Vol. 9, No. 4, pp. 282-297 (2013)
MODIFIED ONE ZONE MODEL FOR FIRE RESISTANCE
DESIGN OF STEEL STRUCTURES
Chao Zhang 1,* and Guo-qiang Li 2
1 College of Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China
2 State Key Laboratory for Disaster Reduction in Civil Engineering, 1239 Siping Road, Shanghai, China
*(Corresponding author: E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.">This email address is being protected from spambots. You need JavaScript enabled to view it. )
Received: 23 February 2012; Revised: 8 July 2012; Accepted: 13 July 2012
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ABSTRACT
A modified one-zone model has been proposed for structural fire safety design. In the model, a quantity which considers the heat sink effect of steel members in fire compartment is added to the heat balance equation for one-zone compartment fire model. In this paper, the proposed model is solved by FEM simulations. The results from FEM simulations are verified by program OZone (V2.0). Case studies have been conducted with investigating parameters including number of steel members, compartment dimension, opening area, fire load density and steel insulation thickness. The results of the studies show that for fire compartments with bare steel members, the steel heat sink effect is greater for compartments with smaller floor area, larger opening, lower fire load density, and more steel members; and for fire compartments with insulated steel members, the steel heat sink effect is greater for compartments with larger floor area, smaller opening, higher fire load density, and more steel members with thinner insulation. Correspondingly, the over-predictions of the maximum steel temperatures by the current model are comparatively more severe for those compartments. The proposed model can yield more economical fire resistance design than the current model, which is recommended for practical usage.
KEYWORDS
Temperature calculation; Steel structures; Post-flashover fires; Fire resistance; Modified one-zone model
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