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• Novel insights into bolted connections to I-section webs and tubular column chords under out-of-plane loads via experimental testing. • Calibration of numerical models with experimental results for improved accuracy. • Extensive analysis of single and double bolt row connections in a parametric study to identify key parameters affecting face plate behavior. • Comparative analysis of existing methods for initial stiffness estimation using parametric analysis data, revealing their limitations. • Proposal of a refined analytical method for initial stiffness prediction, validated by experimental data. This paper presents a comprehensive investigation into the behavior of column webs/faces under out-of-plane loading within steel joints. The experimental component of the study involves testing five profiles, encompassing both open and closed sections with varying web slenderness and steel grade, subjected to direct out-of-plane tensile loads through bolted connections, utilizing both single and double rows of bolts. Concurrently, numerical simulations are conducted using finite element models, thoroughly calibrated with the experimental results. Drawing upon the calibrated numerical models, the paper systematically explores the influence of key parameters, including web slenderness, bolt arrangement, and analysis methods, through a parametric study involving 167 cases. A careful comparison of the observed behavior of the component from experimental tests, numerical models, and analytical models for initial stiffness is presented. Finally, the initial stiffness formulation derived from a recent model developed by the authors is improved to align with the observations from the experimental and numerical results. [ABSTRACT FROM AUTHOR]

• Eight square concrete-filled stainless-clad bimetallic steel tubes are tested. • Two finite element (FE) modelling approaches are developed and validated. • Effects of critical parameters are clarified in depth by verified FE models. • New design methods are proposed. Concrete-filled stainless-clad bimetallic steel tube (CFSCBST) members combines the advantages of excellent corrosion-resistance and good economy compared with conventional concrete-filled steel tube (CFST) members, which has great prospects in engineering application. This paper presents a comprehensive experimental and numerical investigation into the axial compression behaviour of CFSCBST stub columns with square sections. A total of eight specimens was conducted on CFSCBST specimens, incorporating varying width-to-thickness ratios, clad ratios and steel strengths, The experimental investigation provided a detailed report on failure modes, load versus displacement and strain response. The experimental results were utilized in a parallel numerical simulation to validate the finite element (FE) model. Subsequently, an extended parametric analysis was conducted to investigate the influence of the strength of the concrete, the substrate steel grade, the clad ratio, and the width-to-thickness ratio were carried out. The data obtained from tests and numerical studies were used to evaluate the applicability of existing design codes AISC/ANSI 360-22, EN 1994–1-1, GB 50936–2014 and DBJ/T 13-51-2020 for predicting the compressive capacity of square CFSCBST stub columns. Overall, a modified design method was proposed, adapted from DBJ/T 13-51-2020, was proposed for CFSCBST stub columns, demonstrating enhanced accuracy in predictions. [ABSTRACT FROM AUTHOR]

• The effectiveness of thin-walled cellular beams manufactured by RFSSW was developed. • A parameterized finite element model (FEM) of the cellular beam was developed. • Results of numerical simulations and experimental tests were compared. • A parametric FEM model of the cellular beam was developed in the ADINA system. • The numerical model was used to analyze beams with different cross-sections. The paper presents analyses of thin-walled I-beams constructed from 6061-T6 aluminum alloy using refill friction stir spot welding (RFSSW). A parametrized finite element model of the reference cellular beam was developed, and the results from numerical simulations and experiments were compared. Subsequently, the validated numerical model was utilized to conduct an in-depth analysis of three additional beams featuring distinct cross-sections. To assess the weld behavior, experiments were conducted on samples composed of two sheets connected by two spot welds. The outcomes of these investigations underscore the suitability of RFSSW as a method for constructing thin-walled structures in civil engineering applications. [ABSTRACT FROM AUTHOR]

