Experimental and numerical response of unbonded post-tensioned rocking wall under lateral cyclic loading

This study examined the experimental behavior of three unbonded post-tensioned (PT) single rocking wall (SRW) specimens with varied initial prestressing levels and cross-sectional areas of PT strands subjected to a series of quasi-static cyclic lateral loadings. To investigate the cyclic performance of the specimens, the damage patterns, force-displacement relationship, stiffness degradation, stress of PT strands, and neutral axis depths were compared and evaluated. In addition, the prestress losses of the PT strands experienced in the test were also measured and estimated using a theoretical equation. The test results show that the SRW specimens exhibited low damage, good self-centering, and large deformation capacity with a minor residual drift. Moreover, the low energy dissipation capacity indicates that the SRWs without damping elements cannot be recommended in high seismic zones. In addition, the experimental and predicted results demonstrate that the prestress losses of PT strands in SRWs resulted from wedge seating before they achieved the proportional limit. Finally, a multi-spring model based on the idea of a nonlinear macro element was adopted to simulate the rocking walls in OpenSees software, and the calculated results were consistent with the experimental results.