scholarly journals Structural Performance Evaluation of CFT Columns with Built-up Square-shaped Steel Tubes using Production Methods

2020 ◽  
Vol 20 (6) ◽  
pp. 39-46
Author(s):  
U Seok Kim ◽  
Sang Seup Kim ◽  
Sung Bae Kim ◽  
Young Han Choi
Keyword(s):  
Compression Test ◽  
Maximum Load ◽  
Steel Tube ◽  
Structural Performance ◽  
Test Results ◽  
Steel Tubes ◽  
Production Methods ◽  
Steel Bar ◽  
Main Variable

This study obtained compression test results and macro examination results for concrete-filled steel tube (CFT) columns with built-up square-shaped steel tubes to evaluate both the structural performance and the possibility of using the current CFT design for changes in production methods. The CFT columns have three variables, namely, welding details, welding types, and steel bar types, of which welding details are the main variable. The compression test results were compared with the nominal compressive strength, Pn, based on the material test results and complete joint penetration (CJP). The test results indicated that the ratio of the experimental maximum load to the theoretical calculation result was between 1.04 and 1.12 (1.08 on average). This means that it is possible to use the current CFT design in the current Building Structure Standards (KBC 2016, KDS 41 31 00). The macro examination results indicated that the quality of welding will be improved owing to the minimization of defects during welding if the groove angle is improved to 50°.

scholarly journals Research on Compression Behavior of Square Thin-Walled CFST Columns with Steel-Bar Stiffeners

2018 ◽  
Vol 8 (9) ◽  
pp. 1602 ◽  
Author(s):  
Zhao Yang ◽  
Chengxiang Xu
Keyword(s):  
Bearing Capacity ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Tubes ◽  
Compression Behavior ◽  
Steel Bar ◽  
Steel Bars ◽  
Thin Walled ◽  
Structural Measure ◽  
Cfst Columns

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns.

Experimental Study of Post-Fire Bearing Capacity of the Circular Steel Tubes with Different Fire-Resistant Coating

2010 ◽  
Vol 163-167 ◽  
pp. 749-753
Author(s):  
Yao Ji ◽  
Xin Tang Wang ◽  
Ming Zhou ◽  
Wan Zhen Wang
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Fire Test ◽  
Steel Tube ◽  
Test Results ◽  
Fire Response ◽  
Steel Tubes ◽  
Protective Material ◽  
Tubular Columns ◽  
Maximum Value

In order to look into the causes of fire response and post-fire bearing capacity of the steel tubular columns protected with different materials, the fire test was conducted for a set of circular steel tubes protected with different materials such as gypsum fireproof panel, bamboo plywood and the ordinary lumber core plywood, and the steel tube without any protective material. The fire response temperature of surface of steel tubes is measured and the axial compressive bearing capacity of the specimens after fire are tested and analyzed. The test results show that gypsum fireproof panel has the best fire protection characteristics, the ordinary lumber core plywood and bamboo plywood can also retard rising of the surface temperature of the steel tubes during the initial 35min although they are combustible materials. It is found that the post-fire bearing capacity of the steel tubes protected with different materials varies evidently, and the maximum value of response temperature has the greatest effect.

Uniaxial Stress-Strain Model for Concrete Confined by Rectangular Steel Tubes

2010 ◽  
Vol 163-167 ◽  
pp. 1005-1011
Author(s):  
Yue Ling Long ◽  
Jian Cai
Keyword(s):  
Triaxial Compression ◽  
Uniaxial Stress ◽  
Failure Criteria ◽  
Steel Tube ◽  
Test Results ◽  
Stress Strain ◽  
Steel Tubes ◽  
Concrete Core ◽  
Strain Behavior ◽  
The Difference

This paper presents a new model for uniaxial stress-strain relationship of concrete confined by rectangular steel tubes. The difference between concrete confinement effect provided by broad faces and that provided by narrow faces of steel tube is considered in the proposed model. The failure criteria for concrete subjected to triaxial compression is applied to estimate the ultimate strength of concrete core. The parameters of the model are determined based on the test results and the calculation of complete load-stress relationship curves is conducted for axially loaded rectangular CFT specimens using the model proposed in the paper. The concrete core strength and stress-strain behavior of rectangular CFT columns is found to exhibit good agreement with test results.

