Experiment Study on Interfacial Normal Bond Strength of Concrete Filled Steel Tube

2012 ◽  
Vol 594-597 ◽  
pp. 947-954 ◽  
Author(s):  
Zhen Yu Liu
Keyword(s):  
Bond Strength ◽  
Temperature Change ◽  
Concrete Strength ◽  
Steel Tube ◽  
Test Method ◽  
Bending Test ◽  
Concrete Filled Steel Tube ◽  
Normal Bond ◽  
Core Concrete ◽  
Test Result

To study the debonding of concrete filled steel tube (CFST), pulling and bending methods were used to test the normal bond strength. Based on the test result, debonding due to temperature change and shrinkage of core concrete in CFST was analyzed. The test and analysis result shows that the bending method is a better test method; the concrete strength has little influence on bond strength while the surface condition of steel has much influence on it. The bond strength of steel which is rust is greater than that of the steel with smooth surface. According to the analysis on the bending test result, the normal bond strength of 0.86MPa was got and the debonding of CFST arch was analyzed, the analysis result shows that debonding will easily happen under the action of temperature change and shrinkage of core concrete. The test methods and results can provide a reference for engineering applications.

scholarly journals Research on the Bond Behavior of Preplaced Aggregate Concrete-Filled Steel Tube Columns

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 300 ◽  
Author(s):  
Jing Lv ◽  
Tianhua Zhou ◽  
Qiang Du ◽  
Kunlun Li ◽  
Liangwei Jin
Keyword(s):  
Bond Strength ◽  
Concrete Strength ◽  
Peak Load ◽  
Steel Tube ◽  
Bond Stress ◽  
Normal Concrete ◽  
Aggregate Concrete ◽  
Concrete Filled Steel Tube ◽  
Bond Behavior ◽  
The Difference

In order to investigate the bond behavior of preplaced aggregate concrete-filled steel tube (CFT-PAC) columns and the difference of bond behavior between CFT-PAC columns and normal concrete-filled steel tube (CFT-NC) columns, a total of 11 columns were prepared and the push-out tests were conducted. The experimental parameters included the type of concrete (preplaced aggregate concrete and normal concrete), concrete strength (C40, C50 and C60), cross-section dimension (D = 219 mm, 299 mm and 351 mm) and the thickness of steel tube (t = 6 mm and 8 mm). The results indicated that the CTF-PAC columns had a similar load-slip curves with CFT-NC columns. The bond stresses of the CFT-PAC columns were higher than that of the PAC-NC columns at the same concrete strength. Increasing compressive strength of PAC increased the critical bond strength and bond strength of CFT-PAC columns. With an increase of the L/D ratio, both of the slip corresponding to peak load and bond strength of CFT-PAC columns exhibited an increasing trend. A rise in the D/t ratio led to a decrease in the bond stress of CFT-PAC columns and an increase in slip corresponding to the peak load of CFT-PAC columns. The proposed bond stress–slip relationship model considerably matched the bond stress–slip relationship of CFT-PAC columns.

scholarly journals Axial Compression Performance and Ultrasonic Testing of Multicavity Concrete-Filled Steel Tube Shear Wall under Axial Load

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Hongbo Li ◽  
Pengfei Yan ◽  
Hao Sun ◽  
Jianguang Yin
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Ultrasonic Testing ◽  
Axial Load ◽  
Limit Equilibrium ◽  
Concrete Strength ◽  
Shear Wall ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Core Concrete

In this study, the mechanical performance of multicavity concrete-filled steel tube (CFST) shear wall under axial compressive loading is investigated through experimental, numerical, and theoretical methodologies. Further, ultrasonic testing is used to assess the accumulated damage in the core concrete. Two specimens are designed for axial compression test to study the effect of concrete strength and steel ratio on the mechanical behavior of multicavity CFST shear wall. Furthermore, a three-dimensional (3D) finite element model is established for parametric studies to probe into compound effect between multicavity steel tube and core concrete. Based on finite element simulation and limit equilibrium theory, a practical formula is proposed for calculating the axial compressive bearing capacity of the multicavity CFST shear wall, and the corresponding calculation results are found to be in good agreement with the experimental results. This indicates that the proposed formula can serve as a useful reference for engineering applications. In addition, the ultrasonic testing results revealed that the damage process of core concrete under axial load can be divided into three stages: extension of initial cracks (elastic stage), compaction due to hooping effect (elastic-plastic stage), and overall failure of the concrete (failure stage).

scholarly journals Confined Expansion and Bond Property of Micro-Expansive Concrete- Filled Steel Tube Columns

