Investigation of the Axial Bearing Capacity of the Discontinuous-Tube-in-Core Concrete Filled Steel Tubular Column-Slab Joint

2008 ◽  
Vol 400-402 ◽  
pp. 901-910 ◽  
Author(s):  
Fu Jun Liu ◽  
Jian Cai
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Steel Tube ◽  
Working Mechanism ◽  
Engineering Applications ◽  
New Type ◽  
Cfst Columns ◽  
The Cost ◽  
Core Concrete

Based on the principle of restrained concrete, this paper presents a new-type concrete filled steel tubular column-slab joint. This new-type joint is characterized by keeping the concrete floor slab continuous while breaking the steel tube of the column for the joint, thus joining the slab and the concrete filled steel tubular(CFST) columns at the top and the bottom of the slab. The joint has the advantage of transferring loads dependably, constructing conveniently and saving on the cost. Three groups of experiments (21 specimens contained) were performed to test the safety of the joint and investigate its axial bearing capacity. The results show that the joint is dependable and feasible in engineering applications. In addition, this paper studies the working mechanism and mechanical properties of the joint under axial compression, discusses the factors to influence its axial bearing capacity, and finally brings out the formula of the joint’s bearing capacity under axial compression that adapts to engineering applications, which conservatively evaluate the result of the experiments.

scholarly journals Behavior of Concrete-Filled Steel Tube Columns Subjected to Axial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Pengfei Li ◽  
Tao Zhang ◽  
Chengzhi Wang
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Ultimate Load ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Plastic Behavior ◽  
Numerical Comparison ◽  
Reinforcing Bars ◽  
Concrete Filled Steel Tube ◽  
Cfst Columns

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.

scholarly journals A Study on Axial Compression Performance of Concrete-Filled Steel-Tubular Shear Wall with a Multi-Cavity T-Shaped Cross-Section

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4831
Author(s):  
Hao Sun ◽  
Qingyuan Xu ◽  
Pengfei Yan ◽  
Jianguang Yin ◽  
Ping Lou
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Limit State ◽  
Shear Wall ◽  
Steel Tube ◽  
Element Analysis ◽  
Compression Performance ◽  
The Core ◽  
Core Concrete

In order to study the axial compression performance of the T-shaped multi-cavity concrete-filled steel tube shear wall, first, three specimens were designed to perform the axial compression test. Then three-dimensional finite element analysis by the ABAQUS software was used to obtain the axial bearing capacity of the shear wall with different parameters. According to the results of the finite element model, the computational diagram in the limit state was obtained. The diagram was simplified into the core concrete in the non-enhanced area that was not constrained by the steel tube and the core concrete in the enhanced area that was uniformly constrained by the steel tube. Finally, a new practical equation for calculating the axial bearing capacity of a multi-cavity concrete-filled steel tubular shear wall was deduced and proposed based on the theory of ultimate equilibrium. The calculation results of the proposed equation were in good agreement with the finite element results, and the proposed equation can be used in practical engineering design.

scholarly journals Derivation of the unified equation of axial compression of CFST columns

2020 ◽  
Vol 143 ◽  
pp. 01004
Author(s):  
Ruoyang Zhou ◽  
Xiaoxiong Zha
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Limit Equilibrium ◽  
Concrete Columns ◽  
Steel Tube ◽  
Steel Reinforcement ◽  
Steel Plates ◽  
Steel Tubes ◽  
High Rise ◽  
Cfst Columns

The steel tube concrete columns with steel reinforcement cages, steel plates and steel tubes has been used in super high-rise buildings, which are called concrete-filled steel tubular (CFST) columns with internal stiffeners. Based on the theory of limit equilibrium, the unified equation for the axial bearing capacity of the CFST columns with internal stiffeners is obtained. The derived equation in this study can provide reference for the future engineering applications.

