scholarly journals BUCKLING OF SLENDER COMPOSITE CONCRETE‐FILLED STEEL COLUMNS

2010 ◽  
Vol 16 (2) ◽  
pp. 230-236 ◽  
Author(s):  
C. Douglas Goode ◽  
Artiomas Kuranovas ◽  
Audronis Kazimieras Kvedaras
Keyword(s):  
Bearing Capacity ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hollow Section ◽  
Steel Columns ◽  
Tubular Columns ◽  
Cylinder Strength ◽  
Experimental Values ◽  
Concrete Filled Steel Tubes

The paper presents the analysis of the experimental data of 1817 on concrete‐filled steel tubes ‐ CFSTs. These results are compared with the predicted results of the load‐bearing capacity of calculations of slender elements according to the methods suggested by Eurocode 4. The following types of tested CFSTs were analysed: circular and rectangular hollow section stub and long columns fully filled with concrete, which were with or without applied moments at the ends of specimen. During the results obtained in the result of the tests on the load bearing capacity for circular concrete‐filled steel tubular columns correspond with the calculated values based on methods presented by Eurocode 4. The experimental values of load bearing capacity for members of concrete‐filled rectangular hollow sections agree very well with the theoretical values where the concrete cylinder strength is below 75 N/mm2. The analysis demonstrated that preloading of concrete‐filled hollow section members does not influence the load bearing capacity. This paper also presents the examination of stress state distribution for concrete‐filled hollow section members, influence of concrete preloading and of longitudinal stress strain curves. Santrauka Straipsnyje aptariami 1817 betonšerdžiu plieniniu vamzdiniu strypu eksperimentiniai duomenys. Šie duomenys lyginami su rezultatais, gautais remiantis Eurocode 4 pateiktais kompozitiniu elementu laikomosios galios nustatymo metodais. Analizuojami tokie betonšerdžiu plieniniu strypu bandiniu tipai: pilnavidures trumpos arba liaunos apskritojo ir stačiakampio skerspjūvio vamzdines betonšerdes plienines kolonos su ju galuose veikiančiu lenkiamuoju momentu arba be jo. Apskritojo skerspjūvio betonšerdžiu kolonu bandymu metu gautieji laikomosios galios rezultatai atitinka remiantis Eurocode 4 pateiktais metodais apskaičiuotasias ju reikšmes. Stačiakampio skerspjūvio betonšerdžiu elementu laikomosios galios bandymais rastosios reikšmes labai gerai atitinka teorines reikšmes, kai šerdies betono ritininis stipris nesiekia 75 N/mm2. Analizuojant nustatyta, kad išankstinis betonšerdžiu elementu apkrovimas neturi beveik jokio poveikio elementu laikomajai galiai. Šiame straipsnyje taip pat nagrinejamas betonšerdžiu elementu itempiu būviu pasiskirstymas, betono apspaudimo poveikis bei išilginiu deformaciju ir itempiu kreives.

scholarly journals Numerical and Experimental Study on Deficient Short Steel Tubes Strengthened with CFRP Under Compression

2019 ◽  
Author(s):  
Mohammad Reza Ghaemdoust ◽  
Omid Yousefi ◽  
Kambiz Narmashiri ◽  
Masoumeh Karimian
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Local Buckling ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Columns ◽  
Repair Costs ◽  
The Impact

In view of development and repair costs, support of structures is imperative. Several factors, for example, design and calculation errors, absence of appropriate installation, change of structures application, exhaustion, seismic tremor, fire and natural conditions diminish their strength. In such cases, structures have need of rehabilitation and restoration to achieve their original performance. One of the most up to date materials for retrofitting is carbon fiber reinforced polymer (CFRP) that can provide an amount of restriction to postpone buckling of thin steel walls. This paper provides a numerical and experimental investigation on CFRP strengthened short steel tubes with initial horizontal and vertical deficiency under compression. Ten square and circular specimens were tested to study effects of the following parameters: (1) position of deficiency, horizontal or vertical; (2) tube shape, square or circular; (3) CFRP strengthening. In the experiments, axial static loading was gradually applied and for the numerical study three-dimensional (3D) static nonlinear analysis method using ABAQUS software was performed. The results show that deficiency reduces load-bearing capacity of steel columns and the impact of horizontal deficiency is higher than the impact of vertical deficiency, in both square and circular tubes. Use of CFRP materials for strengthening of short steel columns with initial deficiency indicates that fibers play a considerable role on increasing load bearing capacity, reducing stress at the damage location, preventing deformation caused by deficiency and delaying local buckling. Both numerical and experimental outcomes are in good agreement, which underlines the accuracy of the models adopted.