2011 ◽  
Vol 5 (1) ◽  
pp. 173-178 ◽  
Author(s):  
Xu Kai-Cheng ◽  
Chen Meng-Cheng ◽  
Yuan Fang
Keyword(s):  
Bond Strength ◽  
Composite Structures ◽  
Steel Tube ◽  
Concrete Core ◽  
Conventional Concrete ◽  
Obvious Effect ◽  
Concrete Filled Steel Tube ◽  
Swelling Agent ◽  
Short Columns ◽  
Core Concrete

The shrinkage/expansion behavior and bond carrying capacities were investigated through 4 micro-expensive concrete-filled steel tube(MCFST) and 3 conventional concrete-filled steel tube(CFST) short columns. The results show that the temperature field in MCFST is similar to that of ordinary concrete members. Concrete core has obvious effect on shrinkage-compensating with the addition of swelling agent. Pre-stress is produced in the core concrete when it is confined by the steel tube. Both water cement ratio and expansive agent have obvious influence on expansive behaviors of MCFST. The tests also indicate that the pre-stress in core concrete can improve bond strength of core concrete and steel tube of MCFST columns and proposed a new method to improve the interface bond strength of composite structures.

Experimental Study on Expansive Concrete Filled Steel Tube

2013 ◽  
Vol 275-277 ◽  
pp. 2077-2083
Author(s):  
Kai Cheng Huo ◽  
Xian Cheng Shu ◽  
Huan Huan Yue
Keyword(s):  
Experimental Study ◽  
Temperature Change ◽  
Axial Compression ◽  
High Strength ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Vertical Loading ◽  
Expansive Concrete ◽  
Hardening Process ◽  
Mix Proportion

Measure the temperature change of concrete-filled steel tubular with high strength low heat micro-expansive in its hardening process with different mix proportion. Study self-stress of high strength low-heat micro-expansive and study the relations of the expansive admixtures quantity and its changing regularity with the time. Observe the fail of axial compression short column of concrete-filled steel tubular with high strength expansive under vertical loading, study the changing regularity of its stress under loading.

Mechanical Research on Bond-Slip Behaviors of Recycled Aggregate Concrete-Filled Square Steel Tubes

2012 ◽  
Vol 166-169 ◽  
pp. 3233-3236 ◽  
Author(s):  
Jun Tao Li ◽  
Jin Jun Xu ◽  
Zong Ping Chen ◽  
Yi Li ◽  
Ying Liang
Keyword(s):  
Bond Strength ◽  
Concrete Strength ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Ultimate Bond Strength

In order to research the interface bond-slip behaviors of recycled aggregate concrete-filled square steel tube (RACFSST), ten specimens using waste concrete were designed for launch test. The three changing parameters were concrete strength grade, embedded length and recycled coarse aggregate replacement rate. The load–slip curves of square steel tubes and recycled aggregate concrete were obtained, and starting bond strength and ultimate bond strength influenced by each changing parameter were analyzed. The results show that the replacement rate had a slight influence on the starting bond strength and ultimate bond strength, while the embedded length had the opposite effect. The shorter embedded length specimens had larger bond strength. The concrete strength had a relatively large influence on them.

scholarly journals Experimental Studies on the Effect of Properties and Micro-Structure on the Creep of Concrete-Filled Steel Tubes

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1046 ◽  
Author(s):  
Rongling Zhang ◽  
Lina Ma ◽  
Qicai Wang ◽  
Jia Li ◽  
Yu Wang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Steel Tube ◽  
Creep Tests ◽  
Steel Tubes ◽  
Concrete Filled Steel Tube ◽  
Steel Ratio ◽  
Air Content ◽  
Lateral Restraint ◽  
Concrete Filled Steel Tubes ◽  
Core Concrete

To study different lateral restraints, different constituents of expansion agents, the influence of different steel ratios, and concrete creep properties, we carried out experiments with lateral restraint and without lateral restraint conditions separately on 12 specimens with the expansion agent content accounting for 4%, 8%, and 12% respectively. In addition, the creep tests were performed on specimens with different steel ratios of 0.0%, 3.8%, 6.6%, and 9.2%. The test results show that the lateral restraint improves the strength of the system (concrete-filled steel tubes) which resists further load after the concrete ultimate strength is surpassed and reduces the creep. The creep degree of the concrete-filled steel tube with lateral restraint is about 0.09–0.30 times smaller than that of the tube without lateral restraints. The creep degree of the concrete-filled steel tube increases as the steel ratio decreases. Creep tests with different amounts of expansion agent indicate that the creep degree of the concrete structure increases as expansion agent content decreases. To study the internal mechanism of the creep of concrete-filled steel tubes with different lateral restraints and different expansion agent concentrations, a microscopic pore structure test on the steel core concrete was conducted using the RapidAir457 pore structure instrument. Microscopic studies show that the air content and the length of the bubble chord of the laterally restrained core concrete are lower than those without lateral restraint core concrete. The amount of air content and the length of the bubble chord of core concrete specimens increase as the expansion agent content in the core concrete specimens decreases from 12% to 4%. Under the same external loading conditions, as steel ratio increases, the lateral restraint causes a further reduction of creep. The results of this study suggest that the creep of concrete can be reduced by selecting appropriate lateral restraint conditions and an optimal amount of expansion agent in the mix design of concrete for concrete-filled steel tubes.

