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

4.1 Introduction
4 SEISMIC RESPONSE OF PARTIAL-STRENGTH
COMPOSITE JOINTS
In seismic design practice, the possibility of relying appreciably on dissipation
effects translates into seismic design actions lower than those called for in brittle
structures, which can count on elastic resources alone. In turn, lower design
actions, which standards provide through higher values of the behaviour factor,
allow for lower design values of plastic resistance, and therefore smaller structural
sections and lower weights as well. The savings in terms of structural weight, when
coupled with sufficient ease of execution, may render ductile structures very
competitive in seismic areas. Solutions assuring the necessary ductility can be
obtained not only through careful study of building morphology, structural schemes
and construction details, but also through the rational use of materials.
Composite construction design, which represents a good compromise in term of
strength and ductility solution, has been increasingly used over recent decades
(USA, Japan and some European countries) mostly in office buildings, commercial
buildings, parking areas and bridges. However, despite the advantages it presents,
composite construction is still scarcely used in seismic design.
The main reasons could possibly be the lack of experience, skilled workers and
appropriate equipment on the one hand and the non-existence of codes for the
design of these structures on the other hand. In fact, Eurocode 8 (prEN 1998-1,
2002) sets forth general principles for designing composite structures for seismic
areas and imposes precise constructional and performance guidelines; however it
does not provide adequate information on the use of the various structural
schemes, or on the associated constructional solutions and design methodologies,
for which it often refers designers to codes and regulations regarding non-
earthquake-resistant structures.