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    Precast concrete bridge construction has been proved to be an efficient solution in accelerating bridge construction and minimizing traffic disruption. However, due to concerns with the seismic performance of such type of construction, its application in seismic regions is limited. This research presents results of the development of precast segmental post-tensioned concrete bridge  columns for use in seismic regions. The developed bridge columns adopted unbonded post-tensioning systems to decrease
    prestress loss due to strong seismic events.  In addition, to increase hysteretic energy dissipation, mild steel energy dissipation bars (ED bars) which are continuous across the
    segment joints are added to the columns. Moreover, the ED bars are additionally unbonded at the critical joint to avoid premature fracture.  20485
    A simplified analytical model for static pushover analysis and a three-
    dimensional detailed finite element model for cyclic analysis of the proposed bridge
    columns are developed in this research. In addition, a stiffness degrading hysteretic
    model is proposed for response-history analysis. With the analytical models, a parametric
    study is conducted to examine the seismic  performance of the proposed columns with
    different design parameters. 
    A two-phase experimental program is designed to verify the findings of the
    analytical study and to address constructability issues of the proposed segmental columns.
    The first phase focuses on testing of the ED bars at the critical  joint. A methodology is
    proposed to design the additional unbonded length for the bars, taking into account low
    cycle fatigue of steel and progressive damage of bond. The second  phase is testing of
    seven large scale segmental column specimens. Each specimen has a foundation, four
    precast column segments with hollow cross sections and a precast cap beam with a total
    height of 5.7 m (18.7 ft). Four specimens were tested with cyclic loading while three
    were tested with pseudo-dynamic loading. The test results show that three types of ductile
    precast segmental columns are successfully developed with different hysteretic
    characteristics in terms of energy dissipation, lateral strength and residual displacement.   
    ACKNOWLEDGEMENTS
     
    First of all, I would like to thank to my advisor, Professor George C. Lee for his
    guidance to this research and financial support over the past four years. I learned a great
    deal from him not only from his knowledge and experiences in civil engineering but also
    from the wisdom that he gained from his more than four decades of academic career. I
    also would like to thank to Professor Amjad Aref, Professor Stuart S. Chen and Professor
    Andre Filiatrault, my Ph.D. committee members, for their advice to this research. The
    advice from Dr. Methee Chiewanichakorn on developing the analytical models for this
    research is greatly acknowledged. In addition, I would like to thank to Dr. Il-Sang Ahn
    for his advice to this research. 
    I would like to thank to Kuo-Chun Chang, Professor and Chairman of the
    Department of Civil Engineering of the National Taiwan University, for his advice
    throughout this research. His support is the key to  the success of the experimental study
    conducted in this research. I also would like to thank to Dr. Jui-Chen Wang for providing
    valuable information and guidance on developing the new concepts for precast segmental
    bridge columns for seismic regions. Mr. Ping-Hsiung Wang worked relentlessly throughout
    the experimental study. Without his effort, the experiment could not have been completed in
    only one year. Mr. Mu-Sen Tsai also played a significantly role in assisting the experimental
    study. Thank for their effort.     
    I must thank to the Federal Highway Administration for financially supporting
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