Central Europe is usually described as a region with moderate
seismicity. In spite of that the design of civil engineering structures
including seismic effects has recorded in our countries a long history. For
Slovakia territory the actual seismic design of civil engineering structures
started in fifties of 20th Century. The Standard’s provisions passed
during the years through several revisions and modifications including
innovations of seismic zonation maps. The present valid Slovak National
Standard “Seismic Actions on Structures” STN 73 0036:1997 can be
considered as reasonably compatible Standard with main issues of Eurocode 8 and
its Parts.
The response of engineering practice to new Slovak seismic
standard has shown the view of designers and their preparedness to apply
simpler or more sophisticated approaches in the calculation and seismic
design.. This new standard was the occasion for elaboration of innovative
seismic and seismo-tectonic maps, with convenient application of probabilistic
and deterministic approaches in seismic risk analysis. Description of seismic
sources on national territory and in neighbouring countries together with
appropriate attenuation laws appeared to be very suitable tool for assessment
of peak ground acceleration and site effects.
Very soon after the new standard came into the force there
appeared several parametric studies, which evaluated whether or not to consider
the contribution of seismic loading to the total stress-state of a structure.
It was recognised soon that in extreme combinations of unfavourable soil
conditions and seismically inconvenient design the seismic effects should be
verified for the territory of all country. The demands for expert judgement
became more frequent and designers started to realise more and more the
necessities of seismic calculations and design.
Fortunately, basic knowledge of structural dynamics obtained
during university studies created good but not fully sufficient base for many
engineers - designers. The source was a good tradition in the national
technical education of related theoretical disciplines. Usually, the
theoretical education in structural dynamics starts in second or third year of
university studies. This concerns the courses of applied mechanics and dynamics
and the theory of engineering structures. In total, approximately half of
graduate students have got some knowledge about behaviour of structures under
dynamic loading. But on the other hand, some specifically oriented study
courses recorded a lack of respective theoretical education. Therefore, two
ways are suggested: either to add seismic design and theory into basic
university education or to include it into continuous education of engineers -
designers and architects.
One can observe also some objections against more
complicated calculation and different level of structural safety. In national
Slovak conditions the approaches with direct using of q-factor are rare, design
problems are solved using appropriate detailing. In comparison with Eurocode 8
the Slovak Standard STN 73 0036:1007 is more consistently based on wave theory
and structural and soil dynamics. It includes also the provisions for man made
– technical seismicity and seismic effects of transport and explosions.
It is worth to mention that good progress has been recorded
also in the introduction of Eurocode 8 (for a while like ENV 1998 PreStandard)
into the system of Slovak national standards. All Parts of ENV 1998 were
translated, completed with national application documents and edited. Nowadays,
they are fully applied for the completion of detailing and for comparative
studies. Simultaneous use of national seismic standard STN 73/0036:1997 and
Eurocode 8 NADs became the reality. It supports the common process to improve
the seismic design rules and to increase the mean seismic resistance of
different civil engineering structures. However, the introduction of new
knowledge based on research and practice of earthquake engineering is
continuous process with the expected contribution in future EN 1998 Standard
completed where appropriate and necessary with national annexes and provisions.
Prof..
Ing. Emilia Juhasova, DrSc.
Chairwoman of
Slovak Association for Earthquake Engineering
and Chairwoman of
Slovak Standardisation Committee for Loading of Structures