PSI - Issue 64

Maher AL-Hawarneh et al. / Procedia Structural Integrity 64 (2024) 1103–1110 Maher / Structural Integrity Procedia 00 (2019) 000 – 000

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The uni-directional with 2-layer FRCM specimens had similar performance as the 1-layer uni-directional FRCM specimens. They experienced an increase of around 20% and 23% in the compressive strength compared to the average control specimens with an average increase 21.7% as shown in Fig.3. Furthermore, the 2-layer specimens significantly increased the specimen maximum strain compared to the control specimens. However, the 2-layer FRCM specimens did not show any improvement to neither the maximum strain at failure nor to the compressive strength compared to the uni-directional 1-layer specimens. This could be attributed to the method used to apply the second FRCM layer, as it had the same mortar thickness with the only difference being the addition of one layer wrapping.

The results of the concrete specimens with nominal unconfined compressive strength of 55 MPa are shown in Table 4. Similar to the 30 MPa specimens, the FRCM confined specimens had higher stiffness compared to the control specimen. The bi-directional FRCM specimens showed an increase of about 6% and 14% in compressive strength for both specimens compared to that of the average compressive strength of the control specimens (Fig.4). However, unlike for 30 MPa concrete variant, the bi-directional FRCM showed slight improvement in the concrete maximum strain at failure. The uni-directional single layer FRCM had greater effect on the compressive strength increase, as it showed an increase of 14% and 27% with an average increase of 21% compared to the average compressive strength of the control specimens (Fig.5). However, the confined specimens with uni-directional 1-layer did not show any improvement in the maximum concrete strain at failure compared to the control specimens. Fig. 3. Stress vs Strain uni-directional 2-layer FRCM 30 MPa specimens with control specimens

Fig. 4. Stress vs Strain bi-directional FRCM 55 MPa specimens with control specimens