ULTIMATE STRENGTH OF CONCRETE FILLED SQUARE STEEL TUBULAR BEAM-COLUMNS

Author(s):  
Masayuki Haraguchi ◽  
Masae Kido ◽  
Keigo Tsuda

The objective of this study is to examine the ultimate strength of CFT columns. The range of the axial load ratio and the slenderness ratio in which CFT beam-columns reach the full plastic moment are examined on the basis of the strength formulas specified by AIJ Recommendation for Limit State Design of Steel Structures. The CFT columns are subjected to the constant axial compressive force and the monotonic moment at the one end, as the analytical parameters the axial load ratio and slenderness ratio are selected. The analysis is carried out by the shooting method. Bending moment-rotational angle relationships are calculated by the shooting method and the maximum strengths of CFT columns are obtained. When the value obtained by multiplying the axial load ratio and the second power of the slenderness ratio is 0.05, the maximum strength reach 95% of the full plastic moment under the condition that the axial load ratio value is less than or equal to 0.75. When the value obtained by multiplying the axial load ratio and the second power of the slenderness ratio is 0.1, the maximum strength reach 95% of the full plastic moment under the condition that the axial load ratio value is less than or equal to 0.5.

2019 ◽  
Vol 23 (5) ◽  
pp. 969-978
Author(s):  
Jian-gang Wei ◽  
Jun Zhou ◽  
Jiang-nan Huang ◽  
Hui-hui Yuan ◽  
Qing-wei Huang

This article experimentally investigates the cyclic behavior of ultra high performance concrete–filled steel tube beam-columns. A total of eight specimens were tested. The considered parameters were the axial load ratio and steel ratio. The results showed that all ultra high performance concrete–filled steel tube beam-columns had a very good cyclic behavior without significant pinching. Increasing the axial load ratio results in the decrease of strength and ductility, but it has no obvious influence on the initial flexural stiffness. Reducing the steel ratio results in the decrease of the strength, stiffness and ductility, and energy dissipation capacity.


Author(s):  
Nan Lu ◽  
Weibin Li

This study was organized to derive simplified expressions to estimate the effective flange width for T-shaped shear walls at different loading stages. For that purpose, the variation in the effective flange width was explored by introducing dimensionless effective flange width coefficient. According to the principle of minimum potential energy, the theoretical expression of the effective flange width coefficient in the elastic stage was obtained. Furthermore, a parametric study considering the axial load ratio, height-width ratio of flange and width-thickness ratio of the flange, as well as the section aspect ratio was conducted to determine the effective flange width using verified nonlinear finite-element models. In light of the parametric analysis results, a formula model was proposed depending on the axial load ratio and height-width ratio of flange. Finally, the predictions of the proposed simplified formulas were verified with the theoretical solutions or finite element (FE) results, which indicated that the proposed formulas can accurately capture the effective flange width at the elastic, yield and limit state.


2012 ◽  
Vol 166-169 ◽  
pp. 1746-1751
Author(s):  
Kai Ze Ma

Based on the experimental results of twenty three high strength concrete-filled square steel tubular (HCFT) columns subjected to cyclic lateral load, the restoring force model of square HCFT columns is established. Through theoretical analysis and experimental results, the main parameters of the restoring force model which are axial load ratio, confinement effect coefficient as well as slenderness ratio are discussed. The theoretical method is put forward. The results show that the relation of elastic stiffness to degraded stiffness, the relation of ultimate bearing capacity to yielding loads are proportional with confinement effect coefficient, and inversely with axial load ratio as well as slenderness ratio. Many various influential factors are considered in the restoring force model of square HCFT columns. The model is close to the experimental results which can be conveniently applied for nonlinear dynamics analysis of composite structures.


2013 ◽  
Vol 376 ◽  
pp. 231-235
Author(s):  
Cheng Li ◽  
Yun Zou ◽  
Jie Kong ◽  
Zhi Wei Wan

Nonlinear numerical analysis for the force performance of frame middle joint is processed in this paper with the finite element software of ABAQUS. Compared with experimental results, numerical analysis results are found to be reasonable. Then the influence of factors such as shaped steel ratio and axial-load ratio are contrastively analyzed. The results show that shaped steel ratio has a greater influence on the bearing capacity and hysteretic performance of the structure, but the axial-load ratio has less influence.


2014 ◽  
Vol 578-579 ◽  
pp. 936-939 ◽  
Author(s):  
Qian Qian Sun ◽  
Yun Zou ◽  
Qiang Wang

Nonlinear numerical analysis of the stress performance of SRC-RC transfer columns was carried out in this paper with the finite element software of ABAQUS. Compered with the experimental result , numerical analysis result are found to be reasonable.Then the influence of factors such as extension length of shape steel , area ratio of shape steel and axial-load ratio were contrastively analyzed . The results show that extension length of shape steel and the area ratio of shape steel have a greater influence on the bearing capacity and the hysteretic performance of transfer column ,but axial-load ratio has less influence .


2011 ◽  
Vol 243-249 ◽  
pp. 149-155 ◽  
Author(s):  
Zhe Li ◽  
Shao Ji Chen ◽  
Ye Ni Wang ◽  
Cui Ping Zhang ◽  
Jing Xu

The neutral axis change along with axial load ratio, load angle, section size etc. For the neutral axis of SRCLSC(steel reinforced concrete L-shaped column) is neither plumb with the plane that the moment work on, nor parallel with borderlines of SRCLSC section, it is difficult to get loading capacity and ductility of SRCLSC on biaxial eccentric loading. Based on the plane-section assumption, a method for the nonlinear analysis of complete response process for ductility of 15 SRCLSC..It include 36 sets for load angle, 6 sets for axial load ratio, 3 sets for concrete strength, 3 sets for the content of steel, 2 sets for steel style, 3 sets for stirrup ratio, 3 sets for steel location, 3 sets for section size, 3 sets for stirrup diameter about SRCLSC. The ductile behavior of L-shaped, with calculating 1068 loading conditions,are investigated. It concluded that axial load ratio, load angle, and ratio of the spacing of stirrups and longitudinal reinforcement’s diameter (s/d) are most important factors.


Author(s):  
Haruna Utsunomiya ◽  
Masayuki Haraguchi ◽  
Masae Kido ◽  
Keigo Tsuda

In the design of slender steel beam-columns, the moment amplification factor is used to estimate the maximum moment along with the longitudinal direction. While formulas for evaluating the factor have been presented on the basis of elastic or elastic-plastic analysis, the initial deflection of the column is not considered. The effect that the initial deflection on the strength and behavior of the column has been shown only when the initial deflection shape is half sine wave. This paper discusses the effect of the initial deflection shape on the value of the moment amplification factor by performing the analytical work. The analytical model is the hinged-end beam-column subjected to constant axial compressive force and end moments. First of all, the equilibrium differential equation which governs the problem is solved and the formula for calculating the bending moment is presented. In the parametric study, magnitude of initial deflection, initial deflection shape, axial load ratio, slenderness ratio and end moment ratio are selected as the parameters. In this paper, we discuss the effects of the amount of the initial deflection and the initial deflection shape.


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