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

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
the plate thickness; iii) a sudden propagation of the crack in a brittle fracture mode.
However, the test indicates that the fillet welds performed well and were able to
develop the required cyclic strength.
Similar considerations apply to the specimens with plate thickness equal to 18 mm.
As expected, the specimen TM-3 was characterized by a Mode 2 failure according
to Eurocode 3, with two yield lines located at the weld toes, whilst specimen TC-3
failed by plate fracture close to the weld toes following the same sequence
described above for the TC-2 specimen.
60
REACTION FORCE (kN)
800
600
400
200
0
-200
-400
-600
-800
TM-3
TC-3
0 2 4 6 8 10
DISPLACEMENT (mm)
Figure 3.12. Experimental response of TM-3 and TC-3
Isolated Tee stubs
A comparative assessment of the hysteretic performances of TC-2 and TC-3
specimens can be based on the relation between the mean energy ratio (i.e., the
ratio between the absorbed energy, averaged on three cycles, and the energy
dissipated per complete cycle by an equivalent elastic-plastic oscillator) and the
maximum ductility e/ey (ECCS, 1986). Such a comparison pointed out that: (i)
owing to the Mode 1 failure pattern which involves four yield lines, the TC-2
specimen is able to absorb greater amounts of energy also at smaller ductility
ratios; (ii) the ultimate displacement ductility factor e +
u/e +
y (see Figure 3.9) are 73
and 53 for the TC-2 and TC-3 specimen, respectively. Thereby, the TC-2 specimen
performs better both in terms of absorbed energy and of ductility, as illustrated in
Figure 3.13.