• The flexural buckling behaviour of austenitic stainless steel semi-oval hollow section columns was studied. • Twelve pin-ended column tests were conducted. • FE models were developed to validate against the test results and then adopted to conduct parametric studies. • The codified buckling curves were evaluated and led to an overall good level of design accuracy. Semi-oval hollow section is an innovative cross-section profile and consists of one semi-circular flange, one flat flange and two flat webs. While the semi-circular flange (exposed to fluid or wind) offers a low level of hydrodynamic or aerodynamic drag, the flat elements facilitate connections with other members. The flexural buckling behaviour and resistances of austenitic stainless steel semi-oval hollow section columns are investigated in this paper. An experimental programme was firstly conducted on two austenitic stainless steel semi-oval hollow sections, with six column specimens of varying member lengths adopted for each cross-section, and included tensile coupon tests, initial geometric imperfection measurements and pin-ended column tests. Both 'C'-shaped flexural buckling (with failure specimens bowing towards semi-circular flanges) and 'reverse C'-shaped flexural buckling (with failure specimens bowing towards flat flanges) were observed upon testing. The experimental programme was accompanied by a numerical modelling programme, with finite element models developed to simulate the test results and then adopted to conduct parametric studies to generate further numerical data. On the basis of the test and numerical data, the relevant buckling curves for austenitic stainless steel circular hollow section columns, as provided in the European code, American specification and Australian/New Zealand standard, were evaluated for their applicability to austenitic stainless steel semi-oval hollow section columns. The evaluation results generally revealed that the codified buckling curves led to overall accurate and consistent flexural buckling resistance predictions when used for austenitic stainless steel semi-oval hollow section columns. [ABSTRACT FROM AUTHOR]

• Proper quantification of joint rotational stiffness (JRS) of a flight intersection joint (FIJ) influences the dynamic characteristics of a flight vehicle. • JRS of an FIJ is often determined experimentally due to the lack of a right predictive model. • An analytical model is proposed to evaluate the JRS of a radial-type FIJ when subjected to an external bending moment. • Numerical analyses and experiments are performed on six different FIJ configurations. • JRS and moment-rotation behavior predicted by the proposed model are correlated with both experimental and numerical analyses. • Further, the effect of joint clearances on the behavior of FIJ is investigated through the present model. Joint rotational stiffness (JRS) of a flight intersection joint (FIJ) and its accurate quantification play an essential role in studying the dynamic modal characteristics of a flight vehicle. This JRS of a FIJ is mostly determined through elaborate experiments due to the non-availability of a reliable predictive model. Therefore, in this paper, an analytical model is proposed to evaluate JRS of a radial type FIJ when subjected to external bending moment. In this model, at first, the tensile and compressive part of the FIJ section is identified by determining the neutral axis position. The respective part's contributing stiffness is then estimated by employing a spring-mass model. Later, the JRS expression is derived from the moment equilibrium condition and expressed as a function of the stiffness of the tensile and compressive part and neutral axis position. Subsequently, finite element analysis (FEA) is conducted with different numbers of screws, followed by detailed experimental investigations. The proposed analytical model is validated with the results from FEA and experiments for different screw configurations of FIJ. Further, the proposed model is extended to account for the effect of joint clearances on the JRS and the corresponding moment-rotation characteristics of the FIJ. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents results of a numerical finite element parametric study on elastic shear buckling and ultimate shear strength of cold-formed steel channels with longitudinally stiffened slotted webs. The following parameters were varied: channel height, thickness, flange width, flange lip length, longitudinal stiffener size, perforation pattern, aspect ratio, steel yield stress and boundary conditions. Channels with longitudinally stiffened solid webs subjected to shear load were also studied to provide reference data for comparison with the slotted channels. The parametric study described in this paper allowed us to develop equations for predicting the shear buckling coefficient of longitudinally web stiffened solid channels, as well as equations for predicting the elastic shear buckling load and the ultimate shear strength of channels with longitudinally stiffened slotted webs. The developed shear strength equations without and with tension field action are presented in the paper in the traditional and direct strength method formulations. The developed equations account for the studied parameters and showed good agreements with the finite element simulation results. [ABSTRACT FROM AUTHOR]

