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
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES<br />
<strong>and</strong> shear resistance <strong>of</strong> <strong>the</strong> steel sections reduces <strong>of</strong> a half factor, while <strong>the</strong><br />
second one guarantees <strong>the</strong> resistance in bending to be half <strong>of</strong> that belonging to <strong>the</strong><br />
original section. Never<strong>the</strong>less, by diminishing <strong>the</strong> geometrical properties <strong>of</strong> <strong>the</strong><br />
concrete sections we obtained a reduction <strong>of</strong> <strong>the</strong> bending resistance equal to one<br />
fourth <strong>of</strong> <strong>the</strong> original section. Hence, <strong>the</strong> assumptions made for <strong>the</strong> reduction <strong>of</strong> <strong>the</strong><br />
steel pr<strong>of</strong>ile properties were not adoptable. Indeed, it was necessary to calculate<br />
<strong>the</strong> reduced steel sections following <strong>the</strong> design criteria already presented in a<br />
previous paragraph for <strong>the</strong> full-scale steel-concrete composite columns, <strong>and</strong> briefly<br />
summarised below:<br />
a. <strong>the</strong> steel section should at least be able to take alone <strong>the</strong> design axial force <strong>of</strong><br />
<strong>the</strong> <strong>seismic</strong> loading case;<br />
b. <strong>the</strong> steel section alone (not acting composedly) should be able to substitute <strong>the</strong><br />
deficient concrete section;<br />
c. <strong>the</strong> sections have been chosen in order to not modify <strong>the</strong> local stiffness EI <strong>of</strong><br />
<strong>the</strong> columns <strong>and</strong> <strong>the</strong> total stiffness <strong>of</strong> <strong>the</strong> original concrete structure (maximum<br />
level <strong>of</strong> modification <strong>of</strong> <strong>the</strong> order <strong>of</strong> 10%);<br />
d. <strong>the</strong> sections have been chosen in order to achieve a favourable performance<br />
both along <strong>the</strong>ir major axis bending <strong>and</strong> along <strong>the</strong>ir minor axis bending.<br />
In <strong>the</strong> following Figure 5.19 <strong>the</strong> reduced composite column cross sections adopted<br />
in <strong>the</strong> experiments at <strong>the</strong> University <strong>of</strong> Trento are shown.<br />
Figure 5.19. Reduced sections for <strong>the</strong> composite columns to be tested<br />
From <strong>the</strong>se sections, corresponding to <strong>the</strong> respective load cases under study, we<br />
extrapolated <strong>the</strong> scaled 3D composite columns to be analysed. Each cross<br />
composite section generated four scaled samples, two with long steel pr<strong>of</strong>ile (with<br />
or without steel plates in <strong>the</strong> joint), <strong>and</strong> two with short steel pr<strong>of</strong>ile in <strong>the</strong> critical<br />
length (with or without horizontal steel plates) as illustrated in Figure 5.20.<br />
Therefore, to each design category (static <strong>and</strong> <strong>seismic</strong>) belong four composite<br />
samples plus ano<strong>the</strong>r scaled sample without <strong>the</strong> encased steel pr<strong>of</strong>ile. The latter<br />
operating as a comparison trial for <strong>the</strong> o<strong>the</strong>rs. Also four tests along minor axis were<br />
209