Mechanical behavior of outer square inner circular concrete-filled dual steel tubular stub columns

Fa-Xing Ding,Wenjun Wang,Xue-mei Liu,Liping Wang,Yi Sun 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.3

The mechanical behavior of the outer square inner circular concrete-filled dual steel tubular (SCCFT) stub columns under axial compression is investigated by means of experimental research, numerical analysis and theoretical investigation. Parameters such as diameter ratio, concrete strength and steel ratio were discussed to identify their influence on the mechanical properties of SCCFT short columns on the basis of the experimental investigation of seven SCCFT short columns. By establishing a finite element model, nonlinear analysis was performed to discuss the longitudinal and transverse stress of the dual steel tubes. The longitudinal stress characteristics of the core and sandwich concrete were also analyzed. Furthermore, the failure sequence was illustrated and the reasonable cross-section composition of SCCFT stub column was proposed. A formula to predict the axial load capacity of SCCFT stub column was advanced and verified by the results from experiment and the finite element.

Behavior of circular thin-walled steel tube confined concrete stub columns

Fa-Xing Ding,Liu Tan,Xuemei Liu,Liping Wang 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.2

This paper presents a combined numerical and theoretical study on the composite action between steel and concrete of circular steel tube confined concrete (STCC) stub columns under axial compressive loading with a full theoretical elasto-plastic model and finite element (FE) model in comparison with experimental results. Based on continuum mechanics, the elasto-plastic model for STCC stub columns was established and the analysis was realized by a FORTRAN program and the three dimensional FE model was developed using ABAQUS. The steel ratio of the circular STCC columns were defined in range of 0.5% to 2% to analyze the composite action between steel tube and concrete, and make a further study on the advantages of the circular STCC columns. By comparing the results using the elasto-plastic methods with the parametric analysis result of FE model, the appropriate friction coefficient between the steel tube and core concrete was defined as 0.4 to 0.6. Based on ultimate balance theory, the formula of ultimate load capacity applying to the circular STCC stub columns was developed.

Study on flexural capacity of simply supported steel-concrete composite beam

Fa-Xing Ding,Jing Liu,Xuemei Liu,Zhi-wu Yu 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.4

This paper investigates the flexural capacity of simply supported steel-concrete composite I beam and box beam under positive bending moment through combined experimental and finite element (FE) modeling. 24 composite beams are included into the experiments and parameters including shear connection degree, transverse reinforcement ratio, section form of girder, diameter of stud and loading way are also considered and investigated. ABAQUS is employed to establish FE models to simulate the behavior of composite beams. The influences of a few key parameters, such as the shear connection degree, stud arrangement, stud diameter, beam length and loading way, on flexural capacity are discussed. In addition, three methods including GB standard, Eurocode 4, and Nie method are also used to estimate the flexural capacity of composite beams and also for comparison with experimental and numerical results. The results indicate that Nie method may provide a better estimation in comparison to other two standards.

Behavior of concrete-filled round-ended steel tubes under bending

Fa-xing Ding,Tao Zhang,Liping Wang,Lei Fu 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.4

The objective of this paper is to investigate the flexural behavior of concrete-filled round-ended steel tubes (CFRTs) under bending. Beam specimens were tested to investigate the mechanical behavior of the CFRTs, including four CFTs with different concrete strengths and steel ratios, and three CFRTs with varied aspect ratios. The load vs. deflection relationships and the failure modes for CFRTs were analyzed in detail. The composite action between the core concrete and steel tube was also discussed and examined based on the experimental results. In addition, ABAQUS program was used to develop the full-scale finite element model and analyze the effect of different parameters on the moment vs. curvature curves of the CFRTs bending about the major and minor axis, respectively. Furthermore, design formulas were proposed to estimate the ultimate moment and the flexural stiffness of the CFRTs, and the simplified theoretical model of the moment vs. curvature curves was also developed. The predicted results showed satisfactory agreement with the experimental and FE results. Finally, the differences of the experimental, FE and predicted results using the existing codes were illustrated.

Flexural stiffness of steel-concrete composite beam under positive moment

Fa-Xing Ding,Jing Liu,Xuemei Liu,Feng-Qi Guo,Li-Zhong Jiang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6

This paper investigates the flexural stiffness of simply supported steel-concrete composite I-beams under positive bending moment through combined experimental, numerical, and different standard methods. 14 composite beams are tested for experimental study and parameters including shear connection degree, transverse and longitudinal reinforcement ratios, loading way are also investigated. ABAQUS is employed to establish finite element (FE) models to simulate the flexural behavior of composite beams. The influences of a few key parameters, such as the shear connection degree, stud arrangement, stud diameter, beam length, loading way, on the flexural stiffness is also studied by parametric study. In addition, three widely used standard methods including GB, AISC, and British standards are used to estimate the flexural stiffness of the composite beams. The results are compared with the experimental and numerical results. The findings have provided comprehensive understanding of the flexural stiffness and the modelling of the composite beams. The results also indicate that GB 50017-2003 could provide better results in comparison to the other standards.

