Ultimate Bearing Capacity Analysis of Axially Compressive Circular Steel Tube Columns Filled with Bar-Reinforced Concrete

2011 ◽  
Vol 94-96 ◽  
pp. 1205-1210
Author(s):  
Zhao Liu ◽  
Jun Hai Zhao

The mechanical behavior and ultimate bearing capacity of the circular bar-reinforced concrete filled steel tube (BRCFST) short columns under axial compression are analyzed in this paper based on the unified strength theory. Considering the restriction effect of steel tube and hoop bar on concrete, the calculation formula of bearing capacity of the column is deduced. Parametric studies are carried out to evaluate the effects of intermediate principal stresses, diameter-thickness ratio of steel tube and the stirrup ratio on the bearing capacity of the column. A good agreement is reached by comparing the results calculated by the formula with the test results. It is concluded that the unified strength theory is applicable in the theoretical analyses of the BRCFST columns.

2013 ◽  
Vol 690-693 ◽  
pp. 742-746
Author(s):  
Peng Wu ◽  
Jian Feng Xu ◽  
Jun Hai Zhao ◽  
Qian Zhu ◽  
Su Wang

Based on unified strength theory, the mechanical behavior of core-concrete of concrete-filled square steel tubular stub columns was analyzed. Through controlling the constraint effect between square steel tube and core-concrete by width-thickness ratio, the ultimate bearing capacity formula for concrete-filled square steel tubular stub columns under axial compression was proposed, and the influencing factors of which was also discussed. The rationality of proposed formula was proved from the comparison of the analytical results obtained in this paper and experimental data.


2011 ◽  
Vol 94-96 ◽  
pp. 820-825
Author(s):  
Sai Wu ◽  
Jun Hai Zhao ◽  
Xue Ying Wei

This paper based on the unified strength theory, analyzed the ultimate bearing capacity of the reinforced concrete columns combined with FRP under axial loads. First, analyzed the mechanical property of the RC columns combined with FRP. Second, based on the unified strength theory, deduced the three-direction compressive stress of the core concrete and got the unified formula for calculating the ultimate bearing capacity of RC columns combined with FRP. Last, compared the analytical results obtained in this paper with the relevant experimental data, good agreement can be found and it proved the good applicability of the formula. Comparing with other methods in calculating the ultimate bearing capacity of RC columns combined with FRP,this method is well-founded, so it has a significant value in analysis of RC columns combined with FRP.


2013 ◽  
Vol 690-693 ◽  
pp. 797-804
Author(s):  
Jian Feng Xu ◽  
Peng Wu ◽  
Jun Hai Zhao ◽  
Yan Li ◽  
Wen Biao Liang

Directed against the stiffened and thin-walled square concrete-filled steel tubular (CFST) short columns, the paper simplifies the square CFST columns into the circle ones by introducing the strength reduction coefficient of concrete and the equivalent constraint reduction coefficient. On the basis of the unified strength theory, the united solution of the ultimate bearing capacity for square CFST columns is deduced after considering the influence of strength-differential in tension and compression and intermediate principal stress. Some influencing factors are also analyzed in the paper. Through comparing the results of proposed formula with that of experiments of relevant literatures,the rationality of proposed formula is proved. The solution may provide theoretical references for the study of the ultimate bearing capacity for stiffened and thin-walled square CFST short columns.


2012 ◽  
Vol 193-194 ◽  
pp. 1418-1423
Author(s):  
Zhi Jie Liu ◽  
Jun Hai Zhao ◽  
Xu Guang Yu ◽  
Gai Qin Su ◽  
Xin Zhao

The eccentric ultimate load calculation formula of square steel tube columns filled with steel-reinforced concrete was derived based on the Unified Strength Theory in this paper. The influence of intermediate principal stress and the restriction effect and the decrease of longitudinal stress were considered in the formula. Based on the axial compression load and the effect of consider the eccentricity ratio and slenderness ratio on the hearing capacity was considered, by introducing the reduction factor of concrete strength and the equivalent restriction reduction factor, the confinement of square steel tube towards concrete was equivalent to the confinement of circular steel tube towards it, based on unified strength theory solutions of thick tube, the calculation formula of eccentric compression bearing capacity of square steel tube columns filled with steel-reinforced concrete was deduced and analysed the influence complication. The results indicate unified strength theory has the good applicability and the solution has an important practical value for engineering application.


