scholarly journals Experimental Study of Square CFST Stub Columns With a Low Steel Ratio Under Axial Loading

2021 ◽  
Vol 8 ◽  
Author(s):  
Deren Lu ◽  
Yongzhi Gong ◽  
Faxing Ding ◽  
Liping Wang ◽  
Chao Deng ◽  
...  
Keyword(s):  
Numerical Study ◽  
Axial Loading ◽  
Steel Tube ◽  
Confinement Effect ◽  
Experimental Results ◽  
Practical Calculation ◽  
Cross Sectional ◽  
Steel Ratio ◽  
Ultimate Load Carrying Capacity ◽  
Stub Columns

This paper presents an experimental and numerical study on large dimension concrete-filled square low steel ratio steel tubular (CFST) stub columns under axial loading. Four specimens were designed to investigate the effects of steel ratio on the confinement effect of square CFST stub columns with a low steel ratio. ABAQUS was used to establish 3D finite element (FE) models for simulation of square CFST stub columns with a low steel ratio under axial loading. Furthermore, based on the experimental verification, the definition of the confinement index (ϕ = fsAs/(fcAc)) was discussed and the effect of the grade of concrete and steel tube was also investigated. With the same cross-sectional dimensions, the confinement effect of the square CFST stub columns with a low steel ratio (less than 0.05) was better than the others. The stub columns with the yield strength of steel tube fs = 235 MPa (345, 420 MPa) and compressive cubic strength of concrete fcu = 40 MPa (60, 80 MPa) can give fully demonstrate the material performance and reflect the better confinement effect. Based on the experimental results and FE modeling, a practical calculation formula for the ultimate load-carrying capacity of square CFST stub columns with a low steel ratio was proposed. The formula calculation results presented in this paper show good agreement with the experimental results. Compared with the existing formulas, the proposed formula has better precision.

Numerical Study on Concrete Filled GFRP-Steel Tube under Cyclic Loading

2011 ◽  
Vol 368-373 ◽  
pp. 1003-1009
Author(s):  
Chun Yang Zhu ◽  
Ying Hua Zhao ◽  
Dong Sheng Wang
Keyword(s):  
Energy Dissipation ◽  
Axial Compression ◽  
Numerical Study ◽  
Element Model ◽  
Steel Tube ◽  
Cross Sectional ◽  
Static Test ◽  
Steel Ratio ◽  
Energy Dissipation Capacity ◽  
Tube Structure

For the purpose of investigating the strengthening effectiveness of GFRP on concrete filled steel tube structure under combined seismic loading and comparing with CFRP ones, numerical simulations of quasi-static test are developed by using ABAQUS. The establishment of finite element model is tested to be feasible by comparing the numerical load-displacement hysteretic curves and their skeleton curves with the experimental ones. Further studies are carried out through changing models’ FRP (GFRP/CFRP) thickness, axial compression ratio and cross sectional steel ratio. Simulation results show that specimens with thicker FRP (GFRP/CFRP) equip better energy dissipation capacity and higher bearing capacity. In elastic-plastic stage the stiffness of specimen degradation becomes more serious as axial compression increases. Energy dissipation capacity is enhanced as cross sectional steel ratio increases.

Experimental Study on the Axial Loading Tests of RC Columns Strengthened with Steel Tube

2012 ◽  
Vol 204-208 ◽  
pp. 2878-2882 ◽  
Author(s):  
Miao Zhou ◽  
Jian Wei Li ◽  
Jing Min Duan
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Axial Loading ◽  
Steel Tube ◽  
Experimental Results ◽  
Engineering Practice ◽  
Rc Columns ◽  
Short Columns ◽  
Loading Tests ◽  
Engineering Staff

This paper carries out a series of experimental study on 6 column specimens, analyses and compares with the different parameters on the axial loading tests of RC columns and RC columns strengthened with steel tube. The experimental results show that the RC columns strengthened with steel tube take full advantage of loading properties of both materials, thus greatly improve the bearing capacity of specimens. With the same wall thickness steel tube, the improving degree of bearing capacity of long columns is bigger than the short columns, and the reinforcement effect is more obvious. The experimental results can offer reference for scientific research and engineering staff, and promote this reinforcement method to be widely used in engineering practice.

scholarly journals Experimental Study and Direct Strength Method for Cold-Formed Steel Built-Up I-Sectional Columns under Axial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Xingyou Yao
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Numerical Study ◽  
Experimental Results ◽  
Distortional Buckling ◽  
Cross Sectional ◽  
Direct Strength Method ◽  
Comparison Results ◽  
Cold Formed Steel ◽  
Interactive Buckling