Slenderness Sensitivity Analysis of Thin-Walled Square Steel Tubular Columns Filled with Demolished Concrete Lumps

2021 ◽  
Vol 1163 ◽  
pp. 158-173
Author(s):  
Wei Wei Li ◽  
Hui Feng Zhang
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Design Method ◽  
Orthogonal Design ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Replacement Ratio ◽  
Factors Affecting ◽  
Cfst Columns ◽  
Slender Columns

The demolished concrete lumps (DCLs) have been demonstrated to replacement partial coarse aggregates when casting concrete. However, few studies had focused on the sensitivity of factors affecting mechanical behavior of slender square steel slender columns filled with DCLs and fresh concrete (FC) under axial compression. This research was carried out on the basis of Bo Wu's study. The Orthogonal design method was adopted in this experiment. The experimental studied involved 12 Concrete-Filled Steel Tube (CFST) columns. Each columns diameter was 159mm, the length of specimens was 2000, 2200 and 2400 mm. The Diameter-to-thickness (D/t) ratio was 79, 53 and 40. The replacement ratio of FC by DCLs was 0, 20, 40 and 60%. Test results indicated that the slenderness ratio was the most sensitive factor on the bearing capacity of slender columns under axial compression, followed by D/t ratio, and the DCLs replacement ratio was smallest factor. The ultimate bearing capacity decreased slightly with increasing DCL replacement ratio. The DCLs had slightly affect on the mechanical performances of slender CFST columns. the code CECS 28:2012 was used to calculate the bearing capacity of slender CFST columns filled with DCLs under axial compression.

scholarly journals Mechanism Study on the Axial Compressive Performance of Short Square CFST Columns with Different Stiffeners

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Bing Xu ◽  
Fahong Wu ◽  
Guizhong Xu
Keyword(s):  
Bearing Capacity ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Mechanism Study ◽  
Compression Performance ◽  
Compressive Performance ◽  
Combined Action ◽  
Cfst Columns ◽  
Distribution Of Stress ◽  
Core Concrete

In order to limit the disengaging of short square concrete-filled steel tube (CFST) columns and strengthen the combined action of steel tubes and concrete, a reinforcing method of stiffener is put forward in this paper. The axial compression performance and mechanism are studied through experiments, which indicate that (1) the buckling model of stiffening members changes into double wave, (2) stiffeners enforce the constraint in core concrete, (3) stiffeners can effectively improve the ultimate bearing capacity, (4) the stiffeners increase the stress in the middle of the steel tube and improve the distribution of stress for the core concrete, and (5) the direct ribs have more influence on the bearing capacity while ribs with holes have more impact on the deformation of the tube. At the end of the article, a formula for calculating the ultimate bearing capacity is presented, which can bring out a more accurate bearing capacity value.

Study on Ultimate Bearing Capacity of New Steel Composite Tube

2012 ◽  
Vol 482-484 ◽  
pp. 1472-1477
Author(s):  
Guo Ran Xing ◽  
Li Hua Dong
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Experimental Studies ◽  
Steel Tube ◽  
Loading Capacity ◽  
Composite Tube ◽  
Steel Composite ◽  
Ultimate Loading Capacity ◽  
Regressive Analysis

The main purpose of this paper is to research the mechanical properties of polyurethane filled steel tube PFST members with different hoop coefficients and slenderness ratios under axial compression by experimental studies. The influencing laws on stability, ductility and properties of axial compression of the PFST members are got, and the simplified calculating formula for ultimate loading capacity is presented by the regressive analysis.

Finite Element Analysis of Axially Loaded RPC Filled Circular Steel Tube Columns

2013 ◽  
Vol 815 ◽  
pp. 256-261 ◽  
Author(s):  
Zhan Hui Li ◽  
Zhi Gang Yan ◽  
Jun Yang ◽  
Hua Luo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Concrete Strength ◽  
Steel Tube ◽  
Element Analysis ◽  
Circular Steel Tube ◽  
Reactive Powder ◽  
Core Concrete

