PSI - Issue 42

Maha Assad et al. / Procedia Structural Integrity 42 (2022) 1668–1675 Assad et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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predicted curves at all stages of loading. The FE model can perfectly predict the behavior of the slab specimen until the yielding of steel reinforcement occurs (indicated by a clear change in the slope of the curve). After that, the model can predict the slab’s response to a good extent, with a slight underprediction of the capacity of the control slab. On the other hand, there is a quite overprediction of the ultimate load value in both strengthened slabs (EBR and NSM). This minimal difference can be attributed to the variation in material properties between the experimentally tested values and the values assigned to the model. The FE model confirms the superiority of the NSM technique in terms of higher ultimate loads and deformational capacity as can be seen in Fig. 3-b and 3-c.

(a)

(b)

(c)

Fig. 3. Load-deflection curves under ambient temperature (a) Control; (b) EBR; (c) NSM

3.2. Thermal response Temperature profiles were obtained through a heat-transfer analysis under the ASTM E119 standard (ASTM E119, 2000) fire curve. The EB and NSM slab’s soffit were subjected to fire and the heat is transferred through the slab by conduction, convection, and radiation. The time-temperature curve was plotted for one representative point lying on the FRP sheet having the same position, as the one in the experimental setup of Azevedo et al., (2022). The temperature profile curves were compared with their experimental counterpart as shown in Figure 4. Good correlation is depicted in both strengthened slabs. The verification of the temperature profiles is important since the nodal temperatures obtained from this analysis step are inputs on the nodes in the structural model where stresses, displacements, and strains are calculated.