The objective of this paper is to investigate the buckling behavior and design method of the ultimate strength for the cold-formed steel (CFS) built-up I-sectional columns under axial compression which failed in distortional buckling and interactive buckling. A total of 56 CFS built-up I-sectional columns subjected to axial compression were tested, and the different buckling modes and ultimate strengths were analyzed in detail by varying the thickness, the length, the spacing of screws, the end fastener group, and the cross-sectional dimensions of CFS built-up I-sectional columns. It was shown in the test that noticeable interaction of local and distortional buckling or interaction of local, distortional, and global buckling was observed for the built-up I-sectional columns with different lengths and cross-sectional dimensions. A finite element model (FEM) was developed and validated with experimental results. A further parametric study has been conducted including different cross sections and slenderness ratios for the built-up I-sectional columns. The load-carrying capacities obtained from the experimental and numerical study were used to investigate the feasibility of the current direct strength method (DSM) when DSM was applied to CFS built-up I-sectional columns. The comparison results showed that the current DSM is not safe for CFS built-up columns failed in distortional buckling and interactive buckling. Therefore, the improved design formulas were proposed, and their accuracy was verified by using finite element analysis (FEA) and experimental results of CFS built-up I-sectional columns subjected to axial compression.

Research on Machanical Behavior of T-Shaped Concrete-Filled Steel Tubular Stub Columns with Steel Bone

2013 ◽  
Vol 639-640 ◽  
pp. 1077-1082
Author(s):  
Kai Lin Ju ◽  
Qiu Sheng Li ◽  
Guo Feng Du ◽  
Yi Li
Keyword(s):  
Local Buckling ◽  
Steel Tube ◽  
Experimental Results ◽  
Concrete Core ◽  
Concrete Filled Steel Tube ◽  
Tubular Columns ◽  
Calculation Results ◽  
New Type ◽  
Stub Columns ◽  
Tube Structure

Concrete-filled steel tube structure is one of the important load-bearing systems of modern high-rise building.The research indicate that concrete-filled steel tube structure has a good static and seismic performance,and concrete-filled steel tubular component is always used as axial compression and compression-bending component.However,what about the mechanical behavior of this combinational structure (concrete-filled steel tubular columns with steel bone built-in)? So there is a new type of special-shaped cross-section of composite structure,that is the T-shaped concrete-filled steel tubular columns with steel bone.The research about this structure is less throughout domestic and foreign.So the axial compressive experiments of six T-shaped concrete-filled steel tubular stub columns, five with and one without steel bone, were carried out. The effects of tube confining factor, bone indicator on the axial compressive behavior of the columns are analyzed. Experimental results indicate that the ultimate strength of the T-shaped steel tubular stub columns with steel bone increases, can be increased by 71.7%.And that the setting of steel bone improves the confinement of the concrete core, delays or even avoids the local buckling of the steel tube before the stress attains the yield strength. The ductility of the columns is also greatly increased.And at last in this paper, use of static equilibrium conditions and limit yield conditions,and in reference to literature[1],the calculation equation of compression capacity of this combinational column is derived.Moreover,calculation results according to the formula in this paper are in good agreement with the experimental results. The conclusions might be used as reference to structural design and plan.

scholarly journals Behaviour of Shear Connector in CFST for Axial Strength

2021 ◽  
Vol 9 (VI) ◽  
pp. 3349-3366
Keyword(s):  
Numerical Study ◽  
Cost Savings ◽  
Axial Loading ◽  
Steel Structures ◽  
High Strength ◽  
Structural Diversity ◽  
Steel Tube ◽  
Component Part ◽  
Concrete Filled Steel Tube ◽  
The Impact

Concrete Filled Steel structures (CFST) offers wide benefits like high strength, ductility, and energy absorption with the combined benefits of steels and concrete. It also reduces the complexity of the production, as it does not require the shuttering of work, and so it is not commonly used. In addition to CFST elements, are more efficient, and allow for rapid construction and cost savings due to the elimination of the shape and material of component part. Concrete-filled-steel-tube is currently gaining more and more popularity in the construction industry. Concrete-filled-steel-tube it is a component of a good performance, as a result of the impact of the steel and holds it with concrete, and the question of structural diversity. In this paper, it presents a study of the evolution of the load carrying capacity, used for the connection of a variety of sizes and shapes, with a different position. The composite action of steel and concrete there is a need for a strong bond between the steel and concrete interface. Analysis of CFST column using the Finite element method and the numerical study is done on the selected case under axial loading condition.

scholarly journals Numerical Study on Confinement Effect and Efficiency of Concentrically Loaded RACFRST Stub Columns

2021 ◽  
Vol 8 ◽  
Author(s):  
Yicen Liu ◽  
Fei Lyu ◽  
Faxing Ding ◽  
En Wang ◽  
Yunlong Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Confinement Effect ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Superposition Method ◽  
Aggregate Concrete ◽  
Stub Columns

