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This study presents enhancements made to traditional aluminum alloy gusset (AAG) joints, including the integration of a central stiffening (CS) system, an inter-panel stiffening (IS) system, and a peripheral stiffening (PS) system. Three sets of tests on a full-scale specimen are conducted to investigate the improved AAG joint's axial stiffness, in-plane and out-of-plane bending stiffness, as well as ultimate load-bearing capacity. Nonlinear refined finite element models (FEMs) are established and validated through experimental results. Theoretical mechanical models are developed by integrating experiments and FEMs. These models elucidate the contribution of the stiffening systems to the joint's mechanical performance. The CS system is proven to significantly assist in load transfer, particularly in out-of-plane bending conditions. The IS system enhances overall inter-panel integrity, especially during the plastic deformation phase under out-of-plane bending moments. The PS system improves joint stiffness by participating in load transmission under both axial load and in-plane bending moments. Compared to traditional AAG joints, the combined effects of the three stiffening systems enhance overall structural integrity, stiffness, and load-bearing capacity. This enables the full utilization of component material properties and provides excellent ductility before failure occurs. • A theoretical model of an improved aluminum alloy gusset joint was developed. • FEM and mechanical model alignment were achieved, validated by full-scale tests. • Three loading phases in directions confirmed joint enhancements in mechanical model. • Stiffening systems optimized load transfer, increasing joint stiffness and capacity. [ABSTRACT FROM AUTHOR]

For free-form structures with a single layer envelope, the node is subjected to axial load, as well as moment. The purpose of this paper is to develop and evaluate a new hollow spherical connector, termed the FREE (Flexible, Resilient, Efficient, Economic) node, for single layer free-form spatial envelopes. Reducing material and efficient shape are important points in the space structure node. Therefore, hollow spherical node sections with different holes were proposed and finite element analysis was performed, to determine the prototype among these parameters. The parameters are the size and shape of the hollow sphere. Bending experiments were also performed, to evaluate the structural capacities of the proposed node; and the corresponding test results were compared with finite element analysis. As a result, it may be said the proposed FREE node satisfied the required capacities. [ABSTRACT FROM AUTHOR]

T-stubs are generally used to represent the tension zone of bolted moment resisting connections. The bolts are considered at present as components loaded only in tension. This paper investigates the influence of the bolt bending on the behavior of the T-stubs. A 3D finite element model was first developed and validated by comparison with experimental results found in the literature. The numerical model was then used to analyse the behavior of various T-stubs regarding mainly the values of the axial tensile forces and the bending moments in the bolts. The results show the influence of the bolt bending moment on the failure mode of some T-stubs. The numerical model was also used to evaluate the accuracy of the analytical interaction formula determining the resistance of isolated bolts subjected to bending moment and axial tensile force. Finally, an analytical model is proposed to evaluate the bending moments and the axial tensile forces in the bolts considered as T-stub components. The comparisons with the numerical model results show that the analytical model represents well the behavior of T-stubs considering the bending moments in the bolts. [ABSTRACT FROM AUTHOR]

• Tests and numerical analysis of specimens with large width-thickness ratios. • Elastic-plastic local buckling and its effects on hysteretic behaviour of beam-columns. • Design formula for bearing capacity of Q690 high strength beam-columns. To evaluate local buckling and its effect on the hysteretic performance of high-strength Q690 thin-walled H-section beam-columns, cyclic testing was carried out on four H-section columns composed of plates with a nominal yield strength of 690 MPa. Based on China's standard for the design of steel structures (GB 50010-2017), the four H-section columns are categorized as S4 and S5 sections, and the axial load ratio of the columns is 0.2 and 0.35. After the test, the failure mode, second-order effect of bending moment, hysteresis curve, bearing capacity, backbone curve, energy dissipation, ductility and stiffness degradation of the specimens were investigated. The failure mode of the specimens is elastic–plastic local buckling of the column bottom flange and web. The ductility coefficient of the specimens is 2.08–3.04, and they have certain specific deformation and energy dissipation capacities. Following this, a finite element model was established to simulate the hysteretic performance of the Q690 thin-walled H-section beam-columns. The failure mode and hysteresis curve obtained by the finite element simulation corresponded well with the tests. Based on this agreement, a parametric study was carried out to investigate the influence of the flange width-thickness ratio, web width-thickness ratio, and axial load ratio on the local buckling and hysteretic performance of H-section beam-columns. The variation trend of the backbone curve and the bearing capacity were further investigated by the finite element parametric analysis. Finally, a prediction formula for the beam-column bearing capacity was proposed based on the finite element results. The comparison with the test results shows that the proposed formula has sufficient accuracy and can be used in engineering design. [ABSTRACT FROM AUTHOR]

Abstract: This work investigates the capability of two different fiber beam–column finite elements in simulating the dynamic response of a shear wall tested on a shaking table. The two elements account for the axial force-bending moment interaction in a comparable way. The first element can be considered as representative of a class of elements widely available to design engineers for nonlinear (either static or dynamic) analyses. The second element is more refined (and complex) and is specifically derived to reproduce the shear–flexure interaction. The specimen under study is one of the two 5-story, 1/3rd-scale, reinforced concrete (R/C) shear walls, which was subjected to a sequence of accelerograms during the CAMUS I program. The wall was designed according to the French code PS92 and is representative of large lightly reinforced walls, as defined in the Eurocode 8 standard. The measured response is used to assess the benefits and limitations of all the proposed structural models and the adopted finite element formulations; the relevant effects of shear in the response of the specimen are addressed and discussed. Important recommendations on the use of fiber beam–column elements for studying existing R/C structures, which do not comply with the flexure dominated paradigm of walls in the most recent code specifications, are provided. [Copyright &y& Elsevier]

Abstract: The purpose of this research is to examine the behaviour of elliptical concrete-filled steel tubular stub columns under a combination of axial force and bending moment. Most of the research carried out to date involving concrete-filled steel sections has focussed on circular and rectangular tubes, with each shape exhibiting distinct behaviour. The degree of concrete confinement provided by the hollow section wall has been studied under pure compression but remains ambiguous for combined compressive and bending loads, with no current design provision for this loading combination. To explore the structural behaviour, laboratory tests were carried out using eight stub columns of two different tube wall thicknesses and applying axial compression under various eccentricities. Moment-rotation relationships were produced for each specimen to establish the influence of cross-section dimension and axis of bending on overall response. Full 3D finite element models were developed, comparing the effect of different material constitutive models, until good agreement was found. Finally, analytical interaction curves were generated assuming plastic behaviour and compared with the experimental and finite element results. Ground work provided from these tests paves the way for the development of future design guidelines on the member level. [Copyright &y& Elsevier]

Abstract: Steel caging is an effective, economical, easily applied and widely used method of strengthening RC columns. Based on the results of two experimental studies, this paper proposes the finite element modelling of RC columns strengthened by a steel cage under axial loads and bending moments. The FE models were used to obtain the N-M diagrams of experimental cases in which a study was made of the improved resistance of RC columns strengthened with this type of strengthening technique. The paper also includes a comparison of different methods of connecting the cage around the beam–column joint and a parametric study to observe the influence of diverse parameters on the behaviour of the strengthened column, including: angle dimensions, number of strips, the yield stress of the steel used in the strengthening, the dimensions of the capitals at both ends of the column, concrete strength and the characteristics of the reinforcement used in the columns. Finally, the results of the various tests (experimental and numerical) described in the paper are used to be compared with three design proposals and the goodness of fit of each one is analysed. [Copyright &y& Elsevier]