• Steel and Composite Structures
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• v.4 no.2
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• pp.113-132
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• 2004

Double skin composite element (DSCE) is a novel form of construction comprising two skins of profiled steel sheeting with an infill of concrete. DSCEs are thought to be applicable as shear or core walls in a building where they can resist in-plane loads. In this paper, the behaviour of DSCE subjected to combined bending and shear deformation is described. Small-scale model tests on DSCEs manufactured from micro-concrete and very thin sheeting were conducted to investigate the flexural and shear behaviour along with analytical analysis. The model tests provided information on the strength, stiffness, strain conditions and failure modes of DSCEs. Detailed development of analytical models for strength and stiffness and their performance validation by model tests are presented.

• Steel and Composite Structures
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• v.27 no.1
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• pp.123-133
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• 2018

Steel-concrete-steel (SCS) sandwich composite structure with corrugated-strip connectors (CSC) has the potential to be used in buildings and offshore structures. In this structure, CSCs are used to bond steel face plates and concrete. To overcome executive problems, in the proposed system by the authors, shear connectors are one end welded as double skin composites. Hence, this system double skin with corrugated-strip connectors (DSCS) is named. In this paper, finite element model (FEM) of push-out test was presented for the basic component of DSCS. ABAQUS/Explicit solver in ABAQUS was used due to the geometrical complexity of the model, especially in the interaction of the shear connectors with concrete. In order that the explicit analysis has a quasi-static behavior with a proper approximation, the kinetic energy (ALLKE) did not exceed 5% to 10% of the internal energy (ALLIE) using mass-scaling. The FE analysis (FEA) was validated against those from the push-out tests in the previous work of the authors published in this journal. By comparing load-slip curves and failure modes, FEMs with suitable analysis speed were consistent with test results.

• Steel and Composite Structures
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• v.37 no.5
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• pp.533-549
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• 2020

Recently, Concrete-filled double skin steel tubular (CFDST) columns have proven an exceptional structural resistance in terms of strength, stiffness, and ductility. However, the resistance of these column members can be severely affected by the type of loading in which bending stresses increase in direct proportion with axial load and eccentricity value. This paper presents a non-linear finite element based modeling approach that studies the behavior of slender CFDST columns under biaxial loading. Finite element models were calibrated based on the outcomes of experimental work done by other researchers. Results from simulations of slender CFDST columns under axial loading eccentric in one direction showed good agreement with the experimental response. The calibrated models are expanded to a total of thirty models that studies the behavior of slender CFDST columns under combined compression and biaxial bending. The influences of parameters that are usually found in practice are taken into consideration in this paper, namely, eccentricity-to-diameter (e/D) ratios, slenderness ratios, diameter-to-thickness (D/t) ratios, and steel contribution ratios. Finally, an analytical study based on current code provisions is conducted. It is concluded that South African national standards (2011) provided the most accurate results contrasted with the Eurocode 4 (2004) and American Institute of Steel Construction (2016) that are found to be conservative. Accordingly, correction factors are proposed to the current design guidelines to provide more satisfactory results.

• Steel and Composite Structures
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• v.22 no.5
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• pp.1141-1162
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• 2016

Concrete-filled double skin steel tube (CFDST) beam-columns are widely used in industrial plants, subways, high-rise buildings and arch bridges. The CFDST columns have the same advantages as traditional CFT members. Moreover, they have lighter weight, higher bending stiffness, better cyclic performance, and have higher fire resistance capacities than their CFT counterparts. The scope of this study is to develop finite element models that can predict accepted capacities of double skin concrete-filled tube columns under the combined effect of axial and bending actions. The analysis results were studied to determine the distribution of stresses among the different components and the effect of the concrete core on the outer and inner steel tube. The developed models are first verified against the available experimental data. Accordingly, an extensive parametric study was performed considering different key factors including load eccentricity, slenderness ratio, concrete compressive strength, and steel tube yield strength. The results of the performed parametric study are intended to supplement the experimental research and examine the accuracy of the available design formulas.

