|Title:||Performance of reinforced concrete columns under real fire test|
|Subject:||Columns, Concrete -- Fire testing.|
Reinforced concrete -- Fire testing.
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Civil and Structural Engineering|
|Pages:||119 leaves : ill. (some col.) ; 30 cm.|
|Abstract:||This thesis presents the performance of 20 reinforced concrete columns under a real fire (duration of two and half hours at a peak air temperature of about 900 ℃) conducted in the So Uk pump house before its demolition. The columns were preconditioned to attain full water moisture saturation prior to the fire test. The size of the reinforced concrete columns was 300 mm x 300 mm x 1300 mm. Each fire chamber contained 10 reinforced concrete columns. The heated columns with the same concrete grade and the same properties were symmetrically located in the two fire chambers. The concrete grades of columns were C40, C60, C90, HPC (C30) and C90a. When the fire was extinguished, 10 heated columns in one sub-chamber were subjected to immediate water quenching for 15 min before air-cooling, and the remaining 10 heated columns in another sub-chamber were naturally air-cooled only. Without any special provision, concrete cover spalling of a concrete member was found to be unavoidable under fire and its severity increased with concrete strength. Meanwhile, the reduction compressive strength of the reinforced concrete columns with different concrete grades was 40%. Water quenching at the time the fire was extinguished does not have any significant effect on the residual strength of heated columns and the concrete spalling. Protection materials performed differently. Polypropylene fibers with a density of 1 kg per cubic meter or 0.6 kg per cubic meter suppressed the concrete spalling very well. Moreover, the wire mesh prevented columns from reducing their compressive strength. However, the material, quality and installation method of the passive fire protection board should be carefully selected in order to effectively protect reinforced concrete columns from the fire.|
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