Behavior of CFRP-confined Concrete-filled square steel tube columns with section circularized under axial compression

2021 ◽  
pp. 113560
Author(s):  
Zhongjun Hu ◽  
Yuchuan Wen ◽  
Boxin Wang ◽  
Xin Li ◽  
Yan Xu
Author(s):  
Xindong Ding ◽  
Shuqing Wang ◽  
Yu Liu ◽  
Zepeng Zheng

Axial compression tests were carried out on 6 square steel tube confined concrete short columns and 6 BFRP square pipe confined concrete axial compression tests. The concrete strength grades were C30, C40, and C50. The test results show that the failure modes of steel pipe and BFRP pipe are obviously different, and the BFRP pipe undergoes brittle failure. Compared with the short columns of concrete confined by BFRP pipes, the ultimate bearing capacity of axial compression is increased by -76.46%, -76.01%, and -73.06%, and the ultimate displacements are -79.20%, -80.78%, -71.71%.


Author(s):  
Xindong DING ◽  
Shuqing Wang ◽  
Yu Liu ◽  
Zepeng Zheng

Axial compression tests were carried out on 6 square steel tube confined concrete short columns and 6 BFRP square pipe confined concrete axial compression tests. The concrete strength grades were C30, C40, and C50. The test results show that the failure modes of steel pipe and BFRP pipe are obviously different, and the BFRP pipe undergoes brittle failure. Compared with the short columns of concrete confined by BFRP pipes, the ultimate bearing capacity of axial compression is increased by -76.46%, -76.01%, and -73.06%, and the ultimate displacements are -79.20%, -80.78%, -71.71%.


2020 ◽  
Vol 146 ◽  
pp. 106483 ◽  
Author(s):  
Hongyuan Tang ◽  
Junlong Chen ◽  
Luyao Fan ◽  
Xujie Sun ◽  
Chunmei Peng

2021 ◽  
Vol 8 ◽  
Author(s):  
Zongping Chen ◽  
Fan Ning ◽  
Linlin Mo

The square steel tube component has a beautiful appearance, simple joint connection, and it is widely available. However, the uneven distribution of effective constraints in the cross-section of a square steel tube hinders its application. A novel concrete-filled square steel tubular column was tested under axial compression. There were 11 specimens [10 concrete-filled square steel tube columns reinforced with rhombic stirrups with 90-degree internal angle (SSSC specimens) and 1 concrete-filled square steel tube column (SC specimen)]. The load-displacement curves, the law of failure process, failure mode, mechanism analysis, energy consumption, ductility, and stiffness degradation were described, we then investigated the influence of stirrup diameter, stirrup side length, stirrup spacing, steel tube thickness, aspect ratio, and steel ratio on the mechanical properties of the specimens. The results show that the failure process of the SSSC specimens was basically the same. The ultimate failure mode of the specimens with an aspect ratio of 4 was local buckling failure. The specimens with an aspect ratio of 5 and 6 failed due to bending failure in the plastic stage. The steel tube bulged out in different degrees in most of the debonding areas. The longitudinal bars also produced outward bending deformation in the larger bulging area of the steel tube. Some of the stirrups were broken in the later stage of loading. The characteristics of load-displacement curve changed with the changing of stirrup spacing. The strength of longitudinal constraint had an obvious influence on the bearing capacity. In a certain range of steel ratio (ρs = 8.97% ∼ 9.05%), the weakening of the lateral restraint of the stirrup cage had a greater adverse effect on the bearing capacity than the weakening of the effective restraint of the corner. In a certain range of steel ratio (ρs = 8.97% ∼ 9.49%), strengthening the effective corner constraint of stirrups improved the stiffness of the specimen, however, the ductility performance was reduced. The opposite was true for strengthening the lateral constraint of the stirrup cage.


2020 ◽  
Vol 166 ◽  
pp. 105912 ◽  
Author(s):  
Xiaobo Zhao ◽  
Hongjun Liang ◽  
Yiyan Lu ◽  
Pengtuan Zhao

2013 ◽  
Vol 639-640 ◽  
pp. 1069-1072
Author(s):  
Hao Xiong Feng ◽  
Wei Jian Yi

This paper describes principle and working mechanism of the steel tube confined concrete, to analyze impact factors of steel tube confined concrete strength. By the studies, presents several solutions to improve the strength of steel tube confined concrete, fully execute the behavior of steel tube and filled-in-concrete, strengthen the interactions between steel tube and filled-in-concrete to provide theoretical basis for the design and use of steel tube confined concrete.


2011 ◽  
Vol 255-260 ◽  
pp. 151-156 ◽  
Author(s):  
Zhao Qiang Zhang ◽  
Yong Yao

By introducing the reduction coefficient of concrete strength and the equivalent restriction reduction coefficient,the non-uniform confinement force of square steel tube to its core concrete is turned to that of equivalent circular steel tube. Then the ultimate load calculation formula for the solid multibarrel tube-confined concrete short columns (CHS inner and SHS outer) is derived based on the Unified Strength Theory(UST),in which the double restriction effect and the decrease of longitudinal stress because of the hoop tensile tension are considered. The influence of intermediate principal stress on the ultimate load is studied and the failure mechanism is discussed. The applicability of the formulas is testified and the results show that the formulas have significance in exerting material potential.


2010 ◽  
Vol 168-170 ◽  
pp. 2154-2157
Author(s):  
Jing Yu Chen ◽  
Ying Hai

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.


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