Shake table tests of prestressed precast segmental bridge columns under bidirectional earthquake motions

Abstract

Precast segmental bridge columns are commonly used but merely in low-seismicity areas, since their seismic performance is not clear under actual earthquake motions. To evaluate the feasibility of precast segmental columns in high-seismicity areas, it is necessary to investigate the dynamic behavior of such columns under bidirectional seismic excitation owing to multi-dimension characteristics of earthquake ground motions. Two 1/10-scaled columns with continuous low-carbonated rebars between segments were designed and reinforced with ultra-high-performance concrete (UHPC) based on a proposed design method. Then, shake table tests of reinforced columns were conducted to investigate the influence of types of seismic motions (near-filed and far-field) and loading direction (unidirectional and bidirectional) on dynamic responses of precast columns. The experimental results showed that minor concrete damage occurred in the bottom segment, and 0.2 % residual displacement was found, which indicated the column had an excellent re-centering capacity. Compared with the column under unidirectional seismic excitation, the column subjected to bidirectional seismic excitations had more serious concrete damage, more obvious fundamental frequency reduction, and larger displacement responses at the column top, residual displacement, and peak stress of tendons. The displacement of the column top under bidirectional loads was twice that under unidirectional loads. In addition, the response of the column under near-field earthquake motions was more significant than that of the column under far-field seismic excitations.