Further research on constitutive model of RPC (Reactive Powder Concrete) restrained by steel tube under axial compression is analyzed based on the research on concrete-filled steel tube and RPC-filled steel tube at home and abroad. Finite element analysis on RPC-filled steel tube stub columns under axial compression is conducted with ABAQUS to analyze the confinement index, core concrete strength and contact property on ultimate bearing capacity of RPC restrained by steel tube. As the confinement index and the core concrete strength increasing, the bearing capacity of RPC restrained by steel tube increases. The model with frictionless contact form has greater bearing capacity, but the ductility decreases.

scholarly journals Axial Behaviour of Slender RC Circular Columns Strengthened with Circular CFST Jackets

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yiyan Lu ◽  
Tao Zhu ◽  
Shan Li ◽  
Weijie Li ◽  
Na Li
Keyword(s):  
Bearing Capacity ◽  
Ductile Failure ◽  
Steel Tube ◽  
Experimental Results ◽  
Strengthening Effect ◽  
Load Bearing Capacity ◽  
Rc Columns ◽  
Load Bearing ◽  
Cfst Columns ◽  
Material Utilization

This paper investigates the axial behavior of slender reinforced concrete (RC) columns strengthened with concrete filled steel tube (CFST) jacketing technique. It is realized by pouring self-compacting concrete (SCC) into the gap between inner original slender RC columns and outer steel tubes. Nine specimens were prepared and tested to failure under axial compression: a control specimen without strengthening and eight specimens with heights ranging between 1240 and 2140 mm strengthened with CFST jacketing. Experimental variables included four different length-to-diameter (L/D) ratios, three different diameter-to-thickness (D/t) ratios, and three different SCC strengths. The experimental results showed that the outer steel tube provided confinement to the SCC and original slender RC columns and thus effectively improved the behavior of slender RC columns. The failure mode of slender RC columns was changed from brittle failure (concrete peel-off) into ductile failure (global bending) after strengthening. And, the load-bearing capacity, material utilization, and ductility of slender RC columns were significantly enhanced. The strengthening effect of CFST jacketing decreased with the increase of L/D ratio and D/t ratio but showed little variation with higher SCC strength. An existing expression of load-bearing capacity for traditional CFST columns was extended to propose a formula for the load-bearing capacity of CFST jacketed columns, and the predictions showed good agreement with the experimental results.

scholarly journals Research on Compression Behavior of Square Thin-Walled CFST Columns with Steel-Bar Stiffeners

2018 ◽  
Vol 8 (9) ◽  
pp. 1602 ◽  
Author(s):  
Zhao Yang ◽  
Chengxiang Xu
Keyword(s):  
Bearing Capacity ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Tubes ◽  
Compression Behavior ◽  
Steel Bar ◽  
Steel Bars ◽  
Thin Walled ◽  
Structural Measure ◽  
Cfst Columns

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns.

scholarly journals Buckling Analysis and Section Optimum for Square Thin-Wall CFST Columns Sealed by Self-Tapping Screws

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
He Zhang ◽  
Kai Wu ◽  
Chao Xu ◽  
Lijian Ren ◽  
Feng Chen
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Steel Plate ◽  
Local Buckling ◽  
Steel Tube ◽  
Thin Wall ◽  
Type Section ◽  
Plate Buckling ◽  
Thin Walled ◽  
Cfst Columns

Two columns of thin-walled concrete-filled steel tubes (CFSTs), in which tube seams are connected by self-tapping screws, are axial compression tested and FEM simulated; the influence of local buckling on the column compression bearing capacity is discussed. Failure modes of square thin-wall CFST columns are, first, steel tube plate buckling and then the collapse of steel and concrete in some corner edge areas. Interaction between concrete and steel makes the column continue to withstand higher forces after buckling appears. A large deflection analysis for tube elastic buckling reflects that equivalent uniform stress of the steel plate in the buckling area can reach yield stress and that steel can supply enough designing stress. Aiming at failure modes of square thin-walled CFST columns, a B-type section is proposed as an improvement scheme. Comparing the analysis results, the B-type section can address both the problems of corner collapse and steel plate buckling. This new type section can better make full use of the stress of the concrete material and the steel material; this type section can also increase the compression bearing capacity of the column.

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