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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4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS<br />
From <strong>the</strong> processing <strong>of</strong> <strong>the</strong> experimental results it could be observed that <strong>the</strong><br />
beam-to-column joints rotated more at <strong>the</strong> first level. Some remarks can be made:<br />
• at <strong>the</strong> interior joints <strong>the</strong> web panels in shear contributed more than <strong>the</strong><br />
170<br />
connections while on <strong>the</strong> contrary at <strong>the</strong> exterior joints <strong>the</strong> connections rotated<br />
more;<br />
• <strong>the</strong> joints A1 <strong>and</strong> A3 (<strong>the</strong> exterior joints on <strong>the</strong> exterior instrumented frame)<br />
worked quite in <strong>the</strong> same way as in <strong>the</strong> PsD tests.<br />
Although we tested a composite structure <strong>the</strong> <strong>behaviour</strong> <strong>of</strong> all <strong>the</strong> joints was quite<br />
symmetric. This phenomenon was probably due to <strong>the</strong> damage induced during <strong>the</strong><br />
PsD tests on <strong>the</strong> concrete slab.<br />
4.11 Conclusions<br />
The objective <strong>of</strong> this study has been <strong>the</strong> investigation <strong>of</strong> <strong>the</strong> <strong>seismic</strong> performance<br />
<strong>of</strong> a realistic size moment resisting frame structure <strong>of</strong> <strong>high</strong> ductility class according<br />
to Eurocode 8 (2002) under various levels <strong>of</strong> earthquake. Dissipative elements<br />
were conceived to be partial strength beam-to-column joints <strong>and</strong> column base<br />
joints at later stages. Some full-scale substructures, representing <strong>the</strong> interior <strong>and</strong><br />
exterior joints, have been subjected to monotonic <strong>and</strong> cyclic tests at <strong>the</strong> Laboratory<br />
for Materials <strong>and</strong> Structures Testing <strong>of</strong> <strong>the</strong> University <strong>of</strong> Pisa in Italy.<br />
Moreover, a new mechanical model <strong>of</strong> <strong>the</strong> partial strength beam-to-column joint<br />
has been described. The model, which still relies on experimental data, is capable<br />
<strong>of</strong> simulating <strong>the</strong> <strong>behaviour</strong> <strong>of</strong> <strong>the</strong> steel-concrete composite partial strength joints<br />
subjected to monotonic loading. In detail, <strong>the</strong> model is capable <strong>of</strong> defining yielding<br />
<strong>and</strong> failure evolution <strong>of</strong> different components. The component models <strong>of</strong> <strong>the</strong> slab<br />
have indicated clearly that <strong>the</strong> compressive strut strength <strong>of</strong> <strong>the</strong> composite slab<br />
bearing on <strong>the</strong> column flange depends on <strong>the</strong> shear stiffness <strong>of</strong> <strong>the</strong> column web<br />
panel. Moreover, <strong>the</strong> activation <strong>of</strong> diagonal compressive struts on column sides<br />
induced by transversal reinforcing bars is hindered by <strong>the</strong> direct bearing <strong>of</strong> <strong>the</strong><br />
compressive strut. Some force-displacement relationships provided by <strong>the</strong><br />
proposed mechanical model have been compared with analytical formulae <strong>and</strong><br />
current European st<strong>and</strong>ards. The principles set forth have <strong>the</strong>n been applied to <strong>the</strong><br />
design <strong>of</strong> beam-to-column joints <strong>and</strong> columns <strong>of</strong> a full-scale frame structure that<br />
has been built <strong>and</strong> subjected to pseudo-dynamic tests at <strong>the</strong> ELSA Laboratory <strong>of</strong><br />
<strong>the</strong> Joint Research Centre in Ispra. The construction <strong>of</strong> <strong>the</strong> full-scale structure<br />
proved that <strong>the</strong> construction <strong>of</strong> steel-concrete composite structures with partial<br />
strength beam-to-column joints <strong>and</strong> partially encased columns is <strong>high</strong>ly efficient.