PSI - Issue 3

Stavros K. Kourkoulis et al. / Procedia Structural Integrity 3 (2017) 316–325 S. K. Kourkoulis and I. Dakanali / Structural Integrity Procedia 00 (2017) 000–000

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2. The experimental protocol 2.1. The specimen

The scientists working for the Acropolis restoration project in progress cope with fractured epistyles the faults’ angles of which vary in the range 70 o -90 o with respect to the epistyle’s longitudinal axis (Fig.1a,b). The specimen tested here was a copy of an authentic restored epistyle of the Parthenon Temple on the Acropolis of Athens under a scale 1:3 (Fig.1c, Fig.2). Two asymmetric fragments made of Dionysos marble were joined using 3 pairs of bolted titanium bars, driven in pre-drilled holes (Fig.3d) filled with a cement paste (binder and water without aggregates), which acts both as adhesion layer and also as matching element between the two extremely incompatible basic con stituents of the connection (marble and titanium) protecting the authentic building stone. The angle of the fracture plane with respect to the axis of the member was 70 o (Fig.1c). The specific angle was chosen in order to complete a previously implemented protocol which examined numerically the response of restored epistyles with a vertical fault plane under bending (Kourkoulis et. al 2013). The position of the three pairs of reinforcing bars is shown in Fig.1d. The bar’s anchoring length for both fragments was equal to 25cm symmetrically to the fault’s plane. In order to increase the coherence over the fragments’ common surfaces (fault’s plane) a rough pattern was carved as it can be seen in Fig.3a,b. The surfaces of the fragments that were to come in contact were coated with a suitable cement paste (Fig.3c) to ensure optimum matching of the two fragments rather than to increase the element’ bearing capacity.

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Fig. 1. (a); (b) Typical inclined faults in the Parthenon Temple; (c) Specimen’s dimensions and (d) Reinforcement configuration.

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Fig. 2. Specimen’s preparation.

2.2. Materials The building material of the Acropolis monuments was Pentelic marble. Given that the specific quarries are ex hausted, Dionysos marble has been chosen as the most suitable substitute material for the needs of the restoration project of the monuments given that its physical and mechanical properties are very close to those of the authentic marble (Zambas 1994). Dionysos marble is composed by 98% of calcite. It contains very small amounts of muscovite, sericite, quartz and chlorite. It is of white color with a few thin parallel ash green veins following the schistosity of marble and containing locally silver areas due to the existence of chlorite and muscovite (Tassiogianopoulos 1986). The mechanical properties of Dionysos marble vary between board limits due to the anisotropy of the material which is characterized by three anisotropy planes (parallel to the layers, along the width of the web and along the thick ness of the web, (Exadaktylos et al. 2001)). According to Vardoulakis et al. (2001), Dionysos marble can be con sidered as a transversely isotropic material described by five elastic constants: two elastic moduli, in the plane of transverse isotropy and normal to it, two Poisson’s ratios characterizing the lateral response in the plane of transverse isotropy to a tensile stress parallel and normal to it and the shear modulus in the planes normal to the plane of isotropy.