scholarly journals Evaluation of Damage Indices for Rectangular Concrete-filled Steel Tube Structures

2019 ◽  
Vol 19 (4) ◽  
pp. 170-184
Author(s):  
Minsheng Guan ◽  
Siying Lin ◽  
Hongbiao Du ◽  
Jie Cui ◽  
Taizhou Yan
Keyword(s):  
Comprehensive Evaluation ◽  
Selection Process ◽  
Slenderness Ratio ◽  
Damage Index ◽  
Steel Tube ◽  
Stiffness Ratio ◽  
Concrete Filled Steel Tube ◽  
Damage Indices ◽  
Drift Ratio ◽  
Secant Stiffness

Abstract The paper aims to select a simple and effective damage index for estimating the extent of damage of rectangular concrete-filled steel tube (RCFT) structures subjected to ground motions. Two experimental databases of cyclic tests conducted on RCFT columns and frames are compiled. Test results from the database are then used to evaluate six different damage indices, including the ductility ratio (μ), drift ratio, initial-to-secant stiffness ratio (DKJ), modified initial-to-secant stiffness ratio (Dms), energy coefficient (E), and the combined damage index (DPA) as a benchmark indicator. Selection criteria including correlation, efficiency, and proficiency are utilized in the selection process. The optimal alternative for DPA is identified on the basis of a comprehensive evaluation. The evaluations indicate that Dms previously proposed by some of the authors is the most appropriate substitution of DPA, followed by the drift ratio. For the case of the slenderness ratio less than or equal to 30, the same grades of relation between the investigated damage indices and the benchmark are observed. However, in the case of the slenderness ratio larger than 30, the drift ratio tends to be the optimal alternative. In most cases, μ is proved to be an inadequate replacement of DPA.

Predictions of residual carrying-capacities for fire and near-field blast-damaged reactive powder concrete-filled steel tube columns

2018 ◽  
Vol 9 (4) ◽  
pp. 525-553 ◽  
Author(s):  
Wanxiang Chen ◽  
Zixin Zhou ◽  
Huihui Zou ◽  
Zhikun Guo
Keyword(s):  
Carrying Capacity ◽  
Large Scale ◽  
Blast Resistance ◽  
Near Field ◽  
Theoretical Method ◽  
Steel Tube ◽  
Reactive Powder Concrete ◽  
Concrete Filled Steel Tube ◽  
Damage Indices ◽  
Reactive Powder

An approximate approach is developed to estimate the residual carrying-capacities of fire and near-field blast-damaged reactive powder concrete-filled steel tube columns. The single-degree-of-freedom model is employed to calculate the initial deflections of fire-damaged reactive powder concrete-filled steel tube columns subjected to axial and blast-induced transverse loads, and then a modified formula including double coefficient is further proposed to predict the ultimate resistance. Then, a series of blast-resistance and load carrying-capacity tests on six large-scale reactive powder concrete-filled steel tube columns are conducted to validate the suitability of theoretical method presented in this article. Blast tests demonstrate that the blast-resistances of reactive powder concrete-filled steel tube columns are more sensitive to fire durations than to scale distances. In addition, it is indicated that ISO-834 standard fire exposures cause significant degradations of material properties and have remarkable effects on the residual carrying-capacities of reactive powder concrete-filled steel tube columns. No local bucking and burst could be observed in the residual carrying-capacity tests; also, there are no visible hinge-like deformations in the mid-span area, and the excellent fire-resistances and blast-resistances of reactive powder concrete-filled steel tube columns are experimentally verified. Analytical results show that the predicted axial load capacities of six reactive powder concrete-filled steel tube columns are in good agreement with experimental data. All damage indices of the test specimens are within 0.8, meaning only minor to severe damage is done to the reactive powder concrete-filled steel tube column during fire and blast attacks, which is consistent with the test results.

scholarly journals Influence of Lateral Monotonic Loading Upon the Behaviour of Rubberized Concrete Filled Steel Tube

2020 ◽  
Vol 13 (5) ◽  
pp. 193-198
Author(s):  
Abdullah Al-Shwaiter ◽  
◽  
Hanizam Awang ◽  
Ziyad Al-Gaboby
Keyword(s):  
Slenderness Ratio ◽  
Axial Loading ◽  
Major Effect ◽  
Steel Tube ◽  
Monotonic Loading ◽  
Rubberized Concrete ◽  
Plastic Properties ◽  
Concrete Filled Steel Tube ◽  
Strength Capacity ◽  
Adopted Model

