Low-Damage Posttensioned Segmental Bridge Columns with Flexible End Joints for Seismic Accelerated Bridge Construction
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A computational parametric study leading toward the development of a new type of low-damage precast concrete segmental column for accelerated bridge construction in seismic areas is outlined. In contrast to conventional monolithic concrete construction, accelerated bridge construction significantly reduces on-site construction time, total project delivery time, weather-related construction delays, and environmental impact, and it provides improved work zone safety for the traveling public and contractor personnel and high product quality and durability. Low-damage systems provide significantly reduced postearthquake downtimes, repair costs, and casualties. The proposed column design will incorporate internal unbonded posttensioning and flexible joints at the column ends, where large flexural demands occur. These joints will be (flexurally) deformable enough to accommodate large column lateral deformations (drift ratios of 10% or higher) without damage, and (axially) stiff enough to limit initial axial deformations due to initial posttensioning and gravity loads. To investigate this concept, a three-dimensional finite element model of a cantilever segmental concrete column incorporating a flexible joint segment at the bottom was generated, and a comprehensive parametric study was conducted. The parametric study investigated three types of polyurethane elastomers for the flexible joint and various geometric properties of the flexible joint in reference to the column geometry. The findings of this study, as supported by preliminary material testing, have shown that hyperelastic materials, such as stiff rubbers and polyurethanes, are good candidates for the proposed application.