scholarly journals Behavior of the T-Shaped Concrete-Filled Steel Tubular Columns after Elevated Temperature

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Xianglong Liu ◽  
Jicheng Zhang ◽  
Hailin Lu ◽  
Ning Guan ◽  
Jiahao Xiao ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Failure ◽  
Element Model ◽  
Ultimate Bearing Capacity ◽  
Steel Tubes ◽  
Tubular Columns ◽  
Short Columns ◽  
Experimental Values

The mechanical properties of T-shaped concrete-filled steel tubular (TCFST) short columns under axial compression after elevated temperature are investigated in this paper. A total of 30 TCFST short columns with different temperature (T), steel ratio (α), and duration of heating (t) were tested. The TCFST column was directly fabricated by welding two rectangular steel tubes together. The study mainly investigated the failure modes, the ultimate bearing capacity, the load-displacement, and the load-strain performance of the TCFST short columns. Experimental results indicate that the rectangular steel tubes of the TCFST column have deformation consistency, and the failure mode consists of local crack, drum damage, and shear failure. Additionally, the influence of high temperature on the residual bearing capacity of the TCFST is significant, e.g., a higher temperature can downgrade the ultimate bearing capacity. Finally, a finite element model (FEM) is developed to simulate the performance of the TCFST short columns under elevated temperature, and the results agree with experimental values well. Overall, this investigation can provide some guidance for future studies on damage assessment and reinforcement of the TCFST columns.

Effect of Concrete-Filled in Chord Tubes on Mechanical Behavior of RHS Steel Tube Trusses

2010 ◽  
Vol 163-167 ◽  
pp. 2171-2175 ◽  
Author(s):  
Jun Ping Liu ◽  
Yong Jian Liu ◽  
Jian Yang
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Steel Tube ◽  
Structural Stiffness ◽  
Static Behavior ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Compression Load ◽  
Hollow Section ◽  
Joint Deformation

Based on the experimental results, this paper presents the effects of concrete-filled in chord on the static behavior of rectangular hollow section (RHS) steel tubular trusses, including failure modes, load bearing capacity and structural stiffness. Failure of RHS trusses occurs at joints wether concrete-filled in chord or not, concrete-filled in chord changed the failure mode. Load bearing capacity and stiffness of joints subjected to compression load increased significantly, while it is limited to the tension joints. Concrete-filled in the compression chord tube can increase its stiffness significantly, while tension chord tube, it is not that obvious. Finally, based on the results discussed, failure modes and their formulas of calculating the load bearing capacity are discussed. Meanwhile, two methods, that is, amplified factor method and stiffness discounting method, which calculate the structural displacement when considering the joint deformation effects are presented.

An Evaluation of Prestressed Stayed Steel Columns Load Bearing Capacity with Bayesian Neural Networks

2010 ◽  
Author(s):  
Araujo R. R. ◽  
Vellasco P. C. G. S. ◽  
Vellasco M. M. B. R. ◽  
Andrade S. A. L. ◽  
Lima L. R. O. ◽  
...  
Keyword(s):  
Neural Networks ◽  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Bayesian Neural Networks ◽  
Steel Columns

scholarly journals An Analytical Investigation of Modular Concrete-filled Square Steel Tubes based on the Strain Compatibility

2015 ◽  
pp. 424-431
Author(s):  
Seon-Chee Park ◽  
Won-Kee Hong ◽  
Hyo-Jin Ko
Keyword(s):  
Bearing Capacity ◽  
Analytical Methods ◽  
Design Method ◽  
Analytical Investigation ◽  
Design Codes ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Composite Tubes ◽  
Load Bearing ◽  
Strain Compatibility

