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1

Efektywność skrępowania betonu w grubościennych słupach typu Concrete - Filled Steel Tube o przekroju kołowym

Abramski Marcin, Korzeniowski Piotr, Kondrat Jarosław

Materiały Budowlane

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2023

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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

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

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

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2023

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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

Experimental and numerical investigation on punching shear behavior of an enhanced embedded column base for CFSTs

Tan Shasha, Guo Lanhui, Jia Chen

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e157, 2023

EN

To improve the punching shear resistance, an enhanced embedded column base for concrete-filled steel tubes has been proposed, where a pair of strengthening beams are installed on the embedded region of the steel tube by the diaphragm plates. Punching tests were first conducted on eight specimens to investigate the working mechanism of this kind of column base. The test parameters included the length and embedded depth of the strengthening beam. The test results indicated that the punching shear section initiated from the diaphragm plate, which enlarged the punching cone and improved the punching shear resistance. The numerical modelling was also performed. First, finite element models were established and validated against the test results. Full-scale models were then developed to conduct the parametric studies and enrich the database. Finally, a calculation method to evaluate the punching shear resistance of the enhanced embedded column base was proposed and validated. This calculation method takes into account the bonding force, the resistance of the concrete and stirrups on the critical section, and the contribution of the diaphragm plates and strengthening beams.

5

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

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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

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.

7

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

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2021

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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.

8

Experimental behaviour of concrete-filled steel tube composite beams

Farhan Khawla A., Shallal Muhaned A.

Archives of Civil Engineering

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2020

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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.

9

Experimental behaviour of steel tubular columns for varying in filled concrete

Sangeetha P., Senthil R.

Archives of Civil Engineering

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2017

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Vol. 63, nr 4

149--160

EN

This paper investigates the behaviour of axially-loaded tubular columns filled with M20 grade concrete and partially replaced concrete. The parameters varying in the study are slenderness ratio (13.27, 16.58 & 19.9), and normal M20 grade concrete, partially replaced quarry dust and concrete debris. The effects of the various concrete mixes and composite action between the steel tube and the concrete core are studied and a graph visualizing the differences between the load carrying capacity and the axial deflection is plotted. Some of the performance indices like the Ductility Index (DI), Concrete Contribution Ratio (CCR), Confinement Index (θ) and Strength Index (SI) are also evaluated and compared amongst the CFST columns. From the results it has been noted that an increase in the L/D ratio decrease the behaviour of the composite columns irrespective of the in filled materials. The composite action was achieved in the CFST columns filled with partially replaced quarry dust and concrete debris when compared with hollow steel columns. The load carrying capacity of the CFST column increases by 32 % compared with the hollow tubular columns.

