Spalling is defined as damages to concrete exposed to high temperature during fire,
causing cracks and localized bursting of small pieces of concrete. As the concrete strength
increases, the degree of damage caused by spalling becomes more serious due to impaired
permeability. It has been reported that polypropylene(PP) fiber has an important role in protecting
concrete from spalling, and the optimum dosage of PP fiber is 0.2%. However, this result was based
on the fire test of non-reinforced concrete specimens. The high-temperature behavior of highstrength
reinforced concrete columns with various concrete strength and various quantity of PP
fibers is investigated in this study. The results revealed that the ratio of unstressed residual strength
of columns increased as the concrete strength increased and as the quantity of PP fiber increased
from 0% to 0.2% the residual strength of columns increase. However, the effect of PP fiber quantity
on residual strength of column was barely above 0.2%.