Finite Element Modelling of Concrete-Filled Steel Tube Reinforced Concrete Stub Columns under Axial Compression

2013 ◽  
Vol 351-352 ◽  
pp. 138-142
Author(s):  
Zhi Bin Wang ◽  
Li Ying Liu
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Steel Tube ◽  
Fe Model ◽  
Mechanism Analysis ◽  
Test Results ◽  
Seismic Behaviour ◽  
Steel Tubes ◽  
Concrete Filled Steel Tube ◽  
Stub Columns

Concrete-filled steel tube reinforced concrete (CFSTRC) columns are currently being studied as a popular method to improve the shear strength, the ductility and the seismic behaviour of reinforced concrete (RC) columns. Owing to the complexity of confinement provided by steel tubes and stirrups, the behaviour of CFSTRC column is difficult to be accurately simulated. Thus,so far there is not a finite element (FE) model for CFSTRC columns. For studying the performance of this composite column, a FE model was developed based on the existing test results and theories. The predicted results using this FE model agree with the test results, which means that this model can be applied to carry out the further mechanism analysis.

Properties of Recycled Aggregate Concrete Filled Steel Tubes

2014 ◽  
Vol 1065-1069 ◽  
pp. 1323-1326
Author(s):  
Yi Jie Huang ◽  
Huang Sheng Sun
Keyword(s):  
Mechanical Behavior ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Test Results ◽  
Structural Elements ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Flexural Performance ◽  
Concrete Filled Steel Tubes

A review on the properties of recycled aggregate concrete filled steel tubes (RACSFT) was presented, followed by the short overview on the related researches. The uniaxial mechanical behavior, flexural performance, creep performance as well as eccentric loaded behavior of RACSFT specimens were discussed. It was found that the differences between the element made of recycled aggregate concrete (RAC) and that of natural aggregate concrete (NAC) could not be ignored. The performance of the RACFST is inferior to that of natural concrete filled steel tube (CFST). But, the RACSFT can be applied into structural elements safely. Based on the test results, it was also concluded that the RACSFT is an effective method to improve the application of RAC.

Research on Bearing Capacity of Short Concrete Filled Double Skin Steel Tubes Columns under Axial Compression

2010 ◽  
Vol 168-170 ◽  
pp. 2154-2157
Author(s):  
Jing Yu Chen ◽  
Ying Hai
Keyword(s):  
Axial Compression ◽  
Ultimate Load ◽  
Concrete Columns ◽  
Steel Tube ◽  
Confined Concrete ◽  
Load Estimation ◽  
Test Results ◽  
Steel Tubes ◽  
Double Skin ◽  
Structural Engineers

The use of steel tube confined concrete columns has been the interests of many structural engineers. For investigation of the axially loading capacity of short concrete filled double skin tubes (CFDST) columns, axial compression loading experiments were carried on 9 short CFDST column samples. According to experimental results and with numerical analysis, an ultimate load estimation equation of CFDST column with one correction parameter is presented, the linear relation between the parameter and the inner-to-outer diameters ratio Di/Do is given out. The ultimate load estimation equation is validated by the test results of short CFDST column samples.

