Application of Controlled-rocking isolation with shape memory alloys for an Overpass Bridge

Resilience of bridges in seismic zones can be realised by taking the advantage of rocking isolation which aims at reducing the permanent drifts after a seismic event. The seismic forces at the base of the bridge can be reduced by allowing uplift in the foundation when subjected to ground shaking. Conventional monolithic connection of bridge pier to the foundation often leads to severe damages (or even collapse) during high magnitude earthquakes. In this context, this article proposes a novel seismically resilient pier footing which rocks on elastomeric pads and external restrainers (provided by shape memory alloy bars). Seismic performance of a typical existing overpass motorway bridge is compared with the proposed rocking isolation concept. The proposed technique shows good re-centring capability during earthquakes with negligible residual drifts. Furthermore, it is also observed that forces in the pier and size of pier footing are reduced as compared with the reference bridge considered in this study.