Some limits exist when using the existing temperature rise curves（TRCs）of fire-resistance tests to simulate the fire scenarios in subway sectional tunnels.Herein

the improved RABT（IRABT）TRC model is proposed in this paper.Based on the existing TRCs of fire-resistance tests

the model considers such practical factors

as the peak temperature

the fire duration and the heating rate of the fires in subway sectional tunnels.The linear cooling segment is included in the model;the cooling time can also be set to characterize the practical fire scenario.The finite element software SAFIR

specifically for structural fire-resistance analysis

is used to numerically simulate the fire-resistance tests of a 1/3reduced scale subway tunnel segment with IRABT TRCs.The temperature variation and the sectional temperature field distribution

with five different fire scenarios

are obtained

corresponding to such IRABT models as the ones with the cooling moment 60 min and the peak temperature of 700℃and 800℃

respectively;and the ones with the cooling moments 60

45 and 30min

respectively

and the peak temperature of 900 ℃.Numerical simulation results show that the temperature of the section of 20 mm above the heating surface continues rising

and the farther the distance to the heating surface

the longer the temperature rise will last.In addition

as for the section of 90 mm above the heating surface to the top of the segment

no obvious cooling segment occurs

and temperature rise and constant remaining reveals all the same.Moreover

the temperature of the heating surface is lower than that of the adjoining sections within the segment lining;meanwhile

the peak value of the temperature field of the whole segment lining appears at the range of 40 to 60mm above the heating surface.As for the cases with the same temperature rise segment

the later the cooling moment

the higher the final temperature

near the heating surface and the top

will be.Therefore

for the practical fire scenario in subway sectional tunnels

the fire is better to be effectively controlled at the early stage

so as to avoid entering the constant-temperature heat-transfer condition

alleviating the damage degree of the segment concrete caused by heating.The analysis results may provide insight into the performance degradation of the segment linings of subway tunnels under fire.