PL

Stalowe słupy rurowe wypełnione betonem (CFST) są wykorzystywane do różnorodnych zastosowań, takich jak filary mostów, które są stale narażone na oddziaływanie ruchu ulicznego, słupy obsługujace zbiorniki magazynowe, pokłady kolejowe, pale oraz słupy stosowane w wysokich budynkach. Ze względu na zwiększone wykorzystanie tego rodzaju słupów zespolonych, zainteresowanie zachowaniem tego typu słupów przyczyniło się do przeprowadzenia wielu badań teoretycznych i eksperymentalnych. Chociaż słupy CFST nadają się do wykorzystania w wysokich budynkach na obszarach sejsmicznych, ich zastosowanie zostało ograniczone z powodu braku informacji o prawdziwej wytrzymałości i nieelastycznym zachowaniu CFST. Główną zaletą betonu w CFST jest to, że opóźnia on lokalne wyboczenie ściany rury i samego betonu, w umiarkowanym stanie, a zatem jest w stanie utrzymać większe obciążenia i naprężenia niż w stanie nieumiarkowanym. W niniejszej pracy zbadano zachowanie słupów rurowych obciążonych osiowo, wypełnionych betonem klasy M20 i częściowo zastąpionym betonem. Badaniu poddano łącznie 12 próbek, w celu zbadania zachowania stalowych słupów rurowych wypełnionych betonem przy różnym wypełnieniu. Parametry zróżnicowane w badaniu są współczynnikiem smukłości (13,27, 16,58 i 19,9) i betonem standardowej klasy M20, częściowo zastąpionym pyłem z kamieniołomu i odłamkami betonu. Badano wpływ różnych działań betonowych i kompozytowych w rurze stalowej i rdzeniu betonowym, a ponadto sporządzono wykres obciążenia i ugięcia osiowego. Niektóre wskaźniki wydajności, takie jak Wskaźnik Plastyczności (DI), Współczynnik Udziału Betonu (CCR), Wskaźnik Zamknięcia (θ) oraz Wskaźnik Wytrzymałości (SI) zostały również poddane ocenie i porównane z słupami CFST. Na podstawie wyników stwierdzono, że wzrost wskaźnika L/D ogranicza działanie słupów zespolonych, niezależnie od wypełnionych materiałów. Złożone działanie osiągnięto w słupach CFST wypełnionych częściowo wymienionym pyłem z kamieniołomu i odłamkami betonu, w porównaniu z pustymi stalowymi słupami. Wykorzystanie odłamków betonu i pyłu z kamieniołomu doprowadziło do poprawy zachowania konstrukcji słupów zespolonych poddanych obciążeniu osiowemu, w porównaniu do pustych stalowych słupów. Zwiększenie wytrzymałości w przypadku słupów CFST zależy od wytrzymałości na ściskanie wypełnionego betonu oraz od wskaźnika zamknięcia. Nośność słupa CFST wzrasta o 32% w porównaniu z pustymi słupami rurowymi, niezależnie od wypełnienia betonem. Wykorzystanie kruszywa pochodzącego z recyklingu w stalowych kolumnach rurowych jest nie tylko techniką utylizacji odpadów, lecz zmniejsza także koszt wypełnienia betonem.

10

Utilization of artificial neural networks to prediction of the capacity of CCFT short columns subject to short term axial load

Ahmadi M., Naderpour H., Kheyroddin A.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 3

510--517

EN

Due to high strength and ductility, concrete filled steel tube columns have been highly regarded in recent decades and many experimental studies have been carried out in predicting the strength of these columns. Increase in compressive strength of concrete core by the lateral confinement provided by steel tube and delay of the steel local buckling by the contact with the hardened concrete are effective parameters in behavior of concrete filled steel tubes. This study presents a new approach to predict the capacity of circular concrete filled steel tube columns under axial loading condition, using a large number of experimental data by applying artificial neural networks. The effects of yield stress and wall thickness of steel tube, compressive strength of concrete and dimensions of column are examined. Proposed equation is compared with other existing models and indicates that the new model can predict the ultimate strength of axially loaded columns by a high level of precision.

11

Wzrost nośności słupów zespolonych stalowo-betonowych w porównaniu z żelbetowymi

Kupina M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2010

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z. 96

51-52

EN

Concrete-filled steel tubular (CFST) columns are being widely used in buildings and bridges due to their excellent structural performance such as high strength, high stiffness, high ductility and strain energy absorption capacities.

12

Finite element analysis on the flexural behaviour of concrete filled steel tube beams

Arivalagan S., Kandasamy S.

Journal of Theoretical and Applied Mechanics

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2010

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Vol. 48 nr 2

505-516

EN

Concrete-filled steel tube (CFST) beams are studied and verified by the Finite Element program ANSYS against experimental data. In the nu- merical analysis, the cross sections of the CFST are square steel sections, and sections strengthened by being filled with normal mix concrete and quarry waste concrete. Numerical analyses have shown that for square CFST a good confining effect can be provided. This effect is enhanced especially by the filling.

PL

W pracy przedstawiono analizę porównawczą wyników eksperymentalnych i otrzymanych z metody elementów skończonych (ANSYS) w odniesieniu do kolumn zbudowanych ze stalowych rur wypełnionych betonem (CFTS). Analizę numeryczną przeprowadzono dla kolumn o przekroju kwadratowym wzmacnianym normalną mieszanką betonową oraz betonem zawierającymodpady z kamieniołomu. Rezultaty symulacji numerycznych pokazały, że dla kolumn CFTS o przekroju kwadratowym uzyskuje się dobry efekt wzmocnienia wynikający z wypełnienia.