Experimental study and numerical analysis on residual bearing capacity of reinforced concrete columns after fire
In order to study the residual bearing capacity of reinforced concrete columns after fire,15 reinforced concrete columns are tested after standard fire,using fire time(0,90 and 150min),load eccentricity(0,0.8 and 1.6),column height(1224 and 2448mm),section type(square and circular),and section size(153 and 306mm side width)as experimental parameters.The failure mode,load-deformation curve,residual bearing capacity,strain and deflection characteristics are obtained.Numerical method is used to calculate the load-deformation relationship curve of reinforced concrete columns after fire.Based on parametric analysis,a design method for residual bearing capacity of reinforced concrete columns after fire is obtained.The results indicate that after 90min fire exposure,the loss rate of bearing capacity of reinforced concrete columns with a section width of 306mm can be reduced by 16.5％compared to columns with a width of 153mm.The columns with the load eccentricity exceeding 0.8 exhibit more than 60％reduction in post-fire residual bearing capacity than the concentrically loaded columns.With the increase of fire time,load eccentricity or slenderness ratio,the bearing capacity and stiffness of reinforced concrete columns decrease after fire.After 90min and 150min of fire,the bearing capacity can decrease by 52.0～55.8％and 61.1～65.9％respectively.As the section size,reinforcement ratio,and load eccentricity increase or the slenderness ratio decreases,the influence coefficient of post fire bearing capacity increases.The proposed simplified calculation formula for the influence coefficient of bearing capacity of circular,square and rectangular reinforced concrete columns after exposure to fire is in good agreement with the numerical calculation results and experimental results.
after firereinforced concrete columnresidual bearing capacityfire exposure time
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