Seismic design of precast concrete rocking wall systems with varying hysteretic damping

Following the design practice for cast-in-place concrete walls in which energy dissipation is a byproduct of the walls' seismic response, force-based seismic design of precast concrete rocking walls uses a response modification coefficient, or R factor, of 5 and a minimum equivalent viscous damping ratio of about 8%. However, single rocking walls (SRWs) with total damping of 6% and precast concrete walls with end columns (PreWECs) designed with as much as 16% damping showed satisfactory responses when subjected to shake-table testing. These findings suggest that the current design approach used for precast concrete rocking walls is unnecessarily restrictive and does not account for the superior behavior of the wall systems in design. To overcome this challenge, a damping-dependent R is proposed for the seismic design of precast concrete rocking walls and its effectiveness is demonstrated using a parametric study. A cost index is also developed to determine the relative benefits of SRWs and PreWECs.