Behavior of smart concrete beams with embedded shape memory alloy bundles

The behavior of smart concrete beams with embedded shape memory alloy (SMA) bundles is investigated in this study. Two beams measuring 1996 x 99 x 85 cm(3), which will be integrated into a smart bridge in a freeway, are manufactured and examined. Each beam contains six trusses of SMA bundles used as actuators to achieve recovery force. The SMA bundles are connected with pre-stressing steel strands and separated from the concrete matrix, so that temperature interaction between SMA bundles and the matrix can be reduced to as low as possible. Some temperature sensors, reinforcement meters, and displacement sensors are used to monitor the active control effect of SMA bundles, all the data are acquired through a 16-channel dynamic data-acquisition system, and each beam is examined several times with different activating current intensity. Experimental results indicate that the recovery force induced by SMA bundles is significant and controllable, the deflection generated by the SMA bundles at the middle span of the beam is about 0.44 mm, and the capability of resisting overload of each beam is about 2.98 kN (average). A relationship between SMA temperature and activating/inactivating time is also formulated. The conclusion is that SMA can be used in civil engineering structures either from a technological or economic aspect.