In this paper, we compare the failure behaviors of CFRP single and double (S–D) lap joints and analyze the effects of hygrothermal aging on these joints through a comprehensive experiment and simulation. Firstly, we analyze and compare the degradation pattern of the residual strength of S–D​ lap joints under three hygrothermal environments, and reveal the aging mechanism in conjunction with the macro/fine-view failure surfaces of the joints. Secondly, we elucidate the probability distribution of joint aging failure using the two-parameter Weibull distribution. Finally, we develop a finite element model to simulate the failure process of the cohesive behavior, and compare not only the bending moment and contact stress distribution of the two joints, but also analyze the damage condition of the CFRP matrix/fiber. We define environmental degradation factors to express the failure behavior of lap joints after aging. Through the above analysis methods, we find that hygrothermal aging can seriously damage the CFRP and adhesive properties. The mechanical performance of DLJs is significantly superior to that of SLJs, and they also exhibit better reliability. Therefore, DLJs can be substituted for SLJs in some application scenarios. Additionally, our paper provides new insights into the selection of an appropriate lap bonding method. • This paper evaluates the aging durability of single and double lap joints from multiple perspectives. • The failure behavior of single and double lap joints is comprehensively compared by numerical simulations. • This paper provides some new insights into the selection of an appropriate lap bonding method. [ABSTRACT FROM AUTHOR]

Aluminium alloy has recently become popular in New Zealand's construction sector as a sustainable building material. However, in roll-formed aluminium alloy (RFA) channel beams, particularly those having web holes, cripples at points of concentrated or localised loading. In this paper, end-two-flange (ETF) web crippling behaviour of RFA unlipped channels having web holes was investigated using experimental tests, numerical simulations and a deep learning model referred as deep belief network (DBN). A total of 1080 data points was generated to train the DBN, using a finite element (FE) model that was validated using 30 new experimental results reported in this paper. Compared to the test data, the DBN predictions were conservative by around 6%. Using the DBN predictions, a comprehensive parametric study was undertaken which used the validated FE model in order to explore the effects of hole size, hole location, section thickness, and bearing plate on the web crippling strength of RFA channels having web holes. Web crippling strengths obtained from the DBN, tests and finite element analysis (FEA) were utilised to evaluate the performance of current design specifications from the American Iron and Steel Institute (AISI), Australian/New Zealand Standards (AS/NZS 1664; AS/NZS 4600:2018) and Eurocode (CEN 2006, 2007). It is shown that the current design rules are not reliable to predict the web crippling strength of RFA unlipped channels with web holes. As a consequence of the parametric analysis, new web crippling strength and web crippling strength reduction factor formulae for perforated RFA unlipped channels were proposed. A reliability analysis was then conducted, which confirmed that the proposed equations are capable of predicting the ETF web crippling strength of perforated RFA unlipped channels. • ETF web crippling behaviour of roll-formed aluminium alloy channels was studied experimentally and numerically. • Finite element analysis was conducted and validated against test results. • A deep-learning model was developed to predict the web crippling strength. • A parametric study was conducted to investigate the effects of different parameters. • New design equations were proposed for web crippling strength of roll-formed aluminium alloy channels. [ABSTRACT FROM AUTHOR]

This paper presents an experimental test and finite element (FE) study on the ultimate strength of longitudinal X-type plate-to-circular hollow section (CHS) connections reinforced by external ring stiffeners (abbreviated as PCE connections) under in-plane bending moment. Static tests on four large-scale specimens were performed under both symmetrical and anti-symmetrical loadings. Local axial buckling and transverse plastic deformation failures on PCE connections were observed from the test. Further FE analysis reveals that the external ring stiffener can achieve effective strengthening of the connection and the failure modes are affected by the size of the ring. A total of 541 PCE connections with a various range of geometric configurations and chord stress levels were analyzed and the results obtained were transformed into the ultimate strength of “ring models”. Based on the regression analysis of numerical simulation database, the current design equations by JSTA were re-assessed and a set of novel design model has been proposed utilizing the mathematic design model for transverse X-type plate-to-CHS connections by CIDECT design guide. The proposed design model tends to have practical significance by offering a design guideline for the similar connections. [ABSTRACT FROM AUTHOR]

