Impact mitigation of masonry walls with carbon fibre and Auxetic fibre composite renders - A numerical study

Masonry buildings constructed along busy roads are vulnerable to vehicular impacts resulting in damage to property and harm to occupants. This paper presents two strategies that use either carbon fibre or auxetic composite render for mitigating the adverse effects of such impacts and compares the merits of the two strategies. As masonry is a relatively low strength brittle material, the rendering material should possess high energy absorption characteristics (as in auxetic composite) or high strength (as in carbon fibre composite) properties for impact damage mitigation. Towards this end, finite element models incorporating material and contact nonlinearities and (recently developed) carbon fabric and auxetic fabric composite renders possessing positive and negative Poisson's ratios respectively are developed and applied. These models are validated using experimental datasets and then applied to masonry walls impacted laterally at velocities ranging from 6 km/h to 100 km/h. Results show that the failure mechanism of masonry walls varies from global to local with the increase in the impact velocity and that the auxetic composite render significantly minimises debonding risks, enhances energy dissipation characteristics, reduces the impact force and the impact damage on the masonry walls, compared to carbon fibre composite render.