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 />
thin end-plate connection, illustrated in Figure 3, has been chosen, which<br />
guarantees predictable <strong>and</strong> efficient performance for <strong>seismic</strong> actions. The details <strong>of</strong><br />
an exterior beam-to-column joint are illustrated in Figure 4.7. The connections are<br />
partially restrained, or semi-rigid, extended end plate connections. On <strong>the</strong> basis <strong>of</strong><br />
constructional considerations <strong>and</strong> <strong>of</strong> <strong>the</strong> favourable <strong>seismic</strong> <strong>behaviour</strong> <strong>of</strong> <strong>the</strong><br />
column web panel, <strong>the</strong> solution adopted relies on naked steel columns. In detail,<br />
<strong>the</strong> reinforced concrete encasement is interrupted in <strong>the</strong> connection, as shown in<br />
Figure 4.7. A pair <strong>of</strong> stiffening plates, set horizontally <strong>and</strong> welded to <strong>the</strong> column,<br />
guarantees full exploitation <strong>of</strong> <strong>the</strong> web panel's inelastic resources. Additional φ 12<br />
transverse <strong>and</strong> longitudinal reinforcing steel is placed in <strong>the</strong> floor slab at joint<br />
locations so that <strong>the</strong> slab participates to <strong>the</strong> transfer <strong>of</strong> bending moments between<br />
<strong>the</strong> columns <strong>and</strong> <strong>the</strong> beams.<br />
Critical Length<br />
106<br />
Seismic steel rebars<br />
Main<br />
beam<br />
Steel Column<br />
Seismic steel<br />
rebars<br />
270<br />
135<br />
220<br />
Figure 4.7. Details <strong>of</strong> <strong>the</strong> beam-column at <strong>the</strong> exterior joints<br />
150<br />
The transverse beams are IPE240 sections <strong>and</strong> simple shear connections are<br />
used at <strong>the</strong>ir ends. No shear studs are welded to <strong>the</strong> beams, so that <strong>the</strong>ir<br />
contribution to <strong>the</strong> lateral resistance in <strong>the</strong> direction <strong>of</strong> loading is negligible. The<br />
transverse lateral bracing is an X-bracing made with L50x100x8 angles, as shown<br />
in Figure 4.8.<br />
The specifications for <strong>the</strong> structural materials are:<br />
• Structural steel: Class S235 (fy = 235 MPa, fu = 360 MPa, u = 28%)<br />
• Concrete: Class C25/30 (f’c = 25 MPa)<br />
• Reinforcing Steel: Class B450-C (fy = 450 MPa, fy/fu < 1.35, u = 7.5%)