Effect of Hollow Channel Cross-Section Shape on the Damage Mechanism of Reinforced Concrete Slabs Under Near-Field Blast Loading

Abstract

Hollow-core reinforced concrete (RC) slabs are increasingly used for their reduced self-weight and integrated service voids, yet the influence of the internal channel cross-section shape on their behavior under near-field blast loading remains largely unexplored. Existing numerical studies on blast-loaded RC members focus almost exclusively on solid or circular-void cross-sections, leaving the systematic effect of void geometry unresolved. This study numerically investigates the contact detonation response of hollow-core RC slabs with three different channel cross-section shapes (square, circular, and hexagonal) using a coupled finite element method and smoothed particle hydrodynamics (FEM-SPH) approach in Abaqus/Explicit. The TNT charge is represented by the Jones-Wilkins-Lee (JWL) equation of state, concrete is modeled with the Concrete Damaged Plasticity (CDP) constitutive law, and an adaptive FEM-to-SPH conversion is employed in the contact region so that cratering and fragment ejection are captured without element-deletion artifacts. A parametric matrix of 48 models spanning three channel shapes, four lower-flange thicknesses (50-140 mm), and four charge masses (0.5-2.0 kg) was analyzed. The results show that the channel cross-section shape significantly governs blast resistance: the circular and hexagonal sections exhibit comparable performance and undergo approximately 20% lower mean bottom-flange displacement than the square section. The 90-degree corners of the square section promote premature crack initiation and concrete crushing through stress concentration. A critical lower-flange thickness is identified, beyond which the failure mode transitions from global flexural collapse to localized perforation. The predicted crater dimensions agree well with previously reported contact-explosion experiments.