Analysis and modelling of the seismic behaviour of high ... - Ingegneria

5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES
5.6.3 COT11-COT12 Specimens
The test conducted on specimen COT11, is the only one with available data
representing the C3 configuration for the Medium Ductility Case. The test finished
at the real begin of the 10ey cycle with a residual resistance of ≈40kN, after having
reached the maximum value of ≈95kN at 4ey. The failure occurred up to the middle
column height, again far from the joint, which appeared rather deteriorated. Also
the COT12 rupture confirmed this tendency of the other specimens belonging to
the configuration C3, i.e. to show a collapse far from the joint region before the
conventional end of test fixed at 10ey.
COLUMN SHEAR (kN)
125
100
75
50
25
0
-25
-50
-75
-100
-125
-200 -160 -120 -80 -40 0 40 80 120 160 200
DISPLACEMENT (mm)
Figure 5.36. Column shear force vs. top displacement relationship for
COT11 specimen
5.6.4 Comparison of the experimental results and comments
In order to better understand the improvement in the behaviour of the specimens in
term of strength and ductility due to the use of the inserted steel profile is important
to compare the obtained results. A directed comparison is done in Figure 5.37, in
which the envelopes of the behaviour of the specimens in term of shear force–top
displacement are reported. The reader can see clearly that the presence of the
steel profile increases the level of ductility for each level of the reached force. In
others words, the specimens COT9, COT10 and COT11 show a reserve of
strength for each imposed displacement greater than the reaction force exhibited
from the specimen RCT5. This difference has been summarized in Table 5.14.
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