Damage behavior of extra-wide reinforced concrete box girder with multiple chambers under repeated explosive loads: Testing and numerical simulation

Abstract

Explosive tests of scaled girder specimens and numerical simulations of prototype girder segments were implemented to study the dynamic response and failure characteristics of extra-wide reinforced concrete box girders subjected to repeated explosions. First, a segmental girder specimen was manufactured at a reduced scale of 1:3 based on the prototype girder of a real bridge. The damage behavior of the specimen was tested by detonating two 3-kg TNT (trinitrotoluene) grains in sequence at a height of 0.40 m above the center of the middle chamber. Second, LS-DYNA software was used to simulate the explosive response of the specimen. The reliability of the numerical simulation method was verified by comparing its results with test data. Finally, the effects of different TNT equivalents, detonation positions, and repeated explosion modes on the anti-explosion performance of the prototype girder segment are simulated. The results showed that the holes in the top plate of the middle chamber of the girder specimen were 41.50 cm × 45.50 cm and 56.80 cm × 63.50 cm along the longitudinal and transverse directions, respectively, under the two explosions. The concrete at the bottom of the top plate peeled off over a wide area, and cracks appeared in the bottom plate close to the supports. In comparing the simulated damage behavior of different girder segment types along the transverse direction, the dynamic response of the T-beam section segment was found to be greater than that of the box section segment under the same explosive charge. The maximum response was located at the road centerline. Moreover, the degree of damage to the girder was more severe under repeated explosions with a certain amount of charge compared with that under a single explosion with twice the amount of charge. The degree of damage to the web, bottom plate, and crossbeam caused by the explosions in sequence from outside to inside the box with two 200-kg TNT grains was more severe than that caused by a single explosion of 400-kg TNT grains. Simultaneous detonations at multiple positions severely degrade the bridge traffic capacity.