The effect of stand-off distance on damage to clamped square steel plates under enclosed explosion

•A combination of enclosed explosion tests were carried out in a steel box and fully clamped square plates showed less deflection at smaller stand-off distances, which was a phenomenon different from open explosions.•The relationship between deflection of the plate and stand-off distance is discussed.•Four failure modes were observed and theories of each failure mode were analyzed.•Fully clamped square plates showed less deflection at smaller stand-off distances under enclosed explosion.