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

4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS
4.8.3 Validation of the analytical model
The composite beam-to-column joint, named CJ type, is modelled using a
rotational spring to simulate the connections and a rectangular articulated polygon,
whose dimensions are represented in the Figure 4.30, with a non linear
translational spring simulating the column web panel.
136
composite column
b
a
d
rigid truss
composite beams
CJ type – Interior Joint
a = 280 mm
b = 382,8 mm
d = (a + b) 1/2
CJ type – Exterior Joint
a = 260 mm
b = 382,8 mm
d = d = (a + b) 1/2
Figure 4.30. Dimensions of rectangular articulated polygon
The mechanical properties of the rotational spring are obtained using the
Component Method according with ECCS - n°109 Procedure (1999); for the
column panel in shear the Krawinkler’s model has been used. To model the
rotational spring of the connection in a way that closely reproduces the expected
behaviour, each component is modelled separately, taking account of the interior
moments and forces in the members acting at the periphery of the web panel. The
modelling of the actual behaviour of the connection is different in the case of
sagging or hogging bending moment. The basic components identified in this
design are given in Table 4.5, for sagging and hogging bending moment
respectively.
The design moment resistance Mj,Rd of this rotational spring is determined for
sagging bending moment from:
where:
M = F ⋅ z
( 4.26 )
j, Rd
j
t, j, Rd j
Ft,j,Rd is the effective design tension resistance of the bolt-row j;
zj
is the distance from the component j in tension to the center of the
compression.