• Steel and Composite Structures
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• v.47 no.5
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• pp.645-661
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• 2023

Concrete-filled steel tubular columns with double inner steel tubes (CFST-DIST) are a novel type of composite members developed from conventional concrete-filled steel tubular (CFST) columns. This paper investigates the structural performance of circular CFST-DIST stub columns using nonlinear finite element (FE) analysis. A numerical model was developed and verified against existing experimental test results. The validated model was then used to compare circular CFST-DIST stub columns' behavior with their concrete-filled double skin steel tubular (CFDST) and CFST counterparts. A parametric study was performed to ascertain the effects of geometric and material properties on the axial performance of CFST-DISTs. The FE results and the available test data were used to assess the accuracy of the European and American design regulations in predicting the axial compressive capacity of circular CFST-DIST stub columns. Finally, a new design model was recommended for estimating the compressive capacity of CFST-DISTs. Results clarified that circular CFST-DIST columns had the advantages of their CFST counterparts but with better ductility and strength-to-weight ratio. Besides, the investigated design codes led to conservative predictions of the compressive capacity of circular CFST-DIST columns.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.287-299
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• 2023

This article describes experimental and numerical analyses of eccentrically loaded over the axially loaded circular concrete filled double-skinned steel tubular (CFDST) short columns. Tests on circular CFDST short columns under eccentric and concentric loading were conducted to assess their responses to the frequent intensity of 5-30 mm at the interval of each 5 mm eccentric loading conditions with constant cross-sectional proportions and width-to-thickness ratios of the outside and internal tubes. The non-linear finite-element analysis of circular CFDST short columns of eccentrically loaded over the axially loaded was performed using the ABAQUS to predict the structural behavior and compare the concentric loading capacity over the various eccentric loading conditions. The comparison outcomes show that the axial compressive strength of the circular CDFST short columns was 2.38-32.86%, lesser than the concentrically loaded short column with the inner circular section. Also, the influence of computer simulation employed is more efficient in forecasting the experimentally examined performance of circular CFDST stub columns.

• Steel and Composite Structures
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• v.39 no.2
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• pp.201-213
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• 2021

Currently, there is a lack of research in the design approach to avoid column wall failure in the concrete filled double skin steel tubular (CFDST) column-beam connections. In this paper, a finite element model has been developed and verified by available experimental data to analyze the failure mechanism of CFDST column-beam connections. Various finite element models with different column hollow ratios (χ) were established. The simulation result revealed that with increasing χ the failure mode gradually changed from yielding of end plate, to local failure of the column wall. Detailed parametric analyses were performed to study the failure mechanism of column wall for the CFDST column-beam connection, in which the strength of sandwiched concrete and steel tube and thickness of steel tube were incorporated. An analytical model was proposed to predict the moment resistance of the assembled connection considering the failure of column wall. The simulation results indicate that the proposed analytical model can provided a conservative prediction of the moment resistance. Finally, an upper bound value of χ was recommend to avoid column wall failure for CFDST column-beam connections.

• Steel and Composite Structures
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• v.42 no.3
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• pp.325-351
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• 2022

This paper studies the lateral impact behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled double-skin steel tubular (UHPFRCFDST) columns. The impact force, midspan deflection, and strain histories were recorded. Based on the test results, the influences of drop height, axial load, concrete type, and steel tube wall thickness on the impact resistance of UHPFRCFDST members were analyzed. LS-DYNA software was used to establish a finite element (FE) model of UHPFRC filled steel tubular members. The failure modes and histories of impact force and midspan deflection of specimens were obtained. The simulation results were compared to the test results, which demonstrated the accuracy of the finite element analysis (FEA) model. Finally, the effects of the steel tube thickness, impact energy, type of concrete and impact indenter shape, and void ratio on the lateral impact performances of the UHPFRCFDST columns were analyzed.

• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.89-98
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• 2013

In recent years steel-concrete composite shear walls have been widely used in enormous high-rise buildings. Due to high strength and ductility, enhanced stiffness, stable cycle characteristics and large energy absorption, such walls can be adopted in the auxiliary building; surrounding the reactor containment structure of nuclear power plants to resist lateral forces induced by heavy winds and severe earthquakes. This paper demonstrates a set of nonlinear numerical studies on I-shaped composite steel-concrete shear walls of the nuclear power plants subjected to reverse cyclic loading. A three-dimensional finite element model is developed using ABAQUS by emphasizing on constitutive material modeling and element type to represent the real physical behavior of complex shear wall structures. The analysis escalates with parametric variation in steel thickness sandwiching the stipulated amount of concrete panels. Modeling details of structural components, contact conditions between steel and concrete, associated boundary conditions and constitutive relationships for the cyclic loading are explained. Later, the load versus displacement curves, peak load and ultimate strength values, hysteretic characteristics and deflection profiles are verified with experimental data. The convergence of the numerical outcomes has been discussed to conclude the remarks.

• Composites Research
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• v.26 no.4
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• pp.259-264
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• 2013

This study manufactured the radiating element of multi-band antenna skin structure which satisfy electrical and mechanical performance and is made by double injection molding process. Structural test including impact and buckling test is carried out and stress analysis is simulated to evaluate safety of radiating element for the axial and shear loads, when changing of the skin structure is occurred by the external force. To predict allowable load of structure and evaluate safety on impact and buckling, experimental and analytic method is used in strength analysis of structure.