Take a look at this paper:

https://link.springer.com/chapter/10.1007/978-981-33-6389-2_21

Using blast pressure formulas (such as Kingery-Bulmash equations), you can calculate peak overpressure and impulse, then convert them into equivalent uniform loads or time-varying functions for use in ETABS.

To calculate blast load for application in ETABS, determine key parameters such as impulse based on explosive weight and standoff distance, and peak overpressure using empirical formulas(such as Brode’s Formula, Sadovsky’s Formula or Kingery-Bulmash formula), then apply the equivalent static or dynamic pressure load to the building's facade based on these values. For dynamic cases, you can also define time-history functions to represent the blast's impact over time considering factors like angle of incidence and reflected pressure.