Damage assessment of concrete structures subjected to internal explosion under air-backed and water-backed conditions

Abstract

There has been an increasing concern about the dynamic response and damage assessment of offshore structures under blast loads due to accidents and terrorist attacks. These concrete structures will face severe threats of internal explosions from powerful bombs. After the internal detonation of a bomb, the blast wave in the concrete structure will gradually propagate to two types of fluid-structure interfaces: the air-concrete interface or the water-concrete interface. The purpose of this paper is to investigate the nonlinear response and damage assessment of the concrete structures to internal explosion considering air-backed and water-backed conditions. Two types of blast tests are conducted to obtain the damage mechanisms and degrees of the concrete targets under internal explosion conditions. A fully coupled numerical approach is used to model the internal explosion and the fluid-structure interaction, and it is validated through comparing the test and the numerical results. The shock-wave and damage propagation of the concrete targets under air-backed and water-backed conditions are compared. The damage ranges of the concrete targets with various explosive weights, buried depths, and fluid-structure interfaces are presented. Its results are used to propose a damage assessment method for the concrete structures to internal explosion under air-backed and water-backed conditions.