Enhancing structural resilience of honeycomb-steel-tube filled UHPC against sequential penetration and blast

This study investigates the Honeycomb-Steel-Tube filled with Ultra-High Performance Concrete structure (HSTUS), designed to mitigate damage from sequential projectile penetration followed by blast loading. HSTUS leverages the lateral confinement from a hexagonal steel tube array to enhance the compressive strength of the Ultra-High-Performance Concrete (UHPC) core, placing it in a triaxial stress state and improving resistance to penetration and blast. Employing a comprehensive approach that integrates theoretical analysis, numerical simulations, and experimental verification, we evaluate the performance of HSTUS under high-velocity projectile penetration and subsequent blast forces. Tests using 25 mm steel projectiles and TNT charges demonstrate that, compared with ordinary concrete targets, HSTUS reduces penetration depth by about 20 % and decreases blast tunnel depth and blast-induced damage area by approximately 20. Although the penetration stage exhibits a slightly larger surface damage diameter, the coupled penetration and blast response is significantly mitigated, indicating an overall enhancement in protective performance. Refined empirical formulas, derived from experimental and simulation data combined with the theoretical cavity expansion model, provide accurate predictions of penetration depth and blast-induced crater dimensions with an error margin of up to 5 %, validating the effectiveness of the HSTUS design. These findings highlight HSTUS as a promising option for protective systems against coupled penetration-blast threats, bridging gaps in prior research on combined loading effects and offering enhanced structural resilience for civil and military applications. • Propose HSTUS concept to resist sequential penetration–blast loads. • HSTUS reduces penetration depth and blast damage by about 20 %. • Establish empirical formulas for predicting penetration and blast depth.