The Constitutive Relationship of Self-Stress Concrete Filled Steel Tube

2012 ◽  
Vol 428 ◽  
pp. 103-107
Author(s):  
Shui Xing Zhou ◽  
Lu Li ◽  
Yue Ma ◽  
Ling Jun Li
Keyword(s):  
Theoretical Analysis ◽  
Concrete Strength ◽  
Steel Tube ◽  
Constitutive Relationship ◽  
Concrete Filled Steel Tube ◽  
Good Accordance ◽  
Relationship Model ◽  
Experimental Values ◽  
Relationship Of ◽  
Tubular Specimens

Based on the constitutive relationship model of general concrete filled steel tube, and combining with the results and theoretical analysis of several self-stress concrete filled steel tubular specimens, the constitutive relationship model of self-stress concrete filled steel tube was established by introducing an improvement coefficient of concrete strength related to self-stress level. The calculations of specimens’ bearing capacity with different sectional steel ratios, values of self-stress and concrete strengths were performed, which were in a good accordance with those of experimental values.

Effect of Axial Compression Ratio and Concrete Strength on Seismic Performance of Concrete Filled Steel Tube Beam-Column Joints

2014 ◽  
Vol 488-489 ◽  
pp. 704-707
Author(s):  
Ying Wang ◽  
Miao Li ◽  
Jin Hua Xu ◽  
He Fan
Keyword(s):  
Axial Compression ◽  
Seismic Performance ◽  
Compression Ratio ◽  
Concrete Strength ◽  
Steel Tube ◽  
Hysteresis Curve ◽  
Element Analysis ◽  
Concrete Filled Steel Tube ◽  
Axial Compression Ratio ◽  
Strength And Stiffness

Based on finite element analysis o f concrete filled steel tube beam-column joints under the single axial compression ratio and concrete strength, further research was done to analyze the seismic performance of concrete filled steel tube beam-column joints under different axial compression ratio and concrete strength. Beam-column joint which is connected by bolts with welding extended steel sheets at the beam root was analyzed. The results show that with the increase of axial compression ratio, strength and stiffness degradation of the joint accelerated gradually. Axial compression ratio at 0.3, 0.4 are appropriate values for joints specimen, load-displacement hysteresis curve of joint specimens is relatively plump and shows good seismic performance. Chance of concrete strength also had effect on seismic performance of joint specimen, but in contrast it is not so obviously.

Improvement of Volume Stability in Core Concrete of Concrete-Filled Steel Tube

2011 ◽  
Vol 52-54 ◽  
pp. 1097-1106
Author(s):  
De Bin Yang ◽  
Shui Xing Zhou ◽  
Ming Chen ◽  
Wei Wang ◽  
Xiao Yi Zhang
Keyword(s):  
Tube Wall ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Volume Stability ◽  
Expansive Agent ◽  
Shrinkage Effect ◽  
Key Factor ◽  
Curing Condition ◽  
Water Saturated ◽  
Core Concrete

Due to the concrete self-shrinkage, frequent load application and temperature fluctuation, and so on，the gap formed between the inner tube wall and the core concrete surfaces would decrease the performance of concrete-filled steel tube (CFST). To prevent this cavity problem, various types of expansive agents and aggregates were used in this study to improve the volume stability of core concrete. Comparative experiments with mortars and concrete were carried out respectively under standard curing condition and under enclosed curing condition which simulated the environment in steel tube. The results could be summarized as follows: ● Two types of expansive agents, ZY type expansive agent mainly containing sulfates and aluminates and M type expansive agent mainly containing magnesium oxide, presented different expansive behaviors with curing ages in mortar and concrete. Two types of expansive agents combined with each other could produce complementary and superimposition effects to improve continuously the volume stability of mortar and concrete. ● Sufficient water supply is the key factor for the formation and maintenance of expansion. The volume change caused by the self-shrinkage effect of core concrete could not be effectively off-set with whether two types expansive agents or their compounds under enclosed environment in which water was scarce and could not be supplied from outside. ● When some water-saturated ceramsite were used to partially replace aggregates in core concrete,the volume expansion performance of core concrete improved dramatically with the water storage and supply effects of water-saturated ceramsite.

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