load-bearing performance of DCSPSWs under combined shear and compression loads and proposes the design formulas. The results show that the correlation curve of N / N u - V / V u can provide a conservative and accurate design. The research findings of this paper are advantageous for promoting the application of the innovative DCSPSWs. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel combined rivet structure, including a conventional tubular outer rivet and an inner rivet with an outer flange, is proposed. • The effect of new rivet structure on strength improvement and its underlying mechanism is studied. • The joint failure behavior and failure modes of in DSSPR process using the combined rivets are analyzed. Double-sided self-pierce riveting (DSSPR) has great application potential in joining the same or dissimilar sheets due to its simplified die structure, high joining efficiency, and smooth joint surface. Previous studies have shown that changing rivet parameters, such as chamfered angle position, can improve joining strength, but the improvement effect is still relatively limited. In this paper, to significantly enhance the joining strength, a novel combined rivet structure was proposed and used in the DSSPR process of Al5052 sheets, and its effect on strength improvement and the underlying mechanism were investigated. Morphological change, strain, and stress distribution of the combined rivets during the joining process were investigated through experiments and numerical simulations. Tensile shear tests were conducted to compare the shear strength of the combined rivets and conventional rivets. Moreover, the failure behaviors of joints including macroscopic failure mode and microscopic surface morphology were analyzed, and the mechanism for combined rivets to enhance the joining strength was illustrated. Results showed that adopting the new combined rivets can significantly improve joint strength. Compared with a single conventional tubular rivet, the tensile shear strength and energy absorption of combined rivets can increase by up to 91% and 261%, respectively. Two types of failure modes were discovered according to the failure behaviors of sheets, which were characterized by the detachment of rivets and the tearing characteristics of the sheet. This paper provides a new approach for the rivet design and joining strength improvement strategy for the DSSPR process. [Display omitted] [ABSTRACT FROM AUTHOR]

• The low-restraint GLARE is taken as a research object and its deformation characteristics and failure mode are studied using uniaxial tensile, bending experiments and numerical simulation in this paper. • Based on experimental observations, it is found that the low-restraint GLARE produces the phenomenon of interlayer slip, and the interlaminar residual stress is much smaller than the cured laminate, whereas the deformation limit and performance are improved. • The results of bending experiments revealed that the load variation of low-restraint laminate is significantly different from the cured laminate during bending. • The low-restraint GLARE does not obviously delaminate and fracture during bending due to the low interlayer residual stress and a certain degree of interlayer slipping, exhibiting a significant improvement in the bending forming limit. • This paper provides theoretical bases for the in-depth analysis of deformation properties and forming laws of low-restraint GLARE, guiding further applications of laminates. Fiber metal laminates (FMLs) possess a better weight reduction effect than traditional metal materials due to the coupling properties of heterogeneous materials, showing promise in the areas of aviation and aerospace. At present, the research on FMLs mainly focuses on the deformation properties after curing while the mechanical properties in the low-restraint state, i.e. the laminates are temporarily not cured and are formed under lower constraint stresses, are not studied in detail. Herein, the low-restraint GLARE is taken as a research object and its deformation characteristics and failure mode are studied using uniaxial tensile, bending experiments and numerical simulation in this paper. Moreover, the influence of key parameters, such as temperature, laminate structure and span length, is investigated, as well as the tensile and bending deformation behavior of GLARE in a low-restraint state is obtained. In addition, based on experimental observations, it is found that the low-restraint GLARE produces the phenomenon of interlayer slip, and the interlaminar residual stress is much smaller than the cured laminate, whereas the deformation limit and performance are improved. This paper provides theoretical bases for the in-depth analysis of deformation properties and forming laws of low-restraint GLARE, guiding further applications of laminates. [ABSTRACT FROM AUTHOR]

• Contact explosion tests were conducted on the corrugated steel-plain concrete plates. • Compared the dynamic response of corrugated steel-plain concrete composite structures under varying TNT charges. • The blast resistance of corrugated reinforced concrete slabs with different shear connectors arrangements was analyzed. • An engineering collapse coefficient Kz was established to predict the failure level of the CSPC composite slabs. This paper investigates the dynamic response and blast resistance of corrugated steel-plain concrete (CSPC) composite structures subjected to contact blast. A series of explosive tests were conducted to investigate the acceleration, deformation, and damage patterns of CSPC plates under varying blast loads and arrangements of shear connectors, and these findings were compared with reinforced concrete (RC) plates. The results suggested that CSPC plates exhibited superior ductility and blast resistance, and effectively mitigated concrete collapse. The CSPC slab primarily underwent elastic deformation when the TNT charge was small, with the rebound deformation of the concrete and steel plates acting as a significant mode of energy dissipation. As for larger TNT charges, the maximum deformation of the plate progressively increased, especially when exceeding 0.3 kg, the deformation rebound ratio decreased significantly, and the plastic deformation increased. For further increased explosive loads, the concrete and steel plates exhibited a pronounced strain rate effect with a slowed growth rate of deformation. By examining different configurations of shear connectors, it was discovered that the adhesive strength between concrete and steel plates was closely related to the energy dissipation mode, and the elastic recovery capability and deformation resistance of the CSPC structure significantly deteriorated when the shear connectors were shorter, sparser or thinner. A numerical model based on LS-DYNA was designed to further analyze the blast resistance characteristics of CSPC plates. An engineering collapse coefficient Kz was established to predict the failure level of the CSPC plates. This paper provides useful insights for the optimal design and damage assessment of CSPC composite structures. [ABSTRACT FROM AUTHOR]

