Generally the failure modes on structure associates with the explosive loading can be flexure, direct shear or punching shear, bleaching and spalling which is depended on the explosive size and standoff distance between the blast source and the target as shown in Figure 2.
The extend of the damaged on a structure can be classified as light, moderate and also severe.
In Fig-1 the damages by explosion are marked as A,B,C respective to Severe, Moderate, Light.
|Fig -1 Concrete Damaged by Blast|
Light damaged (Fig: 1 C) is referring to the appearance of hair line crack with crack width of less than 1 mm on the exposed surface of the concrete. Moderate damaged (Fig: 1 B)refers to the situation when the bottom surface of the concrete is having cracks width of up to 1.5 mm and also having a minor spalling. Severe damage (Fig: 1 A)refers to the large cracks up to 4 mm wide together with large deflection and also heavy concrete spalling.