Dynamic Response and Numerical Simulation of UHTCC-R-RAC Composite Slab under Contact Explosion

To investigate the blast resistance of Ultra-High Toughness Cementitious Composites-Reinforced Recycled Aggregate Concrete (UHTCC-R-RAC) composite slabs under contact explosion, three sets of UHTCC-R-RAC specimens with varying UHTCC layer thicknesses (0 mm and 10 mm) and recycled coarse aggregate substitution rates (25% and 75%) were designed and subjected to contact explosion tests using 200 g emulsion contact-explosions under different working conditions. Subsequently, a numerical model was developed using the Arbitrary Lagrangian-Eulerian (ALE) method and a fluid-structure coupling algorithm in ANSYS/LS-DYNA, incorporating both a global (10 mm) and a locally refined (5 mm) mesh configuration for the UHTCC-R-RAC composite panels. The experimental results indicate that increasing the replacement rate of recycled coarse aggregate from 25% to 75% reduces peak strain by 11.7% and peak acceleration by 6.4% on the blast-exposed surface of the R-RAC composite slab, demonstrating a negative correlation between RCA content and blast resistance. Conversely, the application of a10 mm UHTCC layer significantly improved blast resistance, evidenced by a 64. 7% increase in peak strain. Numerical simulations further confirmed that the locally refined 5 mm mesh model outperformed the global 10 mm mesh model in both computational accuracy and efficiency.