## 4 Results
### Displacement Results from Simulation  
In this simulation the displacement was taken from elements at different position as shown in Figure 9a. The displacement was taken from the back side of the protection wall structure red dot represents the probe position in structure. The total termination time for the simulation is 10 milliseconds. RC16_120 represents the reinforced protection wall and the stand-off distance between the structure and TNT is 1.6 m with the thickness of protection wall is 0.12 m. Similarly, H_beam16_120 represents the composite protection wall structure with 0.12 m thickness. Denotation of variables follows same notations for Figure 9.  
Figure 8: Incident pressure vs time curve from Conwep and LS-DYNA.  
Figure 9: \(Cont.\)Figure 9: **(a)** Position of displacement probe; (b) Reinforced and composite protection structure displacement at a distance of 1.6 m from different elements; (c) Reinforced and composite protection structure displacement at a distance of 2.6 m from different elements; (d) Reinforced and composite protection structure displacement at a distance of 1.6 m from different elements; (e) Reinforced and composite protection structure displacement at a distance of 2.6 m from different elements; (f) Reinforced and composite protection structure displacement at a distance of 1.6 m from different elements; (g) Reinforced and composite protection structure displacement at a distance of 2.6 m from different elements; (h) Reinforced and composite protection structure displacement at a distance of 3.6 m from different elements.  
RC_16_120 represents the reinforced protection wall and the stand-off distance between the structure and TNT is 1.6 m with the thickness of protection wall is 0.12 m. Similarly, H_beam16_120 represents the composite protection wall structure with 0.12 m thickness. From Figure 9a, the displacement is higher than the other variables. Installation of H-beam reduced the displacement but the difference is minimum during worse-case scenario. Increasing the thickness of the protection wall reduce the displacement of elements after explosion. Figure 9h had a minimum displacement at probe D1, D5 and D9 at a 3.6 m stand-off distance between protection wall and TNT. In Figure 9b,f, D3, D7 and D11 had lower displacement than the D1, D5 and D9 this represents that the blast wave damage more at the shortest distance.  
Failure on Reinforced Concrete and Composite Protection Wall during Worse Case Scenario of Hydrogen Gas Explosion  
An explosion is a sudden process with rapid release of energy. This process last only for few milliseconds and produce a very high pressure and temperature. In this simulation the position of the TNT is 0.55 m from the ground level but the denotation point is at the center of TNT. The total termination time for the simulation is 10 ms. Figures 10 and 11 shows the failure of reinforced concrete and composite protection wall during worse-case scenario of hydrogen gas explosion and an index of damage with strain softening. As the distance increase the damage area on the protection wall was reduced for wall thickness of 0.12 m. But the stand-off distance till 3.6 m for 0.12 wall thickness is not sufficient to resist blast wave. Fragmentation area of protection wall is also high and can cause secondary accident during worse-case scenario and erosion of concrete elements is high in Figure 10 the erode elements had no color. Increasing the stand-off distance and thickness of wall i.e., at 3.6 m and wall thickness of 0.2 m for reinforcement concrete protection wall the damage area is lower than 0.12 m and 1.6 m of stand-off distance. Using of H-beam as a composite structure the damage area on the protection was area was comparatively lower than the reinforced concrete.