Due to the relatively high degree of complexities involved with water jet spot welding process, the experimental and conventional numerical methods are hardly capable of providing all comprehensive analysis. In present paper, water jet spot welding of copper, brass and aluminum plates has been examined experimentally using a gas-gun. Considering the details of the whole process, numerical modeling of jet formation and interaction between jet and solid surface have been performed, employing the coupled Eulerian-Lagrangian (CEL) approach. In addition, Jonson-Cook damage model has been utilized to predict the damage initiation in solid surfaces. The velocity profiles of jet along axial and radial directions; and also time history of jet are obtained to describe the variation of velocity in different points of jet with time. Results confirm that the presented method has been successful in predicting the behavior of jet during the process, and plate deformation and failure patterns. [ABSTRACT FROM AUTHOR]

The focus of this paper is on a non-cutting, single stroke clinching method that produces an axisymmetric joint. Here, a simple procedure based on testing and calculation of volumes is introduced. This paper also presents the clinching parameters for several tool combinations, based on the proposed procedure, as well as the results obtained by simulating the clinching process for two tool combinations using finite element analysis. The numerical simulation was performed in order to verify the proposed procedure, although both methods can be used either separately or together to establish optimal clinching parameters. Furthermore, the suitability of the analysis software for this kind of simulation and the kinds of problems that can be encountered in this procedure are discussed here. [Copyright &y& Elsevier]

Among the different energy absorption mechanisms, axial splitting/curling is known as an efficient method due to its large stroke to length ratio. This paper presents a finite element model for numerical simulation of splitting of circular brazen tubes. Surface-based cohesive technique is employed for modeling fracture and cracks growth. The required material parameters are extracted from stress-strain diagram of simple tensile test. Some experimental tests were performed to validate the numerical results. For implementation of experimental procedure, the specimens were prepared by cutting the commercial brazen tube and some edge notches were created on one end side of tubes. The specimens were axially compressed between a rigid plate on top and a conical die at the bottom using Zwick universal testing machine. Good agreements were found between numerical simulations and experimental tests. The effects of several parameters such as number and length of initial notches, diameters and thickness of tubes and vertex angle of dies on energy absorption capacity of specimens are investigated, numerically. [ABSTRACT FROM AUTHOR]

In the second part of this investigation, numerical simulations are conducted using nonlinear finite element simulations, to define the bending strength and deformation capacity of large-diameter spiral-welded steel tubes. Under bending loading, the principal failure mode of those tubes is local buckling (wrinkling) of the tube wall, as shown experimentally in the companion paper (Part I) in a series of tests on 42-inch-diameter tubes (Van Es et al., 2015) [1] , and this failure mode is explicitly simulated. Initially, a special-purpose numerical simulation of the cold bending process is conducted to calculate the corresponding residual stresses. Subsequently, a comparison with the test data on 42-inch-diameter tubes reported in Part I is conducted, using the actual material properties and initial geometric imperfections obtained from the tested specimens, as well as the residual stresses computed by the numerical process. Finally, a parametric investigation is performed on the influence of material properties, geometric initial imperfections and residual stresses on local buckling of spiral-welded tubes. [ABSTRACT FROM AUTHOR]

Stiffened plates are the most common structural units used in different structural applications ranging from buildings and bridges to ships and offshore structures. The present paper aiming at investigating the influence of using Y-stiffeners profile instead of conventional stiffeners on the load carrying capacity of ship deck panels under vertical hull girder bending moment. ANSYS (Release 15.0) nonlinear finite element software was used to verify the ultimate strength results obtained from applying the International Association Classification Societies-Common Structural Rules (IACS-CSR) on both conventional and novel deck panels. The developed numerical model with conventional stiffeners profile was validated in a good agreement with a benchmark study results included in the International Ship Structures Committee (ISSC). Furthermore, both analytical and numerical simulation results were in good agreement that demonstrates the capability of using IACS-CSR for designing the new stiffeners profile in practical applications. In comparison with the conventional stiffeners profile, the proposed Y-stiffeners resulted in a considerable increase in the panel safety margin to weight (area) ratio and higher ultimate strength. Moreover, the numerical simulations provided that implementing the Y-stiffeners profile can also rise the first yielding stress point of the structural response with nearly the same strain absorption in comparison with T-stiffeners profile. [ABSTRACT FROM AUTHOR]

