EXPERIMENTAL AND ANALYTICAL STUDY ON HOLLOW PRECAST PIERS WITH UNBONDED CONVENTIONAL REINFORCEMENT TO CONTROL SEISMIC AND IN-SERVICE RESPONSE OF ROCKING BRIDGES

Abstract eng:
Common construction practice of cast in-place piers in reinforced concrete bridges presents limitations due to high construction and post-earthquake rehabilitation cost. The latter can become extensive due to the potential development of plastic hinges at the top and bottom of the piers. Another issue that arises due to the large pier stiffness in cast in-place piers is the accommodation of in-service deformations without the development of any plastic deformations that require rehabilitation works, as well. Therefore, alternative solutions that avoid permanent deformations on piers, reduce seismic demand and develop elastic seismic and in-service bridge response have been investigated in the last years. The present paper to address this issue studies, experimentally and analytically, the use of precast piers either fullheight or segmental and proposes a hybrid precast pier system. In the novel approach the connection of the prefabricated segments with the foundation at the pier’s base and the deck at the pier’s top is achieved with unbonded conventional steel reinforcement. The piers are not expected to develop cracking except from the top and base interfaces due to rocking response. In this way, precast piers can accommodate bending deformations from seismic and in-service demand. A benchmark three span R/C Bridge was used for the investigation. Three 1/3 scale pier specimens with precast hollow sections were experimentally tested and compared regarding their flexural response and stiffness. The experimental results were then used in an analytical application on a finite element model of the Benchmark Bridge and time history analysis was conducted to evaluate the bridge seismic response. It is evident from the analytical and experimental outcomes that the different methods that were studied control the flexural stiffness of piers, develop improved seismic response and have positive effects on the economy and constructability of R/C bridges.

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