Experimental response modification of a four-span bridge retrofit with shape memory alloys

A unique shape memory alloy (SMA) restrainer cable is developed and tested to evaluate its effectiveness in limiting the hinge opening in bridges. The SMA cables, connected at the deck–abutment interface, are tested on a four-span, one-quarter scale, concrete slab bridge. The bridge is subjected to a suite of ground motion to assess the performance of the SMAs under different magnitudes of loading. The results of the experimental tests show that the SMA cables were effective in reducing the potential for unseating by reducing the as-built openings by 47 and 32% for low-level and high-level loading, respectively. In addition, the hinge displacements were also accompanied by reductions in column drift. A detailed finite element (FEM) model of the test setup is developed and comparisons are made with the experimental tests. The results of the FEM compare favorably with the experimental tests. Using the FEM, a suite of 40 ground motion records are used to compare the expected performance of the bridge with SMA cables. The results of the analysis show that the SMA cables reduce the mean hinge openings by 57 and 69% for the low-level and high-level loading, respectively.