PSI - Issue 10

C.B. Demakos et al. / Procedia Structural Integrity 10 (2018) 148–154 C.B. Ddemakos et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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Thus, applying and increasing progressively the loading, the stress distribution was calculated and is shown in Fig.6 for both scenarios concerning loading direction. It is worthy of note that the maximum compressive and tensile stresses appeared at the same locations of the arch for both loading patterns. The difference is that at the same point of arch the stresses are in opposite sign along the section of shell. For instance, at the middle of structure the top face suffer to compression stresses for the load acting in gravity direction, whereas the loading acting normally to the surface results to tensile stresses at the top face.

(a) (b) Fig. 6. Stress distribution for (a) loading in gravity direction and (b) loading perpendicular to arch.

4. Experimental results and discussion

Fig.7 shows the failure pattern of a cement arch submitted to previously referred bending loading. It is worth noting that good agreement seems to exist for the cracking points of arch and the points of high stress distribution demonstrated in Fig.6a. The loading vs. displacement at the middle of the arch structure model were numerically evaluated and plotted in Fig.8 for both scenarios of loading distribution. This loading vs. displacement variation was also compared to the experimental values detected for loading and displacement, which were derived by a load trans ducer and a LVT displacement recorder, respectively (Fig.9). Comparing numerical curves concerning both loading scenarios (Fig.8), it seems that when the loading was applied normally to the surface of the arch, the specimen attained higher load capacity than arches subjected to loading acting parallel to gravity direction. Comparison of numerical and experimental values (Fig.9) reveals good agreement between experimental curve and numerical one with loadings in gravity direction until the displacement attains the value of 10 mm, which is apparent also by the crack pattern prevailed at the fractured specimen.

Fig. 7. Cracks pattern of fractured cement arch.