Case Study: Fast Air Scalling Laws

2. BLAST WAVE SCALING LAWS

All impact factors are essentially reliant on the measure of vitality discharged by an explosion as an impact wave and the separation from the blast. The standardized explanation of the blast effects is given by scaling distance relative to (E/Po)1/3 and scaling pressure relative to Po, where E is the energy release (kJ) and Po the ambient pressure (typically 100 kN/m2). In general the basic explosive input or charge weight W is expressed as an equivalent mass of TNT. Outcomes are then given as a function of the dimensional distance parameter. Scaling laws provide parametric connections between a specific explosion and a standard charge of the same substance. Where, R is the actual effective distance on or after

These blasts reflected positive pressures are applied to the front side of building in the form of blast force. These blast forces can be obtained by multiplying the pressures with the contributing area of each node. A sample calculation for forces acting on the nodes due to blast weight of 100kg at standoff distance of 20m is shown below,

i) For node no 83;

Positive pressure= 137.3 kPa

Blast force P83 = 0.1373x0.25x1000= 34.32kN ii) For node no 86;

Positive pressure = 80.8 kPa

Blast force P86 = 0.0808x0.5x1000 =

40.4 kN iii) For node no 89;

Positive pressure = 56.1 kPa

Blast force P89 = 0.0561x0.5x1000 =

28.50kN

iv) For node no 80;

Positive pressure = 42.5 kPa

Blast force P80 = 0.0425x0.25x1000 =

10.63