Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
Analysis and modelling of the seismic behaviour of high ... - Ingegneria
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3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS<br />
The end plate represents an important component for <strong>the</strong> joints considered. The<br />
end plate responses <strong>of</strong> <strong>the</strong> isolated Tee stub TC-2 <strong>and</strong> Complete Joint JA1-2A are<br />
plotted in Figure 3.23. As mentioned above, <strong>the</strong> testing procedure imposes<br />
different cycle amplitudes <strong>and</strong> affects <strong>the</strong> number <strong>of</strong> cycles at failure. However, <strong>the</strong><br />
collapse mode is <strong>the</strong> same, i.e., by plate fracturing, <strong>and</strong> <strong>the</strong> evolution <strong>of</strong> <strong>the</strong><br />
hysteretic <strong>behaviour</strong> has similar features. A comparison between <strong>the</strong> maximum<br />
force <strong>and</strong> displacement shows an overestimate <strong>of</strong> <strong>the</strong> first parameter <strong>of</strong> 7% <strong>and</strong> an<br />
underestimate <strong>of</strong> <strong>the</strong> second <strong>of</strong> 13% with reference to <strong>the</strong> Tee stub response. The<br />
influence <strong>of</strong> <strong>the</strong> interaction between <strong>the</strong> different components in <strong>the</strong> joint appears<br />
to be limited. The same comparison between <strong>the</strong> joint JB1-3 <strong>and</strong> <strong>the</strong> corresponding<br />
Tee stubs TC-3 shows similar results, as evidenced in Figure 3.24.<br />
70<br />
REACTION FORCE (kN)<br />
400<br />
300<br />
200<br />
100<br />
0<br />
-100<br />
-200<br />
-300<br />
-400<br />
TC-2<br />
JA1-2A (ENDPLATE)<br />
0 2 4 6 8 10<br />
DISPLACEMENT (mm)<br />
Figure 3.23. Comparison <strong>of</strong> <strong>the</strong> experimental<br />
response <strong>of</strong> <strong>the</strong> Tee stub TC-2 <strong>and</strong> <strong>the</strong> End plate <strong>of</strong><br />
<strong>the</strong> Complete Joint JA1-2A<br />
A more accurate appraisal <strong>of</strong> <strong>the</strong> responses <strong>of</strong> <strong>the</strong> elemental components can be<br />
obtained if reference is made to key parameters, such as <strong>the</strong> initial elastic stiffness<br />
<strong>and</strong> <strong>the</strong> plastic failure strength, which characterize <strong>the</strong> envelope <strong>of</strong> <strong>the</strong> cyclic<br />
response. A conventional elastic stiffness Ke, a plastic failure strength Fp <strong>and</strong> an<br />
ultimate displacement ductility factor eu/ey were determined by <strong>the</strong> bi- <strong>and</strong> tri-linear<br />
approximations <strong>of</strong> <strong>the</strong> envelope curve, traced on <strong>the</strong> basis <strong>of</strong> best-fitting <strong>and</strong><br />
dissipated energy-equivalence criteria. Values <strong>of</strong> <strong>the</strong> elastic stiffness Ke relevant to<br />
<strong>the</strong> components <strong>of</strong> joints JA1-2 <strong>and</strong> JB1-3 <strong>and</strong> to <strong>the</strong> corresponding isolated <strong>and</strong><br />
coupled Tee stubs are presented in Table 3.6.