Using waste tyres as recycle material in the construction industry seems to be a good solution to the problem of waste management and landfill. The main purpose of this paper is to study the behaviour of rubberized concrete-filled steel tube (RuCFST) analytically for square and rectangular columns under lateral monotonic loading. Seventy-two prototypes modelled using ABAQUS 6.12-1 software with various variables, which are cross-section shape, rubber replacement as a percentage of natural aggregate, column length, sections slenderness ratio and the axial loading level. The results showed that the adopted model in elastic and plastic properties gives a good agreement between numerical and referenced experimental results. Moreover, increasing the rubber replacement percentage has no major effect on the columns’ capacity; meanwhile increasing the columns’ length lead to decrease the strength capacity dramatically. Furthermore, increasing the axial loading percentage leads to reduce the column lateral strength. Similarly, the columns’ capacity decreases with increasing the section slenderness ratio.

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.

scholarly journals Correlation between Flexural Crack and Impedance Signal of Circular Steel Tube Beam

2020 ◽  
Vol 20 (5) ◽  
pp. 225-231
Author(s):  
Jong-Won Lee
Keyword(s):  
Structural Characteristics ◽  
Damage Index ◽  
Steel Tube ◽  
Bending Stiffness ◽  
Structural Safety ◽  
Analysis Model ◽  
Damage Indices ◽  
Circular Steel Tube ◽  
Equivalent Bending Stiffness ◽  
Cracked Beams

It is necessary to develop a technique that can be used to estimate cracks, which indicates a typical type of damage, using sensors to achieve the structural safety of circular steel-tube structural members widely used in infrastructures. Impedance techniques have been actively investigated to detect local damage, such as cracks. The cracks were estimated by experimentally investigating the relationship between the cracks and impedance signals using a damage index. The aim of this study is to investigate the correlation between the change in impedance signal and the change in the analytically obtained equivalent bending stiffness of cracked beams owing to crack formation and propagation in a circular steel-tube beam. In other words, the impedance signal was measured while gradually inducing cracking in circular steel-tube cantilever beams, two damage indices were obtained, and the results were compared with the analytically obtained equivalent bending stiffness of cracked beams constructed using an energy method. It was found that a close correlation between both the damage index for the impedance signal and equivalent bending stiffness for the crack location and the size of each damage case existed. Based on this correlation, the structural characteristics of the current state of a structure can be evaluated more accurately using the damage estimation results, and the behavior of the structure can be predicted using the analysis model.

Simplified Model to Predict Load-Bearing Capacity of Concrete-Filled Steel Tubular Laced Column

2013 ◽  
Vol 405-408 ◽  
pp. 1041-1045 ◽  
Author(s):  
Lian Qiong Zheng ◽  
Shu Li Guo ◽  
Ji Zhong Zhou
Keyword(s):  
Bearing Capacity ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Simplified Model ◽  
Test Results ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Filled Steel Tube ◽  
Simplified Method ◽  
Equivalent Slenderness Ratio

A simplified method using an equivalent slenderness ratio was suggested to calculate load-bearing capacity of concrete-filled steel tubular laced column in this paper. The significant differences between compressive and tensile strengths of concrete-filled steel tube were considered. The comparisons between the predicted Nuc and the tested Nue showed that the predicted method gives generally good predictions of the test results.

The Practice of Concrete Filled Steel Tube Piers to Bridges: A Review

2013 ◽  
Vol 405-408 ◽  
pp. 1602-1605 ◽  
Author(s):  
Zhi Jing Ou
Keyword(s):  
Structural Design ◽  
Slenderness Ratio ◽  
Research Direction ◽  
Steel Tube ◽  
Future Research ◽  
Material Strength ◽  
Concrete Filled Steel Tube ◽  
Construction Methods ◽  
High Pier ◽  
Available Information

Due to the small section dimension, high compressive strength, large stiffness, and excellent deformation capacity, the use of concrete filled steel tube (CFST) piers is attractive, especially to high-pier and super-high-pier bridges located in mountains. This paper reviews available information concerning the application and development of CFST piers. Three bridge examples are then introduced, while the structural design and the construction methods of CFST column piers are described in detail. Furthermore, main parameters of CFST piers, such as slenderness ratio and material strength are concluded. Finally the future research direction of CFST column piers is viewed.