Inflatable structures are already being used for decades now especially in aerospace applications. The Inflatoplane and inflatable space habitats are just examples. On the other hand, the modeling and simulation techniques of inflatable structures are lacking far behind. Most of the available models are concerned with cylindrical beams. In this paper, a nonlinear Finite Element model for axisymmetric inflatable structures is developed using beam elements. The model is validated by comparing its predictions to two cases of cylindrical beams in the literature. The model is then utilized to predict the effect of two parameters on the wrinkling load of the beam. Results show that the wrinkling load is proportional to the square root of the inflation pressure. For the beam radius, it is proportional to the cube of the radius at small radii but then the relation is linear afterwards. The model is also used to predict the performance of an inflated truncated cone as a function of the inflation pressure and the root radius. The proposed nonlinear Finite Element model is a step towards analyzing real-life inflatable structures. [ABSTRACT FROM AUTHOR]

This paper presents a computational study to examine lateral impact behavior of pressurized pipelines and to determine influence of internal pressure on the pipelines on their impact behaviors. A total of more than 300 numerical simulations were carried out on mild steel pipe models with different internal pressure levels and were struck at the mid-span and at the one quarter span positions. These numerical simulations of the impact tests were performed using 3D dynamic nonlinear finite element analysis (FEA) through LS-DYNA, where both geometrical and material nonlinearities were considered. The computational results for the first time systematically revealed the effects of internal pressure, impact position, and outside diameter on the lateral impact behavior of the pipeline models. The outcomes of this study will have potential benefits on research of safety and reliability of civil pipelines and development of advanced pipeline materials. [ABSTRACT FROM AUTHOR]

The paper presents 3D results on stability of thin-walled cylindrical metal silos made from isotropic rolled plates containing bulk solids. The behaviour of bulk solids was described with a hypoplastic constitutive model. Non-linear FE analyses with both geometric and material non-linearity were performed with a perfect and an imperfect silo shell wherein 3 different initial geometric imperfections were taken into account. The influence of a stored bulk solid (dry medium-dense cohesionless sand) during filling on the buckling strength of silos was compared with the strength of an empty silo and with the experimental results available in the literature. Our numerical results indicate a clear strengthening effect of the stored solid on the silo buckling strength as in the experiments, depending upon the wall thickness, wall loading way and imperfection type and amplitude. [ABSTRACT FROM AUTHOR]

In practice, there is a wide variety of commercially available channel sections with complex shapes where the web is stiffened by adding longitudinal intermediate stiffeners. These stiffeners may improve the shear capacity of the channels. Recently, the Direct Strength Method (DSM) of design of cold-formed sections has been extended in the North American Specification for Cold-Formed Steel Structural Members (NAS S100:2012) to include shear based on research by the authors. The prequalified sections include flat webs and webs with small intermediate longitudinal stiffeners. To extend the range to larger intermediate stiffeners as occurs in practice, a series of predominantly shear tests of lipped channel sections with one web stiffener of different shapes and various sizes has been performed at the University of Sydney. Six different types of stiffened web channel sections were tested along with an additional reference plain section. All tests were conducted with straps screwed on the top flanges adjacent to the loading points. These straps provide torsion/distortion restraints which may enhance the shear capacities of the sections. The test failures were observed mainly in the combined bending and shear modes. Numerical simulations based on the Finite Element Method (FEM) using the software package ABAQUS/Standard are also performed to compare with and calibrate against the tests. The accurate results from the FEM models allow extension of the test data. Based on the reliable FEM models, a series of FEM modelling of predominantly shear tests for stiffened web channels has been performed without straps attached to the top flanges adjacent to loading points. The test and FEM results are subsequently plotted against the DSM interaction curves between bending and shear where the interaction is found to be significant. An extended range of DSM prequalified sections with longitudinally stiffened web channels in shear is proposed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the numerical simulations of thin-walled square hollow steel beams subjected to a uniform transverse blast load. The objectives of the numerical simulations were to gain an insight into the temporal distribution of the global and local deformation and the adiabatic temperature rise in the beams as a result of impulsive loading. Additionally, the finite element predictions using Ls-Dyna are compared to the experimentally observed global and local deformations. The full lengths of the beams were modelled using three material models based on the linear piecewise plasticity material model which incorporated strain hardening, with and without strain-rate hardening and with strain-rate hardening and temperature softening. The blast wave was simulated as a rectangular pressure pulse distributed over the top surface of the beams. Ls-Dyna and the material model used were found to predict the global and local deformation of the beams reasonably well. Incorporating strain-rate hardening was found to be important to be able to predict the global and local deformation of the beams. Thermal softening was found to play a small but not negligible role. [Copyright &y& Elsevier]

