This standard provides criteria for designing above-ground structures to resist the effects of blast loading. It outlines methods to determine blast wave characteristics, calculate equivalent static loads from dynamic pressures, and perform dynamic analysis, focusing on the inelastic behavior and energy absorption capacity of structures.
Criteria for blast-resistant design of structures for explosions above ground
Quick Reference Values
Permissible ductility ratio for RC flexural members3 to 10 (depending on damage level)
Permissible ductility ratio for steel flexural members10 to 20 (depending on damage level)
Permissible support rotation for RC one-way slabs (repairable damage)2 degrees
Permissible support rotation for RC beams (repairable damage)2 degrees
Key Formulas
Z = R / W^(1/3) — Scaled distance, where R is distance (m) and W is charge weight (kg TNT)
P_so = f(Z) — Peak overpressure as a function of scaled distance (from charts)
T = 2π * sqrt(m/k) — Natural period of an SDOF system
μ = x_m / x_el — Ductility Ratio, where x_m is max deflection and x_el is elastic limit deflection
Practical Notes
The code's charts and methods are based on data from the 1950s-60s. Modern practice often uses advanced software (FEA/CFD) for more accurate blast analysis, though the principles of this code are still fundamental.
The most critical and often uncertain inputs are the design threat, specifically the equivalent TNT charge weight (W) and the standoff distance (R).
Design for blast resistance is fundamentally about ductility and energy absorption, not just strength. Detailing of reinforcement and connections to prevent brittle failure modes is paramount.