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Conference Article: Contribution of the JRC Ispra to the intercomparison of analysis methods for seismically isolated nuclear structures

Magonette, G.; Renda, V. (European Commission Joint Research Centre Elsa Laboratory, Ispra (Italy))

Abstract

Aim of the work done at JRC has been essentially to investigate the potentiality of the Pseudo-Dynamic (PsD) method to test structures incorporating anti-seismic protection devices based on materials with a strain-rate dependent behaviour. This is of relevant importance due to the interest to perform tests on large-scale mock-ups to assess the behaviour of realistic structure of civil engineering interest. Two specific typologies of protection have been analysed and tested at the European Laboratory for Structural Assessment (ELSA) of JRC Ispra. The first dealing with base isolation and the second with energy dissipation devices. In both cases the protection devices were based on high damping rubber material which is characterised by a moderate dependence from the strain rate of the application of the displacements. To validate a standard procedure to test base isolated structures by the PsD method, a collaboration was set up with the Italian Working Group on Seismic Isolation which includes the national research centre ENEA, the national electricity board ENEL, the industrial research centre ISMES and a manufacturer of isolators ALGA. In the framework of this collaboration it was decided to test at the ELSA laboratory a scaled 5-storey frame structure (provided by ENEL), isolated by means of high damping rubber bearings (HDRBs), which had been tested on the shaking table of ISMES. This experimental activity aimed to compare the results which can be obtained by means of the PsD testing technique with those which can be obtained by means of a truly-dynamic test on a shaking table. To validate a standard procedure to test structures incorporating energy dissipation devices, an international collaboration has been set up with Industries, Research Centres and Universities in the framework of a project partially funded by the European Commission through the General Directorate for Science and Technology. The obtained results show once more that the PsD method, when properly applied, may reliably be used to test structures protected by devices based on high damping rubber. This has been shown effective both in the case of base isolation and energy dissipation devices by using a specific procedure for the improvement of the PsD method.

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key words: bearings; comparative evaluations; coordinated research programs; deformation; dynamic loads; mathematical models; mechanical structures; numerical analysis; seismic isolation; soil-structure interactions; strains
Reference:
Final report of a co-ordinated research project 1996-1999
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--1288, pp:251-351