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 />
A number <strong>of</strong> validation <strong>and</strong> calibration studies were carried out in <strong>the</strong> last decade,<br />
<strong>and</strong> design criteria <strong>and</strong> recommendations were developed <strong>and</strong> included in <strong>the</strong><br />
Eurocodes 3 (2001) <strong>and</strong> Eurocode 4 (2002).<br />
44<br />
5<br />
1<br />
6<br />
2<br />
7 4<br />
3<br />
1. - Column web panel in shear<br />
2. - Column web in compression<br />
3. - Beam flange in compression<br />
4. - Bolts in tension<br />
5. - Column web in tension<br />
6. - Column flange in bending<br />
7. - End plate in bending<br />
Figure 3.2. Mechanical model <strong>of</strong> <strong>the</strong> EC3 - Design <strong>of</strong> joints<br />
A similar development, as to <strong>the</strong> novel importance <strong>of</strong> joints in design, took place in<br />
earthquake engineering. The possible role <strong>of</strong> joints in <strong>the</strong> energy dissipation<br />
mechanism was in fact recognised <strong>and</strong> <strong>the</strong> potential <strong>of</strong> semi-continuous frames in<br />
<strong>seismic</strong> areas investigated. Design approaches based on conceptual design were<br />
also proposed for steel as well as for composite frames. The limits <strong>of</strong> <strong>the</strong> traditional<br />
approaches in appraising <strong>the</strong> joint response become even more evident when<br />
cyclic loads are considered. A clear need for catching stiffness <strong>and</strong> strength<br />
deterioration, <strong>and</strong> possible pinching effects associated with buckling <strong>and</strong> fracturing<br />
<strong>of</strong> components <strong>and</strong> with <strong>the</strong> increase <strong>of</strong> lack-<strong>of</strong>-fit due to plastic deformations (in<br />
particular in bolted connections), makes <strong>the</strong> requirements to be met by prediction<br />
models more strict than in <strong>the</strong> case <strong>of</strong> static loading. The peculiar features listed<br />
above for <strong>the</strong> component method make it a fairly appealing solution for <strong>modelling</strong><br />
joints also in <strong>seismic</strong> analysis. In particular, it should be stressed that it would allow<br />
to concentrate on <strong>the</strong> cyclic response <strong>of</strong> individual components, which can be<br />
investigated in a far more simple <strong>and</strong> economic way than <strong>the</strong> response <strong>of</strong> <strong>the</strong><br />
whole joint.<br />
3.3 Semi-rigid partial-strength extended end plate connection<br />
Extended end plate as well as flush end plate connections allow to realize joints<br />
covering a ra<strong>the</strong>r wide range <strong>of</strong> strength <strong>and</strong> stiffness. In many instances <strong>the</strong>y also<br />
possess an adequate rotation capacity for plastic design. The complexity <strong>of</strong> <strong>the</strong>