Notched Marble Specimens Under Bending: Experimental Study And Numerical Analysis Using An Elastoplastic Model With Contact Elements Z. Agioutantis 1 , S. K. Kourkoulis 2 , S. Maurigiannakis' and E. Papatheodorou 1 ' Technical University of Crete. Department of Mineral Resources Engineering, 731 00 Hania, Crete, HELLAS email: zach@mred.tuc.gr National Technical University of Athens, Department of Mechanics Zografou Campus, Theocaris Building, 157 73 Zografou, Athens, HELLAS email: stakkour@central.ntua.tuc.gr 1. SUMMARY The stress and strain fields developed in centrally notched marble beams under three- point bending (3PB) are studied both numerically and experimentally. The numerical study is carried out using a 2-d Finite Element Analysis. Marble is modeled as a linearly elastic- plastic material obeying a parabolic Mohr- Coulomb failure law. Contact elements are used for better simulation of the load transmission region. The numerical results are in good agreement with the experimental values obtained from 3PB tests. 2. INTRODUCTION The present work constitutes part of a wider effort aiming at the mechanical characterization of the natural building stones used by ancient Greeks for the construction of some of the most important monuments of the classical antiquity. Among these stones the Pentelicon marble is perhaps the most important one since it was used for the construction of the Parthenon Temple on the Acropolis of Athens. The ambitious project for the conservation and restoration of the Temple, in progress today, demands deep knowledge of the mechanical properties of the material used for the construction of patches for damaged structural elements or the reconstruction of destroyed ones, since among the first priorities of the experts working for the project is the mechanical compatibility of the authentic and the substitute material. Experience has indicated that the most suitable substitute material is the white marble quarried from the Dionysos Mountain very close to the Penteli Mountain quarries used by ancient Athenians. The mechanical characterization of rock- type materials is by no means a conventional experimental task. Difficulties arise concerning the sampling and the fabrication of the specimens, the gripping system, the lubrication conditions, the measurement of the strains as well as the correct interpretation of the results (considering the size and the shape of the specimens which is of paramount importance in the case of geomaterials). In the case of Dionysos marble this is further complicated since it is of orthotropic nature and 1