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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
Short steel and concrete columns under high temperatures
It is noted that there was a slight increase in the temperature of
the concrete core in the columns without loads inside the oven.
This finding is due to the load inhibiting the evaporation of free
water in the concrete, thereby slowing the increase in tempera-
ture, as the press system prevented evaporation from the ends
of the composite columns, even with the presence of lateral
holes in the steel tubes that allow for the liberation of vapor. For
the larger diameter columns, it was found that the temperature
of the concrete was lower, as observed in column S63-60. This
column showed a higher temperature on the surface of the steel
tube (Figure 10), although it showed a lower temperature in the
concrete core (Figure 12).
It is evident that the thickness of the steel tube influenced
the increase in the temperature of the concrete core (Fig-
ure 13).
Figures 14 and 15 show the curves for the oven obtained during
Figure 11 – Temperature vs. time curves in
the steel with a 60-minute exposure time
Figure 12 – Temperature vs. time curves
at the steel-concrete interface
with a 60-minute exposure time
Figure 13 – Temperature vs. time curves for
the concrete with a 60-minute exposure time
Figure 14 – Temperatures for the steel,
interface and concrete for
the 30- and 60- minute tests
Figure 15 – Oven temperature curves
for the 30-minute tests
Figure 16 – Oven temperature curves
for the 60-minute tests