Further analysis on the flexural behavior of concrete-filled round-ended steel tubes

Fa-Xing Ding,Tao Zhang,Liping Wang,Lei Fu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.2

A new form of composite column, concrete-filled round-ended steel tubes (CFRTs), has been proposed as piers or columns in bridges and high-rise building and has great potential to be used in civil engineering. Hence, the objective of this paper presents an experimental and numerical investigation on the flexural behavior of CFRTs through combined experimental results and ABAQUS standard solver. The failure mode was discussed in detail and the specimens all behaved in a very ductile manner. The effect of different parameters, including the steel ratio and aspect ratio, on the flexural behavior of CFRTs was further investigated. Furthermore, the feasibility and accuracy of the numerical method was verified by comparing the FE and experimental results. The moment vs. curvature curves of CFRTs during the loading process were analyzed in detail. The development of the stress and strain distributions in the core concrete and steel tube was investigated based on FE models. The composite action between the core concrete and steel tube was discussed and clarified. In addition, the load transfer mechanism of CFRT under bending was introduced comprehensively. Finally, the predicted ultimate moment according to corresponding designed formula is in good agreement with the experimental results.

Mechanical behaviors of concrete-filled rectangular steel tubular under pure torsion

Fa-Xing Ding,Shi-jing Sheng,Yu-jie Yu,Zhi-wu Yu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.3

Pure torsion loading conditions were not frequently occurred in practical engineering, but the torsional researches were important since it’s the basis of mechanical property researches under complex loading. Then a 3D finite element model with precise material constitutive models was established, and the effectiveness was verified with test data. Parametric studies with varying factors as steel yield strength, concrete strength and sectional height-width ratio, were performed. Internal stress state and the interaction effect between encased steel tube and the core concrete were analyzed. Results indicated that due to the confinement effect between steel tube and core concrete, the torsional strength of CFT columns was greatly improved comparing to plain concrete columns. The steel ratio would greatly influence the torque share between the steel tube and the core concrete. Then the torsional strength calculation formulas for core concrete and the whole CFT column were proposed. The proposed formula could be simpler and easier to use with guaranteed accuracy. Related design codes were more conservative than the proposed formula, but the proposed formula presented more satisfactory agreement with experimental results.

Behavior of headed shear stud connectors subjected to cyclic loading

Fa-xing Ding,Guo-an Yin,Hai-bo Wang,Liping Wang,Qiang Guo 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.6

The objective of this study is to investigate the actual behavior of studs in structures under earthquake load through laboratory tests and numerical simulation. A test program including eighteen specimens was devised with consideration of different concrete strengths and stud diameters. Six of specimens were subjected to monotonically increasing loading while the others were subjected to cyclic loading. Mechanical behavior including the failure mechanism, load-slip relationship, stiffness degradation, energy dissipation and the damage accumulation was obtained from the test results. An accurate numerical model based on the ABAQUS software was developed and validated against the test results. The results obtained from the finite element (FE) model matched well with the experimental results. Furthermore, based on the experimental and numerical data, the design formulas for expressing the skeleton curve were proposed and the simplified hysteretic model of load versus displacement was then established. It is demonstrated that the proposed formulas and simplified hysteretic model have a good match with the test results.

Composite action of notched circular CFT stub columns under axial compression

Fa-Xing Ding,Bing Wen,Xuemei Liu,Hai-bo Wang 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.3

This paper conducted both numerical and theoretical studies to investigate the composite action of notched circular concrete-filled steel tubular (CFT) stub columns under axial compression and established a theoretical method to predict their ultimate bearing capacity. 3D finite element (FE) analysis was conducted to simulate the composite action and the results were in good agreement with experimental results on circular CFT stub columns with differently oriented notches in steel tubes. Parametric study was conducted to understand the effects of different parameters on the mechanical behavior of circular CFT stub columns and also the composite action between the steel tube and the core concrete. Based on the results, a theoretical formula was proposed to calculate the ultimate bearing capacity of notched CFT stub columns under compression with consideration of the composite action between the steel tube and the core concrete.

Confinement coefficient of concrete-filled square stainless steel tubular stub columns

Fa-Xing Ding,Yi-xiang Yin,Liping Wang,Yujie Yu,Liang Luo,Zhi-wu Yu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.4

The objective of this paper is to investigate the confinement coefficient of concrete-filled square stainless steel tubular (CFSSST) stub columns under axial loading. A fine finite 3D solid element model was established, which utilized a constitutive model of stainless steel considering the strain-hardening characteristics and a triaxial plastic-damage constitutive model of concrete with features of the parameter certainty under axial compression. The finite element analysis results revealed that the increased ultimate bearing capacity of CFSSST stub columns compared with their carbon steel counterparts was mainly due to that the composite action of CFSSST stub columns is stronger than that of carbon steel counterparts. A further parametric study was carried out based on the verified model, and it was found that the stress contribution of the stainless steel tube is higher than the carbon steel tube. The stress nephogram was simplified reasonably in accordance with the limit state of core concrete and a theoretical formula was proposed to estimate the ultimate bearing capacity of square CFSSST stub columns using superposition method. The predicted results showed satisfactory agreement with both the experimental and FE results. Finally, the comparisons of the experimental and predicted results using the proposed formula and the existing codes were illustrated.