scholarly journals Investigation of the effect of impact load on concrete-filled steel tube columns under fire

2020 ◽  
Vol 14 (54) ◽  
pp. 317-324
Author(s):  
Ali Golsoorat Pahlaviani ◽  
Ali Mohammad Rousta ◽  
Peyman Beiranvand
Keyword(s):  
Impact Load ◽  
High Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Lateral Impact ◽  
Concrete Filled Steel Tube ◽  
Axial Strength ◽  
High Rise ◽  
Working Space ◽  
Cfst Columns

Concrete-filled steel tube (CFST) columns are increasingly used in the construction of high-rise buildings which require high strength and large working space especially at lower stories. As compared to reinforced concrete columns, existence of the exterior steel tube not only bears a portion of axial load but also most importantly provides confinement to the infill concrete.with the confinement provided by the steel tube, axial strength of the infill concrete can be largely enhanced.this paper presents the investigation effect of impact load on concrete-filled steel tube columns under fire by numerical simulations using ABAQUS software.the results indicate that the CFST sections with larger confinement factor ξ=1.23 behaved in a very ductile manner under lateral impact. And the sections with smaller confinement factor ξ=0.44  generally behaved in a brittle mechanism.

scholarly journals Prediction of axial strength in circular steel tube confined concrete columns using artificial intelligence

2021 ◽  
Vol 15 (2) ◽  
pp. 113-126
Author(s):  
Ngoc-Tri Ngo ◽  
Thi-Phuong-Trang Pham ◽  
Le Hoang An ◽  
Quang-Trung Nguyen ◽  
Thi-Thao-Nguyen Nguyen ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
High Strength Concrete ◽  
High Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Confined Concrete ◽  
Support Vector ◽  
Axial Strength ◽  
Strength Concrete ◽  
Circular Steel Tube

In recent years, together with the boom of the industrial revolution 4.0, terms such as artificial intelligence (AI) are gradually gaining popularity engineering domain. This study proposed a number of AI models for predicting the axial strength in circular steel tube confined concrete (STCC) columns. Particularly, artificial neural networks (ANNs), support vector regression (SVR), linear regression (LR), and M5P were applied in this study. This study applied 136 samples of short and intermediate STCC columns infilled with normal strength concrete, high strength concrete, or ultimate high strength concrete to evaluate the AI models. Compressive strengths of concrete cylinders was ranged from 23.20 Mpa to 188.10 Mpa. The AI models were assessed by statistical indexes including MAPE, MAE, RMSE, and R. The analytical results revealed that the M5P the most effective AI model comparing to others. Comparing with the other models, predicted data obtained by the M5P model show the highest agreement with the actual data in predicting the axial strength of STCC columns. Particularly, the MAPE and R of M5P models were 10.62% and 0.977 respectively. Similarly, the RMSE by the M5P model was 330.38 kN which is the lowest value among 419.39 kN by the LR model, 337.84 kN by the ANNs model, and 857.11 kN by the SVR model. Therefore, the M5P model can be considered as a useful tool to accurately predict the compressive capacity of the STCC columns. Keywords: artificial intelligence; circular steel tube confined concrete columns; axial strength; support vector regression.

scholarly journals Axial load behaviour of steel tube columns in-filled with various high performance concretes

2021 ◽  
Author(s):  
Katie Chu
Keyword(s):  
Axial Load ◽  
High Performance ◽  
Failure Modes ◽  
Lightweight Concrete ◽  
High Strength ◽  
Crumb Rubber ◽  
Steel Tube ◽  
Axial Strength ◽  
Coarse Aggregates ◽  
Cfst Columns

This research concentrates on the axial load behaviour of circular, square and rectangular concrete filled steel tube (CFST) columns incorporating high-performance self-consolidating concretes such as ultra-high strength concrete (UHSC), engineered cementitious composite (ECC), lightweight concrete (LWC), and crumb rubber concrete (CRC). Seventy-four CFST specimens with varying slenderness, shape, concrete type and presence of internal bar reinforcements are tested experimentally under axial compression loading. The effect of these variables on axial load-deformation response, strain characteristics, failure modes, concrete confinement and axial strength are evaluated through experimental results. Performance of existing analytical/code based models for axial strength and concrete confined strength is evaluated. Concretes without coarse aggregates including UHSC proved less effective at enhancing axial strength of filled tube columns through confinement. In contrast, confinement in filled steel tube columns was found most effective with the use of concretes with coarse aggregates such as LWC and CRC.

scholarly journals PZT-Based Detection of Compactness of Concrete in Concrete Filled Steel Tube Using Time Reversal Method

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shi Yan ◽  
Jinzhi Fu ◽  
Wei Sun ◽  
Baohui Qi ◽  
Fuxue Liu
Keyword(s):  
Cross Section ◽  
Time Reversal ◽  
Rectangular Cross Section ◽  
Concrete Columns ◽  
Steel Tube ◽  
Time Reversibility ◽  
Concrete Filled Steel Tube ◽  
Sensing System ◽  
Two Indices ◽  
Cfst Columns

A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST) columns. The piezoceramic-based smart aggregates (SAs) were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR) and symmetry (SYM) were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.

