Failure of masonry walls under high velocity impact – A numerical study

Abstract

This paper reports a study on the failure of masonry walls subject to vehicular impacts. The investigation encompasses a homogenised masonry material model incorporating strain rate effects suitable for impact dynamic applications using a layered shell element formulation in an explicit finite element framework. As the focus of the study is on the impact failure of masonry walls, for simplicity the impactor is conservatively modelled as rigid and crashing normal to the surface of the masonry wall. The failure mode, contact-impact forces and the impact energy dissipation characteristics of the masonry wall are reported. It is shown that with the increase in impact velocity, the damage area of the masonry wall reduces, progressively plateuing equal to the contacting area of the impactor. This phenomenon is defined in this paper using a parameter termed as damage index, which is the ratio of the area of the damage of the wall to the area of the impactor at the impact zone. Damage index is shown to be a useful parameter to assess the velocity of the impacting vehicles for forensic investigations. Sensitivity of the incident velocity of the impactor to the characteristics of the global vibration and local damage of the impacted masonry wall is reported; the exit velocity of the impactor is also reported. Examination of the effects of the aspect ratio, boundary conditions and the position of impact relative to the supported edges shows that these parameters are not sensitive to local impact failures.