scholarly journals The Horizontal Bearing Capacity of Composite Concrete-Filled Steel Tube Piles

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yunxiu Dong ◽  
Zhongju Feng ◽  
Haibo Hu ◽  
Jingbin He ◽  
Qilang Zhang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Soil Compaction ◽  
Soil Mass ◽  
Steel Tube ◽  
Continuous Increase ◽  
Concrete Filled Steel Tube ◽  
Concrete Piles ◽  
Compaction Zone ◽  
Reinforced Concrete Piles ◽  
Centrifugal Model

Steel casings (SCs) are extensively and increasingly used to stabilize the borehole wall in the construction of bridge pile foundations. Steel casings (SCs), together with reinforced concrete piles (RCPs), form composite concrete-filled steel tube piles (CCFSTPs), which differ significantly from ordinary RCPs in horizontal bearing capacity. In this study, based on the characteristics of CCFSTPs, the horizontal bearing capacity of a CCFSTP was examined through a centrifugal model test with the length of the steel casing (LSC) and the modulus of the soil mass in the steel casing soil compaction zone (ESCSC_zone) as variables. Pile-side soil resistance, load-displacement curves, and pile moment curves were obtained for the CCFSTP. The results show that increasing LSC within a range of 12 cm significantly increases the ultimate horizontal bearing capacity of the CCFSTP, and further increasing LSC beyond 12 cm produces a continuous increase in the ultimate horizontal bearing capacity of the CCFSTP but only to an insignificant extent. In addition, increasing ESCSC_zone increases the ultimate horizontal bearing capacity of the CCFSTP, but to a relatively small extent. The results of this study provide a theoretical basis and technical support for the design and construction of CCFSTPs.

scholarly journals Effect of Steel Casing on Vertical Bearing Characteristics of Steel Tube-Reinforced Concrete Piles in Loess Area

2019 ◽  
Vol 9 (14) ◽  
pp. 2874 ◽  
Author(s):  
Zhongju Feng ◽  
Haibo Hu ◽  
Yunxiu Dong ◽  
Fuchun Wang ◽  
Minghui Jia ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Steel Tube ◽  
Foundation Engineering ◽  
Loess Area ◽  
Concrete Piles ◽  
Concrete Pile ◽  
Tip Resistance ◽  
Reinforced Concrete Piles ◽  
Vertical Bearing ◽  
Centrifugal Model

This study aims at investigating the effect of steel casing on vertical bearing characteristics of steel tube-reinforced concrete piles in loess area by centrifugal model test. Five piles were selected, one of them was a conventional reinforced concrete pile which was 35 cm in length and 2.5 cm in diameter as a contrast pile, and the length of steel casing for the remaining four steel tube-reinforced concrete piles was 8 cm, 12 cm, 16 cm, and 20 cm respectively. The results show that the axial force, unit skin friction, tip resistance, and shaft resistance of steel tube-reinforced concrete piles with different steel casing lengths were different from conventional reinforced concrete pile. Additionally, the ultimate bearing capacity of steel tube-reinforced concrete piles was compared with a conventional reinforced concrete pile. Moreover, advantages of steel casing in pile foundation engineering were summarized. The results of this study can provide reference for vertical bearing characteristics of steel tube-reinforced concrete piles in loess area.

Bearing capacity of composite shear wall incorporating a concrete-filled steel tube boundary and column-type reinforced wall

2020 ◽  
Vol 23 (10) ◽  
pp. 2188-2203
Author(s):  
Zhao Nannan ◽  
Wang Yaohong ◽  
Han qing ◽  
Su Hao
Keyword(s):  
Bearing Capacity ◽  
Residual Deformation ◽  
Shear Walls ◽  
Shear Wall ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Composite Shear Wall ◽  
Boundary Shear ◽  
Column Type ◽  
Composite Shear

