Shaking table tests on strength degradation behaviour

Structures such as unreinforced masonry walls, soft-storey buildings, gravity structures and components which include free-standing objects are well known to be non-ductile and yet they are commonly found in regions of low-moderate seismicity. Potential significant degradation in strength in these structural systems in projected earthquake scenarios has been a cause for concern. Shaking table experiments undertaken recently by the authors revealed very interesting phenomena with the behaviour of the (“non-ductile”) free-standing objects in an earthquake. Vulnerability to overturning is shown not to be sensitive to the height of the object nor its aspect ratio. The trends revealed earlier by the authors based on analytical modeling have been confirmed experimentally. Importantly, the displacement time histories predicted by program Rowmanry and Romain are shown to be very consistent with recordings from the shaking table experiments.