Challenges for the Next Generation of Seismic Codes - Earthquake Engineering for Structural Design - page 520

10.8.2 Performance-based Design

In the recent years, a new design philosophy for building codes has been discussed
within the engineering community. New building codes for earthquakes must adopt
a performance-based design framework. The goal of a performance-based design
procedure is to produce structures which have predictable seismic performance
under multiple levels of earthquake intensity. Performance-based earthquake
engineering implies design, evaluation and construction of engineering facilities,
whose performance under common and extreme loads responds to the diverse
needs and objectives of owners, users and society (Krawinkler, 1999, Leelataviwat
et al, 1999).
In order to comply with these requirements, it is necessary to pass from the two
levels of the present codes to the three- level approach (Gioncu and Mazzolani,
2002).

Limit Earthquake Avoided Verification Analysis Analsis

state intensity failure method object

Service- low non-structural rigidity elastic story

ability elements drift

Damage- moderate local strength elasto- section

ability collapse plastic capacity

Ultimate severe global ductility kinematics rotation

collapse capacity

• Serviceability limit state, under frequent low earthquakes, for
which the structure must work in elastic field and the non-
structural elements remain undamaged. To guarantee their
integrity, the interaction of the structure and non-structural
elements must be evaluated by means of an elastic analysis (Fig.
10.40), whose result is the reduction of the interstory drifts. The
basic verification refers to the structure rigidity by controlling the
story drifts, which must be framed within the prescribed limits.
• Damageability limit state, under occasional moderate earthquakes,
where the non-structural elements are damaged (so the interaction
structure-non-structural elements is neglected or just partially
considered) and a very limited structural damage occurs. In this
case, the analysis follows the elasto-plastic methodology (Fig.
10.40). The moderate damage to structural elements can be
repaired without great technical difficulties. The basic verification
refers to the structure members, by analyzing their section
capacities.