The mechanical behaviors of recycled aggregate concrete (RAC) are upgraded by outer steel tube confinement, and the performance of recycled aggregate concrete-filled steel tubular (RACFST) columns is similar to that of the traditional concrete-filled steel tube (CFST) columns. The purpose of this study is to investigate the behaviors of recycled aggregate concrete-filled rectangular steel tubular (RACFRST) stub columns under axial loading. Three-dimensional finite element (FE) models were established, which utilized a triaxial plastic-damage constitutive RAC model considering the replacement ratio of recycled aggregates. The finite element analysis results indicated that the lessened ultimate bearing capacity of RACFRST stub columns compared with their traditional concrete infilled counterparts was mainly due to the weakened confinement effect and confinement efficiency. A simplified formula of the bearing capacity of concentrically loaded RACFRST stub columns was proposed. The cross-sectional stress nephogram was reasonably simplified by the limited state of infilled concrete. The basics of proposed formula were the equilibrium condition and the superposition method. Finally, the formula for the bearing capacity of RACFRST stub columns was evaluated by comparing its accuracy and feasibility to some design formulae proposed by specialists and some design codes of different regions.

scholarly journals Axial Loading Behaviour of Self-Compacting Concrete-Filled Thin-Walled Steel Tubular Stub Columns

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Yunyang Wang ◽  
Lei Xiao ◽  
Chu Jiang ◽  
Yandong Jia ◽  
Guang Yang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Ultimate Load ◽  
Local Buckling ◽  
Axial Loading ◽  
Steel Tube ◽  
Self Compacting Concrete ◽  
Steel Tubes ◽  
Thin Walled ◽  
Stub Columns ◽  
Versus Strain

This paper presents an experimental investigation on the mechanical behaviour of self-compacting concrete-filled thin-walled steel tubular (SCCFTST) stub columns loaded in axial compression to failure. Four specimens were tested to study the effect of diameter to wall thickness (D/t) ratios on the ultimate load, failure modes, and ductility of the columns. Confinement of the steel tube to concrete was also addressed. The failure modes, load versus displacement curves, and load versus strain curves were examined in detail. The experimental results showed that the ultimate state is reached when severe local buckling and rupture occurred on the steel tubes, and the concrete near the rupture has been crushed. The columns with larger D/t ratios appeared more local buckling, and its location is more close to the end of the columns. The SCCFTST stub columns with smaller D/t ratios show higher ultimate load and better ductility, and the steel tubes can exert higher confinement to the concrete.

scholarly journals Explicit Simulation of Circular CFST Stub Columns with External Steel Confinement under Axial Compression

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 23 ◽  
Author(s):  
Faesal Alatshan ◽  
Siti Aminah Osman ◽  
Fidelis Mashiri ◽  
Roszilah Hamid
Keyword(s):  
Failure Modes ◽  
Axial Loading ◽  
Steel Tube ◽  
Fe Model ◽  
Explicit Finite Element ◽  
Steel Ratio ◽  
Short Columns ◽  
Early Loading ◽  
Experimental Findings ◽  
The Impact

Concrete-filled steel tube (CFST) structural members have been widely used in engineering projects for their superior strength and ductility. However, the different lateral dilation characteristics between concrete infill and steel tube have caused imperfect composite interaction during the early loading stage. To overcome this issue, external steel confinements in the form of rings and spiral were previously suggested to minimise the lateral expansion of the steel tube and enhance the concrete confinement effects. This study presented the analytical behaviour of circular CFST short columns with an external ring or spiral confinements which are subjected to axial loading. An explicit finite element (FE) model was developed and verified based on previous experimental findings. Besides that, this study analysed the failure modes, axial load–strain relationship, stress distributions, and bond strength of the composite column components. Parametric analysis was also undertaken to evaluate the impact of material strengths, total steel ratio, and diameter-to-thickness ratio. The results suggest that the use of external steel confinement can enhance the compressive behaviour of CFSTs better than increasing the thickness of the steel tube when using the same steel ratio. Finally, simplified design formulations were developed to accurately calculate the ultimate capacity of CFST columns with and without external steel confinement.

scholarly journals Tests of Inclined Concrete-Filled Steel Tubular Stub Columns under Vertical Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Chayanon Hansapinyo ◽  
Chinnapat Buachart ◽  
Preeda Chaimahawan
Keyword(s):  
Cyclic Loading ◽  
Local Buckling ◽  
Steel Tube ◽  
Cyclic Behavior ◽  
Cross Sectional ◽  
Tubular Columns ◽  
Steel Column ◽  
Inclination Angles ◽  
Inclined Angle ◽  
Stub Columns

This paper presents an experimental study on the cyclic behavior of fifteen concrete-filled steel tubular columns subjected to vertical cyclic loading. All test samples’ cross-sectional area is 75 × 75 mm2square, and they are 500 mm long. The main variables in the test are the thickness of the steel tube (1.8 and 3.0 mm with the width-to-thickness ratios (b/t) of 41.7 and 25), the strength of the infilled concrete (no-fill, 23 MPa, and 42 MPa), and the inclined angle (0, 4, and 9 degrees). The results show that all samples failed due to local buckling in compression followed by tearing of the steel tube in tension. The inclination angles of 4 and 9 degrees decreased the vertical compressive capacity of the 1.8 mm vertical hollowed steel column by 34 and 39 percent, respectively. However, the infilled concrete and thicker tube (3.0 mm) could substantially reduce the adverse effect of the inclination angle. The compressive ductility of the hollowed column with the thinner tube was significantly enhanced by the infilled concrete as well.

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