International Journal of High-Rise Buildings (국제초고층학회논문집)

Council on Tall Building and Urban Habitat Korea (한국초고층도시건축학회)
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Preliminary Modelling of Plasco Tower Collapse

  • Yarlagadda, Tejeswar (Department of Building Services Engineering, The Hong Kong Polytechnic University) ;
  • Hajiloo, Hamzeh (Department of Civil Engineering, Queen's University) ;
  • Jiang, Liming (Department of Building Services Engineering, The Hong Kong Polytechnic University) ;
  • Green, Mark (Department of Civil Engineering, Queen's University) ;
  • Usmani, Asif (Department of Building Services Engineering, The Hong Kong Polytechnic University)
  • Published : 2018.12.01
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Abstract

In a recent tragic fire incident, the Plasco Tower collapsed after an intense outburst of fire lasting for three and a half hours and claiming the lives of 16 firefighters and 6 civilians. This paper will present continuing collaborative work between Hong Kong Polytechnic University and Queen's University in Canada to model the progressive collapse of the tower. The fire started at the 10th floor and was observed to have travelled along the floor horizontally and through the staircase and windows vertically. Plasco Tower was steel structure and all the steel sections were fabricated by welding standard European channel or angle profiles and no fire protection was applied. Four internal columns carried the loads transferred by the primary beams, and box columns were constructed along the perimeter of the building as a braced tube for resisting seismic loading. OpenSees fibre-based sections and displacement-based beam-column elements are used to model the frames, while shell elements are used for the reinforced concrete floor slabs. The thermal properties and elevated temperature mechanical properties are as recommended in the Eurocodes. The results in this preliminarily analysis are based on rough estimations of the structure's configuration. The ongoing work looks at modeling the Plasco Tower based on the most accurate findings from reviewing many photographs and collected data.

Keywords

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Figure 2. The Plasco tower under construction: (a) the flooring system; (b) the bracing system on the sides of the tower (adapted from (Shakib et al., 2017)).

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Figure 3. The extent of fire: (a) at early stages; (b) spreading in the northwest side; (c) extending throughout the entire floor levels (all images courtesy of ISNA NEWS Agency).

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Figure 4. The plan view of Plasco tower and collapse locations (Hajiloo et al., 2017).

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Figure 6. 10-storey model with middle floor heated (MF, Magnification Factor); (a), (c), (e), (g), NS (grid line – D); (b), (d), (f), (h), EW (grid line – 1).

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Figure 7. Reference points in the floor for horizontal and vertical deflections.

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Figure 8. Horizontal displacement of columns at 5th floor.

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Figure 9. Vertical displacement of floor at 5th floor.

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Figure 10. Horizontal displacement of columns at 5th floor (single floor fire vs three floor fire).

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Figure 11. Vertical displacement of floor at 5th floor (single floor fire vs three floor fire).

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Figure 12. Horizontal displacement of columns at mid-floor height (Thermal loading at 5th floor).

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Figure 13. Vertical displacement of floor at 5th floor (Thermal loading at 5th floor).

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Figure 14. Horizontal displacement of columns at 5th floor (Thermal loading at 4th, 5th & 6th floors).

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Figure 15. Vertical displacement of floor at 5th floor (Thermal loading at 4th, 5th & 6th floors).

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Figure 16. Floor Deformations at 5th floor, 350℃ (Thermal Loading at 5th floor).

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Figure 1. (a) Steel frame and bracing system around all sides of the Plasco tower; (b) the attached 5-storey shopping centre (all images courtesy of IRNA).

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Figure 5. (a) Full Floor; (b) Primary EW and NS Truss; (c) Primary NS Truss; (d) Primary EW Truss; (e) Secondary Beam EW and NS Truss; (g) Secondary Prestressed Vierendeel Truss (NS); (h) Secondary Tie Truss; (i) Edge Beam (NS); (j) Edge Beam (EW); (k) Multi Floor (NS); (l) Multi Floor (EW); (m) Multi Floor Model.

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