MATTHEW GILBERT University of Sheffield,
BRIAN HOBBS University of Teesside

This paper describes the ongoing programme of impact testing on full-scale unreinforced masonry walls constructed in the laboratory at the University of Teesside. A novel drop hammer and rotating quadrant testing rig has been constructed to allow horizontal impact loadings to be applied to the test walls. Specially shaped timber packs have been used to produce impact characteristics similar to those associated with vehicles. Instrumentation includes high speed video and film, as welt as displacement transducers. Large concrete abutment blocks have been positioned at the ends of relatively short wall specimens in an attempt to simulate longer walls. These can be fixed to the laboratory strongfloor to provide further restraint to the ends of the walls if required, allowing the arching action component of resistance in particular to be investigated more closely. Initial tests show that the modes of failure of walls subjected to actual vehicle impacts can be approximately reproduced using an impactor which is fixed in the plane of the wall. Resistance of the test walls is mobilized in two distinct phases. In Phase I resistance is mobilized by the unit-mortar bond strength, in Phase 2 resistance is mobilized by horizontal arching action. Additionally inertial forces are present in resisting wall movements and have been found to be significant.