Performance of interlocking structures enhanced with meta-blocks against impact loads

Mortarless interlocking brick assemblies have shown to reduce construction costs compared with conventional masonry. Studies have incorporated locally resonant elements (LREs) into interlocking bricks to improve their hazard resistance. This configuration is referred to as a meta-block that uses the pounding between bricks and local resonance of LREs for mitigating dynamic energy propagation, resulting in a strong attenuation of peak responses under impact loading. This study examines the dynamic performance of masonry structures constructed with mortarless interlocking bricks and meta-blocks under low-speed vehicle impact and high-speed windborne debris impact. It assesses the performance of structures enhanced with meta-blocks by comparing them with a conventional interlocking brick structure. First, a full-scale protective barrier was experimentally tested using a pendulum impact testing system. The test results revealed a global rocking mechanism characterised by inter-brick gap openings and in-plane detachment of the impacted column, leading to localised damage and toe crushing. The application of meta-blocks resulted in no measurable improvement under low-speed pendulum impacts, as the frequency of most of the input energy fell below the LRE band gap. Then, the response of a masonry wall subjected to windborne debris impact was numerically simulated. Results demonstrated that the wall met the design requirement of no penetration. The high-frequency input energy from windborne debris impact fell in the LRE band gap and activated local vibrations of heavy cores. Hence, the wall enhanced with meta-blocks showed a reduced maximum deflection by 22% and reduced damage by 61%. The study extends previous small-scale tests on meta-block by evaluating their performance in full-scale masonry structures subjected to low- and high-velocity impacts, contributing to the understanding of the performance of structures constructed with metamaterials.