The widespread use of fuel gas has posed great threats to the security of building structure

on account of the frequent explosion events.Nevertheless

the present method of damage level identification used for explosion damage structure in China is not practical

as it determines the damage level by the residual bearing capacity.In this paper

a finite element model of steel structure is established and the horizontal displacement and residual bearing capacity of steel column are analyzed.The analysis uses the finite element program LS-DYNA to investigate hot rolled H and cut T section steels following GB/T 11263-2017.The concepts of safety factor K and relative deflectionωRare introduced

and their relationships for H-shaped steel columns under explosive loading are analyzed through numerical simulation.Based on this

the criterion for determining the damage of steel column is proposed

together with the damage levels.Compared with the existing classification

the current method of steel column safety grade has a strong operability in practice.