## 5 Discussion  
Compared with the results of the more precise dynamic analyses, the analysis with static equivalent loads leads to very conservative results. Using the static equivalent calculation method, a steel tank cannot be qualified for the blast scenario, which is in contrast to the results of the other analyses. This method should therefore not be used for the economic design of tank structures of any kind of material subject to blast loads. The load behavior in all dynamic analyses follows a similar approach: maximum stresses and deformations occur along the tank wall sides parallel to the direction towards the explosion source. If the highly stressed sides of the tank are taken together from all analyses, this corresponds to a range of approximately 60\({}^{\circ}\) to 120\({}^{\circ}\) of the circumferential angles. This structural response is mostly well reproduced by all analyses. Only the analyses with a roof suction load and varying compressive load (Simulation 2.2a/-b) show the tank wall-roof transition as the area subject to the highest stress and deformation. The simplified load application with uniform pressure over half of the tank seems to produce very conservative results. The unloaded side facing away from the explosion source neglects the shell load-bearing behavior due to the supporting effect inherent in a cylindrical shell under full circumferential pressure, which is also present in the case of non-uniform circumferential pressure (different pressure amplitudes along the circumference). The stress level is calculated to be relatively high. Here, it is to be expected that an adequate design of the tank based on this approach either leads to higher material consumption (thicker shells or more wall stiffeners) or the use of steel with a significantly higher yield strength. For the latter, it should be noted that [23] advies to avoid the use of high strength materials (greater than a nominal 350 MPa yield) in most blast applications to prevent problems with decreased ductility. Alternatively, the use of a steel construction could be completely discarded in favor of a concrete construction when using this simple calculation approach. The consideration of a more precise load application (Simulations 1.2a/-b, 1.3a/-b, 2.2a/-b) shows that a steel construction is basically suitable to withstand long-duration and high-pressure blast loads. Qualitatively, the results are very comparable, both when applying a pressure wave load (Simulations 1.2a/-b) and a shock wave load (Simulations 1.3a/-b). However, the latter leads to higher stresses and higher deformations. Plastic deformations occur. Using the design criteria CL/SS proposed in Section 2.5 inspired by [23] with a limit ductility level of \(\mu=1\), using Equation (4), the plastic deformation can be qualified. With \(\epsilon_{\text{elast}}\) being determined with the nominal material values according to Table 1 to \(\epsilon_{\text{elast}}=0.163\%\), an allowable plastic strain of \(\epsilon_{\text{plast}}=0.0813\%\) is obtained. A look at the plastic strains listed in Table 4 for Simulations 1.3a/-b shows that this limit value is exceeded for beam elements of Simulation 1.3a (\(\epsilon_{\text{plast}}=0.114\%\)). In contrast, the structural response is purely elastic when a pressure wave load according to the developed concept is applied. The difference between a shock wave and a pressure wave is the way in which the blast waves propagate in the surrounding environment. A shock wave is a fast, abrupt blast wave that moves at supersonic speeds. In contrast, a pressure wave is a slower wave that propagates at the speed of sound. In the present research, the approach of applying the pressure wave to the structure uses blast parameters of an impulse congruent shock wave; see Section 3.4. This also adapts the propagation velocity of the shock wave for the pressure wave. For the scenario under consideration, the propagation velocity of the wave is 360.5 m/s according to the blast equation of [56] and is therefore above the speed of sound.