2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yongjun Lin ◽  
Kaiqi Liu ◽  
Tianxu Xiao ◽  
Chang Zhou

In this paper, in order to investigate the shear mechanism and shear capacity of framework joints of steel-reinforced concrete-filled circular steel tube (SRCFCST), a numerical finite element model reflecting the mechanical behavior of framework joints of SRCFCST column-reinforced concrete beam is established through simulating concrete by the damage plastic constitutive model and simulating steel by the ideal elastic-plastic material, and its effectiveness is verified by experimental data. On account of uniform distribution of circular steel reinforced around the section and without definite flange and web, the shear mechanism of the framework joints of SRCFCST is analyzed on the basis of equivalent circular steel tube (CST) to the rectangular steel tube. The method for calculating the superposed shear bearing capacities of the joint core area is proposed, which is composed of four parts, i.e., concrete inside tube, concrete outside tube, hooping and steel-reinforced web; and the corresponding formulas for calculating shear bearing capacity are established. The comparative analysis of joints’ shear bearing capacity indicates that the results of numerical simulation and shear bearing capacity formulas coincide well with the experimental values, which can provide reference for the nonlinear analysis and engineering design of similar joints.


2012 ◽  
Vol 193-194 ◽  
pp. 1461-1464
Author(s):  
Bai Shou Li ◽  
Ai Hua Jin

Based on the characteristics of the special-shaped concrete-filled steel tubes and consideration of material nonlinearity of constitutive relation, stimulation of 6 T-shaped thin-walled ribbed and un-ribbed concrete-filled steel tube short columns is implemented, as well as comparable analysis of stress, strain, displacement and bearing capacity, through the finite element analysis software ANSYS. The result indicates that the rib can effectively improve the ductility, delaying the buckling occurs, which enhances the core concrete confinement effect, so as the stimulated ultimate bearing capacity which is greater than nominal ultimate bearing capacity.


2010 ◽  
Vol 163-167 ◽  
pp. 4542-4545 ◽  
Author(s):  
Xin Zhong Li ◽  
Xue Ying Wei ◽  
Jun Hai Zhao

This paper presents the theoretical and experimental results of concrete-filled steel tube columns subjected to axially compression. A total of 6 specimens with outer square sections reinforced by inner cicular steel tube were constructed for experimental investigation. The ultimate strengths of the columns from tests were obtained. The theoretical strengths of the columns were also investigated based on unified strength theory, and compared with the test results. Good agreement can be observed from the comparison.


2012 ◽  
Vol 204-208 ◽  
pp. 4031-4037
Author(s):  
Gui Yun Xia ◽  
Jia Jun Li ◽  
Mei Liang Yang

Based on the unified strength theory presented by Maohong Yu, the calculating formula for the load-bearing capacity of concrete-filled double steel tube was derived. Through tests, the calculating load-bearing capacity results were compared with testing results, which agreed well. The change of load-bearing capacities with parameter k of the unified strength theory was discussed. It can be drawn that the load-bearing capacity of CFDST will increase with the increase of parameter b, but the increase is not obvious.


2012 ◽  
Vol 588-589 ◽  
pp. 212-216
Author(s):  
Rui Jing ◽  
Yong Sheng Zhang

With the help of large general finite element analysis software ANSYS, under different parameters, this paper will have a finite element analysis of bearing capacity on circular steel tube compile short column filled with steel reinforced concrete(STCSRC).In the paper,it uses separate models to calculate and analyze.Considering the nonlinear constitutive relation of steel and concrete and determining the type of unit,it is shown that stress distribution and load-displacement curve of specimen under the effect of different parameters.According to the curve and data,analysis results of bearing capacity of specimen have been shown that bearing capacity of STCSRC will increase with concrete strength increasing and it also will increase with steel rate increasing under axial load.Because of core concrete working together with steel tube and angle steel,it can significantly improve the bearing capacity of composite columns, slow down and inhibit shearing inclined cracks occur in the core concrete and develop,and improve the ductility of columns.


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