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.

Compressive behavior of concrete-filled steel tubular columns with internal high-strength steel spiral confinement

2020 ◽  
pp. 136943322098165
Author(s):  
J.G. Teng ◽  
J.J. Wang ◽  
Guan Lin ◽  
J. Zhang ◽  
P. Feng
Keyword(s):  
Axial Compression ◽  
High Strength Steel ◽  
Axial Load ◽  
Axial Strain ◽  
High Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Confined Concrete ◽  
Experimental Program ◽  
Cfst Columns

Concrete-filled steel tubular (CFST) columns have been extensively studied and widely used in practice. Existing research has shown that non-circular CFST columns is much less ductile than their circular counterparts, particularly when thin/high strength steel (HSS) tubes and high-strength concrete are used. To address this problem, a new form of CFST columns has recently been proposed by the first author. The new column consists of a steel tube filled with concrete that is confined with HSS spiral reinforcement typically with a yield stress exceeding 1000 MPa. These columns, referred to as confined concrete-filled steel tubular (CCFST) columns, also maintain the ease for connection to CFST or steel beams. This paper presents the results of a series of concentric axial compression tests on such columns of square cross-section to demonstrate their advantages. The experimental program included 13 CCFST columns, four CFST columns without internal spiral confinement, two hollow steel tube (HST) columns, and 11 circular HSS spiral-confined concrete columns. Three different compressive strengths and three HSS spiral pitches were examined in the experimental program. The CFST columns, HST columns, and HSS spiral-confined concrete columns were all tested under axial compression to gain a good understanding of the confinement mechanism in a CCFST column. The test results show that the new columns possess much greater ductility than those without internal spiral confinement, although the use of HSS spirals increases the steel volume by only a small percentage. It is also shown that the axial load-axial strain curve of a CCFST column can be conservatively predicted by summing the axial load-axial strain curves of the hollow steel tube without local buckling, the HSS spiral-confined concrete core, and the sandwiched concrete between the two.

scholarly journals Axial load behaviour of steel tube columns in-filled with various high performance concretes

2021 ◽  
Author(s):  
Katie Chu
Keyword(s):  
Axial Load ◽  
High Performance ◽  
Failure Modes ◽  
Lightweight Concrete ◽  
High Strength ◽  
Crumb Rubber ◽  
Steel Tube ◽  
Axial Strength ◽  
Coarse Aggregates ◽  
Cfst Columns

This research concentrates on the axial load behaviour of circular, square and rectangular concrete filled steel tube (CFST) columns incorporating high-performance self-consolidating concretes such as ultra-high strength concrete (UHSC), engineered cementitious composite (ECC), lightweight concrete (LWC), and crumb rubber concrete (CRC). Seventy-four CFST specimens with varying slenderness, shape, concrete type and presence of internal bar reinforcements are tested experimentally under axial compression loading. The effect of these variables on axial load-deformation response, strain characteristics, failure modes, concrete confinement and axial strength are evaluated through experimental results. Performance of existing analytical/code based models for axial strength and concrete confined strength is evaluated. Concretes without coarse aggregates including UHSC proved less effective at enhancing axial strength of filled tube columns through confinement. In contrast, confinement in filled steel tube columns was found most effective with the use of concretes with coarse aggregates such as LWC and CRC.

scholarly journals Axial Load Behavior of Ultrahigh Strength Concrete-Filled Steel Tube Columns of Various Geometric and Reinforcement Configurations

2021 ◽  
Vol 6 (5) ◽  
pp. 66
Author(s):  
Khandaker M. A. Hossain ◽  
Katie Chu ◽  
Muhammed S. Anwar
Keyword(s):  
Axial Load ◽  
Concrete Strength ◽  
Steel Tube ◽  
Confined Concrete ◽  
Analytical Models ◽  
Concrete Filled Steel Tube ◽  
Axial Strength ◽  
Strength Concrete ◽  
Ultrahigh Strength ◽  
Cfst Columns

This paper presents the behavior of concrete-filled steel tube (CFST) columns infilled with fiber-reinforced self-consolidating ultrahigh strength concrete (UHSC) subjected to axial concentric monotonic loading to failure. UHSC is expected to improve ease of fabrication, strength, and ductility of CFST columns. Seventeen columns having varying geometric properties such as tube wall thickness, cross-sectional shape (circular, rectangular, and square), and slenderness were constructed and tested by applying load through both steel tube and concrete core. Circular columns were further distinguished by the presence or absence of main and hoop steel reinforcing bars in the core concrete. Axial load-displacement response, axial/transverse strain development, and failure modes were recorded during the loading history to analyze the performance. Experimental confined concrete strength and axial strength of UHSC-filled CFST columns were compared with those obtained from three suggested analytical models and three code-based design procedures including Eurocode 4, Canadian CAN/CSA S16, and American AISC. Analytical models were found to over-predict the confined concrete strength and the axial strength of CFST columns. Canadian and American codes were found to be most applicable for predicting axial strength of UHSC-filled CFST columns while remaining conservative.

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