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1
Content available remote Efektywność skrępowania betonu w grubościennych słupach typu Concrete - Filled Steel Tube o przekroju kołowym
Abramski Marcin, Korzeniowski Piotr, Kondrat Jarosław
Materiały Budowlane
|
2023
|
nr 10
1--5
PL
W słupach typu CFST w stanie granicznym dochodzi do zwiększenia wytrzymałości betonu rdzenia na skutek jego skrępowania. Zaistnienie tego zjawiska zależy od wielu czynników. Jednym z najważniejszych z nich jest sztywność obwodowa płaszcza stalowego. Jej wpływ na efektywność wzrostu wytrzymałości betonu rdzenia przebadano eksperymentalnie na grupie 48 grubościennych słupów CFST. Wykazano, że nadmierne zwiększanie grubości płaszcza słupa CFST nie przekłada się na wzrost jego nośności sprowadzonej. Jest wręcz przeciwnie: następuje jej spadek. Znacznie lepsze wykorzystanie pozytywnego wpływu skrępowania betonu rdzenia można osiągnąć z zastosowaniem rur cienkościennych niż grubościennych.
EN
In the limit state of the CFST columns, the core concrete strength increases due to its confinement. This positive effect depends on many factors. One of the most important is the ring stiffness of the steel tube. Its impact on the effectiveness of increasing the core concrete strength was experimentally tested on a group of 48 thick-walled CFST columns. It has been shown that an excessive increase in the tube thickness does not translate into an increase in its relative load capacity. On the contrary, it is decreasing. A much better use of the core concrete confinement can be achieved by using thin-walled tubes rather than thick-walled ones.
2
Content available Mechanical properties of CFST short columns with different void ratios
Song Junxi, Han Zhuowei, Wang Dawei, Lu Xiaorui
Archives of Civil Engineering
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2023
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Vol. 69, nr 3
587--596
EN
In order to study the mechanical behavior of concrete-filled steel tube(CFST) short column with different void ratios under a certain eccentricity. A fiber model of concrete-filled steel tube section with different void heights was established. Compared with existing model test data, the axial force and flexural moment strength models of concrete-filled steel tube columns with different void ratios were established. The results show that, in the case of different void ratios, the cross-section strength envelope shows an overall contraction tendency with the increase of void ratio, and each line is basically parallel. A model for calculating the coefficient of axial load degradation was established. The Han’s flexural moment strength model of the flexural component was revised, and the strength model of concrete-filled steel tube column under eccentric compression considering void ratio was established, which provides a theoretical basis and method for the safety assessment during the operation of concrete-filled steel tube arch bridges.
3
Content available remote Intelligent prediction methods for N–M interaction of CFST under eccentric compression
Hou Chao, Zhou Xiao-Guang, Shen Luming
Archives of Civil and Mechanical Engineering
|
2023
|
Vol. 23, no. 3
art. no. e197, 2023
EN
Machine learning (ML), as a promising artificial intelligence method, gradually begins to be applied in predicting the behavior of structural members and demonstrates its superior capability in capturing the nonlinear data laws between various structural parameters and the targeted capacity. For concrete-filled steel tube (CFST) under eccentric compression, the nonlinear material confinement and the unsymmetrical loading make the application of ML methods both challenging and appealing. In this study, a comprehensive literature review is conducted to gather data from 92 reported test programs, and an experimental database consisting of 899 eccentrically loaded circular CFST samples is established. Through structural behaviors and correlation analysis of the data, input parameters for the ML models are rationally identified. Prediction models are developed using seven single ML algorithms, two ensemble ML algorithms and two reference regression methods, with their predictions compared and explained by the shapely additive explanation (SHAP) approach. Based on Monte Carlo simulation, the uncertainty quantification of predicted capacities is conducted considering four degrees of randomness. The results reveal that extreme gradient boosting (XGBoost) yields the best prediction performance, providing less than 5% prediction errors for more than 58% samples. Compared with existing capacity calculation methods for CFST under eccentric compression in design standards, the established ML models exhibit higher accuracies and wider applicable ranges.
4
Content available remote A novel composite joint with corrugated web and cover plates for simultaneously improving anti‑collapse resistance and seismic behavior
Wang Jing-Xuan, Wang Wen-Qi, Gao Shan
Archives of Civil and Mechanical Engineering
|
2023
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Vol. 23, no. 2
art. no. e77, 2023
EN
This paper presents a numerical study on the progressive collapse response of concrete-filled steel tube (CFST) composite joint. A novel beam-column connection by using corrugated web and cover plate is proposed to enhance the collapse resistance of the joint. The simulated response is evaluated in terms of the ultimate load and deformation capacity of the joints for column removal scenario and cyclic loading. The results indicate that the corrugated web and cover plates connection can effectively delay the local buckling and fracture of the steel beam. Those configuration details have a significantly positive effect on the development of internal force, especially in the catenary mechanism stage to provide tensile force. Moreover, only after the fracture of the bottom fange, the corrugated web of the beam begins to contribute to the anti-collapse capacity of the joint. Compared with the CFST column-steel beam joint with fat beam web, the anti-collapse capacity and the vertical displacement of the joint are increased by 75.9% and 92.8%, respectively. Furthermore, a simplifed calculation method for the anti-collapse capacity of the joint is proposed according to the resistance mechanism analysis. In addition, the seismic evaluation of the novel joint based on anti-collapse design indicates that the novel connection details can signifcantly improve the collapse resistance of the joint, without impairing its seismic resistance.
