Local damage of precast concrete columns with grout sleeve connections under contact detonation

Abstract

Over the past several decades, the global terrorism is looming large and public buildings have become targets of terrorist bomb attacks. To obtain the blast performance of precast concrete (PC) columns with grout sleeve connections at the background of terrorist attacks, the contact detonation is concerned in this paper. An experimental program with six PC columns and one reinforced concrete column against contact detonation was conducted in a blast testing vessel, in which the effects of charge weight and location as well as connection type of columns on blast damage were studied. Then the finite-element-based (FE) numerical models were built up with LS-DYNA and validated with comparison of experimental results. In the FE model, blast load is simulated using multi-material Arbitrary-Lagrangian-Eulerian (MM-ALE) algorithm. After careful validation, the numerical models are extended to conduct parametric studies, including the effects of longitudinal and transverse reinforcement ratio, column section depth (or aspect ratio), charge weight and location, axial compression ratio on the blast damage of PC columns. Finally, curve-fitting-based models are derived to build up relationships between local damage sizes and the studied parameters, and then verified with part of numerical results. The results show that contact detonation destroyed all the concrete cover at the front face supporting the charge, and resulted in severe spall damage along the four corners and side faces, in which the corner connecting the side and rear face suffered larger damage than that connecting the side and front face. Moreover, the grout sleeves are able to mitigate the damage if the detonation is at the splicing segments. Increasing reinforcement ratio, section depth and axial compression ratio are able to reduce damage sizes, but the beneficial effect differs for the local damage at the column corners and front face.