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

5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES
The force reactions are measured by two load cells located under the extreme
faces of the concrete beams, whereas the specimen displacements, slopes, and
deformations are derived from the inclinometers (giving as measure absolute
angles in respect to the vertical axis) and from the digital displacement transducers
described above.
In order to understand the behaviour of the joint under cyclic loading, it is important
to underline the rotation capability of the panel zone. For this reason, the angular
distortion was monitored during the test through the measures of diagonal
transducers TR500-2D, TR500-1D fitting their values in the Krawinkler (1978)
equation:
γ
( )
( U U )
−1 2
2 ∆ TR500−2 D − ∆ TR500−1 D
conn tg ( hj ) bj
= + ( 5.69 )
2 *
( hj bj
)
Where hj and bj are the net height and breadth of the panel zone subjected to
shear given by hb-2cc and bc-2cc. ∆UTR500 represent the diagonal LVDT joint
measures. In this manner it is possible to underline the panel energy absorption
and its performance in terms of ductility due to the plastic deformation.
The rotation of the beam in respect to the connection, ϕconn, gives the relative angle
between the deformed joint panel and the concrete beam in the deformed shape.
The following equations, based on the measure of the horizontal displacement
transducers TR500 3O, 4O, 5O, 6O, can be utilised:
∆U − ∆U
TR500−40 TR500−30
ϕCONN . SX
hj
= ( 5.70 )
∆U − ∆U
TR500−50 TR500−60
ϕCONN . DX
hj
= ( 5.71 )
Another way to derive this quantities is to purify the measures from the “vertical”
inclinometers attached to the two sides of the concrete beam by the reading of the
“horizontal” inclinometer at the joint and adding the panel zone distortion, Equation
[6.17], where panel = connection:
ϕ = Incl − Incl + γ
( 5.72 )
CONN . DX 3 2 panel
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