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

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
2 p p
εij εij
3
PEEQ Index = ( 3.17 )
ε
where ij are the plastic strain components.
y
The triaxiality ratio and PEEQ index are also computed at different locations of the
connection to provide additional means of comparing the analyzed connection
configurations. The locations determined to have the highest fracture potential in
the different analyzed configurations are in the weld toe region, near the interface
of the weld metal and base metal.
Weld matching effects
Analyses with different weld matching conditions were carried out to investigate the
joint response in terms of toughness demand. In detail, two models have been
analysed: the first with overmatching welds characterized by mechanical properties
very close to those of the experimental specimens; the second with matching
welds in which the mechanical properties of welds are equal to those of the end
plate material. Analyses with this different weld-matching conditions were carried
out for:
• the TM-2 specimens. The Tee stub models are designated ITS2-1 and ITS2-2,
respectively, and the corresponding mechanical properties are collected in
Table 3.8. A crack length equal to 1.30 mm has been considered in order to
maximize the effect of residual stresses when included.
• the TM-3 specimens. The Tee stub models are designated ITS3-1 and ITS3-2,
respectively, and the corresponding mechanical properties are collected in
Table 3.8. A crack length equal to 2.34 mm has been considered in order to
maximize the effect of residual stresses when included.
• the JB1-3 specimen. The CJ models are designated CJ3-1 and CJ3-2,
respectively, and the corresponding mechanical properties are collected in
Table 3.8. The same crack length of the TM3 specimen, equal to 2.34 mm, has
been considered.
For brevity, only the results of one specimen will be illustrated. The reaction force
vs. the applied displacement for the TM-3 specimen is reported in Figure 3.39a.
However differently from the overall behaviour, the corresponding CTOD demands
are similar until a total displacement of 0.35 mm (see Figure 3.39b), from which the
CTOD demand increases rapidly for the ITS3-1.
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