Concrete-filled square steel tubes demonstrating good structural resistance against vertical and lateral loads can be used for modular constructions. To promote the applications of the composite tubes to modular construction, it is important to provide simple but accurate analytical methods that can elucidate the structural behaviour of the composite tubes. A number of international design codes are known to calculate the flexural load bearing capacity of the concrete-filled square steel tubes. Some, however, are not predicting the behaviour of the composite tubes accurately. An analytical investigation of concrete-filled square steel tubes was presented in this paper. A strain compatibility based design method considering confinement effect of concrete in tubes was proposed to estimate the flexural strength of composite steel tube filled with concrete. Nominal moment capacities estimated in accordance with the standards of AIJ(Japan), AISC(USA), Eurocode4(Europe) and KSSC(Korea) were compared with the analytical value obtained using the strain compatibility based design method. Since the design method with strain compatibility proposed in the study reflects the concrete confinement with accurate estimation of the neutral axis of composite tube section, the flexural moment capacity of composite tube section can be accurately obtained. The test results of other researchers including Lu and Kennedy were used to verify the reliability of the proposed design method. These experimental results were shown to be the best correlated with the analytical results provided by the proposed method in this paper than any other analytical methods proposed by the international codes that were used to calculate flexural load bearing capacity. The 6% of errors were demonstrated by the proposed approach while bigger errors were observed in the analytical calculations of other design codes as large as 17%.

scholarly journals Investigations into Structural Behavior of Concrete-Filled RHS Columns with Unequal Flange Thickness under Compressive Load

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5463
Author(s):  
Guangyuan Fu ◽  
Gongyi Fu ◽  
Siping Li ◽  
Jian Yang ◽  
Feiliang Wang
Keyword(s):  
Bearing Capacity ◽  
Wall Thickness ◽  
Numerical Models ◽  
Compressive Load ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hollow Section ◽  
Flange Thickness ◽  
Parametric Studies ◽  
Analytical Expressions

Previous studies have shown that components with an unequal-walled concrete-filled rectangular hollow section (CFRHS) can achieve a greater resistance under bending than those with equal-walled CFRHS. However, the study on the compressive behavior of the CFRHS column is limited. Therefore, this paper investigates the performance of compressed CFRHS columns with unequal flange thickness, based on experimental and numerical approaches. In the test, the effects of slenderness and eccentricity on the compressive capacity of the CFRHS columns with unequal shell thickness are discussed. Numerical models based on the finite element method are established, to evaluate the resistance and failure pattern of each specimen in the test. Parametric studies are carried out based on the validated model, to investigate the effect of eccentricity, wall thickness, and steel and concrete material properties on the load-bearing capacity of the compressed CFRHS column. In addition, the analytical expressions of the resistance of CFRHS columns with unequal wall thickness are derived, and the prediction values are validated through comparing with the test results. It is found that eccentric compressed columns with unequal-walled CFRHS have a similar load-bearing capacity and better ductility when compared with the equal-walled CFRHS.

scholarly journals Degradation of Axial Ultimate Load-Bearing Capacity of Circular Thin-Walled Concrete-Filled Steel Tubular Stub Columns after Corrosion

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 795 ◽  
Author(s):  
Fengjie Zhang ◽  
Junwu Xia ◽  
Guo Li ◽  
Zhen Guo ◽  
Hongfei Chang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Ultimate Load ◽  
Steel Tube ◽  
Parameter Analysis ◽  
Loading Test ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Thin Walled ◽  
Stub Columns

This work aimed to investigate the effects of steel tube corrosion on the axial ultimate load-bearing capacity (AULC) of circular thin-walled concrete-filled steel tubular (CFST) members. Circular thin-walled CFST stub column specimens were made of steel tubes with various wall-thicknesses. These CFST column specimens were subjected to an accelerated corrosion test, where the steel tubes were corroded to different degrees of corrosion. Then, these CFST specimens with corroded steel tubes experienced an axial static loading test. Results show that the failure patterns of circular thin-walled CFST stub columns with corroded steel tubes are different from those of the counterpart CFST columns with ordinary wall-thickness steel tubes, which is a typical failure mode of shear bulging with slight local outward buckling. The ultimate strength and plastic deformation capacity of the CFST specimens decreased with the increasing degree of steel corrosion. The failure modes of the specimens still belonged to ductile failure because of the confinement of outer steel tube. The degree of steel tube corrosion, diameter-to-thickness ratio, and confinement coefficient had substantial influences on the AULC and the ultimate compressive strength of circular thin-walled CFST stub columns. A simple AULC prediction model for corroded circular thin-walled CFST stub columns was presented through the regression of the experimental data and parameter analysis.

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