PSI - Issue 64

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

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2.4 Test setup and loading protocol Specimens were tested under the same loading protocol using a universal loading machine in a displacement control mode. A monotonic axial load was applied, with a displacement rate of 0.3 mm/min. The test was stopped when a significant strength reduction was observed, generally being lower than 60 % of the peak load. The axial load was acquired continuously during the test, using the load cell of the universal testing machine. The readings from the load cell and the strain gauges were stored on a computer using a data acquisition system. 3. Results and Discussion The results of the tested specimens will be compared in terms of the maximum compressive strain achieved by each specimen and the compressive strength. Table 3 show s the summary of results for the three FRCM variants for the 30 MPa compressive strength. Fig.1 shows the stress-strain curves for the concrete confined with bi-directional FRCM compared to the control specimens for 30 MPa compressive strength. The confined specimen showed higher stiffness compared to the control specimen, as the stiffness of the confined specimens consist of the unconfined concrete stiffness plus the FRCM stiffness. Also, the confined specimens had higher compressive strength than the average compressive strength of the control specimens by about 4%. The confined specimen showed significantly higher strain at failure contributing to higher concrete ductility compared to the control. The bi-directional confinement did not add a significant compressive strength but increased the concrete ductility significantly (Fig.1). On the other hand, the concrete specimens confined with uni-directional single FRCM layer showed significant increase in both peak compressive strength and ultimate strain as shown in Fig.2. The increase in compressive strength for both specimens compared to the average compressive strength of the control specimens was on average 25%. Moreover, the uni-directional 1-layer FRCM specimens had 3 times maximum strain at failure compared to the control specimens.

Fig. 1. Stress vs Strain bi-directional FRCM 30 MPa specimens with control specimens

Fig. 2. Stress vs Strain uni-directional 1-layer FRCM 30 MPa specimens with control specimens