Challenges for the Next Generation of Seismic Codes - Earthquake Engineering for Structural Design - page 466

been setup from the database of available European records. Type 1 is proposed for
large magnitude earthquakes (M >5.5) and Type 2 for low to moderate magnitude
earthquakes (M <5.5). One can mention that the first type corresponds to intraplate
earthquakes and the second to interplate earthquakes. In case of large magnitude
earthquakes, the amplification is moderate and the corner periods are large.
Contrary, for low to moderate earthquakes, the amplification is very large for
reduced periods, but the corner periods are reduced. These spectra are not
representative of intermediate intraslab earthquakes, like in Vrancea (Romania).
The second main specification refers to the performance requirements. The
Eurocode 8 is based on two-level seismic design, with the following explicit
objectives (Fardis, 2004):
-

Protection of life under rare large seismic actions, by prevention of collapse of
structures or part of them and preservation of structural integrity and residual
capacity. The seismic actions are determined for 10% exceeding probability in
50 years (mean return period of 475 years).

- Limited property loss under frequent low seismic actions, by limitation of

structural and non-structural damage due to lateral displacements of structures.
These seismic actions are determined for 10% exceeding probability in 10
years (main return period of 95 years).

10.2.6 International Codes

A new initiative to create an international system of codes has been proposed by
the International Organization for Standardization (ISO), which is a World
Federation of National Standards body (Ishiyama, 2000, Gioncu, 2006). The works
of preparing an International Standard is carried out through ISO Technical
Committees (TCs). Each TC has several Working Groups (WGs). The draft
elaborated by TC98 is the “ISO 3010. Bases for Design of Structures. Seismic
Actions on Structures”. The first edition was published in 1988 and the second in
2001. The ISO Standards are subjected to periodic review, usually every five years,
so the last one is the 2006 edition.
The main characteristic of the ISO 3010 standard is to include only principles
for determination of seismic actions and for seismic design, together with the main
factors to be considered. It does not give specific values of the design seismic
forces, but it includes information how to evaluate them. Generally, all standards
prepared in the frame of ISO serve as guidelines for the preparation of national
standards. Therefore, frequently, they are called the “CodeforCodeWriters”.

10.3 CHALLENGES FOR NEW DESIGN APPROACHES

10.3.1 Insufficient Impact of New Knowledge in Design Practice

Having the experience of the two last very damaging earthquakes, the USA and
Japan have developed very extensive research programs in order to improve the
new code provisions. All the world's scientists and structural engineers, involved