Cyclic Testing of an Unbonded Pre-tensioned Bridge Column with Rocking Detail: Capbeam Specimen

The seismic performance of the precast system was evaluated with a quasi-static test of one column-to-cap-beam sub-assembly. This column contained a steel dowel bar that extended down from the body of the column into the footing.

The column-to-cap-beam subassembly had a cantilever height of 60 in. and a column diameter of 20 in (42% scale). The specimen was subjected to a constant axial Load of 159 kips and a quasi-static displacement history based on the NEHRP recommendations for precast structural walls.

The lateral displacement history consisted of ten four-cycle sets. Each set had target peak values of 1.2X, 1.44X, 1.44X, and 0.48X, where X is the maximum target drift from the previous set. The maximum target drift of the first set was selected so that the column would remain elastic throughout the duration of the first four cycles (X = 0.167 in.).