Composite shear walls are widely used in high-rise buildings because of their high bearing capacity. To improve the bearing capacity of ordinary shear walls, restraining elements are usually installed at both boundaries or within the wall body. In this article, two different restraining elements, namely, a rectangular steel tube and a column-type reinforcement (the whole wall body was restrained by segmented stirrups and tied by diagonal bars), were applied to the boundary frame and wall body of the shear wall either jointly or separately. A new type of steel-concrete composite shear wall, referred to as a composite shear wall incorporating a concrete-filled steel tube boundary and column-type reinforced wall, was proposed. In addition, three specimens with different restraining elements, namely, a column-type reinforced shear wall, a concrete-filled steel tube boundary shear wall and an ordinary reinforced concrete shear wall, were presented for comparison. The influences of the two different restraining elements on the seismic performance and bearing capacity of the shear walls were analyzed from four perspectives of failure mode, hysteresis behavior, stiffness and residual deformation, and the equivalent lateral pressures of the two restraining elements were calculated. Based on the plane-section assumption, expressions for the crack, yield, peak and ultimate bearing capacities were derived, and the effects of the two restraining elements on the peak and ultimate bearing capacities were considered. The results show that these two restraining elements significantly improved the bearing capacity of the shear wall specimens, and the concrete-filled steel tube restraining element was more effective than the column-type reinforced restraining element. Finally, the calculated values of the bearing capacity of the four different restraining elements of the shear wall specimens proposed in this article were in good agreement with the experimental values.

Study of the Ultimate Bearing Capacity of Concrete-filled Steel Tube K-Joints

2019 ◽  
Vol 23 (5) ◽  
pp. 2254-2262 ◽  
Author(s):  
Kaizhong Xie ◽  
Hongwei Wang ◽  
Jinhao Pang ◽  
Jianxi Zhou
Keyword(s):  
Bearing Capacity ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Concrete Filled Steel Tube

Axial behaviour of slender concrete-filled steel tube square columns strengthened with square concrete-filled steel tube jackets

2019 ◽  
Vol 23 (6) ◽  
pp. 1074-1086 ◽  
Author(s):  
Tao Zhu ◽  
Hongjun Liang ◽  
Yiyan Lu ◽  
Weijie Li ◽  
Hong Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Element Model ◽  
Steel Tube ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Filled Steel Tube ◽  
Experimental Parameters ◽  
Modified Formula

This article investigates the behaviour of slender concrete-filled steel tube square columns strengthened by concrete-filled steel tube jacketing. The columns were realised by placing a square outer steel tube around the original slender concrete-filled steel tube column and pouring strengthening concrete into the gap between the inner and outer steel tubes. Three concrete-filled steel tube square columns and seven retrofitted columns ranging from 1200 to 2000 mm were tested to failure under axial compression. The experimental parameters included three length-to-width ( L/ B1) ratios, three width-to-thickness ( B1/ t1) ratios and three strengths of concrete jacket (C50-grade, C60-grade and C70-grade). Experimentally, the retrofitted columns failed in a similar manner to traditional slender concrete-filled steel tube columns. After strengthening, the retrofitted columns benefitted greatly from the component materials, with their load-bearing capacity and ductility notably enhanced. These enhancements were mainly brought about by sectional enlargement and good confinement of concrete. A finite element model was developed using ABAQUS to better understand the axial behaviour of the retrofitted specimens. A parametric study was conducted, with parameters including the length of the column, thickness of the outer steel tube, strength of the concrete jacket, yield strength of the outer steel tube, thickness of the inner steel tube and strength of the inner concrete. Furthermore, the finite element model was adopted to study the behaviour of rust-damaged and post-fire slender concrete-filled steel tube square columns strengthened by square concrete-filled steel tube jacketing. A modified formula was proposed to predict the load-bearing capacity of retrofitted specimens, and the numerical results agreed well with the experiments and the finite element results of undamaged, rust-damaged and post-fire specimens. It could be used as a reference for practical application.

scholarly journals Axial Compression Performance of Square Thin Walled Concrete-Filled Steel Tube Stub Columns with Reinforcement Stiffener under Constant High-Temperature

