PSI - Issue 55

Dimos Triantis et al. / Procedia Structural Integrity 55 (2024) 185–192 Triantis et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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ten-point bending under quasi-statical displacement-controlled conditions. Analytic description of the specific experi mental protocol is given by Kourkoulis et al. (2017). The maximum overall bending load attained during the specific structural test was equal to about 33 kN. A total of N =951 acoustic events were recorded during the experiment, which was terminated at the instant of abrupt fracture of one of the corners of the restored epistyle. The temporal evolution of the load applied is plotted in Fig.4a together with the energy of each one of the acoustic events recorded.

10 cm

Fig. 3. The geometry and the dimensions of the restored epistyle. The two marble fragments and the position of the three pairs of reinforcing bars are shown. The restored epistyle rests on marble blocks simulating the capitals of the Temple and it is tested under ten-point bending.

1.00

360

1.E+07

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Load

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270

1.E+05

240

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180

1.E+03

120 Load [kN]

0.25

90

1.E+01

0

0.00

0

0

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600

900

1200

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300

600 t [s]

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(a) (b) Fig. 4. Ten-point bending of a restored marble epistyle: (a) The temporal variation of the load applied, together with the energy of each one of the acoustic events recorded; (b) The temporal variation of the load applied in juxtaposition to the respective one of the normalized average energy of the acoustic events. Thorough analysis of the mechanical response of the restored epistyle (by means of data provided by the 3D-Digital Image Correlation technique and with the additional aid of traditional clip gauges measuring the opening of the fault, i.e., the distance between the two constituent blocks of the specimen) has revealed that entrance of the specific system into its critical stage took place at the instant with t cr ≈830 s, namely the instant of the slope change of the load-time curve indicated by the green circle in Fig.4a (Kourkoulis et al. (2024)). At this instant the load applied was equal to about L cr ≈183 kN. It should be emphasized that this critical load does not indicate proximity to fracture of the marble blocks. The complicated nature of the specific structural member, which consists of three materials (marble, titanium and cement paste) with many interfaces, is responsible for a variety of failure mechanisms, including not only fracture of the marble, but, also, debonding of the reinforcing bars from the marble body, fracture of the cement paste surround-