국제초고층학회논문집 (International Journal of High-Rise Buildings)

  • 제7권4호
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  • Pages.313-325
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  • 2018
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  • 2234-7224(pISSN)
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  • 2288-9930(eISSN)
한국초고층도시건축학회 (Council on Tall Building and Urban Habitat Korea)
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Boundary Conditions and Fire Behavior of Concrete Filled Tubular Composite Columns

  • Rodrigues, Joao Paulo C. (LAETA, Department of Civil Engineering, University of Coimbra) ;
  • Correia, Antonio J.M. (LAETA, Department of Civil Engineering, Polytechnic Institute of Coimbra) ;
  • Kodur, Venkatesh (Department of Civil & Environmental Engineering, Michigan State University)
  • 발행 : 2018.12.01
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초록

Concrete-filled steel tubular (CFST) members are commonly used as composite columns in modern construction. However, the current guidelines for members' fire design (EN1994-1-2) have been proved to be unsafe in case the relative slenderness is higher than 0.5. In addition, the simplified design methods of Eurocode 4 are limited to circular and square CFST columns, while in practice columns with rectangular and elliptical hollow sections are being increasingly used because of their architectural aesthetics. In the last years a large experimental research has been carried out at Coimbra University on the topic. They have been tested concrete filled circular, square, rectangular and elliptical hollow columns with restrained thermal elongation. Some parameters such as the slenderness, the type of cross-section geometry as well as the axial and rotational restraint of the surrounding structure to the column have been tested in order to evaluate their influence on the fire resistance of such columns. In this paper it is evaluated the influence of the boundary conditions (pin-ended and semi-rigid end-support conditions) on the behavior of the columns in case of fire. In these tests it could not be seen a marked effect of the tested boundary conditions but it is believed that the increasing of rotational stiffness increases the fire resistance of the columns.

키워드

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Figure 1. General view of the test set-up.

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Figure 2. Details of the end supports: (a), (b) and (c) pin-ended; (d) semi-rigid ended.

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Figure 3. Scheme of the cross-sections of the tested columns.

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Figure 4. Temperatures at column’s mid-height a) CC194-lka-sr, b) EC320-lka-sr, c) RC250-lka-sr and d) SC150-lka-sr.

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Figure 9. Lateral deflections for columns CC194-lka: a) pp-y axis; b) pp-x axis; c) sr-y axis; d) sr-x axis.

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Figure 10. Lateral deflections for column EC320-lka: a) pp-y axis; b) pp-x axis; c) sr-y axis; d) sr-x axis.

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Figure 11. Lateral deflections for column RC250-lka: a) pp-y axis; b) pp-x axis; c) sr-y axis; d) sr-x axis.

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Figure 12. Lateral deflections for column SC150-lka: a) pp-y axis; b) pp-x axis; c) sr-y axis; d) sr-x axis.

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Figure 13. Stiffness of column CC194-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 14. Stiffness of column EC320-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 15. Stiffness of column RC250-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 16. Stiffness of column SC150-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 17. Rotations on top of column CC194-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 18. Rotations on top of column EC320-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 19. Rotations on top of column RC250-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 20. Rotations on top of column SC150-lka for a) pin-ended and b) semi-rigid boundary conditions.

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Figure 21. Columns after fire test a) CC194-lka-pp; b) EC320-lka-pp; c) RC250-lka-pp; d) SC150-lka-pp.

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Figure 22. Columns after fire test a) CC194-lka-sr; b) EC320-lka-sr; c) RC250-lka-sr; d) SC150-lka-sr.

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Figure 23. Deformed shapes of rectangular and square columns showing local buckling of steel profile.

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Figure 5. a) Relative Axial Restraint Force and b) Axial Displacements for column CC194-lka, for semi-rigid and pinended boundary conditions.

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Figure 6. a) Relative Axial Restraining Forces and b) Axial Displacements for column EC320-lka for semi-rigid and pinended boundary conditions.

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Figure 7. a) Relative Axial Restraining Forces and b) Axial Displacements for column RC250-lka for semi-rigid and pinended boundary.

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Figure 8. a) Relative Axial Restraining Forces and b) Axial Displacements for column SC150-lka for cases of semi-rigid and pin-ended boundary.

Table 1. Test programme

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Table 2. Geometric characteristics of specimens

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Table 3. Maximum relative axial restraining forces, time for the maximum axial restraining forces and critical times

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참고문헌

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  2. EN 1097-5 (2009). Test for mechanical and physical properties of aggregates - Part 5: Determination of the water content by drying in a ventilated oven. European Committee for Standardization. Brussels, Belgium.
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