In-plane performance of masonry veneer subjected to blast vibrations

Footing related movement in domestic structures from environmental loads is responsible for widespread cracking in houses. While the severity of cracking may vary significantly, cosmetic cracking frequently goes unnoticed. However, some residential areas in Australia also experience low level vibrations from blasting in nearby mines or quarries. Some residents are alarmed by the noise of a blast and become concerned their dwelling has been damaged, typically in the form of cracking. Common complaints relate to non-structural components such as interior plasterboard and masonry veneer. Despite existing governing vibration limits which are considered conservative relative to international limits, crack related complaints continue to be made and contention exists over the damage potential of low level blast vibrations. An extensive research project at the University of Melbourne has sought to identify the relationship between blast vibration and damage in plasterboard and masonry veneer in houses. An extensive testing program has been the primary avenue of this research, investigating the behaviour of plasterboard and masonry ranging from the local to global scale. The final component of the testing program has been a full-scale uniaxial shaking table test of a single room house in two orthogonal directions. The specimen included a timber frame with unreinforced masonry veneer and had penetrations in all four walls to be considered representative of a typical brick veneer house. This paper focuses on the performance of the masonry veneer, reporting on the deterioration with increasing level of vibration. Damage criteria are presented which relate the severity of cracking over a range of drift limits.