Figure 9 shows the damage occurred on concrete deck in numerical simulation, where dark color represents complete damage while gray region indicates no damage. It is noted that in the region beneath the charge, little damage is observed, although the scale distance in this region is the smallest. In Fig. 5, the same phenomenon is observed that no visible crack can be found in the corresponding region. This can be explained that the overpressure is isolated by the steel plate. For the area away from the detonation center, however, more damage occurs on the deck and extends to a large field longitudinally, which is consistent with the flexural-shear damage observed on girders 4–8 in Fig. 5. Then in the region far from the charge, which is corresponding to the girders 1–3 in Fig. 5, damage is still observed but concentrates on the central portion where flexural cracks were observed in Fig. 5. Therefore, when compared to Fig. 5, a similar damage tendency, which does not follow common knowledge of blast in free air, is observed for both numerical and field investigations, i.e., the numerical failure coincides with the failure identified in the postdisaster investigation. There is, however, still some difference for the damage distribution between numerical modeling and the actual event, as shown in Figs. 5 and 9. From Fig. 9, the symmetry of damage distribution is observed but an asymmetric crack distribution is found in Fig. 5 with respect to crack width. The most severe damage occurs on girders 1–3 where crack widths reached more than 10 mm or rupture happened, while this is not the case in numerical situation, as shown in Fig. 9. These may be again due to the integrity assumption for girder connection and the simplification assumption for the truck isolating system replaced by a steel plate in the numerical simulation. Therefore, from both the damage and the deflection distribution, we can conclude that the presence of a steel plate is effective for modeling the isolation effect on the propagation of overpressure on the deck, and the isolation effect of the truck has a great influence on the amount of damage to the concrete girder.