Seismic performance of precast double-column rocking piers with U-shaped tendons and stiffening steel shoes: Experimental and numerical study

Rocking piers exhibit promising seismic resistance and are suitable for precast bridges. However, their application to engineering practice, especially the widely used double-column piers, is hindered by the difficulty in operating prestressed tendons, protecting rocking toes, and achieving a satisfactory design. Hence, this study proposes novel fully-arranged U-shaped tendons, partially-arranged U-shaped tendons, and stiffening steel shoes for precast double-column rocking piers to improve the seismic performance and facilitate the construction and maintenance. Cyclic tests were conducted on two scaled specimens, both employing steel shoes, with one specimen equipped with a fully-arranged U-shaped tendon and the other with straight tendons and partiallyarranged U-shaped tendons. Then, numerical models were established and validated. Finally, a comparative study was performed to investigate the influences of the U-shaped tendons and steel shoes on the pier performance. The test results show that both specimens behaved as typical low-damage rocking piers and ultimately failed due to extensive fractures of the steel shoes. The comparative study illustrates that the steel shoes can significantly protect the rocking toes, and that the fully-arranged U-shaped tendons can replace the ordinary straight tendons, while the partially-arranged ones can effectively enhance the longitudinal pier capacity without excessively impairing the transverse performance.