Seismic Evaluation of Self-Centering Bi-Rocking Walls via Micro Modeling of Rocking Joints: Locating the Rocking Section

Abstract

The rocking concrete shear wall is one of the new self-centering seismic systems applied in high-rise buildings. To reduce the effects of higher modes on base-rocking walls, the idea of using multiple rocking walls has been evolved. This paper presents a comparative investigation on the seismic performance of base-rocking and bi-rocking wall systems. To this aim, structures of 4-, 8-, 12-, 16-, and 20- stories have been evaluated subjected to three sets of seismic earthquake records including 22 Far Field (FF), 14 Near Field (NF) with pulse, and 14 Near Field (NF) no-pulse ground motions. The nonlinear time-history analyses were conducted in two directions using OpenSEES software. To determine the appropriate location of rocking section in bi-rocking walls, one-quarter (R2-M1), one-half (R2-M2), and three-quarter (R2-M3) models were examined. The obtained results revealed that R2-M3 model is not efficient in reducing the effects of higher modes. However, R2-M2 model in high-rise buildings under FF and NF-no-pulse records could be effective in decreasing the moment by a maximum of nearly 41% and the shears by a maximum of 25% and 18%, respectively. Furthermore, the results showed that bi-rocking walls could not be effective in reducing the influence of higher modes under NF-pulse ground motions. Generally, the residual drifts were negligible in all the rocking systems under study.