Experimental study on the fire resistance of concrete filled steel tube reinforced concrete (CFSTRC) column-RC beam frames

2021 ◽  
pp. 136943322110015
Author(s):  
Lei Xu ◽  
Yan-Hong Bao
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Fire Resistance ◽  
Failure Modes ◽  
Load Ratio ◽  
Steel Tube ◽  
Stiffness Ratio ◽  
Fire Load ◽  
Concrete Core ◽  
Concrete Filled Steel Tube

To reveal the temperature characteristics and mechanical properties of frame structures with concrete filled steel tube reinforced concrete (CFSTRC) columns under fire, the fire resistance of four planar frames consisting of CFSTRC columns and reinforced concrete (RC) beams subjected to ISO-834 standard fire was tested in this study. The test parameters included the column fire load ratio, beam fire load ratio, and beam-to-column linear stiffness ratio. In the test, the temperatures of the column, beam, and slab cross-sections in the joint and nonjoint zones were measured, and the fire resistance, beam and column deformation curves, and failure modes of the frame were investigated. The experimental results showed that the concrete volume was the main factor affecting the temperature distribution on each typical cross-section of the frame: the temperatures at the measuring points of the beam and column in the joint zone were significantly lower than the temperatures at the corresponding points in the nonjoint zone, and the concrete outside the steel tube significantly slowed the propagation of temperature to the steel tube and its concrete core. Hence, there was only a small loss of the bearing capacity of steel tube and the core concrete inside the steel tube. The column fire load ratio, beam fire load ratio, and beam-to-column linear stiffness ratio have obvious influences on the fire resistance: the larger the column fire load ratio or beam fire load ratio, the smaller the fire resistance; and the larger the beam-to-column linear stiffness ratio, the larger the fire resistance.

scholarly journals Bearing Behavior of H-Shaped Honeycombed Steel Web Composite Columns with Rectangular Concrete-Filled Steel Tube Flanges under Eccentrical Compression Load

2022 ◽  
Vol 2022 ◽  
pp. 1-21
Author(s):  
Jing Ji ◽  
Chenyu Yu ◽  
Liangqin Jiang ◽  
Jiedong Zhan ◽  
Hongguo Ren ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Bearing Capacity ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Full Scale ◽  
Fe Model ◽  
Statistical Regression ◽  
Concrete Filled Steel Tube ◽  
Compression Load ◽  
Composite Columns

In order to investigate the bearing capacity of H-shaped honeycombed steel web composite columns with rectangular concrete-filled steel tube flanges (STHCCs) subjected to eccentrical compression load, 33 full-scale STHCCs were designed with the eccentricity(e), the slenderness ratio (λ), the cubic compressive strength of concrete(fcuk), the thickness of the steel tube flange (t1), the thickness of honeycombed steel web (t2), diameter-depth ratio (d/hw), space-depth (s/hw), and the yield strength of the steel tube (fy) as the main parameters. Considering the nonlinear constitutive model of concrete and simplified constitutive model of steel, the finite element (FE) model of STHCCs was established by ABAQUS software. By comparison with the existing test results, the rationality of the constitutive model of materials and FE modeling was verified. The numerical simulation of 33 full-scale STHCCs was conducted, and the influence of different parameters on the ultimate eccentrical compression bearing capacity was discussed. The results show that the cross-sectional stress distribution basically conforms to the plane-section assumption. With the increase in e, λ, and d/hw, the ultimate eccentrical compression bearing capacity of the full-scale STHCCs decreases, whereas it gradually increases with the increase in fcuk, t1, t2, s/hw, and fy. By introducing bias-stress stability coefficient (φ), the calculation formula of full-scale STHCCs under eccentrical compression is proposed by statistical regression, which can lay a foundation for the popularization and application of these types of composite columns in practical engineering.

scholarly journals A Simple Formula for Prediction of Compressive Strength of Square CFT Columns

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Muhammad Aun Bashir
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Composite Structures ◽  
Slenderness Ratio ◽  
Steel Tube ◽  
Experimental Results ◽  
Simple Equation ◽  
Material Strength ◽  
Concrete Filled Steel Tube ◽  
Short Columns

Concrete filled steel tube structures are becoming very popular in the modern civil engineering projects. Studying composite structures is useful, since it is an innovative and contemporary way to build structures. This type of structure has the ability to use respective strength of both steel and concrete due to confinement. Prefabrication of steel tube section is beneficial, and allows rapid installation into main structure. It also reduces the assembly cost and construction time. This paper will present the simple equation to predict the compressive strength of square concrete filled steel tube by using Finite Element Analysis (FEA)based software ABAQUs. In this study, 3D non-linear finite element models of short square composite columns were prepared using ABAQUS. The results were compared with published experimental tests of a concrete filled steel tube short columns. After getting the good agreement with the experimental results, a simple equation for the prediction of compressive strength is presented by considering the width to thickness ratio of steel tube. Results are validated with experimental results. The equation can predict the compressive strength only for the given material strengths and in future, the simple equation can be improved by considering different parameters e.g. material strength, slenderness ratio and end conditions.

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