Behaviour of High Strength Concrete Filled Steel Tube Intermediate Length Columns in Offshore Applications

The concrete filled steel tubes (CFST) column systems consist of steel tubes filled in concrete. The CFST columns systems have many advantages compared to the reinforced concrete or steel structures. The CSFT have been widely used in construction of tall buildings and bridges in countries located...

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Bibliographic Details
Main Author: Nelson Julio Cossa, Nelson
Format: Final Year Project
Language:English
Published: Universiti Teknologi Petronas 2009
Subjects:
Online Access:http://utpedia.utp.edu.my/1556/1/nelson_julio_cossa.pdf
http://utpedia.utp.edu.my/1556/
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Institution: Universiti Teknologi Petronas
Language: English
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Summary:The concrete filled steel tubes (CFST) column systems consist of steel tubes filled in concrete. The CFST columns systems have many advantages compared to the reinforced concrete or steel structures. The CSFT have been widely used in construction of tall buildings and bridges in countries located in high seismic activity zones. The application of the CFST has been limited, due to lack of extensive understanding of on the behaviour of the transform section. The main objective of this research is to study the behaviour of intermediate length, CFST columns, filled in with high strength concrete. In this study, CFST specimens with 30,60 and 80N/mm2 concrete compressive strength and external diameter-to-plate thickness (D / t) ratios of 11 and 14 are subjected to concentric axial compression loading. All the columns were 1200mm long. The results obtained are compared with the EC4, BS5400, ACI, AS and AIJ design code predictions. The effect of thickness, grade of concrete and confinement of concrete are examined. Moreover, application of CFST in offshore structures is discussed. The results indicate that the ultimate compressive strength of the CFST increases as the concrete grade is increased. It also increases when the thickness of the steel section is increased. Although, confinement of concrete increases with thickness of the steel section, it has less effect on the overall failure mode. The intermediate length CFST columns failed largely due to overall elastic buckling. The application of CFST in offshore structures w ould decreaseth e costsm aintenancea nd repairs.