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.

On the Stability Capacity of Steel Tube Filled with Steel-Reinforced Concrete Column Subject to Axial Compression

2012 ◽  
Vol 490-495 ◽  
pp. 3177-3181
Author(s):  
Xiao Liu ◽  
Lei Zhao
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Energy Method ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Least Square ◽  
Stability Coefficient ◽  
Steel Reinforced Concrete ◽  
Axial Stability

Steel tube filled with steel-reinforced concrete (STSRC) is a new kind of heavy load column, which made by inserting steel skeletons into the steel tube, then injecting the concrete to the tube. In order to study the combined column’s stability subject to axial compression, we use energy method and numerical methods analysis derives the formula of stability coefficient in which slenderness ratio as the main parameters. Using the 1/1000 column length as the initial deflection of the STSRC columns by FORTUNE calculation program, stability coefficient is produced through comparison and analysis between calculated results from quantile regression and that from ordinary least square regression respectively. According to the computer results and energy method, the formula for calculating the axial stability bearing capacity of STSRC was established. A good agreement between the calculation results and testing results illustrates, which is feasible to using the calculating formula to calculate the bearing capacity of STSRC

scholarly journals Experimental Study of H-Shaped Honeycombed Stub Columns with Rectangular Concrete-Filled Steel Tube Flanges Subjected to Axial Load

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Jing Ji ◽  
Maomao Yang ◽  
Zhichao Xu ◽  
Liangqin Jiang ◽  
Huayu Song
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Axial Load ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Design Guidelines ◽  
Correction Function ◽  
Concrete Filled Steel Tube ◽  
Load Displacement ◽  
Stub Columns

The behavior of H-shaped honeycombed stub columns with rectangular concrete-filled steel tube flanges (STHCCs) subjected to axial load was investigated experimentally. A total of 16 specimens were studied, and the main parameters varied in the tests included the confinement effect coefficient of the steel tube (ξ), the concrete cubic compressive strength (fcu), the steel web thickness (t2), and the slenderness ratio of specimens (λs). Failure modes, load-displacement curves, load-strain curves of the steel tube flanges and webs, and force mechanisms were obtained by means of axial compression tests. The parameter influences on the axial compression bearing capacity and ductility were then analyzed. The results showed that rudder slip diagonal lines occur on the steel tube outer surface and the concrete-filled steel tube flanges of all specimens exhibit shear failure. Specimen load-displacement curves can be broadly divided into elastic deformation, elastic-plastic deformation, and load descending and residual deformation stages. The specimen axial compression bearing capacity and ductility increase with increasing ξ, and the axial compression bearing capacity increases gradually with increasing fcu, whereas the ductility decreases. The ductility significantly improves with increasing t2, whereas the axial compression bearing capacity increases slightly. The axial compression bearing capacity decreases gradually with increasing λs, whereas the ductility increases. An analytical expression for the STHCC short column axial compression bearing capacity is established by introducing a correction function ( w ), which has good agreement with experimental results. Finally, several design guidelines are suggested, which can provide a foundation for the popularization and application of this kind of novel composite column in practical engineering projects.

Experimental Study on the Effect of Steel-Tube Replacement Ratio on the Eccentric Compression Bearing Capacity of Composite Column

2011 ◽  
Vol 415-417 ◽  
pp. 1421-1426
Author(s):  
Xu Hong Zhang ◽  
Quan Quan Guo
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Test Results ◽  
Replacement Ratio ◽  
Composite Columns ◽  
Eccentric Compression ◽  
Improvement Effect

The improvement effect of the external concrete to stability of the core steel-tube was demonstrated by the steel-tube replacement ratio through experimental study. The test results show that, with the steel-tube replacement ratio increasing, the ultimate bearing capacity of composite columns increased correspondingly, and the ductility of composite columns was improved obviously also. Therefore, the steel-tube replacement ratio should be involved in the formula for calculating the ultimate bearing capacity of composite columns. By finite element method and regression analysis, the slenderness ratio is amended by the steel-tube replacement ratio and the calculation results of the eccentric compression bearing capacity agreed well with the test results．

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 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.

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.

Finite Element Simulation on Behavior of the High-Strength Concrete Filled High-Strength Square Steel Tube Middle-Long Columns under Axial Compressive Load

2014 ◽  
Vol 578-579 ◽  
pp. 340-345
Author(s):  
Guo Chang Li ◽  
Bo Wen Zhu ◽  
Yu Liu
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Slenderness Ratio ◽  
High Strength ◽  
Steel Tube ◽  
New Combination ◽  
Length Variation ◽  
Compression Process ◽  
Strength Concrete ◽  
Square Steel Tube

In this paper, using ABAQUS, 16 high-strength concrete filled high-strength square steel tube middle-long columns’ axial compression process were simulated. The load-deflection relationships were obtained and the new combination in improving the bearing capacity and plastic deformation has a great advantage. Realization of length variation slenderness ratio by changing the length of column, this paper also study the influence of slenderness ratio, the main parameters of the high-strength concrete filled high-strength square steel tube middle-long column. It is found that both bearing capacity and the plastic capacity are associated with slenderness ratio.

Study on the Behaviors of Steel Reinforced Concrete Cloumns

2011 ◽  
Vol 368-373 ◽  
pp. 248-252
Author(s):  
Bao Sheng Yang ◽  
Yun Yun Li
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Compression Ratio ◽  
High Strength Concrete ◽  
Seismic Behavior ◽  
Slenderness Ratio ◽  
High Strength ◽  
Concrete Columns ◽  
Axial Compression Ratio ◽  
High Strength Concrete Columns

The influence on columns behaviors of slenderness ratio are analyzed, and the influence on columns’ anti-seismic behavior of axial compression ratio, stirrup ratio and steel form are analyzed through the test on bearing capacity and level load of low cycle reverse of steel reinforced high-strength concrete columns. The bearing capacity of the long columns reduces along with the slenderness ratio increasing and augments along with concrete strength increasing. Probability of suddenly destruct increases along with the column slenderness ratio augmenting through the test. In addition, anti-seismic behavior of columns are effected not only axial compression ratio, but also steel form. Axial compression coefficien of the steel reinforced high-strength concrete columns with different steel form may be adjusted, however, the influence of stirrup ratio is very little on anti-seismic behavior of columns.

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.

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