Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Final Activity Report Summary - ISOLHER (Base-isolation technology for earthquake protection of cultural heritage)

During the first period of the project, the research team has succeeded the following:
(a) Development of a better understanding of the seismic behaviour of block-like art objects to realistically assess their seismic vulnerability and performance. The dynamic behaviour of rigidly-modelled block objects to ground excitation was examined, and possible modes of response and failure mechanisms were identified.

(b) A structural model consisting of a rigid block supported on a rigid base, beneath which the isolation system is accommodated, was adopted. The entire system is base-isolated with a linear isolation system composed of a spring and a viscous dashpot. Investigation of the rocking response of the object (assuming no sliding) subjected to arbitrary base excitation. The formulation of the problem involved derivation of the nonlinear equations of motion and an appropriate impact model from first principles using classical impact theory.

(c) Development of an ad-hoc computational scheme for the nonlinear dynamic analysis of the block-like isolated structure to determine the response of the system under arbitrary base excitation.

During the second period of the project, the research team has succeeded the following:
(a) The computational scheme developed (on the basis of the analytical model formulated during the first 12-month period of the project) has been refined and integrated into a versatile computer program for the nonlinear dynamic analysis of seismically isolated block-like objects. The computer program calculates numerically the response of an isolated block subjected to ground excitation under general conditions, considering the different possible oscillation patterns, impact, and arbitrary excitation.

(b) Data in terms of typical geometries and material properties were collected from the Cyprus Archaeological Museum in Nicosia and the literature, to characterise the system under consideration.

(c) A set of ground motions having a variety of frequency content and amplitude was selected to be used as input to the nonlinear analysis.
(i) Utilising the aforementioned computer program, extensive numerical investigations under seismic excitation have been carried out to verify the effectiveness of seismic-isolation strategy in mitigating the seismic risk of rigidly-modelled museum artefacts. In particular, numerical investigations were performed on two different levels: (i) on a class of rigid blocks with different geometric characteristics, for both the non-isolated and isolated case, and (ii) on a class of seismic-isolation systems with different characteristics.

(d) The results from the comprehensive numerical study were analysed. Interpretation of the results revealed that seismic isolation may effectively be applied to mitigate the rocking response of block-like objects during earthquakes.

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