PSI - Issue 64

Donatella de Silva et al. / Procedia Structural Integrity 64 (2024) 1806–1814 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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scenarios has been obtained by a linear combination of the single vehicles’ scenarios. Analyzing several reports about fire accidents involving bridges, these scenarios aim to represent the most likely events that bridges might encounter in real-world environments, considering as many vehicle types as possible. The central position in these fire scenarios was considered because it is the most severe for a simply supported bridge. The trend of the HRR curves for the 31 scenarios considered is reported in Figure 3. Regarding the placement, it was assumed that the fire from the center of the deck at the midspan of the bridge deck cross-section.

Figure 3. Fire scenarios heat release rate curves

5. Structural assessment results The thermal analyses were conducted by SAFIR software for a duration of 360 and 180 minutes respectively for r.c. bridge and composite bridge, allowing the heated structure to cool down to ambient temperature once the fire scenario was completed. The temperature trend in the most exposed steel bar for the prestressed reinforced concrete bridge is shown in Figure 4.a), while the temperature of the steel section of the composite bridge are shown in Figure 4.b). It is observed that the temperature reached in the most exposed steel bar of the prestressed reinforced concrete bridge is lower compared to that reached in the steel girder of the composite bridge.

a)

b)