Quasi-Static Testing of a Large-Scale Pre-Cast Bridge With Controlled Rocking Post-Tensioned Connections in the Superstructure

Abstract eng:
Accelerated bridge construction techniques have gained popularity in recent years since they offer many advantages compared to traditional in-situ methods. Such advantages include rapid construction, higher quality concrete, improved work zone safety and minimal traffic disruption. Application of these methods in seismic areas is however currently limited due to a requirement for reliable connections between prefabricated elements that can provide sufficient ductility. The research presented herein aims to address this issue by introducing a hybrid rocking low-damage connection for precast bridge superstructures. A simply supported bridge traditionally uses a combination of shear keys between the superstructure and steel linkages to provide transverse support to the superstructure and to prevent unseating of the spans during earthquake loading. The proposed connection adds longitudinal post-tensioning in combination with axial dissipaters to the superstructure to achieve a deck rocking motion with self-centering and dissipative capabilities respectively given by the un-bonded posttensioned cables and dissipater. As a result adjacent superstructure segments aid each other in countering the transverse seismic load, rather than merely relying on the shear keys to do so. This method is an alternative solution to seismic isolation, leading to low transmission of forces to the superstructure and protection of the bridge. This paper presents the results of quasi-static tests performed on a 1:3 scaled concrete bridge specimen with a length, width and height of 10, 3 and 4 meters respectively. Low-damage hybrid connections were the superstructure and the specimen was subjected to loading in the transverse direction. The two hollow-core decks of this short-span, two-bay bridge were connected using post-tensioning tendons, and mild steel dissipaters linked the two superstructure spans to increase energy dissipation. The testing was carried out using different values of initial post-tensioning in the tendons with and without the dissipaters and the results were compared. The specimen showed promising results in terms of self-centering and dissipation; both which can improve the performance of the bridge during seismic loading.

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