Seismic performance of bridge with unbonded posttensioned self-centering segmented concrete-filled steel-tube columns: An underwater shaking table test

摘要

As one of the prefabricated structures, precast segmented bridges can be used to shorten construction time, reduce traffic delays, improve quality control, and minimize environmental impact. Despite the numerous advantages of segmented pre-fabricated rapid assembly technology, it is not widely used in high seismic hazard zones nor applied to complex water-abundant situations because of the lack of knowledge on its seismic performance. Through experimental and numerical studies, researchers have studied the seismic performance of such type of column under quasi-static testing. The behaviors of the column or bridge under desired strong ground motions (GMs) have been rarely investigated. This paper presents the major findings of an underwater shaking table testing program conducted on a 1/4 scaled single-span bridge with novel self-centering segmented concrete-filled steel tube columns. This study focuses on the performance of the bridge subjected to different GMs under 4 water conditions, which are with water at a height of 1.2 m, 1.5 m, 1.8 m, and without water. The bridge model incorporated two post-tensioned precast self-centering segmented concrete-filled steel tube (PSCFST) single columns with fixed and sliding supports connected to a single span steel box-girder superstructure. The internal unbonded PT tendons are installed at the center of the segment section, and external energy dissipation (ED) bars are installed on the outside of the bottom segment. The bridge model was then subjected to a sequence of natural and artificial GMs with different amplitudes. The well-designed PSCFST bridge demonstrated a desirable seismic performance, and no significant damage was observed. Concerning the overall response of the structure, the maximum drift ratio reached 2.14%. Moreover, a maximum residual drift of 0.09% was observed after the tests, which indicates that the test model demonstrated a desirable self-centering capability after a sequence of GMs. The cumulative energy dissipation and equivalent viscous damping ratio of the bridge were calculated. A comparison is made for the seismic performance of the bridge especially in terms of the displacement and acceleration of the whole structure under the cases of with and without water.