The tenacity of reinforcing bars in resisting earthquake loading, after concrete had spalled away around them, suggests that round bars can be used to dissipate earthquake energy in base isolated buildings, provided a bow is introduced in the bars to allow them to extend as the building deflects on its bearings. Dynamic tests are described which enable a design method for such a system to be evolved. The method has the advantage of simplicity in that round bars available in normal engineering practice can be utilised, while a tensile capacity is introduced between the structure and the foundation which enables the system to progressively lock up under disaster conditions.