A precast segmental concrete bridge pier system is proposed for use in seismic regions. The proposed system uses a state-of-the-art, fiber reinforced concrete that is micro-mechanically designed to be highly ductile in tension, reaching tensile strains of 3% or more. This class of materials, termed engineered cementitious composites (ECC) by some authors, uses roughly 2% polymeric fibers by volume and exhibits many small, evenly distributed cracks that close upon unloading. The concept of the bridge pier system is to use ECC in small, precast segments at potential hinge regions where the unique properties of the material are most needed. The unbonded post-tensioning allows for minimal residual displacements after a seismic event by preventing localized yielding of the reinforcement while the ECC material provides energy dissipation without additional continuous mild reinforcement and can tolerate large cyclic displacements. Small-scale column testing for the proposed system is being conducted to study the behavior of ECC when integrated into structural components. Selected results from short column tests show that with ECC, higher energy dissipation can be achieved at low drift levels, and the post-tensioning can be designed to avoid yielding at high drift levels. The results also show that the ECC maintains its integrity better than reinforced concrete under high compression and that the location of the segmental joint interface below the fixity is an important issue regarding micro-cracking before crack localization.
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