Abstract: Tapered thin-walled tubes have been considered desirable energy absorbers under axial loading due to their relatively stable crush load and deformation response compared with straight tubes. This paper compares the energy absorption response of straight and tapered thin-walled rectangular tubes under quasi-static axial loading, for variations in their wall thickness, taper angle and number of tapered sides. Overall the study highlights the advantages of using tapered tubes as energy absorbers. In particular, the peak load required to crush the tubes decreases with the introduction of a taper, and as the taper angle increases. This is desirable for minimising the impact loads transmitted to the protected structure. The practical outcome of the study is design information for the use of tapered thin-walled rectangular tubes as energy absorbers in impact loading applications. Analysis has been undertaken using a finite element model, validated using existing theoretical and numerical models. [Copyright &y& Elsevier]

Tanks and silos are often designed as ring-stiffened cylindrical shells. Nowadays, the load-increasing effect of closely spaced ring stiffeners under axial compression has received limited attention in research and practice. Considering the structural safety, the ring-stiffened shell needs to be estimated on the conservative side in practice. This is not desirable in terms of modern lightweight steel structures. However, material efficiency is achieved by combining thin plates with ring-stiffeners. In this paper, small specimen experimental series are carried out to calibrate numerical models, which are subsequently used in parameter studies, because the large-scale experiments are cost-intensive and therefore difficult to carry out in the laboratory. The small cylindrical shells are manufactured by welding of two half-cylindrical shells and the ring stiffeners are spot-welded to the cylindrical shell. Geometric dimension of shell specimens is measured by 3D scanning technology. The measured geometric imperfection information is directly imported into the numerical model based on a mapping relationship and the buckling tests are recalculated by means of geometrically and materially nonlinear analysis with imperfection. The results indicate that the buckling resistance calculated by the Finite Element analysis is very close to that of the test results. The initial geometric imperfection is discussed with reference to the Eurocodes design standard. Furthermore, influence of the ring-stiffener parameter, including imperfection amplitude, radius over thickness ratio, geometry of ring stiffener etc., on the buckling load and knockdown factor is discussed based on a large number of parameter study. • Experimental and numerical study of ring-stiffened cylindrical shells presented. • Geometric imperfections of stiffened cylinder were measured and mapped into FE model. • Ring-stiffener can effectively increase the buckling load of cylindrical shells. • High ring parameter for the heavy stiffened cylinder have positive influence. [ABSTRACT FROM AUTHOR]

This paper numerically investigated the effects of manufacturing defects and braiding angle on the impact compressive properties of three-dimensional (3D) carbon fiber/epoxy resin circular braided composite tubes. Based on the realistic geometrical architecture of 3D tubular braided preform, the full-size microstructural finite element analysis (FEA) models of the braided composite tubes with different braiding angles were established for the axial impact compression behavior at the split Hopkinson pressure bar apparatus. The manufacturing defects including fiber breakages and voids in the resin matrix were generated with Monte Carlo method in fiber tows and resin, respectively. The numerical results show the effects of defects in fiber tows and resin on the compressive strength, initial modulus, and failure strain of the braided composite tubes are both dependent on the braiding angle. The random defects have a negative influence on compressive failure mechanisms of the braided tubes. Comparing the failure morphologies of FEA models with experimental results, we found the non-ideal models containing random defects of appropriate content in fiber tows are more accurate than ideal models to simulate the dynamic compressive failure evolution process of 3D braided composite tubes. • The effect of defects on dynamic failure mechanism of three-dimensional (3D) circular braided composite tube was studied. • Fiber breakage defects can cause the initial damage of 3D braided composite tubes. •. Effects of different types of defect on 3D braided composite tubes are both related to the braiding angle. •. Models including defects agree better with experimental results than ideal models. [ABSTRACT FROM AUTHOR]