Issue 40

M. Mentzini, Frattura ed Integrità Strutturale, 40 (2017) 95-107; DOI: 10.3221/IGF-ESIS.40.09 97 A PPLICATION IN THE FIELD t’s very difficult to categorize the Parthenon’s North Colonnade’s drums failures because they were caused mainly due to their fall after the Morosini’s explosion and as a result in many cases the traces of former fractures were covered. The variety of fragments and remains (many of them were carved during N. Balanos’ restoration project) offers the challenge to confront unusual structural problems [15]. It is mentioned characteristically that even in a single member, it is possible to deal with one or more of the following cases:  Join of fragments or supplements which form wedges on the upper or the lower area of the ancient remain.  Repair a fracture which penetrates all over the height or the width of the drum and at the same time join supplements, which extend all over the height or the width of the drum.  Join small fragments to the remaining volume of the drum as well as to repair huge cracks by replacing the existing “Π” and double “T” iron connectors (a short of clamps) which were placed during the previous restoration by N. Balanos. The proper new ones are made of titanium.  Create supplements, which include ancient remains.  Implant ancient fragments in new volumes of marble.  Join of almost horizontal ancient fragments standing the one above the other.  Join supplements to the ancient remain core forming the upper or the lower area of the drum.  Join fragments all-around to a new marble’s core.  Join ancient volumes to a supplement which surrounds all over their height, while at the same time due to the lack of parts of their upper and lower side of the drum, new supplements were also used in these areas. Due to the irregular shape of the fragments a number of problems often arise during the intervention, which makes it extre- mely difficult to join the new supplements with ancient sections of the member and to determine a certain direction of the reinforcement bars. In these cases the theoretical approach has to be in situ redesigned. Attention is paid to avoid crossing of the reinforcement bars coming from different directions, to maintain the proper distance between them, as well as between reinforcement bars and the drum’s external surface or the various irregularities /discontinuities in its mass. It is also very important to maintain the proper anchorage length of the reinforcement bars in order for extrusion (or pull-out) to be avoided. Figure 1 : Joining together the ancient fragments A, B, Γ, with the new insert Π to keep them in the right position within the member’s volume using cement mortar (left). The joining of this group and the main block of a new marble with “montage” reinforcement bars is presented in the right photo. In the foreground view the opposite fractured surface and the points, where reinforcing bars will be inserted during the next step of intervention, are presented. (Author’s note: All pictures in this paper are from the archive of YSMA). After the intervention, a continuous monitoring and control of the member’s response must follow since the work that has been done must provide flexibility to permit future interventions if necessary. The tactic, complexity and difficulty of the steps’ sequence for the intervention of the drums are presented here with a few characteristic examples. I