Numerical Analysis and Axial Bearing Capacity of Composite Columns with Recycled Aggregate Concrete-Filled Steel Tube and Profile Steel

2019 ◽  
Vol 45 (5) ◽  
pp. 3581-3598
Author(s):  
Jing Dong ◽  
Hui Ma ◽  
Yunhe Liu ◽  
Tingting Guo
2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Xianggang Zhang ◽  
Jianhui Yang ◽  
Yaozong Zhang ◽  
Xiang Gao

To study the seismic strength and stiffness for recycled aggregate concrete-filled steel tube (RACFST) frame, two-frame specimens made up of RACFST column and reinforced recycled aggregate concrete (RAC) beam were used for a seismic test under reversed low-cycle loading. The failure mechanism, hysteresis curve, strength attenuation, and stiffness degradation were determined for the specimens. The design methods for the story shear bearing capacity and stiffness for the single-layer single-span RACFST frame were discussed. It is shown that the seismic design requirements including “strong column weak beam” and “strong shear weak bending” can be met. The hysteresis curves are symmetric and the strength attenuation and rigidity degeneration change significantly, then change a little, and then significantly again under the same displacement. It is possible that the methods including elastic bending moment at the column end, plastic hinge at the column end, and plastic hinge at the column bottom can all be applied to the design calculation of the story shear bearing capacity for the single-layer single-span RACFST frame. The method adopted in this paper can be used to estimate the original elastic layer stiffness of the RACFST frame.


2014 ◽  
Vol 711 ◽  
pp. 438-443
Author(s):  
Rong Hua Yang ◽  
Gao Bo Mai

The first degree second order moment method (JC method) is applied to analyze the reliability of recycled aggregate concrete-filled steel tube (RACFST). Several performances are studies, which are the influences of different load combinations, specific values of loads,confinement coefficients and recycled coarse aggregate replacement percentage on the reliability of the column. It is found that the reliability index varied with the load combination and specific value of loads. The analytical results indicate that the reliability index of the round steel tube is higher than square steel tube and the influence of recycled coarse aggregate replacement percentage can almost be ignored It can be concluded that the formula had great influence on reliability index and the revised formula can meet the requirements of the ductility of structure reliability.


2021 ◽  
pp. 136943322110339
Author(s):  
Jiongfeng Liang ◽  
Siqi Lin ◽  
Mizan Ahmed

The behavior of fiber-reinforced polymer (FRP)–confined recycled aggregate concrete-filled steel tube (RACFT) columns is barely studied. Especially, that of slender specimens has not been investigated so far. In this article, an experimental test of FRP-confined RACFT slender square columns was conducted to study the influences of recycled aggregate (RA) replacement ratios, FRP thicknesses, and wrapping schemes on their axial behavior. Results in this article suggest that the RA replacement ratio barely affects the initial stiffness of load-deflection curves of specimens. Moreover, the specimen with a higher RA replacement ratio has a lower axial stress but larger strain at the peak point. The external FRP jackets (either partial or full wrap) can effectively improve the performance of axially loaded RACFT columns, and the improvement of ductility due to the increase of the FRP thickness is more significant than that of axial compressive strength. Additionally, it was found that the axial strength and ultimate axial strain decrease with increasing slenderness ratios. Furthermore, the influences of slenderness ratios on the behavior of such columns are more significant for the column with a larger length-to-width ratio. Finally, a design model for FRP-confined RACFT slender square columns is developed, which can predict the results of the present test accurately.


2021 ◽  
Vol 8 ◽  
Author(s):  
Yicen Liu ◽  
Fei Lyu ◽  
Faxing Ding ◽  
En Wang ◽  
Yunlong Xu ◽  
...  

The mechanical behaviors of recycled aggregate concrete (RAC) are upgraded by outer steel tube confinement, and the performance of recycled aggregate concrete-filled steel tubular (RACFST) columns is similar to that of the traditional concrete-filled steel tube (CFST) columns. The purpose of this study is to investigate the behaviors of recycled aggregate concrete-filled rectangular steel tubular (RACFRST) stub columns under axial loading. Three-dimensional finite element (FE) models were established, which utilized a triaxial plastic-damage constitutive RAC model considering the replacement ratio of recycled aggregates. The finite element analysis results indicated that the lessened ultimate bearing capacity of RACFRST stub columns compared with their traditional concrete infilled counterparts was mainly due to the weakened confinement effect and confinement efficiency. A simplified formula of the bearing capacity of concentrically loaded RACFRST stub columns was proposed. The cross-sectional stress nephogram was reasonably simplified by the limited state of infilled concrete. The basics of proposed formula were the equilibrium condition and the superposition method. Finally, the formula for the bearing capacity of RACFRST stub columns was evaluated by comparing its accuracy and feasibility to some design formulae proposed by specialists and some design codes of different regions.


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