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1098 ◽  
Author(s):  
Xuetao Lyu ◽  
Yang Xu ◽  
Qian Xu ◽  
Yang Yu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Bearing Capacity ◽  
Numerical Models ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Displacement Curve ◽  
Concrete Filled Steel Tube ◽  
Finite Element Software ◽  
Thin Walled

This study investigated the axial compressive performance of six thin-walled concrete-filled steel tube (CFST) square column specimens with steel bar stiffeners and two non-stiffened specimens at constant temperatures of 20 °C, 100 °C, 200 °C, 400 °C, 600 °C and 800 °C. The mechanical properties of the specimens at different temperatures were analyzed in terms of the ultimate bearing capacity, failure mode, and load–displacement curve. The experiment results show that at high temperature, even though the mechanical properties of the specimens declined, leading to a decrease of the ultimate bearing capacity, the ductility and deformation capacity of the specimens improved inversely. Based on finite element software ABAQUS, numerical models were developed to calculate both temperature and mechanical fields, the results of which were in good agreement with experimental results. Then, the stress mechanism of eight specimens was analyzed using established numerical models. The analysis results show that with the increase of temperature, the longitudinal stress gradient of the concrete in the specimen column increases while the stress value decreases. The lateral restraint of the stiffeners is capable of restraining the steel outer buckling and enhancing the restraint effect on the concrete.

Coupled bending-shear-torsion bearing capacity of concrete filled steel tube short columns

2018 ◽  
Vol 123 ◽  
pp. 305-316 ◽  
Author(s):  
Nie Xin ◽  
Wang Yu-Hang ◽  
Li Shuo ◽  
Chen Ju
Keyword(s):  
Bearing Capacity ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Short Columns

Optimal Calculation Method of Eccentric Bearing Capacity of Concrete-Filled Steel Tube Short Columns

2012 ◽  
Vol 238 ◽  
pp. 666-668
Author(s):  
Jian Wei Zhang ◽  
Xing Jie Kuang ◽  
Wei Feng Bai ◽  
Juan Wang
Keyword(s):  
Experimental Data ◽  
Bearing Capacity ◽  
Engineering Design ◽  
Calculation Method ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
Short Columns ◽  
Optimal Calculation

The currently formulae with many coefficients are too complicated to calculate the bearing capacity of concrete-filled steel tube (CFST) short columns. In this paper, an optimal calculation method was proposed for calculating the eccentric bearing capacity of CFST short columns by means of mechanical derivation. Additionally, the calculating results are compared with experimental data. It is shown that the optimal calculating formulae are highly accurate and easily applicable in engineering design.

Nonlinear Finite Element Analysis of Stiffened T-Shaped Thin-Walled Concrete-Filled Steel Tube Composite Columns

2012 ◽  
Vol 193-194 ◽  
pp. 1461-1464
Author(s):  
Bai Shou Li ◽  
Ai Hua Jin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bearing Capacity ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Element Analysis ◽  
Concrete Filled Steel Tube ◽  
Composite Columns ◽  
Short Columns ◽  
Thin Walled

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.

scholarly journals Bearing Capacity of Concrete-Filled Steel Tube Column Sections under Long-Term Loading

2019 ◽  
Vol 8 (10) ◽  
pp. 3530-3536
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Steel Tube ◽  
Design Methods ◽  
Contribution Ratio ◽  
Concrete Filled Steel Tube ◽  
Numerical Example ◽  
European Code

This article presents the design methods for concrete filled circular columns subjected to long-term axial compression and bending. . There are two approaches: stress-based and strain-based for formulations. Both approaches are specified in Russian Code, SP 266.1325800.2016, and in European Code, EN 1994-1-1:2004. A numerical example shows the procedures to calculate the strength of a given column according to two different Codes, the influence of parameters such as steel contribution ratio, relative slenderness to the results in two methods are consider.

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