A comparison of calculated residual
moment capacity and applied moment
is shown in Fig. 8. Note that the values
are almost equal. This clearly illustrates
that the moment capacity during a fire
can be predicted and that behavior during fires follows basic engineering principles.
As noted above, steel temperatures
were monitored throughout the fire
tests. Fig. 9 shows temperatures for 1,
2, and 3-in, cover of the normal weight
concrete specimens. Similar data were
obtained for lightweight concrete. If,
for a particular load intensity, the "critical" steel temperature is 900 F and if
the cover is 2 in., the fire endurance of
a simply supported prestressed concrete
slab would be slightly less than 3 hr.
Similarly, it is possible to estimate the
fire endurance for various cover thicknesses and load intensities