Experimental Study on Concrete-Filled Double Skin Circular Steel Tubular Beams under Bending Load

2020 ◽  
Vol 995 ◽  
pp. 136-142
Author(s):  
Seung Jo Lee ◽  
Jung Min Park
Keyword(s):  
Concrete Strength ◽  
Maximum Load ◽  
Steel Tube ◽  
Outer Diameter ◽  
Steel Tubes ◽  
Displacement Ductility ◽  
Circular Steel Tube ◽  
Bending Load ◽  
Pattern Maximum ◽  
Behavior Characteristics

This paper examines the structural and mechanical behavior characteristics of the concrete-filled double circular steel tube (CFDT) fabricated with the installation of shape memory alloys (SMAs) and reinforcement bars in the inner and outer steel tubes, the inner-outer diameter ratio (Di/Do), and the concrete strength as the main variables. Towards this end, the displacement ductility, crack patterns, load-central deflection relationship, displacement ductility, and flexural shear strength were compared and analyzed. The results verified that a change in the Di/Do has significant effects on the crack pattern, maximum load, and ductility. The specimens with SMAs installed between the inner and outer steel tubes generally showed good results.

Behavior of CFRP-confined reactive powder concrete-filled steel tubes under axial compression

2020 ◽  
pp. 136943322097478
Author(s):  
Song Li ◽  
Chu-Jie Jiao
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Local Buckling ◽  
Steel Tube ◽  
Experimental Results ◽  
Reactive Powder Concrete ◽  
Test Results ◽  
Steel Tubes ◽  
Reactive Powder ◽  
Concrete Filled Steel Tubes

Reactive powder concrete-filled steel tubes (RPCFSTs) have become an important research target in recent years. In engineering applications, RPCFSTs can provide superior vertical components for high-rise and tower buildings, thereby enabling developers to provide more floor space. However, this type of composite structure is prone to inelastic outward local buckling. The use of carbon fiber reinforced polymer (CFRP) wrapping to suppress such local buckling has shown great potential in limited test results. This paper presents experimental results concerning the axial compression of CFRP-confined reactive powder concrete-filled circular steel tubes (CF-RPCFSTs). We included 18 specimens in our experimental investigation, varying the number of CFRP layers, steel tube thickness, and RPC strength. According to our test results, CF-RPCFSTs exhibit compression shear failure and drum-shaped failure. The CFRP wrap can effectively enhance bearing capacity and postpone local buckling of the steel tube. In addition, three-layer CFRP-confined RPC-filled thin-wall steel tubes are suitable for engineering. We also propose a model to calculate the bearing capacity of CF-RPCFSTs. Compared to the existing model of CFRP-confined concrete-filled steel tubes, the results obtained using the proposed model are in good agreement with our experimental results.

scholarly journals Improvement of a Truss-Reinforced, Half-Concrete Slab Floor System for Construction Sustainability

2021 ◽  
Vol 13 (7) ◽  
pp. 3731
Author(s):  
Jiarui Qi ◽  
Hsi-Chi Yang
Keyword(s):  
Concrete Slab ◽  
Experimental Tests ◽  
Construction Cost ◽  
Steel Tube ◽  
Structural Performance ◽  
Initial Stiffness ◽  
Component Design ◽  
Steel Bar ◽  
Component Form ◽  
Floor System

The truss-reinforced half-concrete slab has been widely used in prefabricated construction all over the world. It has become the most widely used prefabricated component form in China. However, its construction cost is higher than using the conventional construction method. To improve the half slab floor system, it is essential to have a comprehensive understanding of the truss-reinforced half slab’s structural performance over its complete loading history. Six experimental tests on such slabs were carried out. Three of them were reinforced with a steel bar truss (SBT) and the other three with a steel tube/bar truss (STBT). The steel tube in an STBT was grouted. The results show that when the specimen is damaged, the grouted steel tube does not undergo out-of-plane or in-plane buckling, and its force performance is good when compared to the steel bar in SBT. Compared with the SBT-reinforced slab specimens, the load characteristic values of the STBT-reinforced slabs were significantly improved, and the slabs had greater initial stiffness and resistance to deformation. Due to the fact that good structural performance of the steel tube was observed, after having studied the half slab component design, a dry, prefabricated, STBT-reinforced half slab system that can reduce the volume of concrete and amount of steel used in the present slab system is proposed. The proposed system has the advantages of allowing easier construction, cost reduction, and reuse of the components afterward to make the prefabrication construction more sustainable.

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