scholarly journals Theoretical Analysis on Mechanical Behavior of Axially Loaded Recycled Aggregate Concrete Filled Steel Tubes

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Yijie Huang ◽  
Yuedong Sun ◽  
Huangsheng Sun ◽  
Qing Wang
Keyword(s):  
Mechanical Behaviour ◽  
Mechanical Model ◽  
Confining Pressure ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Steel Tubes ◽  
Concrete Filled Steel Tubes ◽  
Numerical Program ◽  
Core Concrete

A new mechanical model for analysing the behaviour of axially loaded recycled aggregate concrete filled steel tubes (RACFSTs) stub columns is presented in this study. The model is derived from the typical elastoplasticity, the nonlinear elastic mechanics, and the properties of materials. Based on the mechanical model, a novel numerical program is developed. The mechanical model and the numerical program are adopted to study the effect of recycled coarse aggregate (RCA) replacement percentage on RACFST mechanical behaviour. The complete load-deformation relationship of specimens, the steel tube axial and circumferential stresses, and the performance of the confined core concrete and the variation of interaction are also investigated. The analytical results indicate that this model is able to capture the mechanical behaviour of RACFST. It is also found that the axial and circumferential stresses of steel tube change nonlinearly during the loading stages. It is concluded that the behaviour of the confined core concrete is significantly influenced by the confining pressure. The steel tube confinement could improve the mechanical behaviour of RAC effectively and the RCA replacement percentage slightly changes the response of core concrete. Finally, the relations between confined core concrete and confining pressure are analysed.

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.

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.

scholarly journals Bond Properties of RAC-Filled Square Steel Tubes after High Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Wanjie Zou ◽  
Jiongfeng Liang ◽  
Guangwu Zhang ◽  
Haifeng Yang
Keyword(s):  
Coarse Aggregate ◽  
Concrete Strength ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Bond Properties ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Square Steel Tube

This paper presents the results of an experimental study to investigate the influence of high temperatures on the bond properties between the recycled coarse aggregate (RCA) concrete and square steel tubes. A total of 27 pushout recycled aggregate concrete- (RAC-) filled square steel tube specimens are cast and heated under five different temperatures (20°C, 200°C, 400°C, 600°C, and 800°C) for testing. The main parameters considered in the test are temperature, exposure time of heating, RCA replacement ratio, interface length-to-width ratio, and concrete strength. The experimental results indicate that the bond strength for recycled coarse aggregate concrete and square steel tube increases with increasing temperatures.

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