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

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
2. Connection uplift measured on the beam web at 20 mm above the end
plate (LVDTs B);
3. Lateral displacements measured on the beam flange in the web plane
(LVDTs C);
4. Column flange movement along the end plate edge (LVDTs D);
5. Column web movement along the beam flange (LVDTs E);
6. Bottom column flange displacements located at 20 mm from the column
web plane (LVDTs F);
7. Displacements of the column ends (see LVDTs G in Figure 3.6).
We note that all the above measurements are taken with respect to a reference
frame. Moreover, four LVDTs H were adopted to measure the vertical movement of
bolts, while the bolt shank elongation was detected by means of LVDTs I as
illustrated in Figure 3.7b. The calibration of LVDTs I by means of companion bolts
tested under a universal machine allowed also bolt forces to be detected. As a
result, the prying forces that were developed at the end plate-column flange
interface were estimated indirectly in a rather accurate fashion.
Joint components can be characterized directly by means of LVDT measurements
while the joint behaviour of CJ specimens can be summarized in moment-rotation
relationships. In detail, the joint rotation reads
ϕ = ϕb − ϕf − ϕr
( 3.2 )
in which ϕb represents the rotation of the beam at the end plate level as illustrated
in Figure 3.8, ϕf denotes the elastic deformation of the column while ϕr denotes any
rigid rotation of the column owing to the flexibility of the equipment supporting the
column. Such a rigid rotation was detected by means of LVDTs G illustrated in
Figure 3.6b. Besides the joint rotation ϕ defined in Eq. (3.2), the measuring
apparatus allows the following rotations to be estimated:
ϕconn = ϕb − ϕc
( 3.3 )
γ = ϕc −ϕf − ϕr
( 3.4 )
viz. the connection rotation ϕcon and the shear deformation γ of the column web
panel, respectively.
55