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

2. DUCTILITY AND SEISMIC RESPONSE OF STRUCTURES
ultimate strength. The ductility of a structure allows prediction of the ultimate
capacity of a structure, which is the most important criterion for designing
structures under conventional loads. In the practice of earthquake resistant design
the term ductility is used for evaluating the seismic performance of structures, by
indicating the quantity of seismic energy, which may be dissipated through plastic
deformations. The use of this concept of ductility gives the possibility to reduce
seismic design forces and allows the production of some controlled damage in the
structure, also in case of strong earthquakes. The following ductility types are
widely used in literature (see Figure 2.1):
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• material ductility, or axial ductility, which characterizes the material plastic
deformations;
• cross-section ductility, or curvature ductility, which refers to the plastic
deformations of cross-section, considering the interaction between the
parts composing the cross-section itself;
• member ductility, or rotation ductility, when the properties of member are
considered;
• structure ductility, or displacement ductility, which considers the behaviour
of the whole structure.
Figure 2.1. Ductility types