Energy Dissipation Components of Precast Concrete Single Rocking Walls

Abstract eng:
Though not widely used in practice due to their limited energy dissipation capacity, recent research has shown that single post-tensioned precast concrete rocking walls can be used to satisfactorily resist earthquake loads. These walls, dissipate energy imparted to them during rocking due to the wall impacting the foundation, limited hysteretic action resulting from concrete nonlinearity, and inherent viscous damping. Relying only on the limited energy dissipation, a shake table study was conducted on four Single Rocking Walls (SRWs) using multiple-level earthquake input motions. Using the experimental data, participation of different damping components of SRWs in their seismic energy dissipation was evaluated. On average, an equivalent viscous damping ratio of 6% was estimated for SRWs, with dynamic impacts contributing to about one third of the total damping. For analytical predictions, it is shown that the impact energy loss can be satisfactorily captured using a 3% tangent stiffness damping. Despite the low amount of energy dissipation, all four SRWs generally produced satisfactory responses. While the peak displacement was somewhat higher due to the low amount of energy dissipation, the duration of rocking of these walls was found to be reduced by negative rate of input energy, which ultimately reduced the seismic energy imparted to the walls.

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