5
Content available Performance of rubberized concrete-filled hollow steel column under monotonic and cyclic loadings
Mastor Muhammad Najmi Mohamad Ali, Kadir Mariyana Aida Ab, Zuhan Nurizaty, Mujedu Kasali Adebayo, Ramli Mohd Zamri, Jaya Ramadhansyah Putra, Noor Norhazilan Md, Shah Mohamad Syazwan Ahmad
Archives of Civil Engineering
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2022
|
Vol. 68, nr 1
519--538
EN
Concrete-filled hollow steel (CFHS) has become more popular due to its advantages and benefits compared to reinforced concrete. This paper presents the experimental investigation on the performance of rubberized pozzolanic concrete-filled hollow steel column (RuPCFHS) under monotonic and cyclic lateral load in comparison to bare hollow steel column and normal concrete-filled hollow steel column (NCFHS). The test parameters included the type of concrete infill and the level of axial load. Modified rubberized pozzolanic concrete with comparable compressive strength to that of normal concrete was used. Two types of axial load conditions: no axial load and 20% axial load were considered in the testing. The test results indicate that the performance of the columns improved when concrete infill was introduced in the hollow steel. The application of axial loading also increased the capacity of the column specimens. RuPCFHS behaved with comparable performance with NCFHS in both monotonic and cyclic testing. RuPCFHS recorded the highest increment in the energy dissipation capability when 20% axial load was applied to the column when compared to the other specimens. The comparable performance indicated the possibility of RuPC as an infill material of CFHS and RuPCFHS as a structural component.
6
Content available A study on RCFST column instability modes
Lu Zhengran, Guo Chao
Archives of Civil Engineering
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2022
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Vol. 68, nr 2
211--225
EN
In this work, the instability damage modes of yield state of a steel tube at the tension side of a rectangular steel tube-confined concrete (RCFST) column under eccentric compression were classified into two types based on the coupling effect of slenderness ratio (λ) and eccentricity ratio (γ). The two types include the unilateral compression yield failure mode with a smaller value of γ and tensile and compressive yield failure modes on both column sides with a larger value of γ. Further, the parametric analyses were performed by employing the finite element (FE) method and the analytical analysis to test 16 groups of RCFST columns by varying the γ value with different λ values. It was observed that the results of the analysis for the mechanical properties like the responses of load-strain (Ρ-ε) and RCFST column instability modes correlated well with the results obtained in the experiments. Furthermore, the proposed theoretical method could be used to investigate the roles of γ as a controller against the instability in RCFST columns when compared with λ.
7
Content available remote Analysis on axial compressive capacity of hybrid fiber cement-based composites encased CFST columns
Sun Linzhu, Wu Weiji, Li Wei
Archives of Civil and Mechanical Engineering
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2022
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Vol. 22, no. 4
art. no. e197, 2022
EN
In order to investigate the ultimate bearing capacity of hybrid fiber cement-based composite (HFC) encased concrete-filled steel tube (CFST) columns under axial compression. This study conducted theoretical analysis on HFC encased CFST columns. Theoretical formulas of the ultimate bearing capacity for the HFC encased CFST columns based on the elastoplastic theory and limit analysis method are presented. The calculated results of the theoretical formulas are compared with the experimental results and the values calculated by the typical codes. The results show that the theoretical models have high accuracy in predicting the ultimate bearing capacity of HFC encased CFST columns.
8
Content available Study on sling replacement of concrete-filled steel tube arch bridge
Zhang Kexin, Qi Tianyu, Xue Xingwei, Li Yanfeng, Zhu Zhimin
Archives of Civil Engineering
|
2021
|
Vol. 67, nr 2
597--610
EN
Concrete-filled steel tube arch bridge is filled with concrete inside the steel tube. The radial constraint of the steel tube limits the expansion of the compression concrete, which makes the concrete in the three-way compression state, thus significantly improving the compressive strength of the concrete. At the same time, it can simplify the construction process and shorten the construction period. Since the rapid development of concrete-filled steel tubular tied arch bridge in the 1990s, a large number of such Bridges have suffered from the defects of steel concrete, loose tie rod, and hanger rod rust, etc. Therefore, the reinforcement technology for various diseases has been studied, among which the reinforcement technology for hanger rod replacement is the most complicated and more difficult. As more and more bridges of this type enter the period of reinforcement, it is more and more urgent to study the reinforcement technology of suspenders. Taking a bridge that has been in service for 23 years as an example, this paper discusses the construction method and construction monitoring of replacing the suspender, so as to guide the construction monitoring of the bridge. Finally, the construction monitoring results of the bridge are given, which can provide reference for the replacement of the suspender of this type of bridge.
9
Content available Experimental behaviour of concrete-filled steel tube composite beams
Farhan Khawla A., Shallal Muhaned A.
Archives of Civil Engineering
|
2020
|
Vol. 66, nr 2
235--251
EN
The main objective of this study is to highlight the performance of beams composed of lightweight concrete-filled steel tubes (square and circle sections) composite with reinforced concrete deck slab. A total of nine composite beams were tested included two circular and seven square concrete-filled steel tubes. Among the nine composite beams, one beam, S20-0-2000, was prepared without a deck slab to act as a reference specimen. The chief parameters investigated were the length of the specimen, the compressive strength of the concrete slab, and the effect of the steel tube section type. All beams were tested using the three-point bending test with a concentrated central point load and simple supports. The test results showed that the first crack in the concrete deck slab was recorded at load levels ranging from 50.9% to 77.2% of the ultimate load for composite beams with square steel tubes. The ultimate load increased with increasing the compressive strength of the concrete slab. Shorter specimens were more stiffness than the other specimens but were less ductile. The slip values were equal to zero until the loads reached their final stages, while the specimen S20-55-1100 (short specimen) exhibited zero slip at all stages of the load. The ultimate load of the hollow steel tube composite beam was 13.2% lower than that of the reference beam. Moreover, the ductility and stiffness of the beam were also higher for beams with composite-filled steel tubes.
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