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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
The oven temperature was monitored using internal rod thermo-
couples coupled to a data acquisition system.
After the tests in the oven, the models were cooled and tested with
a monotonic load on the 5000-kN press.
4.1 Experimental results and data analysis
Table 2 presents the stress values that caused the initiation of
plastic deformation at room temperature, as obtained by SIMÕES
[3], and at high temperatures, as obtained by ARAÚJO [5]. Figure
5 was prepared to better visualize the data. The stress values
for plastic deformation were obtained according to the procedure
presented by HAN et al. [6].
For the columns tested at 30 and 60 minutes, which were then
cooled and tested under a static load, it can be observed that the
yield strength was less than that obtained for the same columns
left at room temperature. This reduction in strength occurred main-
ly for the columns that were loaded during heating. The columns
with a 30-minute exposure time that were not loaded during the
test were not different in terms of yield strength from those that
were not heated.
Table 3 presents the maximum axial yield strength values for the
columns at room temperature and the columns that were heated
and cooled. Figure 5 was prepared to better visualize the data.
Figure 6 shows the Specific Linear Stress-Strain Diagram of col-
ture elevation curves for different cases, as well as the standard fire
curve ISO 834 [1]. A test system was prepared that coupled the
oven with the 600-kN press to allow static loads to be applied and
maintained while the temperature was varied, as shown in Figure 4.
Figure 4 – High-temperature load
application system
Table 2 – Maximum temperatures and yield strengths
F – Yield strength for the columns at room temperature
esc
q
F – Yield strength for the columns after cooling
esc,
Group
Composite TRRF
Oven
Temp.
Steel
Temp.
Concrete
Temp.
F
esc
q
F
esc,
F
esc
q
F
esc,
Column (min)
(°C)
(°C)
(°C)
(kN)
(kN)
C 6-30
1
30
890
800
290
780
640
0.821
2
30
890
500
150
780
750
0.962
S 6-30
1
30
880
570
150
780
780
1
C 6-60
1
60
1,200
1,140
690
780
500
0.641
2
60
940
630
370
780
680
0.872
S 6-60
1
60
940
670
440
780
700
0.897
C 8-30
1
30
750
700
170
1,150
950
0.826
2
30
880
500
150
1,150
S 8-30
1
30
880
450
170
1,150
1,150
1
C 8-60
1
60
860
810
660
1,150
1,000
0.870
2
60
940
630
380
1,150
1,150
–
–
–
–
–
–
1
S 8-60
1
60
900
640
470
1,150
C 63-30
1
30
750
550
125
1,200
2
30
890
450
100
1,200
1,000
0.833
S 63-30
1
30
890
450
100
1,200
1,190
0.992
C 63-60
1
60
945
650
250
1,200
1,050
0.875
2
60
940
590
230
1,200
880
0.733
S 63-60
1
60
950
700
330
1,200
910
0.758