Shake Table Test of Retrofitted and Repaired RC Bridge Columns Using Shape Memory Alloy Spirals

Abstract eng:
RC bridge columns are required to maintain their functionality after strong seismic events without collapsing. Many existing bridges constructed based on old seismic design provisions lack the sufficient lateral confinement and are exposed to risk of severe column damage. Seismic damage of bridge columns may interrupt the immediate use of the bridge or lead to the collapse of the bridge under subsequent seismic events. As a new retrofit/repair technique for vulnerable RC columns, the application of Shape Memory Alloys (SMAs) in applying active confinement at plastic hinges has gained great interest recently. The substantially improved seismic performance of RC columns retrofitted and repaired with SMA spirals was proven in previous quasi-static cyclic tests. This experimental study aims to explore the effectiveness of using SMA spirals as retrofit and repair tool for RC columns through a series of shake table dynamic tests. Two 1/6-scale circular RC columns are tested under bidirectional earthquake loading. One of the specimens is retrofitted with SMA spirals, while the other specimen remains in the as-built condition. After moderate damage was imposed to the as-built specimen under seismic excitations, emergency repair is performed with SMA spirals followed by sequential seismic loading. Experimental results indicate that SMA spirals can effectively mitigate the damage and enhance the performance of RC columns under strong sequential ground shakings.

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