• The results of more than 4 000 non-linear shell F.E. computations are presented, detailed and analysed. • Prior to the numerical parametric studies, the numerical models were validated against test data on full-scale specimens, as detailed in the companion paper. • Various parameters such as the base cross-section profile, the bending moment distribution, the size and position of the openings, the steel grade and member slenderness have been studied. • Besides, a dedicated design model is presented. Systematic comparisons with the results of software ACB+, which is by far the most highly used tool in design practice, are described. • A significantly improved performance of the proposed design approach in terms of accuracy, consistency and reliability is demonstrated. The present paper investigates the lateral torsional buckling resistance of cellular steel beams numerically. Such beams are quite sensitive to lateral instability owing to a substantial increase in depth of the cross-section with respect to the base profile. While a companion paper was dedicated to (i) characterising experimentally the behaviour of cellular and Angelina beams and to (ii) validating dedicated non-linear shell F.E. models, this paper details the results of extensive numerical studies. Several key parameters in the structural response are investigated, such as the base cross-section profile, bending moment distribution, size and position of the openings, steel grade and member slenderness. The results have further been used to assess an original design proposal for the lateral torsional buckling resistance of such girders. The improved design rules are shown to provide accurate yet safe ultimate load predictions. Also, in comparison with existing and available design rules, the proposal is seen to allow for substantially higher design loads – still safe-sided –, potentially leading to significant material savings. [ABSTRACT FROM AUTHOR]

Abstract As the design methodology of the corrugated steel shear wall (CSSW) has not yet been included in the design standards, this paper presents a step-by-step design procedure based on the corrugated panel-frame interaction (CPFI). To ensure that the plastic hinges occur at the beam ends and not within the beam span or in the columns, a reduced beam section (RBS) connection was used in steel plate shear walls (SPSWs). In this paper, the corrugated steel shear wall with a reduced boundary beam section (RBS-CSSW) is presented as a promising type of lateral-load‐resisting system. Analytical equations were proposed to estimate the strength of RBS-CSSW based on the frame plastic hinge development considering the interactive shear buckling stress in the corrugated panel. The equations of strength estimation for RBS-CSSW were also evaluated by comparing their results with the numerical results of the two models. The comparison showed that the strength based on the proposed analytical equations were accurate (with more than 95% accuracy) compared to the strength from the FE pushover analyses for the two models. Highlights • The step-by-step design guideline based on the corrugated panel-frame interaction is proposed. • The implementation of the reduced beam section with corrugated plate is investigated. • The strength equation for corrugated steel shear walls with reduced beam section is proposed. • The computational finite element analysis shows the proposed equations has 95% accuracy. [ABSTRACT FROM AUTHOR]

• This paper studies the overall topology and the arrangements of the cables and struts for the conical cable dome in detailed. • This paper gives a simplified method for calculating feasible prestress of the components. • This paper introduces prestress and energy uniformity index to evaluate the structural mechanical properties. • The single-criterion and multi-criterion optimization based on the genetic algorithm is used to enhance the uniformity of the feasible prestress and the load-bearing capacity. The conical cable dome with a rotating cone and zero Gaussian curvature is a new type of cable dome with the generatrix that follows a straight line. The paper studies the prestress design and mechanical properties of such cable domes. First, on the basis of the section and vertical diagrams of the proposed cone, a simplified method is developed to calculate feasible prestresses of cables and struts using the principle of nodal balance. Second, prestress distribution, load-bearing capacity, and prestress of the conical cable domes with 15 different combinations of rise-span ratio and inner triangular slope under both prestress and load states are studied. Additionally, the paper proposes five load conditions to assess the performance of the conical cable domes. Finally, the total strain energy, basic frequency, radial reaction, and gravity are optimized through single-criterion and multi-criterion based on the combination of a genetic algorithm and the Newton iteration method. To keep the outer appearance of the conical cable dome, the work selects the strut length as the optimization variable. An optimized conical cable dome is recommended with a low prestress uniformity index and high uniformity index. The results indicate that the conical cable dome is sensitive to the asymmetrical loads, especially the wind loads. For the single-criterion optimization, the structure with the basic frequency under loads as the objective function has the best load-bearing capacity. After optimization, the maximum nodal displacement is 32% and 43% of the original one under LC4 and LC5. Besides, to get a synthetic optimization result, a multi-criterion optimization is suggested. [ABSTRACT FROM AUTHOR]

