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

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
RELATIVE ENERGY
0.5
0.4
0.3
0.2
0.1
3.5.2 Coupled Tee Stubs
0
TC-2
TC-3
eu/ey
0 20 40 60 80 100 120 140 160
PARTIAL DUCTILITY
Figure 3.13. Relative dissipated energy vs. partial
ductility for the TC-2 and TC-3 Isolated Tee stubs
Different inelastic mechanisms were observed in coupled Tee stub tests,
associated with different relative stiffness and strength of the relevant components:
the Tee stub, the column flange and the bolts. The total thickness of the connected
parts; i.e. column flange and Tee stub plate, also seems to affect the response.
Figure 3.14a compares the responses of specimens C1A1-2 and C1A2-2, different
for the column section, which is a HEA180 in the former and a HEA280 in the latter
test. It is apparent that specimen C1A1-2 is characterized by large energy
absorption and displacement ductility, due to the extensive plastic deformation
occurring in both the Tee stub with t = 12mm and the column flange with tf = 9.5
mm. Failure was attained by brittle fracture of the Tee stub weld toes after crack
propagation. The C1A2-2 specimen has a thicker column flange, i.e. tf = 13mm,
which caused inelastic phenomena to concentrate in the Tee stub only. This results
in lower displacement ductility and energy absorption, while pinching phenomena
appear in last cycles. As to the corresponding two 18 mm plate thickness
specimens (see Figure 3.14b), specimen C1B1-3 with a HEB180 column section
with tf = 14mm experienced inelastic phenomena in the sole column flange, which
resulted in a limited energy absorption and maximum displacements capability,
while in the specimen C1B2-3 with a HEB280 profile and tf = 18mm plastic
phenomena occurred both in the Tee stub and in the column flange, enabling
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