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

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
extended plate connections have been analysed. In detail, the effects of the weld-
to-base metal yield strength ratio, the end plate yield-to-ultimate strength ratio and
the residual stress influence have been determined through detailed two- and
three-dimensional non-linear finite element analyses. Such analyses conducted in
the monotonic regime permitted fracture toughness demands in terms of
performance indices to be evaluated. In addition, the analyses provided insights to
develop a better intuitive understanding of fracture in the aforementioned
connections.
3.2 The component method
Design of MR frame with semi-rigid partial strength joints is one of the major
developments in the structural design of steel and composite steel-concrete
buildings.
The importance of joint action has been perceived since the beginning of the last
century. However, only in the 80's the tools available to the practitioners, and in
particular the structural analysis programs, made the new methodology ready for
practical use. Since then a number of research studies were carried on worldwide,
aimed at building up the necessary knowledge to develop design tools ranging
from general criteria to specific methods and rules for joints and frames (Bjorhovde
et al,1988; Narayanan, 1988; Bjorhovde et al, 1992; Colson, 1992; Lorenz et al,
1993; Wald, 1994; Bjorhovde et al, 1996; Maquoi, 1999; Easterling and Leon,
2002).
All the key facets of the problem were investigated via experimental, numerical and
theoretical analysis, including the behaviour of a wide range of joint types, the
design models to approximate joint response and the influence of joint action on
frames performance. Design criteria as well as specific recommendations were set
up and included in Codes (Eurocode 3, 2001) and design aids were developed in
order to make the new philosophy accepted in practice.
Following the recommendation included in Eurocode 3 (2001), it is possible to
classify the joint by stiffness or by strength. Depending on the stiffness, a joint can
be classified as rigid, nominally pinned or semi-rigid on the basis of particular or
general experimental evidence or significant experience of previous satisfactory
performance in similar cases or by calculations based on test evidence. A rigid joint
shall be so designed that its deformations have no significant influence on the
distribution of the internal forces and moments in the structure or on its overall
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