• This paper reviews investigations on energy absorption and dynamic response of sandwich structures over the past few decades. • The impact loading includes low-velocity impact, explosive loading as well as ballistic impact. • Core configurations of sandwich structures include metal foam and polymer foam, ungraded and graded honeycomb, auxetic honeycomb and foam inserted honeycomb, corrugated core and foam inserted corrugated core, truss core, undrilled and drilled I-core, and Y-shaped core. • The excellent characteristics concerning load resistance and energy absorption of sandwich structures can guide their application in engineering practice. With the swift advancement of aerospace, shipbuilding and engineering, the significance of sandwich structures with cellular cores is becoming increasingly prominent due to their multi-functional and lightweight attributes. In addition, impact loadings are very common in the engineering practice and may potentially cause significant adverse impact on products and equipment. Emerging manufacturing technologies facilitate the fabrication of high quality sandwich plates with improved stiffness and strength to withstand impact loadings. Therefore, extensive investigations have been conducted on sandwich structures under various impact loadings. This paper provides a comprehensive review of the valuable experimental, analytical, and numerical investigations conducted on the dynamic response of sandwich structures spanning several decades. The paper aims to reveal the underlying deformation mechanisms governing the response of sandwich structures subject to impact loadings. The focus is primarily on popular sandwich structures, such as beams, plates, and curved plates, under low-velocity impact, blast loading, and ballistic impact. Various core configurations of sandwich structures are explored, including metal and polymer foams, uniform and graded honeycombs, auxetic honeycombs, foam inserted honeycombs, corrugated core and foam inserted corrugated core, truss core, undrilled and drilled I-core, chiral core, star-shaped core and Y-shaped core. Current challenges and recommendations for future work have also been articulated. [ABSTRACT FROM AUTHOR]

• A new analysis model of the cylindrical shell with dynamic vibration absorbers has been established in the current research. • Fast convergence, high accuracy and reliability of the model presented in the current research have been proved. • The efficiency of equivalent mass solution is greatly improved through the mathematical model proposed in the current research. • Cylindrical shell and dynamic vibration absorbers with different parameters can be achieved only by changing geometry parameters in self-made program, which does not need reconstructing the model. • We discover that when the antinodes of different vibration modes of the cylindrical shell coincide, multiple resonance peaks can be controlled simultaneously by placing a single dynamic vibration absorption at the coinciding point. Dynamic vibration absorber is efficient in controlling low frequency vibration of cylindrical shell, which is meaningful for engineering practice. However, the efficiency of designing dynamic vibration absorber using traditional method is low. This paper demonstrates a semi-analytical method for designing dynamic vibration absorber of cylindrical shell. The convergence analysis presented in the research proves the accuracy of the current method when handling different edge constraints through limited truncation numbers. Additionaly, forced vibration and control of multi-line spectrum vibration of cylindrical shell have also been studied. The comparison between FEM and current method shows a significant improvement when handling equivalent mass, which is a key process when designing dynamic vibration absorbers. Finally, an intriguing relationship is discovered when controlling multiple resonance peaks through a single dynamic vibration absorber. The semi-analytical method described in this paper may be beneficial when controlling the vibration of cylindrical shell structures in the further research. [ABSTRACT FROM AUTHOR]

• Proposed an innovative active hydroforming & curing hybrid method to manufacture complex thin-walled FML structures. • The new method enhances the formability of thin-walled FMLs and enable the forming and curing in a single step. • The new method increases the ultimate stress by 10 % and reduces the curing deformation from 3.1 mm to 1.3 mm. • Four typical defects during forming of thin-walled FMLs have been characterized and analyzed. • Influence of key parameters on forming accuracy has been discussed. Fiber Metal Laminates (FMLs) are preferable thin-walled structures in several fields for their exceptional mechanical properties. However, how to manufacture thin-walled FMLs structures with complex shapes and guarantee the high mechanical properties is still a challenge. To address these, this paper proposes an innovative hybrid forming method, referred to as active warm hydroforming and curing, to enhance the formability and performance of FMLs in GLARE form by combining the forming and curing process into a single step. The hybrid method was verified on a box-shaped part as a proof-of-concept to assess the feasibility and parameter influence. Online curing was utilized to enhance efficiency and quality. The outcomes revealed that the new method increases the ultimate tensile stress by 12.1 % and reduces curing deformation from 3.1 mm to 1.3 mm compared to the vacuum bagging method. Furthermore, the critical parameters in forming of thin-walled structures, including blank holder force (BHF), pressure rate (PR), maximum pressure (MP), and forming temperature (FT), were identified using experimental, mathematical, and numerical approaches. Four defects in the formed thin-walled structures were observed and successfully eliminated through the control of these parameters. The method and results presented in this paper also provide direct guidance for optimizing the process parameters of FMLs warm hydroforming. [ABSTRACT FROM AUTHOR]