Impact of geometric imperfections on the dynamic response characteristics of interlocking assemblies

Interlocking bricks have emerged as a promising alternative to traditional masonry, primarily due to their self-aligning capabilities, which accelerate construction and reduce dependency on skilled labour—advantages particularly valuable for addressing Australia's labour shortages and high costs. However, dry-stacked interlocking brick assemblies inherently exhibit gaps between bricks arising from surface roughness and dimensional variations. Extensive research has shown that these gaps induce stress concentrations and initial non-linear behaviour under static compressive and shear loading while enhancing energy absorption and dissipation under dynamic loading. Despite their known influence on dynamic performance parameters, the impacts of inter-brick gaps on the dynamic response of dry-stacked interlocking bricks during impact loading remain unknown. This study characterises the dynamic response through a combination of experimental testing, analytical simplifications, and stochastic analysis of interlocking brick assemblies. Instrumented impact hammer tests conducted on interlocking assemblies revealed that the inherent gaps cause pounding between adjacent bricks, resulting in high-frequency dynamic responses. An analytical approach was developed to characterise the inter-brick pounding, with results indicating that the timing of pounding events primarily influences the dominant frequency of the assembly. A stochastic method was employed to directly assess the influence of inter-brick gaps on the Fourier spectrum and to establish the boundaries of the analytical analysis. Furthermore, a novel design integrating meta-concrete with interlocking bricks is proposed to exploit these high-frequency responses beneficially. Numerical simulations demonstrated that meta-concrete interlocking brick systems attenuated acceleration responses induced by impact forces by up to 26 %, highlighting the synergy between these technologies for potential applications. • Inter-brick gaps cause independent brick motion, preventing a unified global system response. • Gaps induce inertial responses and sequential momentum transfer through inter-brick impacts. • Repeated pounding forms high-frequency clusters, shaped by inherently stochastic inter-brick gaps. • Analytical and stochastic models show pounding timing controls frequency clusters and gap sensitivity. • Meta-concrete reduces peak acceleration by 26 % and aligns with the frequency clusters of dry-stacked systems.