Modelling the behaviour of concrete-encased concrete-filled steel tube (CFST) columns subjected to full-range fire

2019 ◽  
Vol 183 ◽  
pp. 265-280 ◽  
Author(s):  
Kan Zhou ◽  
Lin-Hai Han
2018 ◽  
Vol 878 ◽  
pp. 126-131 ◽  
Author(s):  
Anatoly L. Krishan ◽  
Elvira P. Chernyshova ◽  
Rustam R. Sabirov

New approach to creating deformation charts for concrete core and steel shell of round CFST columns is offered. For creating such charts the power resistance of short central the compressed concrete filled steel tube element is considered. At the same time two major factors are considered. First, the steel shell and the concrete core function under conditions of complex tension. Secondly, at step-by-step strengthening of axial deformations the side pressure upon concrete core and steel shell constantly changes. As a result coordinates of parametrical points of deformation charts for concrete and steel change. Such approach allows describing the real intense deformed condition of concrete filled steel tube columns more precisely.


2020 ◽  
Vol 14 (54) ◽  
pp. 317-324
Author(s):  
Ali Golsoorat Pahlaviani ◽  
Ali Mohammad Rousta ◽  
Peyman Beiranvand

Concrete-filled steel tube (CFST) columns are increasingly used in the construction of high-rise buildings which require high strength and large working space especially at lower stories. As compared to reinforced concrete columns, existence of the exterior steel tube not only bears a portion of axial load but also most importantly provides confinement to the infill concrete.with the confinement provided by the steel tube, axial strength of the infill concrete can be largely enhanced.this paper presents the investigation effect of impact load on concrete-filled steel tube columns under fire by numerical simulations using ABAQUS software.the results indicate that the CFST sections with larger confinement factor ξ=1.23 behaved in a very ductile manner under lateral impact. And the sections with smaller confinement factor ξ=0.44  generally behaved in a brittle mechanism.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5564
Author(s):  
Yongzhi Gong ◽  
Faxing Ding ◽  
Liping Wang ◽  
Borong Huang ◽  
Yingjie Shan ◽  
...  

The objective of this study is to investigate the mechanical properties and the composite action of circular concrete-filled steel tube (CFST) columns subjected to compression-torsion load using finite element model analysis. Load–strain (T–γ) curves, normal stress, shear stress, and the composite action between the steel tubes and the interior concrete were analyzed based on the verified 3D finite element models. The results indicate that with the increase of axial force, the maximum shear stress at the core concrete increased significantly, and the maximum shear stress of the steel tubes gradually decreased. Meanwhile, the torsional bearing capacity of the column increased at first and then decreased. The torque share in the columns changed from the tube-sharing domain to the concrete-sharing domain, while the axial force of the steel tube remained unchanged. Practical design equations for the torsional capacity of axially loaded circular CFST columns were proposed based on the parametric analysis. The accuracy and validity of the proposed equations were verified against the collected experimental results.


2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shi Yan ◽  
Jinzhi Fu ◽  
Wei Sun ◽  
Baohui Qi ◽  
Fuxue Liu

A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST) columns. The piezoceramic-based smart aggregates (SAs) were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR) and symmetry (SYM) were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.


2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Pengfei Li ◽  
Tao Zhang ◽  
Chengzhi Wang

The behavior of concrete-filled steel tube (CFST) columns subjected to axial compression was experimentally investigated in this paper. Two kinds of columns, including CFST columns with foundation and columns without foundation, were tested. Columns of pure concrete and concrete with reinforcing bars as well as two steel tube thicknesses were considered. The experimental results showed that the CFST column with reinforcing bars has a higher bearing capacity, more effective plastic behavior, and greater toughness, and the elastoplastic boundary point occurs when the load is approximately 0.4–0.5 times of the ultimate bearing capacity. The change of rock-socketed depth and the presence of steel tube will affect the ultimate bearing capacity of rock-socketed pile. The bearing capacities of the rock-socketed CFST columns are lower than those of rock-socketed columns without a steel tube under a vertical load; besides, the greater the rock-socketed depth, the greater the bearing capacity of the rock-socketed piles. In addition, a numerical comparison between the ultimate load and the theoretical value calculated from the relevant specifications shows that the ultimate load is generally considerably greater than the theoretical calculation results.


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