Marble epistyles under shear: an experimental study of the role of “Relieving Space”

Abstract

The mechanical response of mutually interconnected epistyles is studied experimentally. The specimens are made of two marble blocks connected to each other with an “I”-shaped titanium connector placed in grooves sculptured on the blocks and covered with cementitious material. The specific way of connecting epistyles simulates the one used by scientists restoring the ancient “connections” of the epistyles of the Parthenon Temple. This “connection”, although designed to sustain mainly tensile loading, undertakes, also, shear load, in case of excitations imposing to the epistyles displacements normal to the connector’s axis. Attention is focused to enlighten the role of a novel design technique aiming to relieve the stress field around the connector. According to this technique, part of the connector’s web is left uncovered, forming the so-called “Relieving Space”, assisting the unconstrained deformation of the connector. Both traditional and innovative sensing techniques were employed in an effort to obtain data from the interior of the three-material-complex (marble-cementitious material-titanium). Analysis of the data indicated that the “Relieving Space” reduces the overall stiffness of the system, protecting marble in case of over-loading. Moreover, it was concluded that the innovative techniques employed provide pre-failure indicators well in advance of the catastrophic failure of the specimens.

Keywords

monuments of cultural heritage / marble epistyles / pressure stimulated currents / acoustic emission / digital image correlation

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Acknowledgments

The authors are indebted to civil engineer Mrs Antigone Vrouva of the “Acropolis Restoration Service” and to Mr Ignatios Chiou, technician of the Parthenon work-site. Their experience, gathered during long employment in the restoration of the monument, was extremely valuable, both during the design of the protocol and also during the preparation of the specimens.

The authors express their sincere thanks to the two anonymous reviewers of the present manuscript. Their comments and suggestions were extremely valuable in the direction of significantly improving its quality and scientific integrity.

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