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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
A. E. P. G. A. JACINTHO | V. P. SILVA | J. A. V. REQUENA | R. C. C. LINTZ
| L. A. G. BARBOSA | L. L. PIMENTEL
tube, at the steel-concrete interface and in the concrete core.
Figures 9 and 12 show the behavior of the temperature in the con-
crete core where it is evident that, as expected, the temperature
was lower in the tubes with larger diameters and thicknesses.
The graph in Figure 13 shows the temperatures of the columns
tested in the oven with and without loads at 30 min. and 60 min.
The results indicate that at 30 min. the steel tube surface was ap-
proximately 400 to 500ºC, with practically no loss of load bearing
capacity for this temperature range. In the case of a 60-minute ex-
posure time, however, the columns showed temperatures ranging
from 600 to 700ºC. An indication of the influence of the thickness
of the tube wall and the diameter of the tube on the temperature of
the concrete core can also be observed.
Figure 6 – Maximum axial stress: columns at room temperatures X columns after exposure
to high temperatures
FORCE kN
TESTS
Figure 7 – Stress-strain diagram for the columns
at room temperature and the columns
after exposure to high temperatures
Figure 8 – Temperature vs. time curves in
the steel with a 30-minute exposure time
Figure 9 – Temperature vs. time curves at the
steel-concrete interface with a 30-minute
exposure time
Figure 10 – Temperature vs. time curves
in the concrete core with a 30-minute
exposure time