Experiments on prefabricated segmental bridge piers with continuous longitudinal reinforcing bars Changsu Shim a,⇑ , Sangyong Lee b , Seongjun Park b , Chandara Koem b a School of Civil and Environmental Engineering, Urban Design and Studies, Chung-Ang University, Seoul, Republic of Korea b Chung-Ang University, Seoul, Republic of Korea article info Article history: Received 4 August 2016 Revised 29 November 2016 Accepted 30 November 2016 Keywords: Cyclic test Post-tensioned precast bridge pier Seismic performance Ductility Energy absorption capacity abstract Prestressed precast concrete bridge piers have recently been considered as an excellent design alterna- tives because of their recentering capability under seismic actions. Axial prestressing is designed to con- trol cracking at precast joints by service loads. In this paper, a combination of continuous mild reinforcing bars and prestressing tendons is suggested for enhancing the seismic performance as well as economy of post-tensioned precast bridge piers. Cyclic tests were conducted to measure and observe the behavior of the proposed bridge pier system. By preventing buckling and fracture of the reinforcing bars in the plastic hinge region, the test specimens showed improved structural behavior up to a drift level of 8% without reduction in their flexural strength. Energy absorption capacity was also investigated. An appropriate magnitude of initial prestressing force was found to be an essential design consideration for preventing fracture of tendons by lateral displacement of columns. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction In seismic regions, a prestressed precast segmental bridge pier has many design challenges in terms of structural performance, durability and cost. For the structural performance of the pier, con- nections between segments are main concerns to ensure service- ability, safety and seismic performance. Even though quality control of precast segments is better than cast-in-place concrete members, the joints between segments must be properly protected against corrosion. Assembly of the segments requires accurate geometry control, and 3D engineering emerged in precast concrete industry for digital manufacturing and geometry control [1–4]. Axial prestressing is introduced to control joint opening and cracking at service loadings. For short columns, full prestressing can be used for design philosophy while partial prestressing is more appropriate for high-rise bridge piers. Billington and Yoon [5] have done cyclic tests on unbonded post-tensioned precast col- umns with ductile fiber-reinforced concrete. This combination consisting of post-tensioning with the ductile fiber-reinforced cement-based composite in precast segments at potential hinging regions, resulted in increased energy dissipation and improved integrity under cyclic loadings. Ou et al. [6] investigated seismic performance of precast unbonded posttensioned bridge columns with bonded longitudinal mild steel reinforcements continuous across the segment joints. Optimum ratio of energy dissipation bars to enhance hysteretic behavior was proposed as 0.5%. Kwan and Billington [7] proposed a segmental precast bridge pier system using both bonded reinforcement and unbonded post-tensioning. Bonded mild reinforcement crossing the precast joints provides hysteretic energy dissipation as well as controlling crack widths. However, there are issues of durability, serviceability and effi- ciency of prestressing steels for given design conditions. Sideris et al. [8] performed shake table tests on hybrid sliding-rocking bridge with internal unbonded posttensioning. The tests showed that joint sliding at the columns provided energy dissipation, while joint rocking provided self-centering to the structure. The axial steel design using prestressing bars and steel tubes can provide enough strength and ductility even though the axial reinforcing bars are not continuous across the joints that was investigated by Shim et al [9]. Experimental study on prefabricated composite columns was also conducted by Shim et al [10]. Precast composite columns with prestressing showed a significant increase in the maximum strength of columns as the applied pre- stress increased. While the ultimate strength of composite col- umns with prestressing can be increased by higher prestress, the displacement ductility of the prestressed composite column decreased as the prestress increased. Level of prestressing to enhance seismic performance needs more investigation. Bonded http://dx.doi.org/10.1016/j.engstruct.2016.11.070 0141-0296/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail addresses: csshim@cau.ac.kr (C. Shim), lsy12344@cau.ac.kr (S. Lee), sakano@nate.com (S. Park), koemchandara@cau.ac.kr (C. Koem). Engineering Structures 132 (2017) 671–683 Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct