PSI - Issue 47

A. Vrouva et al. / Procedia Structural Integrity 47 (2023) 521–534 Vrouva et al. / Structural Integrity Procedia 00 (2019) 000 – 000

523

3

In the initial construction several connections were provided to unite the two individual parts of the tympanon (see Fig. 3) along with the substrate of the cornice and the superimposed raking cornice. Those were iron clamps and dowels and were the sole joining elements since the whole structure consisted of marble blocks closely fitted together in total absence of mortars. Those connections are essential as the backing wall acts as a counter weight to the lean orthostates that have a natural tendency to overturn during seismic excitation. The so- called “twisted connectors” - term intrduced by Penrose in Penrose, 1888- were a special feature in the original structure (their name derives from an interpretation of their form, but not sufficient archaeological evidence is yet provided for that matter).

Fig. 3. The ancient connections of the tympanon orthostates (Manidaki, Palaiologos, 2016).

In the current restoration project where the central part of the west pediment of the Parthenon is being restored the need for the redesign of those connections arose. The redesign had to account for the damages of the monument and meet the standards of safety especially during earthquakes. 2. Preservation state of the construction The monument in its long course – surviving more than 2500 years- has suffered damages from manly imposed and accidental actions as well as the ageing of the materials (Korres, 1983). More specifically as can be seen in Fig. 4 the blocks of the orthostates have developed fractures in the anchorage area of the connecting elements (clamps and dowels) relative with their actions (in red lines) (Toumbakari, 2008), along with damages caused by the bombardment of the monument during the Turcovenetian war (in green) and vertical cracking of the blocks relative to the crystallic structure of the material itself. Those blocks were dismantled and restored before being put back in their original position.

Fig. 4. Categorization of damages on the orthostate blocks. Photogrammetric survey of the west pediment’s orthostate, Photo archive Acropolis Restoration Service, photogrammetric development D. Mavromati.